Perspectives and New Technologies

#### **Chapter 4**

## Perspective Chapter: From Data to Design – Leveraging Façade Sensors for Intelligent Architecture

*Mubarak Reme Ibrahim*

#### **Abstract**

This chapter explores the fascinating domain of leveraging façade sensors for intelligent architecture, focusing on the seamless transition from data to design. This study will delve into the integration of advanced sensor technologies within building façades to collect valuable data that inform the architectural design process. This chapter investigates how these sensors provide real-time information on various aspects, such as environmental conditions, occupancy and energy usage, enabling architects to design responsive, sustainable and occupant-centric buildings. Architects can improve building performance, optimise user experience and shape the future of intelligent architecture by harnessing the capabilities of façade sensors.

**Keywords:** sensors, façades, integration, monitoring, performance, real-time data, intelligent architecture, occupancy sensor

#### **1. Introduction**

The built environment has been significantly affected by the incorporation of technology into architecture. Developments in sensor technologies have paved the way for intelligent architecture. The design, construction and operation of buildings can be completely transformed by the use of sensors [1]. By integrating these sensors, architects can gain real-time insights into a building's surroundings, empowering them to design façades that respond intelligently to climate, natural ventilation, solar heat gain and daylighting. As a result, buildings have become more sustainable and energy efficient, decreasing their reliance on artificial lighting, heating and ventilation systems [2]. To design spaces that satisfy the needs of their occupants, architects can use façade sensors to monitor occupancy patterns. These data assist architects in designing spaces that meet their requirements, such as optimising low-occupancy spaces to save energy while still providing sufficient social and seating areas for high occupancy. By identifying unauthorised access or unusual movement patterns, occupancy sensor data can also help improve building security [3].

Façade sensors also play a significant role in monitoring and improving energy utilisation in buildings by coordinating energy use sensors into the façade, and architects can monitor and analyse the use of power, water and different utilities, empowering them to make informed design decisions that focus on energy efficiency [4]. These data can be used as a guide for design interventions such as better insulation, appliances that use less energy and renewable energy systems. It can also be used to show building users' real-time energy consumption data to encourage environmentally friendly behaviour. The capability of façade sensors is not only to collect data but also to translate these data into practical recommendations. Architects can now use real-time data to make informed design decisions thanks to advancements in data analytics and visualisation methods. This iterative design process permits architects to enhance their designs for numerous parameters simultaneously, guaranteeing a balance between aesthetic, function and performance considerations.

The integration of façade sensors into intelligent architecture has far-reaching implications beyond the planning stage of a project. By enhancing the user experience and contributing to a more sustainable and occupant-centric built environment, buildings that use façade sensors can shape the future of intelligent architecture. Façade sensors help reduce a building's impact on the environment while also improving user health and safety, productivity and satisfaction. For example, buildings can create spaces that adjust to individual inclinations, advancing occupant comfort and satisfaction by tailoring the indoor climate based on real-time data. The seamless change from data to design is reforming the field of architecture by providing architects with a deeper understanding of different aspects of design, such as site conditions, environmental factors, building performance and user behaviour. Because of this change in practise, architects are now able to make design decisions based on evidence, which enables them to come up with solutions that are more responsive and appropriate to the context. The capacity to enhance building performance is one of the primary advantages of the seamless transition from data to design. The seamless integration of data into the design process also enables architects to evaluate design alternatives more effectively. Before construction begins, data-driven simulations and modelling can help architects evaluate the performance of various design options, thereby minimising errors and avoiding costly modifications during construction. In addition, the effortless transition from data to design encourages interdisciplinarity and collaboration. For holistic and integrated design solutions, architects can work with builders, environmental consultants and other relevant professionals to collect and analyse relevant data [5].

However, there are obstacles in achieving a seamless transition from data to design. One of the major questions is the shear volume and intricacy of the information accessible. Architects must be equipped with the necessary skills and tools to collect, analyse and interpret data effectively. Realising the potential of data-driven design requires embracing parametric modelling, data visualisation, and computational design methods. The incorporation of data into the design process itself is yet another disadvantage. To achieve a balance between artistic vision and empirical evidence, architects must adopt a mindset that views data as an essential resource [6]. This chapter explores the seamless application of façade sensors in intelligent architecture. This study focuses on the collection and analysis of valuable data as it explores the incorporation of cutting-edge sensor technologies into building façades. This chapter features the pragmatic uses of façade sensors, such as monitoring climate data, predicting user behaviour and optimising energy consumption. Additionally, it emphasises the advantages of user-centred design, flexible spaces, responsive design and the incorporation of façade sensors into intelligent architecture. This chapter accentuates the enhancement of building performance through sensor-driven tasks, propelling sustainability by designing green buildings and the inventive capability of occupant-centric buildings, as well as enhancing health and safety.

*Perspective Chapter: From Data to Design – Leveraging Façade Sensors for Intelligent Architecture DOI: http://dx.doi.org/10.5772/intechopen.113747*

#### **2. Overview of façade sensors**

In architecture, façade sensors play a key role in the development of smart and sustainable buildings. These sensors are integrated into the exterior surfaces of a building's façade to monitor and respond to various environmental factors, occupancy and energy usage. They offer rich data and insights that architects, builders and building operators can use to optimise the building's performance, comfort and energy efficiency.

#### **2.1 Definition and type of façade sensors**

#### *2.1.1 Definition façade sensors*

Façade sensors, also referred to as building envelope sensors or climate sensors, are instruments strategically positioned on the exterior surface of a building's façade to measure and monitor several environmental parameters [7]. These parameters include temperature, humidity, wind speed, solar radiation, air quality and noise levels.

Façade sensors are specialised devices placed on the outer surface of buildings to retrieve data on environmental conditions such as temperature, humidity, light levels and wind speed, which are crucial for improving energy consumption and comfort [8].

Façade sensors entail various sensing technologies installed in the building envelope. These sensors enable real-time monitoring and assessment of external factors, enabling responsive and energy-efficient building operations [9].

Façade sensors are tools incorporated on the external faces of buildings to detect environmental parameters. They offer data that supports smart building management systems, allowing for dynamic modifications in lighting, heating and ventilation to conserve energy and improve comfort [10].

Façade sensors include multiple sensors and data gathering instruments integrated into a building's façade. These devices continuously monitor parameters such as solar radiation, air quality and temperature. The retrieved data are used to improve energy utilisation and form sustainable and responsive building environments [11].

#### *2.1.2 Types of façade sensors*

#### *2.1.2.1 Temperature sensors*

Temperature sensors are important for contemporary architecture because they provide valuable data that helps architects and building operators create efficient, comfortable and sustainable environments. These sensors are integral components of smart buildings, enabling real-time monitoring and control of indoor and outdoor temperatures. Their application in architecture spans several phases, from initial design to post-occupancy evaluation. In the early stages of architectural design, temperature sensors facilitate building energy simulations and modelling. They assist architects in assessing how sunlight and outdoor temperature variations affect the building's thermal comfort. This insight enables the design of passive heating and cooling systems, such as building orientation, shading and natural ventilation, to reduce the dependence on energy-consuming heating, ventilation and air conditioning (HVAC) systems. After a building is completed, temperature sensors are installed indoors to sustain thermal comfort for the occupants. These sensors monitor indoor temperatures, ensuring that they remain within a designed range for different

locations of the building. Architects can create responsive and zoned climate control, allowing personalised comfort for occupants while optimising energy consumption by linking temperature data to HVAC systems [12].

Temperature sensors provide real-time data that can be incorporated into building management systems. This data allow for the dynamic regulation of heating, cooling and ventilation systems based on existing situations. For example, if a class room experiences a sudden increase in occupancy, temperature sensors can signal the HVAC system to adapt and sustain an optimised environment. When combined with occupancy sensors, temperature sensors facilitate smart climate control systems that adjust to the number of people in an area. Unused spaces can be conditioned to a reduced level, reducing energy use while ensuring comfort when occupants are around. Architects are gradually integrating temperature sensors into adaptive façades and building envelopes. These sensors deliver data to manage dynamic shading devices, louvres and phase-changing materials that respond to outdoor weather conditions. This approach improves energy efficiency and reduces the building's environmental impact. When the building is in use, temperature sensors continue to contribute to its performance evaluation. Architects can identify areas for improvement and fine-tune the building's systems to achieve superior performance and comfort by evaluating temperature data with a combination of energy consumption data. In larger construction projects, temperature sensors play a role in smart grid integration. Buildings equipped with temperature sensors can participate in demand response programmes, regulating their energy utilisation during peak periods, thus enabling grid stability [13].

#### *2.1.2.2 Humidity sensors*

Humidity sensors gauge the amount of moisture in the air, providing data that assists architects and facility managers in optimising HVAC systems, preventing moisture-related issues and improving the general health and safety of occupants. Humidity sensors are crucial for sustaining optimal indoor air quality and comfort. Architects can guarantee that indoor areas remain within the planned relative humidity level (typically 30–60%) [12]. Appropriate humidity regulation hinders the growth of mould and mildew, minimises the risk of respiratory issues, and promotes a better indoor environment by continuously controlling humidity levels. In areas with fluctuating weather, humidity sensors help avoid condensation problems on windows and walls. By providing real-time humidity data, these sensors enable architects to design proper insulation ventilation systems. Humidity sensors are influential in improving HVAC systems, mainly in humid environments. When incorporated with building automation systems, these sensors allow smart control of humidification and dehumidification processes and reduce energy waste [14].

Humidity levels can, to a large extent influence, the durability of building materials such as timber, steel and paint. Architects can prolong the service life of these materials, thereby reducing maintenance budgets and preserving the building's aesthetics by maintaining suitable humidity levels. Humidity sensors are essential in critical spaces of the building, such as bathrooms, kitchens and basements, where moisture levels tend to vary. Early identification of high humidity in these areas can enable proper ventilation and humidity control measures, mitigating potential dampness and growth of biological deterioration agents. In construction projects involving indoor agriculture or greenhouses, humidity sensors play a critical role in improving the growth environment for plants [12]. These sensors help maintain the appropriate

#### *Perspective Chapter: From Data to Design – Leveraging Façade Sensors for Intelligent Architecture DOI: http://dx.doi.org/10.5772/intechopen.113747*

level of humidity to support plant growth and prevent pest diseases. Humidity sensors allow for data-driven design and post-occupancy evaluations. Building designers can identify areas for improvement, optimise system performance and ensure that the building meets its performance objectives by analysing humidity data with other environmental parameters.

#### *2.1.2.3 Light sensors in the architecture*

Light sensors, also referred to as photodetectors, are instrumental devices in modern architecture, that enable accurate monitoring of artificial lighting systems and optimise energy efficiency. These sensors create green and human-centric built environments, by providing real-time data on natural and artificial light conditions. Light sensors are an integral element of energy-efficient lighting systems in architecture [15]. By measuring the intensity of natural light in a space, light sensors enable the automatic regulation of artificial lighting [16]. When daylight levels are satisfactory, artificial lighting dims or turns off, thereby minimising electricity usage immensely. This dynamic lighting control system not only lowers energy consumption but also reduces greenhouse gas emissions. Integrating light sensors into building design allows effective daylight harvesting, an approach that uses natural light as the main source of lighting. Light sensors can detect the varying daylight levels and match with lighting regulators to sustain a continuous lighting condition. Buildings can attain higher energy efficiency and Leadership in Energy and Environmental Design (LEED) certification by reducing the use of natural light [17]. Light sensors contribute to improving occupant health and safety by considering the human circadian rhythm. These sensors can control artificial lighting intensity and colour temperature during the day to align with sunlight's varying qualities. Buildings can positively impact occupants' sleep behaviours, productivity, and well-being by promoting a circadian lighting environment [18].

Light sensors are often integrated with occupancy sensors to produce occupantresponsive lighting systems. When occupants are identified in a specific location, the light sensors evaluate the available sunlight and alter the artificial lighting levels. Thus, energy is preserved by providing lighting only when needed, thereby minimising running costs [19]. Combining light sensors with adaptive façades and building envelopes enhances the sustainability of architecture. These sensors detect incoming artificial lighting and alter shading devices, glass tinting or dynamic elements on the façade to improve sunlight diffusion and thermal comfort [20]. The adaptive nature of the façades reduces the building's energy demands, forming a more environmentally friendly design. Light sensors allow architects to assess the effectiveness of lighting design approaches. Architects can fine-tune their design and improve the building's performance by collecting data on light levels, usage behaviours and occupant feedback [21, 22].

#### *2.1.2.4 Air quality sensors*

Air quality sensors are indispensable devices in smart architecture, allowing precise monitoring and control of indoor air contaminants. These sensors are crucial for creating healthy and comfortable indoor environments while contributing to energy efficiency and sustainability. Air quality sensors allow architects to consistently control indoor air pollutants, such as volatile organic compounds (VOCs), particulate matter, carbon dioxide (CO2) and formaldehyde [23]. These sensors allow timely

responses to variations in contaminant levels, ensuring that occupants breathe clean and safe air by offering real-time data on air quality. Air quality sensors are combined with ventilation systems to facilitate demand-based ventilation. When pollutant levels are above satisfactory thresholds, the sensors activate increased ventilation flow rates to eliminate toxins and improve indoor air quality [24]. This adaptive ventilation strategy not only improves occupant comfort but also reduces electricity consumption by avoiding unnecessary ventilation. Maintaining good indoor air quality is critical for the welfare and productivity of building occupants. Air quality sensors facilitate the identification of harmful contaminants that can cause respiratory diseases. Architects can contribute to a healthier and more productive indoor environment by proactively managing indoor air quality.

#### *2.1.2.5 Solar radiation sensors*

Solar radiation sensors, also referred to as solar pyranometers, are vital tools in modern architecture for evaluating solar energy availability and improving sustainable building design. These sensors allow architects to harness sunlight to enhance the energy efficiency of buildings. Solar radiation sensors play a crucial role in Site analysis during the early stages of architectural design [25]. By measuring solar irradiance, architects can evaluate solar access and detect areas with improved sunlight. These data help in determining the orientation of the building to reduce natural light consumption and eliminate the need for artificial lighting during the day. Architects can design passive solar systems that use solar energy for heating and lighting. By strategically placing windows, roof lights and shading instruments based on solar radiation data, buildings can achieve improved thermal comfort and energy efficiency [26]. Passive solar design reduces dependence on artificial heating and cooling systems, leading to energy savings and reducing carbon footprint.

For buildings that integrate photovoltaic cells (PV) systems, solar radiation sensors are essential for system improvement. By controlling solar irradiance levels, architects can determine the most suitable positions and angles for PV panels to increase energy generation. This improvement ensures that PV systems produce the highest electricity output from existing sunlight. Solar radiation sensors are incorporated into building energy simulation tools to model solar gains and evaluate building performance. Using solar radiation data, architects can simulate a building's energy performance, forecast cooling and heating demands, and assess passive solar design approaches [27]. This assessment helps in making informed design decisions to design energy-saving buildings. Solar radiation sensors contribute to dynamic façade design. These sensors can identify incoming solar radiation and activate responsive shading systems. The dynamic façade adapts to varying solar conditions, maintaining a comfortable indoor environment and lowering cooling needs.

#### *2.1.2.6 Occupancy sensors*

Occupancy sensors, also referred to as motion detectors, identify the movement of occupants in an area to allow accurate monitoring of lighting, heating, ventilation and air conditioning (HVAC) systems. Occupancy sensors are valuable in sustainable lighting control in architecture because they identifying the occupants in a space and activate automatic on/off of lighting systems [28]. Consequently, electricity usage is reduced by eliminating the need for illumination in vacant spaces. Combining occupancy sensors with HVAC systems allows for adaptive climate control in buildings.

#### *Perspective Chapter: From Data to Design – Leveraging Façade Sensors for Intelligent Architecture DOI: http://dx.doi.org/10.5772/intechopen.113747*

When people are identified in an area, the sensors can alter the heating or cooling levels to maintain thermal comfort. In vacant spaces, the ventilation system can work at lower levels to save energy. Occupancy sensors enable personalised user experience in building spaces [29]. The sensors can adapt lighting, ventilation and other environmental parameters to satisfy user needs, which improves occupant indoor comfort.

These sensors are usually integrated with light sensors in a daylight harvesting system to regulate artificial lighting settings based on the available sunlight which will enable energy saving by lowering artificial lighting when sunlight is adequate. They also help in enhancing building security and safety. In vacant spaces, sensors can initiate lighting or security systems. When integrated with a building automation system, data from occupancy sensors aid smart and energy-saving building operation, which contributes to a green built environment. Architects use occupancy sensor data to inform data-based design, improve space allocation, identify opportunities for energy saving and comfort optimisation by analysing occupant behaviours.

#### *2.1.2.7 Structural health monitoring sensors*

Structural health monitoring (SHM) sensors allow consistent monitoring and surveillance of buildings. These ensure the safety, reliability and maintenance of the building. They facilitate real-time and consistent monitoring of the structural integrity of buildings. They are strategically installed in structural elements, such as slabs, beams, columns and foundations, to determine shear stress, deflection, vibration and uneven settlement. SHM sensors help in the timely identification of structural decay. Any changes in the behaviour of a building, such as differential settlement or sudden shock, can indicate potential issues; they provide a warning signal of potential structural problems for preventive maintenance [30]. With SHM sensors, architects can develop performance-driven design and appraisal methodologies. Instead of relying on design codes, architects can use real-time data from sensors to validate design assumptions and improve structural stability. This method results in cost-effective designs.

The application of micro-electro-mechanical systems (MEMS) sensors in the diagnosis of seismic capacity for historic structural glass systems indicates a new advancement in structural engineering. These sensors offer real-time monitoring capabilities, enabling continuous data capture of structural vibrations and responses. This information supports structural engineers in understanding the dynamic behaviour of these glass structures, mainly under seismic loads [31]. MEMS sensors, characterised by their high precision and sensitivity, can detect subtle structural movements and potential problems. In addition, MEMS sensors are important for evaluating the mechanical performance of glass façades subjected to seismic loads. These sensors monitor vibrations, strain and deformation in real time, providing invaluable data for structural engineers to analyse structural integrity during earthquakes. By allowing detailed data capture and assessment, MEMS sensors support informed decision-making for maintenance, improving the safety and resilience of glass façades in seismic-prone regions [32].

#### **2.2 Integration of advanced sensor technologies into building façades**

In the quest for smart architecture, the incorporation of smart sensor technologies into building façades has emerged as a promising strategy. These smart sensor technologies, ranging from occupancy sensors to light detectors, are critical to improving user experience, improving building performance and reducing carbon footprints. Photodetectors are important when incorporated into building façades for daylight harvesting. They gauge the quantity of sunlight in buildings and regulate artificial lighting settings. Through this adaptive lighting control, electricity usage in buildings can be reduced by using available natural sunlight. Sunlight harvesting not only conserves energy but also contributes to occupant health by providing natural lighting environment. Incorporating humidity detectors in building façades enables accurate climate control. These sensors monitor indoor humidity, allowing HVAC systems to regulate heating and ventilation by optimising thermal comfort in real time, which facilitates energy savings without detriment to user satisfaction [33]. Moreover, they help prevent condensation, ensuring a healthier indoor environment. They are also instrumental in creating energy-efficient spaces within building façades. These sensors detect the presence or absence of occupants in rooms and trigger the lighting and HVAC systems accordingly. By turning off lights and reducing heating or cooling in unoccupied areas, buildings can achieve substantial energy savings.

