**6.1 Options for wireless service**

The first point highlighted in the study is that building occupants are now demanding increasingly higher data rate, as new applications are emerging. Examples of these are: Augmented Reality (AR), Virtual Reality (VR), Mixed Reality (MR), and Extended Reality (XR). The global mobile data traffic is expected to increase from 19.01 exabytes per month in 2018 to 77.5 exabytes per month by 2022, at an annual growth rate of 46 percent [7].

The wireless connectivity in the building can be supported by many different technologies, as shown below.

	- For IoT devices, Narrowband-IoT (NB-IoT) or Extended Coverage GSM (EC-GSM) can be used.
	- In-Building Solutions (IBS): femtocells, picocells and Distributed Antenna System (DAS)
	- Bluetooth and BLE (Bluetooth Low Energy): Originally, standardized as IEEE 802.15.1 for operation in ISM radio bands.
	- ZigBee: Standardized as IEEE 802.15.4 for operation in ISM radio bands.
	- Thread: An IPv6-based, low-power mesh networking technology for IoT products.
	- Z-Wave: A low-power mesh networking technology, primarily used for home automation.
	- Sigfox: A global cellular based network operator that supports IoT products at low-power.

*Internet Connectivity in Building Interiors: Architecture and Sustainability Considerations DOI: http://dx.doi.org/10.5772/intechopen.95968*


The chosen option for any particular building, will be affected by the geometry of the space, and its material quality. Therefore, contributions from architects can ease the job, towards ensuring proper wireless coverage and connectivity. Architects and RF engineers can complement each other, to address the growing challenge better. Green architecture considerations, apart from the physical features of the built spaces, can incorporate suggestions for various other measures, for example, solar panels, thermal mass building construction, green materials, including wood, stone, or earth, recycled waste materials, and so forth.

Architectural intervention can improve wireless signal coverage, by ensuring maximum signal power, minimizing interference to its path. Such intervention is significant, since the building will undoubtedly last much more than a few decades, and should thus be ready for the rapid changes that are predicted in the wireless support arena. However, there has not been enough engagement of architects in this area so far, and mostly, analytical discussions have been made in this regard [8], restricted within RF engineering circles, often beyond the knowledge of Architects.

#### **6.2 Shifting gears: from 4G to 5G**

4G has changed the life of people, but 5G is set to change society in its entirety. While the key focus of the developers for generations up to 4G, has been to improve data rate support, 5G has an additional focus, which is to support numerous use cases, with diverse technological requirements. These use cases are categorized with three basic types of requirements as shown below [9], all of which are seeing increasing applicability in new urban paradigms:


The categorization of various use cases towards the three classes for 5G is illustrated in **Figure 2** [9].

Another complication in wireless connectivity, arises from the rapid changes taking place in the related technology. Due to the exponential growth of internet use, the lower frequencies of propagation are getting saturated. Service providers have incrementally shifted from 2G to 3G to 4G in the space of fewer than

*Green Computing Technologies and Computing Industry in 2021*

**Figure 2.**

*Categorization of various use cases towards the three classes for 5G [9].*

2 decades, and are now geared to shift to 5G coverage. So cellular operation, functioning at frequencies below 6 GHz, were suitable for systems designed for propagations up to 4G. However, the need for 5G cellular systems is to encompass much higher frequencies – starting from 500 MHz to 100 GHz. The BUET study [6], identified the following issues as the reason for wireless service in the buildings becoming increasingly challenging:


Ensuring proper radio coverage gets much more challenging, as the frequency increases, which is displayed in the three categories of use cases fit into the spectrum of 5G (**Figure 3**). Evidently, IoT based applications, typically, require low data rate and extended coverage, and thus, they suit lower frequencies. On the other hand, HD videos, VR, and other high data rate applications, require wide bandwidth and thus, high frequencies are used to facilitate eMBB. Similarly, URLLC applications fit in what ranges up to moderately high frequencies.

Building design, clearly plays an important role in wireless connectivity. Undoubtedly, existing buildings will have their own difficulties in addressing the connectivity issues, but proper attention to the related problems is of paramount

*Internet Connectivity in Building Interiors: Architecture and Sustainability Considerations DOI: http://dx.doi.org/10.5772/intechopen.95968*

**Figure 3.**

*Distribution of the categories of use cases within the Spectrum for 5G [9].*

importance, for making new buildings suitable to this need, at the earliest design stages. This will ensure proper connectivity, as well as, user satisfaction, while addressing any adverse effects that this very propagation may have, on human well-being and health.