Solar radiation sensors, also called pyranometers, are important the design of green building façades. They gauge solar irradiance and support architects in determining building orientation and shading design [34]. Buildings can reduce dependence on mechanical lighting and ventilation systems, leading to less energy utilisation and environmental impact by leveraging sunlight. Incorporating air quality detectors in building façades aids in the realisation of a healthy indoor environment. These sensors detect volatile organic compounds (VOCs) and carbon dioxide (CO2), providing sensible ventilation control [12]. Maintaining acceptable indoor air quality improves occupants' mental health and productivity, making it a critical consideration in contemporary architecture. Integrating proximity sensors in building façades allows touchless interaction in building areas. They sense hand gestures and enable touchless control of doors, elevators and windows. Touchless control encourages hygiene, reduces the spread of diseases and addresses post-COVID design considerations. The incorporation of SHM detectors in building façades, guarantees the safety and longevity of buildings by monitoring stresses and vibrations to assess structural integrity. The timely identification of structural problems through SHM detectors allows for preventive maintenance and disaster management [31].

#### **2.3 Collection and analysis of sensor data**

In the field of smart architecture, the collection and analysis of sensor data in building façades have become important for creating energy-saving, user-centric and resilient buildings. Smart sensor technologies installed in building façades enable real-time data gathering, giving architects valuable insight into numerous areas of building performance. Environmental sensor networks are embedded in building façades to offer real-time surveillance of environmental parameters [33]. They monitor temperature, humidity, air quality and solar radiation, assisting architects in understanding the building's response to environmental conditions. The data captured helps in enhancing indoor climate control systems, optimising occupant comfort and saving energy. Light sensors, installed in building façades, allow daylight harvesting through the measurement of sunlight intensities [35]. This data-driven method enables for adaptive lighting adjustment, where mechanical lighting is controlled based on available sunlight. Sunlight harvesting also improves the health of the occupants by creating a dynamic lighting environment.

#### *Perspective Chapter: From Data to Design – Leveraging Façade Sensors for Intelligent Architecture DOI: http://dx.doi.org/10.5772/intechopen.113747*

Occupancy sensors, a vital component of building façades, detect the presence or absence of occupants in various spaces [3]. The data captured by these detectors enable energy-efficient building operations by activating lighting and climate control systems based on real-time occupancy behaviours. This automated system enhances resource use and agrees with green building agenda. SHM sensors are embedded in building façades to monitor their structural integrity [32]. Data from SHM detectors enable architects to perform early maintenance to ensure the safety and resilience of the building. The valuable data retrieved from several detectors in building façades allow designers to embrace data-informed design solutions and decision-making [36]. Analysing the retrieved data enables for evidence-based design adjustments. Data-driven decisions lead to better space allocation, improved energy efficiency and improved user satisfaction. Incorporating data retrieved from building façade detectors into smart building systems improves building performance. Data integration enables dynamic building operations, where different systems work together to enhance energy utilisation, user experience and sustainability. Smart building sensors leverage big data to create an adaptive and user-centric building environment.

#### **3. Real-time information on architectural design**

#### **3.1 Environmental condition sensors**

In the search for sustainable and climate-responsive architecture, monitoring and analysing climate data play a significant role in shaping state-of-the-art façade. Façades, as the outer skin of buildings, act as the interface between the outdoor and indoor environments. Architects can design façades that adapt to dynamic weather by integrating climate data into the design processes. Monitoring climate data offers a better understanding of local weather patterns, temperature and radiation levels. This information aids architects in choosing suitable façade materials, shapes and shading to enhance building performance. Climate data-driven design approaches enable the development of passive façades that respond to environmental conditions, thereby reducing the building's reliance on artificial heating, ventilation and lighting. Analysing climate data is important for optimising thermal comfort in façade design. Understanding temperature variations and wind patterns helps architects implement passive design measures that control internal temperature [37]. Double-skin façades, thermal mass incorporation and natural ventilation can drastically impact the internal thermal environment and safeguard user health. Climate data inform sunlight harvesting agendas and solar gain control in façade design. Architects can determine optimum glazing ratios, orientation and shading to reduce sunlight while minimising undesirable solar heat gain by analysing solar radiation data. This approach optimises visual comfort and supports circadian rhythms. Integrating climate data into façade design allows climate adaptation measures. Architects can design façades that resist heavy rains, lateral forces and heat by understanding the climate conditions [38]. Climate adaptive façades contribute to the long-term durability and functionality of buildings in dynamic climates.

Monitoring and analysing climate data are key in considering the embodied energy of façade materials. Studying the environmental impacts of material selection aids architects in choosing green materials [39]. Climate-conscious material selection helps reduce the greenhouse gases in buildings. Climate data plays a critical role in forecasting and measuring building energy performance. Energy simulation

platforms, integrated with climate data, allow architects to assess the energy efficiency of different façade design strategies [40]. This analysis allows for iterative design processes, leading to energy-efficient façades that align with sustainable goals. Monitoring and analysis of climate data after construction aid data-driven façade improvement. User experience helps architects evaluate the actual performance of the façade design. Real-world data aids in detecting spaces for optimising design, ensuring that the façade performs as intended during its life cycle.

Incorporating weather patterns into façade design decisions has emerged as a transformative approach. Architects can design façades that adjust to change environmental conditions, and enhance occupant comfort by harnessing. Integrating weather patterns into façade design includes using climate data to inform design strategies. By evaluating previous weather data and climate forecasts, architects can obtain insights into temperature variation, radiation level and wind direction [41]. This data-driven methodology allows the design of façades that respond to environmental conditions, facilitating passive design that reduces dependence on artificial heating, ventilation and lighting. Integration of weather patterns into façade design improves thermal comfort for building occupants. Understanding temperature variations and wind patterns allows architects to optimise the façade's thermal performance [37]. Features such as advanced insulation, glazing with appropriate solar heat gain coefficients, and passive solar design principles contribute to a comfortable indoor environment, thereby reducing energy consumption and improving occupant well-being.

Climate data empower architects to harness sunlight and control solar gain. By analysing solar radiation data, architects can improve façade fenestration, shading systems and light redirection elements. Amplifying sunlight while minimising heat gain reduces the building's energy load and creates visually comfortable and healthy spaces. Weather-based façade design contributes to climate adaptation. Integrating weather patterns into façade design aligns with sustainability goals. Climate-driven design includes selecting materials with less environmental impact that lower energy consumption [38]. Such considerations foster environmentally friendly architecture and reduce the building carbon footprint. Monitoring and analysing climate data enable energy improvement in façade design. Building performance simulations, combined with climate data, allow architects to assess the energy efficiency of different façade [4]. Monitoring weather patterns after construction aids in data-driven façade improvement. Real-world performance feedback informs architects of the façade's actual response to the climate. This data-driven approach allows for finetuning, ensuring that the façade remains climate-responsive throughout its lifespan.

#### **3.2 Occupancy sensors**

Architects are increasingly integrating technology to track user behaviour in buildings. This method seeks to enhance creating user-centric buildings. Designers can understand how occupants use the building façade, enabling for bespoke design that responds to change preferences by leveraging data analytics. Monitoring user behaviour enables architects to understand how occupants interact with the façade. Designers can identify patterns of user movement by analysing data from motion sensors and occupancy detectors [42]. This data-driven strategy allows architects to design façades that cater to specific user preferences. Architects can anticipate user preferences and adjust the façade's features. For instance, the façade could automatically adjust shading, ventilation or lighting based on user comfort needs, resulting in a user-friendly building. Tracking occupant behaviour contributes to optimising

#### *Perspective Chapter: From Data to Design – Leveraging Façade Sensors for Intelligent Architecture DOI: http://dx.doi.org/10.5772/intechopen.113747*

thermal comfort. Architects can enhance façade design to provide adequate sunlight and regulate the indoor environment by tracking occupant movements. Real-time data feedback informs design decisions, leading to efficient sunlight use and reducing the need for artificial lighting.

Predicting occupant behaviour promotes architectural innovation. Continuous data gathering and analysis enable architects to assess the efficiency of design [43]. This approach leads to innovative façade designs that evolve with occupant preferences. Design decisions are driven by the goal of designing buildings that ensure the health and safety of occupants. This approach promotes a stronger link between the building and its users, resulting in more functional spaces. Data-driven insights into occupant behaviour support building maintenance. Facility managers can enhance space allocation and manage resources by understanding user preferences.

Designing façades based on user behaviour includes the incorporation of sensors in buildings. Motion detectors and thermal cameras are used to gather data on occupant's behaviour [28]. These sensors offer real-time and past data, which architects can leverage to enhance façade design for occupant comfort. Architects can design façades that respond in real-time to the changing preferences of building users by analysing user activity data. Designing façades based on occupancy behaviour improves user experience. Understanding how occupants use spaces aids architects in designing intuitive layouts [44]. Architects can fine-tune building systems to align with actual needs by monitoring occupant movement. This approach supports environmentally responsible design. Data on occupancy patterns aid facility management. Facility managers can use the data to improve HVAC systems, and manage space allocation [45].

#### **3.3 Energy usage sensors**

Monitoring energy usage in façade design includes the incorporation of sensor technology. Smart metres, occupancy sensors and environmental detectors aid real-time data collection on energy usage, indoor environments and lighting conditions [28]. This information informs architects about building performance. They are vital in enhancing energy savings through façade design. Architects can detect energy-intensive spaces and energy-saving opportunities by analysing sensor data. This approach facilitates evidence-based design strategies, resulting in façades that minimise operational costs. Façade design can integrate passive strategies such as thermal mass, shading devices and natural ventilation to regulate indoor airflow and optimise energy consumption. Monitoring energy usage through façade design aligns with green building practises. Implementing energy-efficient façades is essential for achieving global sustainability goals [44]. Façade design can incorporate passive strategies to enhance sustainability. Passive design harnesses natural resources, enhancing daylight and thermal conditions to reduce the need for HVAC.

Façade design can incorporate energy-saving glazing. By using high-performance glazing with low U-values and effective insulation materials, architects can greatly reduce energy loss [46]. Improved glazing contributes to better thermal comfort, thus creating a sustainable building. Dynamic façades offer an innovative approach to energy saving. By incorporating sensors, façades can adjust to varying environmental conditions and user preferences. Switchable glazing and adaptive insulation optimise façade's performance and occupant comfort. Architects can maximise sunlight penetration into the building, reducing the reliance on artificial lighting by using light-redirecting devices. Incorporating sustainable materials into façade

design is key to sustainability. Architects can assess the environmental impacts of façade materials and construction methods. Net-zero energy façades are the pinnacle of sustainable building design. These façades produce as much energy as they use, often through integrated renewable energy sources. Net-zero energy façades demonstrate a commitment to environmental responsibility and mitigating climate change. Climate-responsive façade design tailors buildings to local climatic conditions. Using weather patterns, architects can design façades that adapt to varying temperatures, sun exposure and wind [28].

#### **4. Leveraging façade sensors for a responsive design**

#### **4.1 Designing adaptable spaces**

#### *4.1.1 Dynamic façades that respond to environmental conditions*

Dynamic façades in architecture characterise an important development in the area, where building externals are designed to react smartly to dynamic weather conditions. These façades are designed to communicate with environmental factors such as sunlight, temperature and wind, demonstrating a state-of-the-art combination of technology, sustainability and aesthetics [4]. This architectural approach supports diverse purposes, ranging from improving energy efficiency to creating appealing visual experiences. The core idea behind dynamic façades is to design building envelopes that are capable of adapting themselves to enhance the indoor environment. Such flexibility can greatly influence a building's energy utilisation and thermal comfort, aligning with the overall objectives of sustainable architecture. The components used in dynamic façades differ, integrating several technologies and design methods. One strategy includes the application of photochromic and thermochromic materials in façade mechanisms. These materials respond to variations in luminous intensity and temperature, triggering the façade's appearance to change. Another method integrates kinetic components, such as movable louvres, panels and shading devices. These components can be manually regulated or automated to control parameters such as light infiltration, ventilation and sensible heat gain.

Researchers have shown a growing attention to dynamic façades. Bedon et al. [36] discusses the structural aspects and performance assessment of adaptive façades in modern buildings. Adaptive façades are designed to respond to changing conditions and improve the overall building performance. They highlight the need for experimental methods and regulations to evaluate the structural safety, durability and fire safety of these innovative façade systems. It also presents a classification proposal and possible metrics for assessing their structural performance. The chapter emphasises the importance of considering material-related, kinematic, geometrical and mechanical aspects in the design of adaptive façades. The goal is to develop standardised and reliable procedures for the mechanical and thermo-physical characterisation of these novel structural systems. In the same vein, Bedon et al. [47] discuss the importance of experimental testing for adaptive façades, which are building enclosures that can respond to changing conditions. It discusses the performance requirements of façades, including airtightness, water-permeability, fire resistance and structural performance. The study explains that testing can be done in a laboratory or on-site, and that the configuration of the testing should include all relevant details for performance assessment. It also discusses the challenges of testing adaptive façades, such as

#### *Perspective Chapter: From Data to Design – Leveraging Façade Sensors for Intelligent Architecture DOI: http://dx.doi.org/10.5772/intechopen.113747*

determining the limit deformations and addressing impact and blast load scenarios. The article concludes by emphasising the importance of certified facilities for testing adaptive façades. Sudhakaran et al. [48] studied the performance of a dynamic façade system in campus buildings. This research involved the application of a climateadaptive building envelope on a base model and validates and analyses it through thermal simulation and prototype experimentation. The results indicated a noticeable projected energy saving of more than half in annual energy usage (approximately 60% less) as against the normal condition without the adaptive building envelope. It proves that the adoption of adaptive building envelopes that are tailored to the solar movement, incident solar radiation and summer and winter conditions show an improved functioning of the building envelope.

#### *4.1.2 Creating flexible interiors for changing occupancy needs*

Flexible interiors improve the functionality of a space and also contribute to sustainability, as they can prolong the life of a building and reduce the need for costly maintenance. One key aspect of creating flexible interiors is the incorporation of adaptable spatial configurations. This comprises the use of movable partitions, furniture and flexible partitioning approaches that allow spaces to be easily reconfigured to satisfy diverse needs. Architects have increasingly turned to solutions such as demountable walls, sliding components and convertible furniture to allow rapid alterations of spaces. These elements enable the swift adaptation of space, for example, an open office into individual workstations, a conference room or a lounge, based on specific requirements. This approach is in sync with the principles of sustainable architecture by reducing the need for new construction when occupancy requirements change. According to Zhang et al. [49] flexible interiors not only reduce construction waste but also lead to lower energy consumption and reduced greenhouse gases associated with construction activities, demonstrating that such design approaches contribute to the sustainability of buildings.

Additionally, the integration of smart building technologies plays a crucial role in achieving adaptable interiors. Sensors, automation and building management systems can be installed to monitor space utilisation and occupancy patterns in real time. This data can inform the dynamic changes in lighting, temperature and ventilation, creating an environment tailored to the existing occupants. Such intelligent systems boost user experience and support the prudent use of space. The benefits of flexible interiors extend beyond commercial buildings. In residential buildings, adaptable interiors allow landlords to reallocate spaces to accommodate changes in family sizes, lifestyle preferences or the need for remote workspaces. This adaptability increases the long-term value of residential properties and aids sustainable living practises.

#### **4.2 Personalising user experience based on real-time data**

Real-time data analytics is a vehicle for personalising user experiences. Sensors and Internet of Things (IoT) devices installed in buildings incessantly gather data on user behaviours, temperature, lighting and user preferences. This pool of data serves as the basis for designing spaces that adjust dynamically to the needs of each user. Real-time data permits the customisation of many features of the built environment. For example, smart lighting systems can alter colour intensity based on the time of day, occupancy in a room or user preferences. Likewise, heating, ventilation and air conditioning (HVAC) systems can be adjusted to maintain ideal thermal comfort for

each occupant. This level of customisation improves user comfort and also contributes to energy efficiency by curtailing unnecessary energy consumption.

Furthermore, personalising the user experience is more important than environmental controls. Architectural designs are increasingly integrating responsive systems such as flexible partitions and spatial configurations that can be modified to suit particular applications. These systems can be controlled manually or automatically on the basis of data inputs. For instance, an office building might reconfigure itself into a conference room or workstation depending on the user's needs. Neuhofer et al. [50] identify the requirements of smart technologies for experience creation, including information aggregation, mobile connectedness and real-time synchronisation. It also highlights how smart technology integration can lead to two levels of personalised tourism experiences.

#### **5. Shaping the future of intelligent architecture**

#### **5.1 Optimising building performance**

#### *5.1.1 Using sensor data to enhance building operations*

Sensor devices have become a vital component in the pursuit of intelligent building practises. These devices can monitor a plethora of critical factors, such as temperature, humidity, air quality, lighting and electricity consumption. The data collected by these sensors serves as a valuable resource for architects, builders and facility managers to gain a deeper understanding of the dynamic of building use. One of the advantages of sensor data is that it enhances energy efficiency. For example, temperature and occupancy sensors can work together to regulate the heating, ventilation and air conditioning (HVAC) systems. When no building is occupied, this system can automatically reduce energy usage. Dong et al. [51] demonstrated substantial energy savings through sensor-driven HVAC optimisation. They found that buildings integrated with such systems gain a significant reduction in energy consumption, resulting in both cost savings and less carbon monoxide emissions.

Advanced lighting control systems, for instance, can alter brightness based on the natural circadian rhythms of occupants, thus improving comfort. Moreover, data on indoor air quality can activate ventilation systems to dissipate fresh air when contaminants pass threshold levels, contributing to a better indoor setting. Also, the addition of sensor extends to proactive maintenance. Sensors implanted in critical building systems, such as elevators, HVAC systems and electrical systems, endlessly monitor their performance. By evaluating this data, facility managers can predict when systems are expected to fail, allowing preventive maintenance and preventing downtime. The application of sensor data in architecture can also be scaled to create smarter and efficient urban cities. Cities are increasingly installing sensors to monitor traffic flow, energy usage, waste management and air quality. This data-driven approach informs urban planning and policymakers, paving the way for more sustainable cities.

#### *5.1.2 Improving efficiency and reducing maintenance costs*

Efficiency improvements in design often begin with the selection of façade materials. High-performance materials such as double-glazed windows, insulated panels and advanced coatings can significantly enhance the thermal performance of a building.

#### *Perspective Chapter: From Data to Design – Leveraging Façade Sensors for Intelligent Architecture DOI: http://dx.doi.org/10.5772/intechopen.113747*

These materials aid in reducing heat loss during winter and heat gain during summer, thus improving energy efficiency. In addition, well-made façades can integrate passive solar systems, exploiting natural daylight while reducing glare and heat gain, consequently minimising the need for artificial lighting and cooling systems. Sheikh and Asghar [52] explore the design of an adaptive biomimetic façade for highly glazed buildings in hot and humid regions. The façade reduces solar heat gain and energy consumption while maintaining visual comfort. The design is inspired by the *Oxalis oregana* leaf, which tracks the sun's path and adjusts its position accordingly. The façade module can be folded horizontally and vertically, providing shading under both high and low sun angles. A case study of a 20-story office building in Lahore, Pakistan, demonstrates that retrofitting the façade reduces energy load by 32% and maintains recommended lighting levels in 50% of the interior space. The biomimetic façade offers significant energy savings while preserving visual comfort.

Likewise, the choice of façade materials can impact the cost of maintenance. Durable and maintenance-free materials can reduce the frequency and cost of maintenance. For example, the application of cladding can extend the useful life of façade, thereby minimising the need for regular painting. Façade designs that integrate rain screens and drainage systems can also impede dampness. Integrating smart technologies into façades can further improve productivity and lower the maintenance costs. Automated shading mechanisms, for instance, can regulate changing sunlight, thus reducing HVAC load. Self-cleaning coatings, which can be useful for façade surfaces, can reduce the build-up of dirt, thereby minimising maintenance needs.

#### **5.2 Advancing sustainability**

#### *5.2.1 Designing eco-friendly buildings using data-driven approaches*

Data-driven approaches include the gathering and analysing of data to inform the design of building façades. Sensors are deployed to collect data on temperature, solar radiation, humidity and wind patterns. This data is then used to make informed decisions throughout the lifespan of a building, from inception to demolition. Through data-driven analysis, designers can determine the effective approaches for increasing natural daylight while reducing heat gain or loss. For example, computational simulations can model the trajectory of the sun during the day and across seasons, enabling designers to position windows and shading devices to enhance daylighting and reduce the need for artificial lighting and cooling. Hosseini et al. [53] underscore the benefits of data-driven daylighting approaches in façades. They assess the concept of an interactive façade that can dynamically adjust to optimise daylight and enhance occupant comfort. The study develops a kinetic interactive façade that can transform based on dynamic daylight and occupant position, improving visual comfort. Daylight parametric simulations demonstrate the high performance of the kinetic interactive façades in improving visual comfort and controlling solar radiation. The results highlight the multifunctional aspects of the façade, which can prevent thermal discomfort and improve occupant health.

#### *5.2.2 Reducing carbon footprints and energy waste*

Buildings are responsible for a significant share of global greenhouse gas emissions. In the United States, they account for over 35% of the overall energy utilised and greenhouse gas emissions [54]. Façades, as the main barrier between the

interior of a building and the building's exterior, can overcome these environmental impacts. Energy waste is a direct impact of unproductive building practises. The poorly designed façades can lead to excessive heating and cooling loads, resulting in higher energy utilisation. Architects contribute to the energy efficiency of buildings by minimising energy consumption through façade design. Reducing carbon greenhouse gases aligns with sustainability goals. Sustainable architecture aims to design buildings that harmonise with their surroundings, use resources prudently and have less negative environmental impact. Green façades are the cornerstone of this approach.

Façades should integrate advanced insulation systems and techniques to reduce heat gain/loss. Good insulation minimises the need for heating and cooling, thus minimising the use of energy. Selecting energy-efficient glazing materials with low U-values and better solar heat gain coefficients can considerably enhance the performance of façade. Integrating vents into façades enables natural ventilation, lowering dependence on HVAC installations and reducing energy usage. Using exterior shading components such as sunshades, louvres and brise-soleil can prevent extreme heat gain while allowing natural lighting and reducing the demand for artificial lighting and ventilation. Incorporating renewable energy sources, such as photovoltaic cells into façade design can generate clean energy. Sensor-driven can be used as an automatic control for lighting, heating and ventilation based on user conditions. Assessment of façade materials and the construction technique through life cycle assessments to ensure they have minimal environmental impact over their intended life. Bui et al. [4] propose a computational optimisation approach to improve the energy efficiency of buildings through the design of adaptive façades. Adaptive façades can adjust their thermal and visible transmittance according to changing climatic conditions. The approach combines a building energy simulation programme with an optimisation technique to design the adaptive façade system. The modified firefly algorithm is used in this study, but the method is not limited to a specific optimisation tool or building type. The proposed adaptive façade system is validated through two case studies, showing energy consumption reductions of 14.9–29.0% and 14.2–22.3% compared to static façades. This highlights the potential of adaptive façades to enhance building energy efficiency.

#### **5.3 Innovating occupant-specific buildings**

#### *5.3.1 Designing spaces that are tailored to individual needs and preferences*

The pursuit of designing spaces personalised to person's preferences denotes a fundamental shift in design philosophy. This is evident in the design of building façades, which serve as a link between the built environment and its occupants. Contemporary architects recognise that tailored spaces not only improve user satisfaction but also contribute to enhanced health and safety. Individual spaces are intrinsically user-specific, providing buildings that suit the unique requirements of users. This improved individual experience contributes to comfort, satisfaction and a sense of ownership over the space. Designing façades with personalisation in mind helps improve space allocation. Spaces can be modified for numerous functions, accommodating different tasks and dynamic requirements with minor refurbishment. Individualised spaces have been shown to positively impact welfare and productivity. For example, a well-lit space with adaptable lighting can minimise eye strain and increase awareness,

#### *Perspective Chapter: From Data to Design – Leveraging Façade Sensors for Intelligent Architecture DOI: http://dx.doi.org/10.5772/intechopen.113747*

whereas customisable interiors help relaxation. Spaces that are personalised to person's preferences tend to be used more efficiently. This can reduce resource utilisation of energy, water and materials are assigned based on actual needs rather than standardised norms [55].

User-specific design begin by conducting extensive user research to understand the specific requirements of the building's occupants. This information underpins the design decisions. Integrating spatial shapes that allow easy adaptation. Use partitions, modular furniture and versatile zoning strategies that can be adjusted to accommodate different activities and user preferences. Customisable façade elements that enable customisation, for example integrating windows, adjustable shading devices and balcony spaces that can be tailored to suit person's requirements. Material and finish choices offer options for interior elements such as the floor, wall and cabinet. This enables users to choose finishes that match their needs. Lee et al. [56] assessed control strategy for adaptive façades, specifically movable shading devices. The aim is to determine the optimal positions of the shades based on various control objectives such as daylighting, thermal comfort, glare prevention and energy conservation. Lee et al. [56] propose a multi-purpose control strategy that considers all these factors and aims to optimise heating, cooling, lighting energy and glare. The strategy aims to provide an effective and efficient solution for controlling adaptive façades.

#### *5.3.2 Enhancing productivity and well-being*

Increasing the use of daylight is a vital aspect of façade design. Well-placed windows, skylights and glass façades permit natural light to infiltrate into internal spaces, minimising the need for man-made lighting. Exposure to daylight has been associated with enhanced mood, reduced stress and improved productivity among building users. Façades that offer access to views of the natural environment, such as green areas, parks and water bodies, can have a positive impact on welfare. Research demonstrated that views of nature can reduce mental fatigue and improve cognitive function. Façades play a critical role in adjusting the thermal comfort of a building. Better insulation, shading materials and cooling techniques can help achieve thermal comfort annually. A comfortable indoor environment supports productivity and mitigates elevated temperature-based health problems. Façades can also contribute to acoustic performance by decreasing outdoor noise penetration. Noise-resistance components and glazing can provide a noiseless internal environment, minimise disturbance and anxiety and improve awareness and comfort. The aesthetic qualities of a façade, including its design, colour and texture, can influence persons' perception of the space. An appealing façade can offer a sense of self-importance and identity among individuals, positively impacting their welfare. Allowing occupants some level of control over ventilation, and lighting can contribute to a sense of comfort. Customised control allows occupants to regulate their environment to suit their needs, thus, improving well-being [57]. Hongisto et al. [58] investigate the relationship between the physical environment of an open-plan office and employee satisfaction. The researchers conducted a quasi-field experiment in a 135-employee office, where various refurbishments were made to improve thermal conditions, visual and acoustic privacy, ergonomics, interior design and spatial density. All employees were surveyed twice, before and after the refurbishment, and physical measurements were taken. The study sought to provide evidence of the impact of the office environment on job.

#### **6. Conclusion and areas of future research**

#### **6.1 Conclusion**

In conclusion, the incorporation of façade sensors into intelligent architecture represents a transformative leap forward in the way buildings are designed, constructed, operated and maintained. Façade sensors, including temperature, humidity, light, air quality, solar radiation and occupancy sensors, provide architects with a wealth of real-time data that empowers them to design buildings that are not only energy-efficient and sustainable but also user-centric and responsive to environmental conditions. The use of these sensors enables architects to make data-driven design decisions, resulting in more efficient and environmentally friendly buildings. By harnessing the capability of sensor data, architects can optimise energy consumption, improve indoor comfort and reduce their carbon footprint. These sensors facilitate the development of dynamic façades that adjust to vary weather conditions, offering occupants a more comfortable and visually aesthetic environment. In addition, the seamless integration of sensor data within architectural design process, fosters teamwork and interdisciplinary approaches, bringing together design, technology and sustainability. However, it presents challenges such as the control of a large volume of data and the need for architects to embrace computational design approaches and data visualisation techniques.

As we dive into the future of intelligent architecture, it is clear that façade sensors will continue to play a critical role in configuring buildings that are at the core of sustainability, user experience and productivity. By leveraging the insights gained from sensor data, architects can design buildings that satisfy current needs and contribute to a more sustainable and resilient future. The journey towards intelligent architecture is ongoing, and façade sensors will remain at the forefront of this transformative evolution, driving innovation and enhancing the built environment for generations to come.

#### **6.2 Further research**

There are numerous areas for further research that can offer a better understanding and extend the application of façade sensors in intelligent architecture. Further studies can investigate the following: [1] how nanoscale sensors can provide real-time data on structural health, air quality and other parameters without changing the appearance of the façade, [2] how 3D printing can be used to produce personalised building components with built-in sensors, allowing for highly personalised and responsive architectural designs and [3] how blockchain can improve data integrity, privacy and transparency in multistakeholder environments. Finally, how sensorinstalled buildings can contribute to early warning systems, rapid response and post-disaster recovery efforts, thereby improving urban resilience.

*Perspective Chapter: From Data to Design – Leveraging Façade Sensors for Intelligent Architecture DOI: http://dx.doi.org/10.5772/intechopen.113747*

#### **Author details**

Mubarak Reme Ibrahim Baze University, Abuja, Nigeria

\*Address all correspondence to: mubarak.ibrahim@bazeuniversity.edu.ng

© 2023 The Author(s). Licensee IntechOpen. This chapter is distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/3.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

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#### **Chapter 5**

## Adaptive Textile Façade Systems – The Experimental Works at D1244

*Lucio Blandini, Christina Eisenbarth, Walter Haase, Moon-Young Jeong, Michael Voigt, Daniel Roth, Arina Cazan and Maria Matheou*

#### **Abstract**

Adaptive façade systems are a promising approach to achieve a dynamic response to varying weather conditions and to individual user demands. Within the framework of the Collaborative Research Center (CRC) 1244 at the University of Stuttgart the use of adaptive systems and the related architectural potential is explored with the aim of reducing the consumption of natural resources as well as waste generation and hazardous emissions. The targeted parameters for the façade design include solar radiation, temperature, wind speed, relative humidity, daylighting, and user interaction. To generate an experimental platform for the research work, a 36.5 m high adaptive experimental tower, D1244, has been designed and built on the University campus. The temporary façade of the tower is currently being replaced floor by floor, in order to validate different research approaches. The first implemented façades focus on textile systems, because of their lightweight and the different functions that can be easily integrated. Further material systems will be investigated in the next future.

**Keywords:** adaptivity, textile solutions, resilience, interaction, kinetic architecture

#### **1. Introduction**

The Collaborative Research Center (CRC) 1244 "Adaptive Skins and Structures for the Built Environment of Tomorrow" at the University of Stuttgart has been working since 2017 on the question of how future built environments can be created reducing the use of resources and the associated greenhouse gas emissions (GHG). The building sector is responsible for more than 50% of global resource consumption and for more than 38% of global CO2 emissions [1]. The target of the interdisciplinary program is the development of new design strategies and technologies, which enable structures and envelopes to be adaptive against loading and environmental actions. The research group comprises architects as well as structural, mechanical, control, and aeronautical engineers and computer scientists.

Within the scope of CRC 1244, adaptive structures and façades are understood as systems whose physical properties are actively manipulated by means of control systems. The state of the system is monitored by sensors. In the specific case of façades, the overall target is the design and validation of systems that enable the manipulation of transparency, reflectivity, humidity rate, insulation, cooling and acoustic properties, in order to control indoor as well as outdoor conditions in the vicinity of the building envelope.

Conventional envelopes can only provide a very limited range of reactions to varying external agents or to changing user needs. When using such systems, façade engineers often can achieve sub-optimal design [2]. While other researchers have been in the past investigating performances and design methods of adaptive skins in general [3], in this chapter the focus is on a specific field: adaptive textile façades. The reason for this focus is the lightweight character of such façade types and the potential of integrating and combining different functions while keeping a low ecological footprint.

CRC 1244 has set a strong experimental background for the research work. A 36.5 m high adaptive experimental tower, called D1244, has been built to test the proposed approaches on a large-scale experimental structure that offers real-world conditions (**Figure 1**). D1244 is the world's first adaptive high-rise building [4]. The unique feature of this demonstrator is the integration of sensors and adaptive components into the load-bearing structure and skin. All elements are assembled in such a way that they can be later substituted without generating any waste. The adaptive components in the load-bearing structure enable it to react autonomously against external disturbances such as winds and earthquakes. The building envelope currently consists of a single-layer recycled membrane that is being gradually replaced by adaptive façades as the research projects unfold.

This chapter focuses on three systems: *HydroSKIN* on the tenth floor, addressing rainwater collecting strategies and the potential of evaporative cooling; *FiberSKIN* and *MagneticSKIN* on the ground floor which are targeting the interaction between

**Figure 1.** *View of the experimental high-rise building D1244, Stuttgart © R. Müller.*

people with inside and outside spaces. Additionally, it provides an overview of further textile systems such as *KineticSKIN,* which is currently in the design stage.

### **2. HydroSKIN**

*HydroSKIN* represents the first lightweight building skin, that collects the winddriven rainwater hitting the building façade and releases water in heat periods to cool the interior and exterior environment by evaporation (**Figure 2**). The aim is a drastic reduction of urban inundation and heat risks by relieving the sewage infrastructure as well as providing natural microclimate regulation with a minimal amount of embedded mass, energy, and emissions.

#### **2.1 Climate context**

Heavy rainfall events and extreme heat are becoming more intense, frequent, and long-lasting [5]. The increasing urban densification with coherent surface sealing in urban agglomerations enhances precipitation runoff on the one hand, as well as solar radiation absorption, thus causing urban heat island effects on the other hand. While social developments lead to increasing urban densification, surface sealing, and the construction of high-rise buildings, the effects of climate change, such as extreme heat and heavy rainfall, require the opposite: the creation of more permeable surfaces and buffer areas for reducing inundation and heat exposure. The average annual ratio between evaporation and runoff for non-built-up surfaces, such as green areas,

is about 60% evapotranspiration, 25% groundwater recharge, and 15% rainwater runoff. In comparison, sealed surfaces demonstrate an average runoff of over 90% [6]. In conclusion, the aim is to approximate the water balance of built-up areas to that of non-built-up areas by reducing the precipitation runoff after heavy rainfall events, as well as by increasing evaporation and latent cooling in urban areas.

To avoid irreversible damage to humans and the environment, the Intergovernmental Panel on Climate Change is pursuing two complementary approaches, based on the concepts of mitigation and adaption. The first aim is to reduce climate change by significant and sustained reductions in greenhouse gasses (mitigation). However, since climatic consequences are to be expected even with zero manmade CO2 emissions, strategies and technologies for adaptation to the expected climate situation are being developed [5].

The combination of climate mitigation and adaptation strategies, by addressing both climate challenges of urban heat islands as well as pluvial inundation risks, is seen to have great potential for dealing with global environmental issues sustainably and effectively.

#### **2.2 Concept**

Most façade systems only focus on the building-physical performance. *HydroSKIN* faces the current climatic challenges by addressing both climate mitigation and adaptation strategies with a new type of functionalities in the building skin (**Figure 3**). The incorporation of textile and foil-based materials into the building skin opens a revolutionary new spectrum of performances in the façade: with a minimal weight per unit area, the use of a special, functionalized, multi-layered textile enables integration of decentralized rainwater harvesting into the façade, with time-delayed evaporative cooling of the building and its environment. The aim of the *HydroSKIN* is to improve drastically and sustainably the climate resilience of buildings and cities by simultaneously reducing precipitation runoff and inundation risks as well as urban heat island effects; achieving this with a minimum amount of technical effort, resource and energy consumption [7].

During heavy rainfall events accompanied by wind, the *HydroSKIN* add-on element absorbs the wind-driven rain striking the building façade. Thereby the

#### **Figure 3.**

*HydroSKIN concept for rainwater harvesting of wind-driven rain and for evaporative cooling © C. Eisenbarth/ ILEK.*

#### *Adaptive Textile Façade Systems – The Experimental Works at D1244 DOI: http://dx.doi.org/10.5772/intechopen.113125*

minimal material façade element reduces the load on urban sewage infrastructure and decreases the risk of flooding. Wind causes rain to have a horizontal velocity component and therefore increases the water impact on the façade. During hot periods, the absorbed rainwater can be targeted and time-delayed and released by wetting and evaporating on the façade. This improves the urban microclimate by cooling the building envelope and causing a down-flow of cold air into the urban area around the building thereby mitigating urban heat islands. The hybrid component addresses both rising climatic impacts of heat and inundation risks on urban architecture in a single hybrid envelopment solution. Depending on the prevailing climatic conditions, *HydroSKIN* can also be configured to perform only as one mono-functional device for rainwater harvesting or evaporative cooling [7–9].

#### **2.3 System design**

*HydroSKIN* is designed as a multi-layered textile structure to fulfill the multiple requirements of water absorption, storage, transport as well as evaporation (see **Figure 4**). The first layer provides a water-permeable filter facing to the outside. It protects the structure behind it from accumulation of dirt particles, insects, etc., thus favoring the water permeation into the multi-layered system by splitting the incoming raindrops. The second layer consists of a three-dimensional water-transporting spacer fabric whose pile threads on the one hand transport the incoming and outgoing water droplets and on the other hand favor air circulation by an open porous structure with large surface area, thereby enhancing the evaporative cooling performance.

An intermediate layer with high water absorbency can optionally be integrated to increase water storage capacity and evaporation duration of the textile multi-layer system in very hot and dry regions. The water-bearing layer, consisting e.g., of a foil, is on the inside and serves to provide water drainage and collection into the lower profile system. The individual layers are assembled by a force fit and are fixed in a frame profile system by means of textile joining techniques. The polymer-based textiles can be manufactured out of recycled material. Besides the textile mono-material system

**Figure 4.** *Multi-layer system design of HydroSKIN © C. Eisenbarth/ILEK.*

can be easily detached from the enclosing frame profile to return all system components to the material cycle. The water supply and discharge conduits are connected to the frame profile, enabling both the wetting of the *HydroSKIN* during hot periods and water drainage of the absorbed precipitation yields [9].

#### **2.4 Potential**

The advantages of façade-integrated rainwater harvesting consist not only in relieving the load on urban sewage infrastructure but also in reducing global freshwater consumption of residential buildings by up to 46% as well as in saving energy by up to 26% [7, 10].

Compared to conventional hard building surfaces, such as glass, optical investigations of the droplet impact behavior indicate a high permeability of textile materials. Evaporative cooling is one of the oldest and simplest principles of air-conditioning technology: the phase transition of water from the liquid to the gaseous state at temperatures below the boiling point extracts heat energy from the surrounding air. Frescoes from around 2500 BC show the fanning out of ceramic vessels filled with water, whose large pore content allows a large amount of water to be absorbed and evaporated on its surface [11, 12]. By the specifically adjustable surface structure and porosity of textiles, one can obtain a maximum surface area for water evaporation with a minimum amount of material. Thus, textiles are of particular interest for their application as evaporative cooling materials. The development of synthetic fibers since 1945 has even increased their evaporative cooling potential, since their large surface structure can be functionalized precisely [9, 13].

The evaporative cooling potential of water-saturated textile fabrics shown in **Figure 5** was investigated by empirical test series on an evaporation test bench under laboratory conditions of approx. 35°C room air temperature and 20–30% room air humidity. Humidification of the textile results in an immediate temperature reduction of 8–12 K, which under real weather conditions including wind velocity increases to

a façade surface temperature reduction of more than 20 K. The temperature decrease is accompanied by a coherent cool downdraft of about 0.2–0.4 m/s, which indicates a potentially useful implementation in tall buildings providing a cooling tower for the urban space below.

#### **2.5 Implementation**

*HydroSKIN* elements are designed to be applied to both new and existing buildings. Retrofitting of existing façades is limited to the static restriction of reducing the additive loads to a minimum, as these were not considered in the original design of the existing construction. The lightweight elements comply with such a constraint, still allowing for a wide range of design options and performance scenarios. The multi-layer design of *HydroSKIN* can be individually customized to the respective climate conditions, user requirements, and design guidelines. Creating a unique translucent esthetic effect with a textile, tactile surface texture, these climate-adaptive textile façades can be applied in a huge variety of design options, such as printed, colored, illuminated, 3D-shaped, or kinematic elements, that provide different states of shade and visibility in the façade from opaque closing over partial shading to fully transparency. The multi-layered collector and evaporator element provides a minimal weight per unit area of only approx. 1 kg/ m<sup>2</sup> in a dry state and approx. 5 kg/m<sup>2</sup> in a water-saturated state, allowing it to be retrofitted to most conventional façade systems.

Further development of the *HydroSKIN* leads to a completely textile and filmbased, multi-functional façade system [14]. In combination with an automated control and regulation strategy, the use of adaptive *HydroSKIN* façades can significantly improve indoor conditions and user comfort while reducing the consumption of water, materials, and energy at the same time [15].

Conventional high-rise buildings are characterized by a significant consumption of material and energy as well as high emission values, offering at best only marginal qualities for urban climate resilience. As Fazlur Khan once pointed out by his expression "Premium for height," the material consumption, as well as the embedded amount of "gray" energy bound up in the building, increases disproportionally with the building height due to the rising wind loads acting on the building façade [16]. On the other side, benefits result from the implementation of the *HydroSKIN* façades on high-rise buildings, as the first prototype façades at the D1244 building in Stuttgart demonstrate.

The façade surface of tall buildings such as skyscrapers offers not only a much larger absorption surface than its horizontal roof or ground surface. Simulations show, that above a building height of approx. 30 m, the amount of wind-driven rain yields per square meter façade surface is even greater than the amount of vertically falling precipitation per square meter on horizontal roof or ground surfaces. With the building height, wind speed rises, thus causing a stronger horizontal deflection of the precipitation drops and increasing wind-driven rain yields hitting the building façade [7]. During hot days, such wind velocities cause higher evaporation of water and enhance the cooling performance. Considering this potential of vertical retention and evaporation surfaces as a new "benefit for height" we wish for a new era of climate-adaptive and climate-resilient high-rise buildings (**Figure 6**).

#### **Figure 6.**

*Increase of wind speed (left) and wind-driven rainwater yields per square meter in comparison to vertically falling precipitation per square meter (right) with the building height [7].*

#### **3. FiberSKIN**

#### **3.1 Concept**

The idea behind the design of *FiberSKIN* is a moving screen on the ground floor that allows for a smooth transition from the interior space, where the hydraulic structural system of D1244 is showcased, to the surrounding platform area, where events and various activities take place. An interdisciplinary team of architects, structural engineers, and mechanical engineers came up with a customized veil-like screen made of lightweight and fully recyclable glass and basalt fibers [17]. The project was also a methodological test to validate early interdisciplinary collaborations in the field of adaptive façades [18]. The tight link to the panel manufacturers allowed for a highly customized solution, especially in the definition of the fiber pattern. The developed solution has a wide range of potential applications where no thermal insulation is required and lightweight and movable panels are required.

Featuring the integration of lightweight textiles and a double-sliding mechanism, *FiberSKIN* blends the conventional notions of curtain wall and curtain (see **Figures 7** and **8**): it prevents water penetration into the interior and regulates light transmission while generating special visual effects. The fiber panels cover three sides of the ground floor: two fixed panels clad on the southwest and northeast sides and two layers of movable panels clad on the southeast side. During the opening sequence, the permeability of the screen varies, creating an extraordinary spatial experience as the overlapping patterns of the two sliding panels constantly change. When closed, the panels overlap to provide a semitransparent screen; when fully open, the interior space is visually linked to the outdoors.

#### **3.2 Panel design**

The design is based on a geometric pattern radiating from intentionally placed clamping points. The number of clamping points differs depending on the function of the panels: the two 5.2 m wide movable panels are clamped with 17 nodes along

*Adaptive Textile Façade Systems – The Experimental Works at D1244 DOI: http://dx.doi.org/10.5772/intechopen.113125*

**Figure 7.** *View of FiberSKIN at the south corner of D1244 © M. Jeong/ILEK.*

**Figure 8.** *View through the SW fixed panel from inside D1244 © M. Jeong/ILEK.*

the horizontal edge to glide smoothly along the curved corners, while the 6.6 m long fixed panels only need 10 nodes to withstand wind forces (see **Figure 9**). In order to achieve a consistent pattern across all sides, a geometric rule is applied. This rule

**Figure 9.** *Drawing for fixed panels and clamping pockets © M. Jeong/ILEK.*

affects the pattern parametrically in response to variations in distance between nodes. The resulting pattern design leads to an extraordinary spatial experience indoors and outdoors based on the way the shadows are cast and the angle at which they are cast.

A color scheme inspired by the constituent materials of the fibers (basalt and glass) has been laid out to enhance the metaphorical level of the design. In the fixed panel both materials are laid together by engaging the i-Mesh fiber placement technology: the basalt fibers are concentrated in the bottom part and generate a metaphorical and optical link to the ground and the earth, given their volcanic origin. Meanwhile, glass fibers placed primarily at the top of the panel transmit considerably more light and are used to create a link to the sky. In the moving panel, the two material constituents are made visible in a different way since the two panels overlap in the closed position: the front panel is made entirely out of glass fibers and the back panel is made entirely out of basalt fibers.

#### **3.3 Kinetic concept and mechanical implementation**

The task for the kinetic concept was to arrange a semitransparent façade with a weather protection function, to be flexible enough to allow the interior to be fully opened for events. To meet these requirements, various methods were applied in an interdisciplinary manner between architects and mechanical engineers to find a variety of innovative solutions. With the help of brainwriting and the gallery method [19], more than 20 different opening concepts were developed within a very short period of time, which on the one hand were reminiscent of familiar openings such as theater curtains, but on the other hand also exhibited quite complex and organic movement patterns.

The concepts generated were then evaluated and selected based on various factors such as visual appearance and ease of implementation. The result was a concept in which two layers of textile move in front of each other, and the irregular distribution of fibers creates a superimposed interference effect. This also plays with the visibility of the building's interior technology, as some sections are more transparent than others, as well as with the incident light.

#### *Adaptive Textile Façade Systems – The Experimental Works at D1244 DOI: http://dx.doi.org/10.5772/intechopen.113125*

To implement the mechanical structure, some reference applications were studied at the beginning. For example, sailboats, garage doors, or conveyor systems in mechanical engineering have similar properties to those required for this façade. In order to gain an insight into the design and construction as well as the special features, manufacturers of each of these products were contacted and expert opinions on the transferability of this façade system were obtained. In the course of this exchange, industrial partners were also acquired to support the implementation of the adaptive façade with knowledge and technical components.

In the end, the mechanical system was inspired by the side sectional garage doors from Hörmann KG. These move in a similar way on the horizontal plane and their guide system was therefore a good reference. In addition, the thematic proximity to the construction industry was another advantage. The CAD model for the substructure of FiberSKIN is depicted in **Figure 10**. One major challenge in designing the façade was the transition from tolerances between the structure of the building (some cm) to the façade (a few mm). In order to achieve this, two specially designed support structures were integrated into the design. The first one is shown in **Figure 10** in the right upper corner. The sheet-metal design was selected as it meets the requirements for lightweight design and a high degree of design freedom. Here, another industry partner (TRUMPF Werkzeugmaschinen SE + Co. KG) was supporting to proper design of the brackets.

On the lower side of the façade, a classic L-profile was used, in which sufficient adjustment possibilities were provided by means of elongated holes in order to meet the small tolerances of the adaptive façade. As a measure to compensate for further tolerances and, in particular, to pre-tension the textile, a variety of roller carriers with corresponding compression springs were installed (see **Figure 10**, middle detail picture). These springs allow continuous adjustment of the pre-tensioning of the façade and are at the same time reliable even under high wind loads on the textile since they cannot overstretch in contrast to tension springs.

These combined measures jointly made it possible to meet a tolerance of approx. 2 mm over the entire width of 6 meters. Corresponding laboratory tests confirmed the design through endurance tests in which the façade underwent over 20,000 cycles.

The kinetic movement of the adaptive façade can be seen in the **Video 1**, https:// bit.ly/46n1DgX.

#### **3.4 Details embedded in manufacture**

In order to keep the engineering effort and the costs for the prototype as low as possible, while maintaining a high degree of design freedom, suitable reference applications were selected. The advantage here is that a large number of components have already been designed for similar use cases, which can only be slightly adapted and transferred for our prototype. A high degree of design freedom was otherwise allowed by the customized pattern design or by bespoke detailing. The focus was set on the clamps and on the large brackets that hold the façade. The clamps, which were placed regularly along the façade, served as an interface between the mechanical and architectural components. These are an integral part of the kinetic mechanism and fix the textile through special keder connections (see nodes blue marked in **Figure 9**).

The interdisciplinary and integrated design process of the clamps can be visualized based on their development. As these form the interface between the architectural part and the mechanical engineering part, they were subject to the most iterations. **Figure 11** visualizes the different development stages. It can be seen, that the design process started with a very rudimentary functional oriented CAD model of the assembly (**Figure 11**, Gen. (1). After the first discussions the improvements in the clamp design were mostly linked to lightweight design but also included some first shape finding aspects. Afterward, the shape was significantly improved in the third generation. Further improvements integrating new functionalities (Gen. 4 and 5, further connection possibilities were added) led finally to the stage where the clamps were integrated in the whole assembly back again. Generation 6 shows the detailed and final manufacturing version of the assembly including the clamps. This assembly was then used to frame and pre-tension the mesh. Therefore, on each of the blue-marked connection points in **Figure 9**, one of the clamp assemblies was mounted. Together with the mesh, this forms the two movable panels of the adaptive FiberSKIN façade.

#### **4. MagneticSKIN**

A user-centric approach in façade design involves placing the needs, preferences, and experiences of building occupants and users at the forefront of the design process. It emphasizes creating façades that not only fulfill functional requirements

#### **Figure 11.**

*Design process of the keder clamp–optimizing shape, weight, and functionality © M. Voigt/IKTD.*

but also enhance the well-being, comfort, and overall satisfaction of the people who interact with the building skin.

#### **4.1 Concept**

*MagneticSKIN* is a pioneering interactive façade system designed to respond dynamically to human touch (see **Figure 12**). By exploring non-verbal ways of communication through haptic interaction, this approach aims to create a harmonious interplay between architectural esthetics and human experience. The ground level of D1244 is ideal for this purpose since it offers direct and convenient accessibility for individuals to engage with both the external and internal layers of the system.

In contemporary architectural practices, there is a growing emphasis on the ability to tailor specific properties of building envelopes to enhance comfort and overall space usability [20]. This focus primarily revolves around meeting physiological needs and individual preferences. However, the exploration of psychological needs and the broader activation of human senses remains largely uncharted territory. The proposed system delves into the significance of bridging this gap and investigates the potential benefits of integrating sensory stimuli to create more engaging and immersive built environments.

"Touch is the sensory mode that integrates our experience of the world with that of ourselves" according to Juhani Pallasmaa [21]. By considering touch and other sensory experiences during the design process, architects can enhance the emotional connection people have with their surroundings, leading to more memorable and enjoyable spaces [22]. The overall aim is to create a system that places the user at the core of the design process and to start understanding how haptic experiences influence perception, emotions, and behavior.

The interaction system follows the principles of system dynamics comprising of a set of sensors and actuators interconnected through a microcontroller and a specific

set of rules or code. This design allows the system's behavior to be dynamically shaped by continuous interaction with users.

#### **4.2 Pattern design**

The arrangement of the round permanent magnets on the membrane surface follows a deliberate pattern inspired by the key trigger points found in an averagesized human hand. The abstract representation of these points results in a group of eight magnets. There is a total of five variations of this group, out of which the overall semi-regular clustered pattern is created by organically arranging them across the canvas (see **Figure 13**).

Each group of eight magnets corresponds to an electromagnet and sensor, working together to form what is referred to as an "active module." In addition to the active modules, there are "passive modules" composed of either individual permanent magnets or groups of magnets, to which no actuator is assigned. The role of these passive modules is to harmoniously integrate the pattern, especially in areas not easily reachable by hand for users interacting with the façade.

#### **4.3 Detailing**

The structural system consists of a wooden frame placed on adjustable steel posts for water protection and supported at the top by steel brackets (see **Figure 10**). By employing exclusively bolt/screw connections, the entire system can be easily disassembled, making it highly reusable and recyclable. The same principle applies to both inner and outer lightweight textile layers, which cover up the substructure, as well as to all components of the interaction system.

#### **Figure 13.**

*Pattern creation based on trigger points inside a human hand combined with spatial point arrangements © A. Cazan/ILEK.*

#### *Adaptive Textile Façade Systems – The Experimental Works at D1244 DOI: http://dx.doi.org/10.5772/intechopen.113125*

To achieve a sleek, canvas-like appearance, an aluminum tendering frame from Roho is utilized to secure and prestress the outer membrane also around the corners. This frame is raised 8 cm above the ground, creating a hovering effect that gives the illusion of the façade smoothly floating above the concrete platform.

The outer membrane protects the inside space and the electrical components. It consists of a silver PVC-coated PES membrane onto which round permanent neodymium magnets are positioned: these measure 15 mm in diameter and 2–3 mm in thickness. By placing one magnet on the inside and one on the outside of the membrane, the connection is made solely by the electromagnetic field, making a later dismantling, reuse, and even repositioning of magnets extremely simple.

On the inside of the façade system, there is an additional layer made of highly flexible elastane with iridescent visual properties, onto which round permanent magnets with the same 15 mm diameter but only half the thickness (1, 5 mm) are placed (see **Figure 14**).

This configuration allows for a dynamic interaction between the inner and outer layers, enhancing the overall sensory experience and interaction. While the outer membrane was completed in May 2023, a mock-up of the inner layer has been temporarily installed. It offers visitors a chance to experience the different haptic qualities and to test interaction scenarios between inside and outside space.

#### **4.4 System dynamics**

By touching the inner or outer side of the façade, users push that specific area of the textile back toward the core of the system, thus triggering an interaction. This inward movement is continuously monitored by ultrasonic sensors, which measure the distance to the default state of the membrane. The sensors then transmit this information to the Arduino microcontroller, which processes the data and sends corresponding commands to the appropriate actuators (**Figure 15**). For each sensor in the system, there is an associated actuator, which is turned on only when the predefined conditions stipulated in the Arduino code are being met. Distance and time are the defining parameters in reaching the desired effect. By experimenting with the time intervals between activations, changes in polarity, and the natural vibration frequency of the membrane, different pulsation rhythms can be achieved.

**Figure 14.** *Prototype of the inner layer of MagneticSKIN © U. Regenscheit.*

**Figure 15.** *Part of the interaction system seen from the inside © A. Cazan/ILEK.*

The name *MagneticSKIN* derives from the use of electromagnetic properties to activate the double-layer textile skin. 24 V powered electromagnets, each capable of generating an attraction force of 800 N, are being used as actuators. By placing permanent magnets on the membrane, the electromagnets behind the membrane are able to attract and repel the latter at predefined time intervals, thereby creating a puls-like sensation on the surface. The intensity of the effect directly correlates with the number of activation points perceived by the ultrasonic sensors and the depth of the inward movement. The greater the number of active points, the more intense the overall effect, which can be seen and (more importantly) also be felt by the users interacting with it. Thus, a new form of non-verbal haptic communication is made possible, connecting users with the outer layer of the built environment and fostering interaction and communication among the users themselves.

#### **4.5 Output and future perspectives**

The feedback from the users who have interacted with the system since May 2023 has been overwhelmingly positive, with many describing a puls-like sensation similar to a heartbeat and expressing a willingness to engage with it, thus confirming the relevance of the interaction with building skins and the perception of the built environment. By having had the opportunity to observe the system in use, it can be stated that incorporating interactive elements in the façade design encourages user engagement and instills a sense of ownership over the building.

Embracing interactive technologies and haptic qualities of materials could give architects the opportunity to create immersive experiences, where architecture transcends its traditional role and becomes a dynamic medium for human interaction and sensory perception. Moreover, the research on *MagneticSKIN* and its successful implementation serves as a significant step forward in understanding the potential of haptic communication in architecture, paving the way for the creation of more immersive and user-oriented built environments in the future.

*Adaptive Textile Façade Systems – The Experimental Works at D1244 DOI: http://dx.doi.org/10.5772/intechopen.113125*

#### **5. Outlook**

The three façade systems described in the present article show the high range of functionalities that can be achieved by using textile skin systems in new ways. Due to their lightweight and flexibility, it is easy to move and deform such panels. Thus, they can easily be adapted to different architectural purposes. Moreover, extended production ranges (as shown e.g. at the multi-layered 3D-textile for *HydroSKIN* or the customized non-woven planar mesh for *FiberSKIN*) allow for new fields of application to be explored. This fits very well in the attempt to design innovative adaptive systems, that react to different conditions in a dynamic and effective way. Modern textile skins can be also designed and built in such a way that each component has a low carbon footprint and is fully recyclable. Moreover, the experimental interdisciplinary setup of the CRC 1244 allows not only to explore the potential of new systems, geometries, and functions but also to validate experimentally the developed solutions in a real-world condition and showcase the quality of the application in full scale. Currently, the first applications clad two floors of D1244 (out of 12). Additional cladding systems are to be built in the coming months. One of the next textile façade systems is called *KineticSKIN* and will be installed on the second level of the building (see **Figure 16**).

In general, adaptive kinetic façades are designed to respond in real-time to changing environmental conditions and indoor comfort requirements by means of kinetic mechanisms that allow them to dynamically adjust their form, position, or transparency. Such façade systems can allow for proper shading and enhance occupant comfort while improving energy efficiency [23, 24].

The objective of this research is the optimization of indoor daylighting conditions and the reduction of solar heat gain as well as unwanted solar radiation in the urban canyon [25]. Excess solar radiation is reflected into the atmosphere, reducing the urban heat island effect. This is performed by reorienting the wings (façade modules) in response to changing weather conditions. The upper wing tracks the sun and reflects solar radiation to its source, thereby reducing undesired solar heat gain

**Figure 16.** *Rendering of KineticSKIN to be installed at the D1244. © M. Jeong/ILEK.*

and reducing building energy consumption. At the same time, the lower wing serves users' visual comfort (illuminance and view).

A small number of actuators were employed to prevent adding weight to the façade and to keep energy usage low. During the hot summer months, the façade can minimize solar heat gain by shading the windows, thus reducing the demand for air-conditioning. In winter, it can allow sunlight to naturally warm up the interior, minimizing the need for heating. The system is designed to optimize natural daylight penetration into a building's interior so that artificial lighting needs are reduced. Moreover, it enhances comfort by regulating indoor temperatures and reducing glare.

PAOSS represents another approach of a targeted, kinetic sun and glare protection system using a simple, resilient, and low-energy actuation mechanism. The pneumatically operated origami sun shading system-abbreviated "PAOSS"—is used for the targeted control of light transmission. It combines the esthetic and material-immanent qualities of textile materials with the functional aspects of integrated active pneumatic actuators to initiate the change of shape e.g. to open the elements (**Figure 17**). Textile folding structures are particularly suitable for changing their shape from a large shading area to a minimal folded state and vice versa by reversible folding. They are therefore highly interesting as selective sun and glare protection elements for improving user comfort and reducing energy consumption. The National Aeronautics and Space Administration (NASA) has developed an origami folding geometry for astrophysical purposes called "Starshade" [26], which is characterized by a particularly large difference in area between the opened and folded closed state. An adaptive, pneumatically actuated sun and glare protection system inspired by "Starshade" was designed and developed to be embedded as an interlayer in ETFE cushion façades. Through the use of active components, it is possible to achieve a targeted, partial, or full-surface regulation of light and radiation transmission, as well as the back-reflection properties of the façade [27]. The ETFE façade is planned to be installed on the eleventh floor of D1244.

Within three to four years all 12 floors of D1244 will be clad with different adaptive façade systems. One of the focuses will be set on insulated glass units, integrating further functions such as cooling, energy harvesting and storage, etc. As soon as all the façades are installed, the next cycle will start, thus establishing for the D1244 the experimental character of a laboratory at a real scale.

#### **Figure 17.**

*Visualization of PAOSS in un-activated closed state (right), targeted partial glare protection state (middle), and full-surface shading state (left) © C. Eisenbarth/ILEK.*

#### **Acknowledgements**

The Collaborative Research Center CRC 1244 has been funded by the German Research Foundation (DFG)-Project-ID 279064222–SFB 1244. The five described projects have been made possible through the research work of different interdisciplinary teams and thanks to the support of several industrial partners and the engagement of the ILEK technicians (T. Tronsberg and M. Berndt). The authors are grateful for the support. *HydroSKIN* Team: C. Eisenbarth, W. Haase, L. Blandini, W. Sobek (ILEK) Partners: Dr. Zwissler Holding AG, Essedea GmbH & Co. KG *FiberSKIN* Team: M. Jeong, L. Blandini, J. Lopez, F. Kokud, M. Matheou (ILEK)/M. Voigt, D. Roth (IKTD) Partners: Sailmaker International (i-Mesh), Hörmann KG Verkaufsgesellschaft, TRUMPF Werkzeugmaschinen SE + Co. KG *MagneticSKIN* Team: A. Cazan, L. Blandini, H. Raisch, F. Kokud (ILEK) Partners: Roho GmbH, Koch Membranen GmbH, Mehler-Texnologies GmbH *KineticSKIN* Team: M. Jeong, M. Matheou (ILEK) Partners: Josef Gartner GmbH PAOSS Team: C. Eisenbarth, W. Haase, Y. Klett, L. Blandini, W. Sobek (ILEK) Partners: Global Safety Textiles GmbH, Carl Stahl AG, Mehler Texnologies GmbH

### **Video materials**

Video materials referenced in this chapter can be downloaded at: https://bit. ly/46n1DgX

### **Author details**

Lucio Blandini1 \*, Christina Eisenbarth1 , Walter Haase1 , Moon-Young Jeong1 , Michael Voigt2 , Daniel Roth<sup>2</sup> , Arina Cazan1 and Maria Matheou1

1 Institute for Lightweight Structures and Conceptual Design (ILEK), University of Stuttgart, Germany

2 Institute for Engineering Design and Industrial Design (IKTD), University of Stuttgart, Germany

\*Address all correspondence to: lucio.blandini@ilek.uni-stuttgart.de

© 2023 The Author(s). Licensee IntechOpen. This chapter is distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/3.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

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[5] Intergovernmental Panel on Climate Change (IPCC). Climate change 2021: The physical science basis. In: Contribution of Working Group I to the Sixth Assessment Report of the Intergovernmental Panel on Climate Change. Cambridge: Cambridge University Press; 2021

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[7] Eisenbarth C, Haase W, Blandini L, Sobek W. Potentials of hydroactive lightweight façades for urban climate resilience. Civil Engineering

Design. 2022;**4**:14-24. DOI: 10.1002/ cend.202200003

[8] Eisenbarth C, Haase W, Blandini L, Sobek W. Climate-adaptive façades: An integral approach for urban rainwater and temperature management. In: Structures and Architecture A Viable Urban Perspective?. Aalborg: CRC Press; 2022

[9] Eisenbarth C, Haase W, Blandini L, Sobek W. HydroSKIN: Lightweight façade element for urban rainwater harvesting and evaporative cooling. In: Proceedings of the Facade Tectonics 2022 World Congress. Los Angeles: Facade Tectonics Institute; 2022

[10] Smith A, Gill G. Residensity-A Carbon Analysis of Residential Typologies. Chicago: Adrian Smith + Gordon Gill Architecture (ASGG); 2018

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[15] Rentz A, Oei M, Eisenbarth C, Haase W, Böhm M, Blandini L, et al. A hydroactive facade for rainwater harvesting and evaporative cooling: Dynamic modeling and simplification for application in optimization-based long-term building operation strategy. In: Proceedings of the Conference on Control Technology and Applications (CCTA 2022). Trieste: IEEE; 2022

[16] Khan FR. Appendix I-Current trends in concrete high-rise buildings. In: Coull A, Smith BS, editors. Tall Buildings. Pergamon: University of Southampton; 1967. pp. 571-590. DOI: 10.1016/ B978-0-08-011692-1.50033-X

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#### **Chapter 6**

## Smart Façades: Technological Innovations in Dynamic and Advanced Glazed Building Skins for Energy Saving

*Silvia Brunoro and Valentina Frighi*

#### **Abstract**

This chapter deals with the analysis of the potential offered by the integration of smart solutions in dynamic glass façades to improve buildings' energy performances. Dynamic solutions are here examined with reference to dry ventilated systems, active and passive cooling, solar gain, greenhouse effect, and technologies able to react and self-regulate, according to the environmental inputs. The first part is dedicated to the state of knowledge, assessing the performance evolution of dynamic and interactive architectural envelopes (smart skins). Then, the core of the chapter is divided into clusters according to different strategies that allow the building skin to react and selfregulate according to the environmental inputs: double-layer glass façades, solar shadings, PV integration, etc. The goal is to produce a sort of "smart skin guideline" divided by requirements/strategies of intervention to investigate a range of solutions able to regulate buildings' behavior and characterize their image: from systems that allow to transform solar gain into heat to improve buildings' energy performance in winter season, to others that integrate passive cooling, to systems that transform the façades in a real active element of energy production, thanks to the integration of renewable energy sources.

**Keywords:** glass building skin, smart envelope, double layer façades, active and passive system, advanced building skin, smart windows

#### **1. Introduction**

The aim of this chapter is to explore the innovative incorporation of glass into façade systems to promote the energy efficiency and enhance the architectural perception of buildings. The research is focused on the sustainability of glass as a material for façade, as a very powerful opportunity, often associated with natural light, and lightness, and other qualities that have earned universal reception from modern architecture.

Firstly, a brief introduction frames the research background, the concept of glass envelope, its evolution, and role toward the definition of dynamic and smart envelope.

Then, the methodology is explained in paragraph 2; later technical solutions are classified by their technical requirements and energy performance. The core of the chapter is divided into clusters according to different strategies that allow the building skin to become an active and dynamic layer: double layer glass façades, solar shadings, PV integration, etc.

Finally, the goal is to produce a sort of "smart skin guideline" divided by requirements/strategies of intervention to investigate a range of solutions able to regulate buildings' behavior and characterize their image.

Historically, the use of glass envelopes was mainly focused on esthetics, as it was estimated that it did not need to be ecologically responsive to the environment.

Adverse energy and mechanical performances usually associate with excessive thermal gain and direct sunlight, have created uncomfortable buildings, and caused inefficient energy consumption [1, 2].

Hence, the application of a glazing system cannot be followed without truly understanding the underlying principles and implications.

Since energy costs have been affordable (before the oil crisis of the 1970s), the low thermal performances of the fully glazed building have been compensated by totally mechanical heating and cooling systems. By the 1970, the high costs of fuel led the building industry to develop new and performing glass products such as photosensitive and photochromic glass, and new coatings such as reflective or selective (Low-E) to help in reducing energy consumption in buildings with large glass area [3, 4].

The increasingly frequent use of transparent surfaces for the construction of building development began in the nineteenth century, during the Industrial Revolution, and involves the research and development of new materials able to guarantee energy performance like massive walls [5].

The envelope becomes progressively independent from the load-bearing structure of the building and its first requirements are to regulate the energy flows such as heat transfer, light transmission, protection of solar radiation (**Figure 1**) [6].

In the recent years, sustainability has become a more and more important feature in architecture: A sustainable design process can produce high-performance buildings that are energy efficient, healthy, and economically feasible, wisely using renewable resources to minimize the impact on the environment and to reduce, as much as possible, the energy demand [7–9].

Following the developments in international environmental policy, after the Kyoto agreement on climate change [10], the International Energy Agency has developed a set of scenarios on international energy development up to 2030 and 2050, showing how the construction sector remains, alongside the industrial sector, the most responsible for energy consumption and CO2 emissions [11].

Consequently, several European standards and regulations concerning energy efficiency in buildings have been promulgated, focusing on the importance of the energetic control of buildings to reach, since 2020, NZEB requirements for new and relevant refurbishment actions [12].

Since the publication of the European Directive 31/2010 UE, the building envelope has been the subject of a great number of research aimed at demonstrating the possibility of build with zero or passive emission house [13].

Among the European research in recent years contributing to the envelope evolution, through experimentation of new components and materials characterized by high performance, it can be cited: Best practice for double-skin Façades (BESTFACADE), European High Quality Low Energy Buildings (EULEB), Building Advanced Ventilation Technological examples (BUILDING ADVent).

*Smart Façades: Technological Innovations in Dynamic and Advanced Glazed Building… DOI: http://dx.doi.org/10.5772/intechopen.113127*

#### **Figure 1.**

*GSW Headquarters, Berlin. Architects: Sauerbruch & Hutton. One of the first examples of high-efficient double layer glass façade. All moveable curtains of the façades can be controlled by the individual occupant but are also operated by a central building management system. This individual control provides for a continuously changing appearance, especially of the west façade.*

As remarked in Ref. [14], for smart glass façades, the thermal and insulation properties, in addition to other important requirements like transparency to allow solar gains or solar control, are relevant aspects that are strictly linked on climate conditions and the desirable level of comfort.

Nowadays, the standardized prefabrication of high-quality multifunctional façades represents a foreseen frontier in the improvement of the envelope's performance. Dry-mounted prefabricated façades reduce the on-site construction costs and time by incorporating numerous functionalities into the same component, thanks to the inclusion of smart materials. This approach also integrates both solar active and passive solutions and optimizes building equipment, including heating, cooling, and ventilation.

Therefore, glass components'system becomes a multifunctional building layer, not only to be physically and functionally "integrated" in the building, but also to be used as an innovative chance for the building envelope design. For this reason, the façade system plays an important role for achieving energy and environmental goals [15].

Architecture of light envelopes is made of structural skins just like a shell, the first significant experiment took place in Northern Europe such as in the design experiences of Sauerbruch & Hutton, Herzog & de Meuron, Jean Nouvel, etc. [16].

In the design of dynamic envelope systems, it is fundamental to analyze the climatic and environmental conditions, to reach an adequate balance between climatic parameters, inner thermal and hygrometric conditions, and technical components/ solutions.

Starting from this point, the chapter proposes an analysis of the most relevant active technologies based on their performances.

Relying on the most efficient products in terms of energy efficiency of glass components for façades, the aim of this work is to perform a multi-criteria analysis based on different requirement categories, to compare several technological possibilities for façade in terms of technological, architectural, energetic, and environmental requirements.

#### **2. The role of glazed components**

While glazed elements are an important aspect of architectural design, they are regarded as the least energy-efficient elements of the building envelope [17] since they contribute to approximately 60% of the overall energy usage of buildings [18]. In contrast to insulated walls of equivalent size, the heat-gain occurrences on windows can result in effects that are many times more impactful [19], resulting in significant implications for buildings' lighting, heating, and cooling needs.

The challenges associated with glazed elements lead to winter heat losses, due to air leaks and insufficient insulation. Similarly, in summer, they can lead to overheating due to the entering of solar radiation, which significantly elevates indoor temperatures. Additionally, beyond their architectural and energy-related aspects, these components must also fulfill essential structural prerequisites. These requirements encompass structural integrity, usability, longevity, resilience, and fire performance [20–22], particularly if considering systems with adaptive features.

Hence, effectively intervening in the design of glazing systems offers a significant chance for the construction industry to manage energy needs, contributing to the advancement of the objectives set by the European energy agenda.

#### **2.1 Characteristics of glass products**

Throughout years, artists and architects have worked with glass due to its shaping, tactile qualities, and interaction with light, also considering its stability, waterproofing, and see-through nature [23].

Since the development of the float glass technique in the 1950s, glass surfaces appropriate for construction purposes are primarily made of silica (SiO2). Transparent typical glasses have a light-transmission coefficient ranging from 60 to 80% for wavelengths approximately falling within the 400- to 2500-nm range. Nevertheless, by altering the chemical composition of the glass through adjustments in its mixture, it becomes possible to alter this threshold or impact other aspects like its chemical, physical, or mechanical characteristics.

Due to the evolution of technological advancements and industrial methods, glass is nowadays available in a variety of shapes and compositions, typically distinguishable based on the production techniques that generated them.

#### **2.2 Glass energy performance features**

The primary characteristic of glass is its ability to transmit light, facilitated by its transparency, which arises from the interactions between light photons and the atomic structure of the glass. Generally, a glazed surface transmits most of the

*Smart Façades: Technological Innovations in Dynamic and Advanced Glazed Building… DOI: http://dx.doi.org/10.5772/intechopen.113127*

incoming solar radiation, depending on the constituents that form it and/or any surface modifications it undergoes.

Within the entire solar spectrum, three segments significantly impact the comfort of indoor environments in buildings, as they pass through the glass: Ultraviolet (UV), Visible Light (VL), and Infrared Energy (IR). UV light can be further categorized into three groups; two of them are rejected by the earth's atmosphere and float glass as well.

IR constitutes the heat energy emitted by the sun that enters an interior space. Managing this transmission involves limiting heat within rooms, thus averting potential overheating during the summer. The greater the ability of a glass panel to block IR, the more energy and cost can be saved.

Lastly, VL represents the portion of light visible to the human eye and encompasses natural daylight. It can contribute to undesired glare and strain on the eyes. Generally, the VL of a glass pane can be decreased by adjusting tints.

Regarding VL, glass is almost completely transparent, whereas concerning IR, it behaves opaquely; this is the cause of the so-called greenhouse effect, due to which, bodies located in a space protected by glass surfaces experience temperature elevation due to direct exposure to radiation. This energy is then re-emitted as sensible heat in the form of infrared radiation, which remains confined within the space.

IR solar radiation upon a glass surface can be reflected, transmitted, or absorbed. In normal incidence conditions, the reflected energy is the quantity of solar radiation bounced back into the atmosphere. The transmitted energy represents the solar radiation directly passing through the glass's surface, while the absorbed energy expresses the quantity of solar radiation absorbed by the glass, leading to an increase in its temperature.

Total transmission instead represents the total amount of solar radiation that, in normal incidence conditions, is transmitted through the glass. This measurement encompasses direct transmission (short-wave component) as well as the component dissipated inward due to radiation and convection (long-wave component).

The ability of a surface to absorb or emit electromagnetic radiation is reflected by the emissivity value. By its nature, glass has a high emissivity. Coatings able to act on this feature are existing, reflecting heat inside buildings and thus reducing heat losses through windows, increasing in this way the system's U-value.

#### *2.2.1 Reference parameter for glass energy performance evaluation in buildings*

Defining and characterizing the energy performance of transparent components is quite tricky due to their interaction with solar radiation. Because of these complexities, such building elements must adhere to specific criteria and be described using both thermal and optical parameters. These parameters address the system's thermal insulation capacity and the ability in regulating the quantity of solar energy into rooms. The benchmarks commonly used for assessing the performance of glazing include the following:


**Figure 2.**

*Correlation between the Solar Factor (SHGC) and the Light Transmission (LT) coefficient.*

lower SHGC means reduced solar heat transmission and enhanced shading capabilities. Glazed elements with high SHGC effectively capture solar heat in winter, while systems with low SHGC are efficient at reducing cooling loads in summer.

• Visible Light Transmittance, or light-transmission coefficient (τl), is the fraction of the visible sunlight spectrum perceived by the human eye which passes through the glazing. It is represented by a value between 0 and 1, with higher values denoting more transmitted visible light.

An additional crucial parameter for assessing the energy performance of transparent systems is the Light to Solar Gain (LSG) ratio, which measures the spectral selectivity of a glass system as an expression of the efficiency of different glass types in transmitting daylight (the visible solar radiation) while blocking heat gains. It is calculated as the ratio of VLT to SHGC; a higher LSG means more daylight transmitted without adding excessive heat. This parameter becomes particularly important for daylighting, especially in summer when more light is desired with minimal solar gain. Therefore, a higher LSG number implies a brighter room without excessive heat accumulation (**Figure 2**).

#### **3. Methodology: Categories of requirements and performances**

This work focuses on the technological innovation in glass façades systems and investigates the most relevant aspects from architectural and energetic point of view.

The first analysis involves identifying relevant factors—presented in the form of criteria—that define the main features of each system.


#### **Table 1.**

*Significant criteria for façade components.*

Each macro-category of requirements (architectural, energy, environmental, and economic) is further divided into sub-categories to define the peculiar aspects of components under investigation, as well as their operational strategies, in terms of the environmental and dynamic benefits within the overall concept of the building.

The assessment methodology for the analysis of the architectural and technological characteristics of the façade systems is based on the categories and sub-categories of requirements listed below (**Table 1**). These have been defined by authors based on their significance concerning the whole building envelope system—in relation to both technical and aesthetic features—and parameters indexed in the regulation framework for transparent building components, plus other qualitative considerations made based on their description related to the integration with technical systems and costrelated aspects.

According to this criteria, three macro-categories of environmental strategies have been proposed, to classify, in the following paragraphs, the most relevant technological innovations in advanced glass building skins for energy saving:


The purpose is to outline criteria and operational tools to guide and inform the design of innovative envelopes, allowing targeted choices to be made in relation to the foreseen interventions, to obtain the desirable levels of quality.

Finally, a technological multi-criteria matrix is defined, in which the façade solutions are briefly described and compared by crossing the strategies of interventions with the requirements described in **Tables A1**–**A3**.

#### **3.1 Passive solar heat gain: double layer glass façades**

Solar gain holds significant importance in cold and temperate climates, as it plays a crucial role in reducing heat losses and harnessing passive solar incidence, thus contributing to the overall energy balance. Historical solar passive design—e.g., the

"Trombe wall"—can be considered as a precursor to modern double skin systems [24].

A double Skin Façade is an advanced building skin, originally born in Northern Europe, that can dynamically respond to varying ambient conditions, able to:


A typical double glass envelope system comprises a layer of single glass and a layer of double-glazing, separated by an air space that can incorporate a range of integrated sun-shading, natural ventilation, and thermal insulation devices or strategies. During the winter season, a double skin façade can improve heat gains coming from solar radiation by means of the greenhouse effect and reduce the heat losses due to the slow air flow that can lower the heat transfer from inside to outside. Glass panes maintain a warm surface temperature on the inside, enabling more effective utilization of the space close to the window [14].

In winter, the air cavity, heated by the sun, becomes a warm buffer zone, while in summer the stack effect of fresh air (passive ventilation) removes the exceeding heat [25].

In addition to energy efficiency and the U-value of the glass, other important requirements include acoustic control, water penetration resistance, and daylight control, which are crucial for ensuring office building comfort.

In summer, control of solar heat gain is ensured through shading devices placed within the air cavity. Additionally, the cavity itself can help dissipate some of the incoming solar radiation through the passive ventilation effect. Various configurations for shading devices exist; they can either be fixed elements or, typically, operable units that are either controlled by the occupant or by sensors within the building [26].

**Figure 3.** *Conceptual scheme of a double layer glass façade.*

#### *Smart Façades: Technological Innovations in Dynamic and Advanced Glazed Building… DOI: http://dx.doi.org/10.5772/intechopen.113127*

In Mediterranean Countries, solar gains control in building design that is relevant; therefore, double skin façades may lead to overheating during summer months if there is no appropriate façade design, ventilation technique building orientation, and provision of shading [27].

The use of improved solar U values for glazing favors the absorption and reflection of heat, to minimize solar heat gain. This can be accomplished using spectrally selective glazing, which can selectively respond to different wavelengths of solar energy. It allows visible light to pass through while rejecting unwanted invisible infrared heat [28]. There are products available on the market that have successfully achieved this characteristic, permitting for much clearer glass than previously available for solar control glazing, as reported in paragraph 3.

In addition, complete glass façades need an accurate daylighting control to avoid excessive glare and heat. This is important primarily for two reasons: firstly, it reduces the amount of electrical lighting required, and secondly, because the quality of light from daylight is preferential to electrical lighting. It is proved that the health and productivity of office personnel are highly influenced by the quality of lighting in the environmental workplace; natural light is particularly relevant for well-being and mental health of the occupants [28].

A classification system to assess and compare different kinds of double skin façades is proposed, by considering their main characteristics regarding building construction and their environmental behavior, related to the ventilation system.

According to these parameters, a categorization can be done by considering different typologies of construction and cavity ventilation [29].

Based on their construction features, façades can be classified by full height, corridors, or cells, depending on the air cavity dimension and division. An appropriate design of the air space is crucial to the double façade.

In full height façades, the façade is undivided from the bottom to the top, creating a unique air cavity that benefits from the stack effect. On warm days, hot air collects at the top of the air space. In certain cases, the undivided air space can be a big atrium, in which people can stay and enjoy this "environmentally dynamic interstitial space" [30] that can be used for spaces with low occupancy (meeting rooms or cafeterias). Sometimes, vegetation is used instead of traditional shading devices, to improve air quality and well-being [31].

Corridors façades are divided by floor, best for fire protection, heat, and sound transmission, or divided vertically into bays to optimize the stack effect.

This kind of construction is commonly used when it is needed to have fresh air and exhaust intakes on every floor, allowing for maximum air changes. When the cavity is divided into vertical corridors, air flows across the façade through openings, allowing for better natural ventilation.

A third typology consists of high prefabrication elements—one floor high—ready to be installed, that are called cells. Double layer glass cell façades have a floor-byfloor divisions that allow a construction speed by a simple repeating unit, which can maximize ventilation thanks to fresh air and exhaust intakes on every floor. Moreover, the compartmentalization of the air cavity divided into small zones improves fire security, noise requirements, and heat transfer from one section to another (**Figure 4**).

Another classification can be made according to ventilation.

When ventilation is natural, the air entered from the bottom, warms thanks to the sun radiation across the glass panes. Hot air rises according to natural physics principals until openings at the top of the cavity allowing expelling it out and replacing it by

**Figure 4.** *Different types of double glass skin. From left to right: full height, corridors, cells.*

cooler air drawn in from the outside. Sometimes, especially in hot climates—when there is the risk of low pressure and lack of stack effect—the offices on the top floors can suffer from overheating due to the accumulation of hot air in the cavity adjacent to their space. For this reason, it is a good practice to insert mechanical air vents to assure the hot air will be discharged [32].

In this configuration, the single-glazed outer skin is used primarily for moderate to extreme temperature within the façade and for the protection of the air cavity contents (e.g., shading devices). External single glass is generally safety or laminated glass, while the internal skin offers the insulating properties to minimize heat loss (double or triple glass) [33].

Natural ventilation includes the necessity of openings in the outer skin (moveable glass panes or grids), while windows on the interior façade can be opened or not. Ventilation openings in the inner skin allow the building's users access to airflow that can be used to cool and ventilate the space.

The exterior glazing of the double skin creates a layer that in most case can be accessible by the inhabitants for natural ventilation: This buffer zone is a key component of the naturally ventilated double skin façade, typically 60-90 cm of thickness, and can include plants and vegetation to mitigate the temperature.

Furthermore, the use of internal moveable windows can allow for night-time cooling of the interior thereby lessening cooling loads of the building's HVAC system.

In double layer glass façades with forced ventilation, the air space between the two layers of glazing becomes part of the HVAC system. In this configuration, the thermopane units (optimal U-value) are placed on the external of the main façade of double glazing. In winter, the heated air between the glazing layers flows through the cavity and the outer layer of insulating glass minimizes heat-transmission loss. In summer, fresh air is supplied by HVAC through the cavity and contributes to the façade cooling.

Numerous studies prove that double skin façade presents many advantages over a conventional—single skin—façade [34–36]. A double skin dynamic envelope in a cold temperate climate, like the United Kingdom, can reduce energy consumptions by 65%, running costs by 65%, and cut CO2 emissions by 50%, compared to a single skin building. The same study reports that cost exercises of buildings employing a double skin façade may cost as little as 2.5% based on gross internal floor area [37].

Regarding sustainable design, the double layer façade offers strategies of solar heat gain control, increased daylight, moderation of temperature, and natural ventilation strategies to improve the thermal behaviour of the building. The ability to engage and *Smart Façades: Technological Innovations in Dynamic and Advanced Glazed Building… DOI: http://dx.doi.org/10.5772/intechopen.113127*

control these environmental aspects inevitably leads to increased energy efficiency and improved occupants' comfort.

Significant studies in sustainable architectural design have shown that construction cost of double layer glass façades can be two or three times higher than a traditional curtain wall, anyway double skin buildings can significantly reduce overall long-term operating/energy costs making the increased initial capital costs justifiable (affordable). The goal of these systems is not only to be environmentally responsible but also to greatly improve working conditions for the occupants of these buildings through access to day lighting, natural ventilation, and greater control over the workplace atmosphere. Moreover, a double skin system also offers a choice for renovation of existing building façades to transform into more energy efficiency buildings and improve the architectural value.

#### **3.2 Strategies to control summer overheating**

Over time, glass, a material that once performed only the function to allow the entrance of light, has evolved into a dynamic filter, capable of assuming a more interactive role in managing the internal environment of buildings.

Various experimental and groundbreaking glazed systems, encompassing a broad array of functions and applications, are currently accessible in the market or, at the very least, in the developmental phase, having different features from many points of view.

This group includes what is referred to as "dynamic glazing," fenestration products capable of altering their performance attributes by modifying their characteristics of transparency, gloss, coloration, and solar radiation screen while maintaining the structural properties of the glass [38].

Dynamic glasses, otherwise defined as "smart windows," can be controlled through a variety of means, enabling end-users to govern the interactions between external conditions and the internal environment. This capability results in the creation of a smart, adaptive building envelope that contributes to cost savings related to heating, cooling, and lighting.

Therefore, the massive adoption of these innovations holds the potential for substantial decreases in energy usage and, by obviating the need for supplementary devices to regulate incoming solar radiation, also in costs, maximizing at his best natural daylight while minimizing issues like glare and heating/cooling demands.

To fully understand the potential of these glazing components, a brief description of the most promising glazing technologies has been compiled, drawing from recent literature on the subject. These technologies have been categorized based on their performance characteristics, whether they are equipped with static or active features.

#### *3.2.1 Static performance glazed components*

Static performance glazed components are technologies that act passively on the control of incident solar radiation, thus meaning without varying their performance feature over time.

An example of passive solar control is provided in glass treated with metal oxides, during the production process. This is the case of tinted glasses, in which the applied oxides allow to vary color and optical properties of glass, conferring to it the ability to absorb certain sections of incident solar radiation, thereby reducing the amount that passes through them. Normally, the coloring is achieved using ionic or phasedispersed color substances, formed by particles' aggregates that affect the level of

transparency as they lead to light diffraction and reflection due to the particles dispersed throughout the glass material. A colored glass with discrete properties should block solar energy wavelengths ranging from 800 to 2000 nm, still maintaining a reasonable level of visible transmission. Thermal transmission in a room with tinted glass can be reduced by more than 20% [39].

The application of metallic oxides in the form of coating can generate also reflective glasses, in which the pane's reflection toward near IR is increased; they are characterized by a predetermined selective reflection toward solar radiation and by a low SHGC. Compared to tinted glazing, reflective glasses have significant effects on diminishing solar transmission; this attribute makes them a favorable choice for regions characterized by climates where the reduction of solar heat gain is crucial, particularly in cooling-dominant environments.

Acting on the emissivity of the glazed panes allows to reduce heat exchanges through them, without compromising their transparency. This is the case of lowemissive glasses (Low-E), transparent toward solar thermal radiation but reflecting regarding IR radiations. A weak point of Low-E is that they multiply the effect of thermal solar radiation, increasing overheating as well; for this reason, they are particularly suitable to be applied in heating-dominate climates (rigid climatic contexts) where high solar factor (SHGC) is required, as well as a low thermal transmittance coefficient (U-factor). Employing Low-E in Insulated Glass Units (IGUs) allows to obtain thermal transmittance values between 1.7 and 1.0 W/m2 K, for double glazing, and lower than 0.7 W/m<sup>2</sup> K for triple glazing, reducing solar heat gain through windows up to the 48% [40].

Combining the thermal insulation property of Low-E with the sun-blocking features of reflecting glasses results in selective glasses. These glasses utilize coatings to hinder the entry of infrared radiation, while maintaining controlled levels of light transmission and simultaneously restricting the solar factor's impact. These selective coatings filter the electromagnetic waves, admitting most of the incoming solar radiation in both visible and near-infrared spectra. However, they reflect long-wave radiations (far-IR) emitted by warm objects inside rooms. This approach has the effect that during the winter season, when solar rays are inclined—typically parallel to the slender glazed element—the radiations can permeate the system, triggering the greenhouse effect, exploited in passive thermal energy strategies to decrease heating demands (**Figure 5**).

Other static-performance glazing technologies are Vacuum Insulated Glasses (VIG) and TIM (Transparent Insulating Material) glasses. Both are fully available on the market but still with a quite high cost.

#### **Figure 5.**

*From left to right: tinted glass at Miami International Airport; reflective glass at Mann Island Development Building; selective glass at the Blue Pavilion, Fiera del Mare, Genova.*

#### *Smart Façades: Technological Innovations in Dynamic and Advanced Glazed Building… DOI: http://dx.doi.org/10.5772/intechopen.113127*

Standard VIGs consist of two glass panes, generally of low emissive, set apart by a vacuum cavity. The benefit of this technology is the combination of an exceedingly thin profile with highly effective thermal insulation characteristics<sup>1</sup> , due to the vacuum in the space between the glass panes, which prevents convective exchanges between them. However, they still present some shortcomings; these encompass vulnerabilities to pressures originating from wind and vibrations that could impact the glass surface, as well as the challenge of maintaining an airtight seal along the edges to prevent the reestablishment of conduction to its normal level.

TIM glazing systems instead comprise in the space between two glass' panes a transparent or translucent insulating material [19], combining diffused lighting features with very limited thermal losses<sup>2</sup> [43].

With their translucency (typically having a SHGC equivalent to that of a standard IGU), these materials enable the dispersion of natural light, encompassing both direct and diffused illuminations. This feature proves advantageous in spaces where there's no necessity for complete visual transparency to the external environment, effectively averting instances of glare.

TIMs are generally classified under four categories, according to the structure of the TIM layer; TIM glazing systems generally employ plastic capillaries or honeycomb structures insulating materials that can be made of polycarbonate, poly-methylmethacrylate, or aerogel [44]. Nonetheless, a limited number of investigations have delved into the thermal and optical capabilities of glazed systems incorporating Transparent Insulation Materials (TIMs), as the majority of prior research has primarily focused on their usage within solar collectors and solar walls [45].

Another worth-mentioning technology is the one employed in Heating Glasses (HG) where an electrically connected metallic coating is introduced to the inner pane of an IGU; upon applying a low voltage, this coating heats up and directs warmth toward the interior, effectively minimizing heat loss through the transparent surface. These systems completely remove the risk of condensation between glass' panes, contributing also to the heating system of the entire building, as they generate about 0.42 Kw/m<sup>2</sup> of heat. Typically, heating glasses require 100–300 W/m2 to operate, resulting in a pane temperature of roughly 40°C. If used solely for preventing condensation, their operational power can be reduced by half.

Appeared on the market in 1980, now heating glasses are produced by several companies all over the world; among the others, significant is the device produced by Vitrius Technology since it can re-calibrate and re-program itself in real time, improving its performance based on end-user needs.

#### *3.2.2 Dynamic performance glazed components*

Contrary to static performance components, dynamic performance systems, otherwise called "smart glazing," can modulate their optical characteristics according to different inputs of various natures. Smart glazing technologies can be active if they change using external signals (such as electrical direct currents) or passive if they automatically respond to environmental variations, such as air temperatures or solar radiation.

<sup>1</sup> VIG systems reach for a U-value of about 0.4 W/m<sup>2</sup> K [41].

<sup>2</sup> A study [42] reveals that the presence of a TIM structure can suppress convective heat transfer through the windowpanes and cause a significant reduction in radiative heat transfer.

Active systems comprise of technologies based on Electrochromic (EC), Gasochromic (GC), Suspended Particles Devices (SPD), and Liquid Crystal Devices (LCD), while Thermochromic (TC) and Photochromic (PC) technologies are examples of passive smart glazing types.

Electrochromic glasses are systems capable of altering their light transmission characteristics, usually achieved by modifying their color and optical attributes after the application of an electric field. ECs are obtained by introducing a layer of micro-liquid crystals between two glass panes within the gap. These liquid crystals facilitate reversible electrolytic reactions that, when exposed to a potential difference, can change their coloration to the extent of becoming transparent [46].

During the transition, light transmission of the system modifies from about 1-4% (in the opaque state) to 60–63% (in the transparent state); the SHGC instead stays between 0.63 and 0.26 for the clearest state and between the 0.31 and 0.04 for the darkest state.

Once the change has occurred, no electricity is needed for maintaining the shade that has been reached.

The speed at which EC devices switch can range from a few seconds to several minutes, according to the type of technology used and the size of the window.

Most of today's available devices function in either on- or off-states only, although technologies enabling adjustable degrees of transparency can be readily implemented [47].

Recent progresses in EC materials, particularly those based on transition-metal hydrides, have resulted in the creation of hybrid systems with reflective properties. These systems shift from being absorbent to reflective, allowing them to alternate between transparent and mirror-like states. While these materials adhere to the foundational concept of conventional EC, they approach the issue differently: transitioning from a transparent state (when inactive) to a reflective state upon the application of voltage.

Additionally, the exploration of self-powered EC glazed components activated by photovoltaics (PVs) has been undertaken [48]. However, their transparency is substantially limited due to the presence of the PV layer. These devices employ sputtered titanium and tungsten oxide films as the electrochromic layer, combined with a photoactive layer composed of dye solar cells, often constructed using dye-sensitized titanium oxide (TiO2) [49].

Gasochromic glasses are obtained by introducing a gasochromic layer between two transparent panes. This layer reacts with a mixture of diluted hydrogen gas (usually combined with Argon), resulting in a color change and alteration of the system's transparency due to a catalytic reaction with the glass composition. The degree of transparency in these devices depends on the quantity of hydrogen the gasochromic layer has been exposed to. GC glasses maintain unobstructed visibility from the interior to the exterior in all operational states.

Tungsten oxide is the most used material for GC applications [50], often accompanied by a thin catalyst layer, although devices employing a thin layer of Wolfram are also accessible.

The alteration in the transmission characteristics of glass enables a reduction in both visible and overall solar energy transmittance rates of an IGU, reducing them from 0.63 and 0.49 to 0.20 and 0.17, respectively (when the interior pane is coated with a conventional low-E coating). By introducing a solar-control coating, even lower SHGC values can be achieved.

*Smart Façades: Technological Innovations in Dynamic and Advanced Glazed Building… DOI: http://dx.doi.org/10.5772/intechopen.113127*

In contrast to other passive smart glazing systems, GCs require additional control equipment, such as a gas supply unit and a control unit. The gas supply unit encompasses an electrolyzer and a pump, linked *via* pipes to the glazing system in a closed-loop arrangement. Ideally, this gas supply unit is integrated within the external façade of the building. A single gas supply unit has the capacity to furnish sufficient gas to activate gasochromic glazing covering an area of 10 m<sup>2</sup> [51]. On the other hand, the control unit facilitates both manual and automatic regulations. When integrated into a bus system, this unit allows the glazing to be switched, optimizing lighting conditions, thermal comfort, and/or overall building energy consumption.

SPDs are electroactive devices in which the application of an AC voltage prompts particles to transition from a random arrangement to an aligned one, becoming the glazed components transparent. In the absence of an electric charge, SP windows absorb light, leading to a reduction in light transmission. The typical ranges of light transmission and SHGC—when transitioning between transparent and opaque states—are approximately 60–0.5% for VLT and 0.57–0.06% for SHGC, with switching times of some seconds.

Simulation outcomes have demonstrated that switchable SPD smart windows, when in the off and automated states, can result in a net energy reduction of up to 58% compared to double-glazing low emissive IGUs [52].

Conversely, LCDs employ materials with a bars-molecular structure that, under the influence of an applied voltage, can alter the light transmission characteristics of the systems; most of the LCDs tend to disperse light, leading to their becoming white and semi-transparent [51].

Typically, LCDs consist of a layer containing droplets dispersed within a polymer matrix. When the voltage is off, these droplets scatter light due to the disparity in refractive indices between the matrix and the droplets.

In the active state, the light transmittance of liquid crystal glazing does not exceed 70%, whereas in the inactive state, it remains around 50%. These systems diffuse direct incident solar radiation without effectively blocking it, which results in a SHGC usually ranging from 0.69 to 0.55.

In contrast to SPDs, these systems are primarily used for privacy applications [53] and need of a continuous supply of electrical energy to remain operational.

Thermochromic are glazed systems in which a temperature variation triggers a response in the material. This reaction enhances its reflective capability, making it particularly responsive to IR. Consequently, there is a modification in light absorption related to the external surface temperature, making these devices opaque when reaching a critical temperature (specific for each product).

In general, the most employed TC technology is the one that uses tungsten trioxide or vanadium dioxide (VO2) coatings to obtain this reversible behavior [54]. VO2 is the most common material, despite its many shortcomings as the high transition temperature, comprised between 10°C and 65°C, so much higher than indoor temperatures [55]. To address these limitations, alternative approaches involve incorporating additional substances like W and F into VO2 to lower its transition temperature, or utilizing specialized gels placed between the two layers of plastic film.

Nevertheless, this leads to a reduction in the VLT of these systems. To counteract this effect, anti-reflective coatings are applied to increase it [46]. Another notable limitation of traditional fully passive thermochromic technology is its inability to adequately adapt transparency based on outdoor climate conditions. While it does regulate solar radiation, it overlooks the indoor temperature rise due to heat entering per convection [17]. However, these systems maintain a relatively low cost in comparison with more complex alternatives [56].

Photochromic glasses can vary their optical properties due to external lightintensity variations by means of the presence of organic or inorganic compounds that act as optical sensitizers [57]. Their conduction becomes reversible once the exposure to radiation stops; this reversibility is allowed by the breakdown of micro-silver halide crystals (chlorides, bromides, iodides), responsive to UV rays and contained in the glass mixture.

The transparency of these systems is related to the level of light striking the glass surface, as they adjust their transmission characteristics in response to intensity, duration, and type of incoming solar radiation. The more global solar radiation hits the glass pane, the darker it tints. The specific configuration of the system's response to varying global solar radiation levels can differ based on manufacturing methods, and it can be tailored to align with the preferences and requirements of users (**Figure 6**).

Generally, SHGC of PC systems varies between 0.48 and 0.31 (for the clearest state) and 0.41 and 0.22 (for the darkest state), while VLT varies between 0.78 and 0.13 (for the clearest state) and 0.73 and 0.09 (for the darkest state) [58].

Due to the ambient temperature's influence on the coloring process of photochromic glasses, with more pronounced effects at lower temperatures and minimal effects at higher temperatures, their applicability in building contexts is significantly limited [59].

Other relevant technologies are PCM systems, which incorporate Phase Change Materials to manage and reduce the energy demands of buildings during peak hours and mitigate fluctuations in building temperatures<sup>3</sup> . These systems leverage the concept of latent heat thermal storage (LHTS) to absorb energy and subsequently release it at different times.

Variable substances are viable to be used as PCMs, enabling the regulation of temperatures within a particular range, determined by the chosen material. PCM glasses typically enable the soft dispersion of natural light within spaces: In their solid state, PCMs allow around 28% of visible light to pass through, whereas in their liquid state, VLT rises to more than 40% [61]. Despite the existence of translucent PCMs [62], the effectiveness of these technologies in terms of transmitting high-quality light remains a drawback. Furthermore, PCMs still have limitations, including challenges associated with selecting the appropriate melting temperature, concerning about the

#### **Figure 6.** *Transition phase in a thermochromic glazed façade.*

<sup>3</sup> In a study [60], it was found that wall and indoor air temperature fluctuation is decreased by 2.7°C and 1.4°C, respectively, in a building that incorporates PCM; moreover, also energy demand was reduced by 57% during winter.

*Smart Façades: Technological Innovations in Dynamic and Advanced Glazed Building… DOI: http://dx.doi.org/10.5772/intechopen.113127*

flammability of paraffin, and the complexity of efficiently dissipating thermal energy from the material following extended periods of elevated temperature exposure.

#### **3.3 Renewable solar energy**

By considering that around 40% of the worldwide energy demand is consumed by buildings, "solar Architecture is not about fashion, but about survival," as Architect Norman Foster said, becomes a reality. Anyway, the planning of buildings with multifunctional, integrated façade elements capable of fulfilling the technical demands becomes an essential part of the architectonic mainstream and can contribute to an esthetic valorization.

#### *3.3.1 Semi-transparent PV*

The goal of energy change linked to greater use of renewables is successfully achieved when visual appeal and energy efficiency merge together: This architectonic feature finds its optimum in the semi-transparent photovoltaic systems. At the basis of the photovoltaic panel functionality, there is its ability to absorb solar energy and convert it into electricity, transforming photons into electrons (**Figure 7**).

The phenomenon is very similar to selective glass: In the case of transparent photovoltaic panels, a transparent luminescent solar concentrator (TLSC) is used to make the panels completely transparent like glass and, on the other hand, to allow them to absorb wavelengths of light nonvisible to the human eye, such as infrared and ultraviolet light [63].

Today, Building Integrated Photovoltaic (BIPV) can provide optimum U-value (ranging from 0.5 in triple glass glazing to 1.1 W/m<sup>2</sup> K in double glass), with optimum

#### **Figure 7.**

*The Hauptbahnhof, Berlin (Germany): Detail of the 1700 m<sup>2</sup> curved surface covered with 780 semi-transparent c-Si panels (Energy output: 180 kWp, Architect: Meinhard von Gerkan; System provider: Optisol, 2003).*

solar factor (G value) and light transmission (TL value) and in the main time to produce solar energy.

Semitransparent PV is formed by Solar PV Cells placed between two panels of glass.

The light transmission and the level of shading inside the building can be controlled and regulated by adjusting the distance between solar PV cells. The panels become transparent when solar PV Cells are positioned far apart; instead, when the cells are positioned closely together, they become semi-transparent and produce a shading effect. Apart from generating electricity, modules can be customized in different dimension, thickness, shape, and color.

Efficiency is quite lower comparing to traditional polycrystalline PV panels.

The average efficiency in intermediate seasons reaches values of about 7.5%, while the conversion efficiency is always calculated as the ratio between generated power and incident radiation, it reaches values equal to 15.5% [64].

Anyway, as this technology is widespread and can be used on a large scale, for example, to cover entire façades of buildings, its lower efficiency is destined to be overcompensated with greater surface development [65].

Semitransparent PV can reduce the carbon footprint of a building, improve thermal insulation, acoustic insulation, and comfort increase, and in general increase the environmental and sustainable value of a building, being a solution that joins functionality, utility, and design.

#### *3.3.2 Bio-adaptive glasses*

A novel emerging category of energy-generating glazed systems are bio-adaptive glasses, realized employing photobioreactors, commonly featuring algae as their main component.

Photobioreactors are transparent structures housing a "culture medium" that contains nutrients (typically water), in which microalgae circulate in accordance with the intensity of direct sunlight exposure [66]. These microalgae are consistently supplied with nutrients, and sunlight facilitates photosynthesis, leading to a responsive adaptation of solar shading levels.

Microalgae are often favored over other plant varieties due to their remarkable growth rates and their ability to sequester more CO2 as they can even double their volume within a week. Moreover, their capability to grow vertically makes them an ideal choice for integration of photobioreactors into building components.

The biomasses produced by bioreactors (the algae) can subsequently be collected for energy-generating purposes (i.e., as biogas to heat water); at the same time, they can capture solar-thermal heat, providing an energy source used to power the building.

This technology has been installed in buildings for the first time in the BIQ house, during the International Building Exhibition in Hamburg in 2013. SolarLeaf's bioreactors, conceived and developed by Arup in cooperation with SSC (Strategic Science Consult of Germany), have four glass layers. The two inner panes are designed with a cavity capacity of 24 liters to facilitate the circulation of the growth medium. Insulating argon-filled gaps flank these panes, contributing to the reduction of heat loss. The front glass panel is composed of white anti-reflective glass, while the rear glass panel offers the option for incorporating decorative glass treatments. A total of 129 modules of photobioreactors, each measuring 70 cm in width, 270 cm in height, and 8 cm in thickness, have been integrated into the façade of this building. With a cultivation area spanning 200 m<sup>2</sup> , this system produces 900 kg of biomass annually and generates *Smart Façades: Technological Innovations in Dynamic and Advanced Glazed Building… DOI: http://dx.doi.org/10.5772/intechopen.113127*

#### **Figure 8.**

*SolarLeaf bioreactor installed in the BIQ House in Hamburg (2013, Arup and Splitterwerk Architects).*

around 6000 kWh/year of energy. This energy output is sufficient to cater to the heating requirements of 4 units within the building [67]. For comparison, photovoltaic systems have an efficiency of 12–15% and solar thermal systems of 60–65% (**Figure 8**).

#### *3.3.3 Emerging technologies*

Strategies to improve glazing performance can be grouped into four family approaches: The first is the most "traditional one," which acts on the interspace of multilayer glazing assembly (IGU) by using films, low-conductance gases of thermally improved edge spacers, to improve insulation capacity of the system; the second is aimed at altering material composition (e.g., tinted glazing); the third approach involves the application of coatings onto the glass surface to alter hoe it reflects light (such as selective, reflective of low-e coatings). Finally, the fourth resorts to external inputs (whether they are passive or active) to modify the optical characteristics of the glass.

Despite their validity, these approaches still have some limitations; to overcome such issues, researches aimed at discovering new emerging solutions are existing. Some investigate the development of self-regulating window materials as an alternative to glass, such as the reversible thermochromic transparent bamboo smart windows [68], prepared by impregnating delignified bamboo (DB) with epoxy resin containing thermochromic microcapsule powders (TMP), which is colorless at high temperatures and purple at low temperatures, or the air-sandwich glazing systems [69], based on the idea of a set of plastic films, with spacers and air trapped inbetween, used as insulation.

Other promising technologies are those resorting to energy storage strategies. One such example is the High Thermal Energy Storage Thermoresponsive (HTEST) smart window [70], which encloses a hydrogel-derived liquid within glass panels. These panels exhibit impressive thermoresponsive optical attributes, boasting 90% luminous transmittance and 68.1% solar modulation. Additionally, the hydrogel-based liquid possesses remarkable specific heat capacity, contributing to the exceptional energy conservation performance of the HTEST smart window.

Unconventional types of smart windows also exist, including humidity-triggered smart windows, that alter light transmittance or window color based on humidity variations. This adaptation influences the transmission of both luminous and nearinfrared (IR) light, leading to modifications in transparency or coloration. There are also mechanochromic smart windows, constructed from optically responsive materials that undergo reversible structural adjustments, such as modifications in surface morphology and configuration, in reaction to basic mechanical strain. Consequently, these changes influence optical transmittance through scattering or diffraction of visible light. Moreover, magnetochromic smart windows operate by responding to magnetic field intensity. Changes in magnetic field strength cause nanoparticles to move closer together or farther apart, thereby controlling the smart window's behavior [71].

Again, some concepts concerning emerging glazing technologies are present in literature even if, to the authors' knowledge, they still do not find real development of market applications. Some of them are the Vacuum Tube Window Technology [72], described as a combination of evacuated glass tubes and a glazed frame with Argon in the air gap between them, the Water-flow window [39], originated from the concept of removing the heat stored inside IGU's air-gap thanks to water flooding; the Solarpond window [69] aimed at integrating into fenestration functions of lighting, heat collection, heat storage, heat preservation and photoperiod control, and the selfsufficient smart window [73] able to regulate the amount of light entering the buildings, varying its color from a transparent state to a blue state without adding energy electricity.

#### **4. Conclusions**

This study has allowed defining a synthetic but comprehensive set of requirements concerning several complementary aspects of glazed building components, ranging from architectural to technological, energetic, and economic features of innovative products for advanced glazed skins.

The relationship of façade systems with other building construction technologies has led to emphasizing and underlining the general opportunities for smart materials and solutions in the construction process as a technological and architectural chance, in a sustainable and affordable way.

To summarize the most relevant factors for each category of intervention, a multicriteria matrix has been defined, in which the façade solutions are briefly described and compared qualitatively by crossing the strategies of interventions with the main requirement set in **Table 1**, Paragraph 3.

The comparison between the strategies identified can be found in the tables included in Appendix A.

This can become a useful tool to define, at first glance, and design criteria and operational tools to guide the design of innovative envelopes, allowing targeted choices to be made about the foreseen interventions, to obtain the desirable levels of quality.

However, it has to be said that despite their potential to reduce energy consumption in buildings while increasing user's comfort<sup>4</sup> , the general application of smart

<sup>4</sup> Compared with traditional static windows, smart windows reduce total building energy consumption by approximately 10% [71].

*Smart Façades: Technological Innovations in Dynamic and Advanced Glazed Building… DOI: http://dx.doi.org/10.5772/intechopen.113127*

glazed façades is currently hampered by economic and technological factors. Although some of the technologies presented are already in the market, their widespread application is limited because of their elevated price and relatively low fatigue resistance; the main driver for building owners to install smart windows is the desire to eliminate the need for attached shades to allow full access to the outdoor views [74] even if very limited analyses are available on assessing their energy efficiency potential when deployed for residential buildings.

Besides this general overview, the real suitability of each component must be specifically evaluated for each single requirement in each context depending on the design needs.

#### **Acknowledgements**

The chapter is the results of a common reflection of the authors, based on their expertise in the specific fields of research.

Specifically, Silvia Brunoro was responsible of the Introduction "The evolution of glass façades performances. State of the art and scientific background" and of the sections "3. Methodology. Categories of requirements and performances," "3.1 Passive solar heat gain: double layer glass façades," "3.3. Renewable solar energy," and "3.3.1. Semi-transparent PV."

Valentina Frighi writes the whole section "2. The role of glazed components," and sections: "3.2 Strategies to control summer overheating," "3.3.2. Bio-adaptive glasses," and "3.3.3. Emerging technologies."

Conclusions are attributable to both the authors, so as the final revision of the work and the approval of the manuscript version to be published.

This work has been funded thanks to the FIRD2022 project "AWARE A multiscalar approach for a resilient and adaptive built environment" grant-aided by the Department of Architecture of the University of Ferrara.

#### **Conflict of interest**

The authors declare no conflict of interest.

#### **Appendix**

#### See **Tables A1**–**A3.**



#### **Table A1.**

*Matrix of the main features of façade solution systems for comparison: STRATEGY 1 – Passive solar gain.*


#### *Smart Façades: Technological Innovations in Dynamic and Advanced Glazed Building… DOI: http://dx.doi.org/10.5772/intechopen.113127*

**Table A2.** *Matrix of the main features of façade solution systems for comparison: STRATEGY 2 – Summer overheating control.*

*Construction cost is approximate and related to single glass pane, thus means non-referred to a IGU technical solution.*


**Table A3.** *Matrix of the main features of façade solution systems for comparison:*

*STRATEGY*

 *3 –*

*Renewable*

 *solar energy.*

#### *Fa çade Design – Challenges and Future Perspective*

*Smart Façades: Technological Innovations in Dynamic and Advanced Glazed Building… DOI: http://dx.doi.org/10.5772/intechopen.113127*

### **Author details**

Silvia Brunoro\* and Valentina Frighi Department of Architecture, University of Ferrara, Italy

\*Address all correspondence to: silvia.brunoro@unife.it

© 2023 The Author(s). Licensee IntechOpen. This chapter is distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/3.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

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#### **Chapter 7**

## The 7D BIM Model Used in the Estimation of the Useful Life of Façade Materials

*Alcínia Zita Sampaio, Inês Domingos and Augusto Gomes*

#### **Abstract**

The Building Information Modelling (BIM) methodology is supported on the concept of centralizing, in a parametric virtual model, all information related with the project, the construction and the overall lifecycle of a building. The building maintenance and management activities, requires the development of working facilities planned in an early project phase. The maintenance planning has been improved supported in BIM, as it allows professionals to easily retrieve, add and update the database of the BIM model. The definition of adequate maintenance strategies requires knowledge regarding the durability of the materials, mainly the degradation perdition of the materials. The present work is focused on the estimation of the useful lifetime of materials usually applied on the finishing of traditional building façades and terraces. Based on the knowledge of durability of the selected materials a Dynamo script was created allowing to obtain an estimation value concerning the degradation perdition of the materials. Other Dynamo script was developed oriented to the visualization of the degradation level of the materials. This innovative approach intends to support the maintenance engineers to make assertive decisions concerning the maintenance activity. In this study Dynamo programming improved BIM-FM systems integration, providing a positive contribution in construction maintenance context.

**Keywords:** BIM, 7D model, management planning, degradation prediction, wall's finishing, dynamo script

#### **1. Introduction**

Building Information Modelling (BIM) methodology offers a rigorous and complete representation of the building and presents a great potential to support the design, construction and occupation phases. However, the implementation of BIM requires an initial effort to train human resources, in order to acquire the skills mandatory in the use of the available tools, and a financial investment in the acquisition of new technologies and equipment.

The construction industry has been progressively incorporating the implementation of BIM methodology, supported by the permanent dissemination of its benefits recognised in reports and in recent technologic advances [1]. This methodology reveals a new and different way of working in the construction sector when compared to traditional methods based on two-dimensional (2D) technical documents. The BIM work transmits more transparency, better communication and a greater level of collaboration between all partners involved in the development of building projects [2]. When developing a project, using BIM platforms, a digital three-dimensional (3D) model of the physical and functional characteristics of the building in analyses is created. The model brings together the information produced in the various phases of the building life cycle forming a complete database supporting decision-makers [3].

The Facility Management (FM) activity, in a building, covers several disciplines in ensuring the functionality of the built environment integrating people, places, processes and technologies. The principal advantage that BIM can bring to this discipline is mainly related to the great capacity of storing a large volume of information, which normally is required in the maintenance activity [4]. The capacity to archive a great volume of data and allowing its accessibility with the connection to several FM systems make BIM strategies a very interesting perspective. During the occupation of a building, BIM implementation within the management and maintenance phases is not yet a recurrent concept, despite the benefits that have been reported. The research in this area, although it is currently growing, is still at an early stage [5].

The maintenance of a building starts immediately after its construction and ends with its demolition. It creates an accurate depiction of the physical conditions, environment, and assets of a facility. Currently, BIM-FM integration is still unusual. However, retrieving data from the model requires experience and relevant waste of time [6]. The FM professional is the 'expert in charge of a building whose concern covers operational issues of maintenance, cleanliness and safety of tenants'. The growing complexity of buildings and the significant cost of their administration has led to the need to introduce 'strategic and tactically based management functions', associated with other support activities such as the control of the human resources involved and the use of adequate and integrated software.

The present study intends to contribute to the reuse the information created and stored in the database of the model and its application in the maintenance activity in an integrated way [7]. The text introduces the current practices in BIM-FM and the main advantages and limitations in using BIM platforms, in the maintenance context. The study considers the development of two Dynamo scripts created to improve the integration of BIM models to FM functionalities. This innovative approach intends to support the management professionals to define adequate maintenance planning with the use of the created Dynamo scripts, to estimate service life of some frequent materials applied as finishing of exterior walls and roofs.

#### **2. BIM-FM integration**

The concept of Facility Management (FM) is understood as an interdisciplinary practice related to the management of buildings and facilities organised by the experts involved. The distinct applicability of BIM is referred to in the literature as the 'n' dimensions of BIM. Each dimension is associated with a set of distinct information, added to the 3D model, complementing it with the activities that can be elaborated, based on a selective retrieving and extraction from the 3D BIM model database [8]: the time factor (4D); the quantity and costs estimation (5D), simulation

#### *The 7D BIM Model Used in the Estimation of the Useful Life of Façade Materials DOI: http://dx.doi.org/10.5772/intechopen.112645*

of energetic consume (6D) and the operation process (7D). So, the seventh dimension comprises the application of BIM methodology in the Facility Management activity. This activity supported in BIM platforms can be improved with recognised benefits. It can enable procedures like archiving, retrieving and reusing a great volume of data that is normally required in the context of the activity [9].

The 7D model gathers the information regarding each component and space, the applied materials, their quantification and costs and the specific information required to support maintenance actions. These data englobes data relate to material enterprises, to technical documents the products, to warranties and to guide manuals [10]. The 7D model supports the professional to take on the management phase of every achieved and retrieved data. By combining the quality of the facilities with the active control of costs, the FM allows to increase the efficiency of the organisation that uses the building and improves the quality of the employees' work [11].

The FM concept is still relatively recent in the construction industry. The International Facility Management Association (IFMA) was created in the United States of America in 1978 and was integrated in 1984 into the European entity by the European Facility Management Network (EuroFM), in order to implement FM in the practice of construction, education and research. Since then, its importance has been increasing and recognised as necessary in the management of a building, along with its occupation [12]. Based on the usual requirements and practices used in FM, IFMA has identified the 11 main competencies related to FM activity [13]:


As the generation of a BIM model is based on the use of parametric objects, each component of a building includes a large amount of data such as the type of the applied materials and its related proprieties. In BIM-FM integration, the degree of interoperability performed between different software is the main limitation in applying BIM in the operational phase of the building [14]. However, using the native data format of the modelling system, the transfer process of information from BIM model to FM systems can be effectuated without loss of relevant information. Additionally, the model can be permanently updated, allowing the facility manager to update the building's operation services [15]. Therefore, it is possible to contribute to the reduction of investment costs and better facilities management services in a building [16].

Technological advances in BIM software and integration capacity aimed to improve the efficiency in supporting FM practices. BIM-FM integration allowed the development of a more comprehensive and reliable computational solution related to the collection, categorisation, visualisation and updating of information about the operation and maintenance of a building. This information must be complete, organised, accurate and accessible. The main challenge is to integrate the gathered information with the data acquired in the design and construction phases and the storage of this data in the BIM model, using adequate building management and operation systems [17].

The life cycle of a building involves several stages: The design of the project; the construction process; the building occupation; the demolition procedure. The phase of longest duration corresponds to the occupation of the building. To maintain the quality of the building, throughout this phase, it is necessary to carry out maintenance, conservation or renovation actions applied to the components of the building, in order to ensure the service conditions and to prolong the useful life of the building.

#### **3. Estimation of the service life of materials**

The service life period considers the definition of a minimum acceptable level for the performance of a building, depending not only on the evaluation criteria of the expert but also on the safety aspects, functionality for a given time or the environmental or regulatory context in which the assessment carried out is inserted. Considering this great diversity of influences, the prediction of the useful life of a building is difficult to estimate with accuracy. The value of the predate service life is estimated based on simple and linear mathematic models. In addition, a building does not age in a homogeneous way and its surroundings are subject to a high number of aggressive agents, resulting in a faster ageing rate when compared to the interior components [18].

The ageing process of the building encompasses a chain of events, directly conditioned, by the decisions implemented in the design phase and by the use or occurrences developed during the occupation period. The ageing mode also depends on the functional changes and constructive changes imposed, resulting from the technical evolution of aesthetic and comfort requirements, according to the users' needs. The components of the building are subjected to a diversity of deterioration processes, contributing to the ageing phenomenon [19]. The following prediction methods can be considered deterministic, probabilistic (or stochastic) and engineering methods [20].

The method considered in the study is the factor deterministic procedure. This method is a simplified approach that allows to calculate the estimated service life

#### *The 7D BIM Model Used in the Estimation of the Useful Life of Façade Materials DOI: http://dx.doi.org/10.5772/intechopen.112645*

(ESL) value for the construction materials. This value is obtained by the product of the reference service life (RSL) value by several values related with a set of deterministic factors (**Table 1**).


In order to obtain a correlative database, the bibliographical references of Raposo [21], Lopes [22], and Matos [23] were checked. In it, three cases of application of the factor method according to the guidelines of the ISO 15686-1 standard were analysed [24]. The preliminary bibliographic research was conducted to define the durability matrix of the database. The retrieved data concerns the required factors and are related to the materials analysed in the present study, namely, cladding applied on the flat roof (**Table 2**), adherent ceramic tiling finishing one façade and the ventilated façade tiling type. In the aim of the study, the developed Dynamo script uses the factor values listed in independent tables concerning each material.


#### **Table 1.**

*The factors that interfere with estimation of the service life value.*


#### **Table 2.**

*Factor A of the durability matrix of cladding applied on terrace roofs.*

#### **4. Visual programming in dynamo**

Deterministic methods are based on the analysis of the factors and mechanisms that affect the degradation of the constructive elements, under the normal conditions of use, allowing for quantifying the level of degradation of the material. The present study proposes to include the factor method for estimating the service life of elements in construction. It involves the development of two scripts, using the visual programming tool Dynamo [25]: the 'Estimate Service Life' script and the 'ESL Analysis'. The scripts were applied over a case study allowing verifying its efficiency.

#### **4.1 Dynamo script 'Estimate Service Life'**

The tables of durability matrices previously created were used to support the development of the script 'Estimate Service Life'. The tables were integrated into the script so that the options of each factor can be selected according to the element and material used in order to estimate the respective service life value. The script can run over projects modelled in Revit and applied over the considered constructive elements: roof waterproofing membranes; adherent ceramic tiling on façades; ventilated façade claddings.

After obtaining the ESL value, for each of the elements under study, it is possible to make a prediction of the state of degradation of the elements for the horizon of a given year. The degradation process follows an incremental and uniform evolution. A set of colours was assigned according to the range in which the calculated % of useful life is. The script 'Estimate Service Life' was created using Dynamo visual programming whose main structure is represented in **Figure 1**.

In the development of the script 'Estimate Service Life (ESL)', it required the installation of the package Data-Shapes, which allows the programmer to collect

#### **Figure 1.** *Dynamo script 'Estimate Service Life'.*

#### *The 7D BIM Model Used in the Estimation of the Useful Life of Façade Materials DOI: http://dx.doi.org/10.5772/intechopen.112645*

various types of user inputs depending on the type of data to be inserted. This package is very flexible, allowing an easy control of the type and order of input data to be considered. The Code Block node, available in Dynamo standard library, is responsible for the insertion of various types of data. The connection to each entry in the master node is made through the use of lists. Due to the high volume of information to be presented in the interfaces, it was decided to use the Python Script node for the creation of the lists, simplifying the programming in the Dynamo interface.

To connect the tables inserted in the database to Dynamo it was necessary to instal the Slingshot package. This package presents a collection of nodes used in the database management system. They allow the connection and communication to the databases created in MySQL and SQLite formats, using the SQL language.

The inputs of the Dynamo script can be easily adapted to the needs of the user. The scripts can be configured to request input data prior to triggering the script. To perform this the Boolean node, selected as an input command, accessed in Dynamo menu, was set as input data for Dynamo Player. The Boolean (True or False) node displays the false option and deletes the data recorded in the last use of the script; the true option allows you to run the program and display the interface for a new use.

The selection of the project site allows us to suggest filling options for the factor E (to be addressed later) related to the characteristics of the outdoor environment. As an example of localization, the Lisbon, Porto and Algarve options were incorporated, chosen because they are associated with the examples used in the script programming. The interface also allows you to enter the type of fixation of the coating, variable according to the support structure chosen for the ventilated façade, and the data for identification of the technician. In this case, the fastening system chosen is a sight fastening system using clips.

#### **4.2 Generation of the 'ESL analysis' script**

The 'ESL Analysis' script was developed in association with the 'Estimate Service Life' script and allows:

#### **Figure 2.**

*Dynamo script 'ESL analyses' and the assignment of colours.*


For each model component associated with the ESL parameter, the obtained ESL value is assigned. Based on it is possible to make an evaluation of the degradation state of the material for a given year. According to the value of ESL, the related percentage is considered, and the component presented the colour assigned to the respective interval of values. An initial degradation state corresponds to the green colour and an advanced degradation state is related to the red colour. In the second script, a set of colours was allocated according to the level of the achieved deterioration, in which the *% of lifespan* is established (**Figure 2**).

### **5. Application of the scripts**

The selected building case, located in Lisbon, is composed of eight floors and a terrace. Using the Revit software (Autodesk), the architectural BIM model was created, having been modelled with a great detail, namely, the coatings applied to the façades and the roof (**Figure 3**).


For the representation of the walls, new parametric objects were created. A first selection of a wall is made from the available elements of the library of the system in use. The adaptation of objects related to walls is made based on the addition of successive layers in their composition, being assigned the type of material appropriate to each layer and indicating the respective thickness. The materials defined as membranes do not assume any thickness. Materials can be selected from the library of predefined materials, characterised with parameters related to graphic appearance and thermal and physical properties, controlled through the interfaces.

**Figure 3.** *Main façade with tiles (a), rear façade with fibre cement (b) and flat roof (c).*

*The 7D BIM Model Used in the Estimation of the Useful Life of Façade Materials DOI: http://dx.doi.org/10.5772/intechopen.112645*

#### **Figure 4.**

*Double wall in brick masonry (11 + 15 cm) with porcelain stoneware coating and wall in ventilated façade with fibre-cement plates.*

The materials available in the system can be adapted to the graphic characteristics and properties required in each specific case. In the present case, there were selected materials close to those required, and later carried out the modelling of the outer cladding layers of the walls, adapted to the intended solutions. The layers of the coating materials applied to the façades were porcelain stoneware and fibre-cement boards (**Figure 4**).

The parametric objects used in the modelling process of the building were incremented with the necessary parameters related to the ESL of the components under analysis. The mentioned parameters, ESL and % lifespan, were assigned to the materials applied in both façades and the terrace roof. This allows the user to calculate the respective values obtained from the generated Dynamo scripts:


#### **5.1 Execution of the 'Estimate service life' script**

The execution of the script is running through Dynamo Player option included in the upper menu of Revit. The script was successfully executed to estimate the service life of each of the materials identified and the result is visualised in **Figure 5**.

A table with the numerical results can be accessed and the aspect of the deterioration is illustrated by the colour assumed by each element. A period of ten years, from year 2020 and 2030, was tested. These years were referred to as the construction stage and a life forecast year.

#### **5.2 Execution of the 'ESL analysis' script**

Like the 'Estimate Service Lifetime' script, the 'ESL Analysis' script can be triggered through the Dynamo Player window. Having been configured as inputs of this script the selection of the elements in the created view and the Boolean node,


#### **Figure 5.**

*Visualisation of the degree of deterioration and respective values.*

it is possible to proceed to the selection of all the elements present in the view 'Analysis of useful life' where the two façades and the roof under analysis are inserted. Next, the 'VUE Analysis' script requires the indication of the year of construction and the year for which the user wants to make the prediction of the state of degradation of the element under analysis. In the lower area of the interface, it is displayed the colour legend that has been assigned according to different intervals of the % lifetime value. The execution of each of the scripts over the case study went smoothly and no errors were reported by Dynamo. After, an Excel table is obtained and exported supporting professionals to define or verify maintenance actions or plans.

This script considers the prediction of the useful life, in a global way. In the second script, an adequate colour is associated to a complete element (façade or terrace), and, as so, it not possible to define distinct zones or areas of an element with different level of deterioration. It allows to make a general comparison between the elements of the building and can even lead to rethinking the choice of some materials so that they are closer to the life of the project. However, in a more realistic situation, a more fragmented modelling of each of the elements could be applied.

#### **6. Results and discussion**

In the occupation-building phase, the BIM methodology can be implemented in order to improve the maintenance activity, namely, in the support of retrieving the required information within the database of the model and in the capacity of promoting an agile handling of data used for maintenance propose. The principal aim of the study was to incorporate into the BIM model, which must be created for each building in analyses, the degradation perdition value concerning some of the components of the building, with an important role in the exterior protection of the building, the façades and roofs.

Using the perdition value, a new strategy of visual impact was introduced supporting experts to improve their studies and easily present results to other partners

#### *The 7D BIM Model Used in the Estimation of the Useful Life of Façade Materials DOI: http://dx.doi.org/10.5772/intechopen.112645*

and building owners, as it is possible to observe with distinct colours applied over the model, the level of degradation of the components for a horizontal period of time. In it, two Dynamo scripts were developed.

The application of the scripts developed for the case study allowed to achieve the objectives intended for the study, allowing to make an analysis of the durability of the elements to be applied in the building under study, in the design phase where the solution changes have less impact at the global costs. However, the BIM objects did not have the necessary parameters for the application of the factor method. It needs to include the reference useful life (RUL) found in the digital catalogue of each material, in order to evaluate the durability of the constructive elements in the project to which they are applied, taking into account all the factors to be filled in by the maintenance expert.

However, for the application of these scripts to a BIM model, it is necessary to create the design parameters: ESL, Excel Maintenance, % Useful life and the parameters related to costs, such as mentioned, because that's what they were called when programming was done in Dynamo. At this point, it was necessary to include, in the definition of each script, the creation of these parameters, using the node Parameter. Whenever the script was executed, the parameters were created and in the next execution, there was duplication of parameters. It would be more efficient if these new parameters were added directly and previously in Revit. Alternatively, one could proceed to the programming of independent scripts to create the necessary parameters, but the goal was to be all integrated into the same script.

The export of all the information to Excel was successful, and Dynamo proved to be a good programming software to collect and manage information from the initial model for the maintenance phase such as the composition of the elements, the corresponding area and the associated costs that served as the basis for the proposed maintenance plan. The file is also available from the BIM model, which can be accessed by selecting the Excel Maintenance parameter of the respective element and can be updated throughout its useful life.

#### **7. Conclusion**

Programing in Dynamo improved BIM performance concerning the maintenance activity, namely, concerning the estimation of the service live values of the selected materials, frequently applied in façades and terraces as finishing elements. The developed scripts allowed an analysis of the durability of the elements in the design phase where the change of solutions has less impact on overall costs. These scripts, elaborated for the presented study case, can be easily adapted to other components of the building and to other buildings. Two new parameters must be added to parametric objects representative of other components, of the present model, or of other building cases, and then the described procedure can be applied.

The application of the scripts developed for the case study allowed to achieve the objectives intended for the study, allowing to make an analysis of the durability of the elements to be applied in the building under study in the design phase where the change of solutions has less impact on the level of general costs. In it, it was necessary to assign new parameters for the application of the factorial method. Highlighting the need to include the reference useful life (ESL) in the digital catalogue of each object in order to evaluate the durability of the constructive elements in the project to which

they are applied, taking into account all the factors to be filled in by the technician. The execution of each of the scripts for the case study went smoothly and no errors were reported by Dynamo.

In addition, an architectural BIM model was developed, where only the essential steps for the modelling of the analysed elements were described, also illustrating the insertion of some types of data and additional parameters in order to enrich the BIM model with relevant information for this analysis. It is also notorious for a computer aspect in the skills of a civil engineer that increasingly tends to be necessary to explore more complex scenarios. This led to the learning of visual programming in Dynamo, and the textual syntax language in Python was also used to achieve the desired objectives through a self-learning process using tutorials available online that allowed us to explore the capabilities of this tool. Since the use of the BIM methodology is increasingly evident and the curricular plan attended does not guarantee appetite in the field of this application, this work allowed to acquire knowledge of its use.

The proposed approach supports the maintenance engineers as decision-makers concerning the maintenance activity. The developed Dynamo scripts improved the BIM-FM activity, providing the maintenance engineer with a prediction of the service life of the materials analysed, and bringing a positive contribution in the context of the building maintenance.

#### **Author details**

Alcínia Zita Sampaio\*, Inês Domingos and Augusto Gomes Deparment of Civil Engineering, University of Lisbon, Lisbon, Portugal

\*Address all correspondence to: zita.sampaio@tecnico.ulisboa.pt

© 2023 The Author(s). Licensee IntechOpen. This chapter is distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/3.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

*The 7D BIM Model Used in the Estimation of the Useful Life of Façade Materials DOI: http://dx.doi.org/10.5772/intechopen.112645*

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### *Edited by Chiara Bedon, Marcin Kozlowski and Mislav Stepinac*

Façade design is a challenging task, in which multidisciplinary issues and aspects should be optimally considered and addressed. This is especially the case of building façades exposed to seismic events, impacts, or fire. Special attention and major efforts are required for the detection and application of new technologies in the generation of modern, adaptive façade systems. This book presents a selection of research contributions to provide a comprehensive overview of façade design. It discusses the experimental analysis and numerical investigation of existing or traditional façades, as well as the development and optimal application of new technologies for modern adaptive façades and building envelopes.

### *Assed Haddad, Civil Engineering Series Editor*

Published in London, UK © 2024 IntechOpen © Jarwis / iStock

Façade Design - Challenges and Future Perspective

IntechOpen Series

Civil Engineering, Volume 4

Façade Design

Challenges and Future Perspective

*Edited by Chiara Bedon,* 

*Marcin Kozlowski and Mislav Stepinac*