#### **6.3 The building interior and internet connectivity**

This section looks at internet connectivity, as it is affected by the design of interior spaces. Previous studies, have pointed out the role of penetration losses of various building materials, a quality that largely affects internet connectivity. Good connectivity can cause more homogenous data rate within buildings, thus operating at lower transmit power, conserving their batteries and affecting energy efficiency. An architect's consideration of wireless coverage at the design stage, can help improve coverage significantly. It is an established fact that signal coverage significantly depends on the nature of the space, and its bounding surfaces [3]. However, there is very little work done on establishing these qualities of building materials used in everyday construction.

Addressing this gap, penetration loss levels of some common building materials were determined, as part of the BUET study. The research also related the measured data with other existing information. Based on those measurements, taking into account the scope of architectural design, some guidelines were proposed for architectural intervention, to address the growing challenge of supporting wireless services in buildings. As an outcome of this research, a MATLAB program was developed, using radio propagation theories, which an architect can use during the design phase, to predetermine the impact of the proposed use of different penetration losses of building materials at various frequencies.

#### **6.4 Effects on building design**

Studies show that there is a sharp penetration loss at higher frequencies, in typical commercial buildings [10], which use infra-red reflective glass facades, in order to achieve energy efficiency. This will likely have grave consequences on internet connectivity, when the transmission source is outdoors. Propagation losses in interiors, either due to partitions, or space layout, are also considerable at these higher frequencies, and are dependent on the materials used in the layering of the spaces. Such consequences are likely to affect the 'smart' indicators within building interiors, which largely depend on M2M.

Surprisingly, the higher the operating frequency, the faster is the deterioration of radio frequencies, and so the distance, between the transmitting source and receiver in building interiors, needs to be controlled. Another important factor is the path that the wave has to travel between these two points. The higher the

frequency, the less its ability to bend around obstacles, therefore requiring more direct visibility/paths between the points. This puts additional restrictions on the design of spaces, than previously encountered. Thus, clearly, both the building structure, and interior partitions can severely obstruct signal strength and internet connectivity, which will result in high propagation losses. This in turn will affect the battery life of the devices, which in itself is challenging under present options, as in many instances they are irreplaceable. Corrective measures like setting up an IBS (in-building solution) is often not feasible for small buildings or residences.

It is important for Architects, as well as interior designers, to be involved in the design and setting up of the wireless connection system, as space layout and the materials chosen, are all decisions taken by the Architect, and an understanding of these issues needs to be one of the considerations, that determine the ultimate design of the interior.

### **7. Suggested guidelines**

This section summarizes the main guidelines suggested as a result of the BUET study [6]. The first of the guidelines concerned the choice of materials for internal partitions. Concrete and infrared reflective (IRR) glass exhibit high penetration losses. Loss due to concrete, takes place on account of it being a very heavy and dense material. Loss from IRR glass, which is not a heavy material, happens due to the reflection of a major part of the signal. On the other hand, plain glass and particle board exhibit low penetration losses, as they are light materials. Also, the higher the number of layers of a material used in a partition, and hence the thickness of the tested material, the higher was the measured penetration loss, with the loss increase being non-linear. In general, clear glass and particle board were found to be low penetration loss materials, while concrete and IRR glass was found to present high penetration losses at the frequencies they were tested for. For higher frequencies the loss would be likely to increase exponentially, pointing to the problems that would be encountered, in a shift from 4G to 5G transmission scenarios.

A stepped process of design was suggested for design to incorporate internet connectivity within buildings. Firstly, Selection of Options for Wireless Service, needs to be considered during building design, suitable for the particular wireless service option chosen. If the wireless signal from an outside cellular base station, seems sufficient for the wireless service in the building, then neither IBS nor Wi-Fi, Zigbee, WiGig, etc. are required. Then the architect should design, ensuring that the signal from outside can enter the building adequately, i.e. taking particular care of the building fenestration.

However, if an IBS is selected, the architect should design for better coverage from the IBS. If Wi-Fi, Zigbee, WiGig, etc. are selected, the installation locations of the sources may be pre-designed in the building, similar to designs produced for electric lights and plumbing. During the design phase, the architect may use indoor radio planning tools, and perform simulations, to check the potential wireless coverage, thereby making valuable adjustments in the architectural design of the building, to improve coverage and signal paths. A few indoor radio planning tools are currently available, like iBwave.

The second step would be to focus on connectivity issues related to architectural design. For any wireless service option, open planning inside the building can help signals propagate better, and pervade throughout the whole building, as the wireless coverage will be dependent on uninterrupted paths within the building. The following points were highlighted to ensure smooth paths and transmission:

*Internet Connectivity in Building Interiors: Architecture and Sustainability Considerations DOI: http://dx.doi.org/10.5772/intechopen.95968*


The suggested guidelines have been presented for the consideration of an architect, but they also create awareness within other professionals, particularly RF Engineers, of the need to collaborate during the design phase, in order to bring relevant connectivity issues to the design board. The possible outcome of such collaboration and the architect's contribution can be summarized as follows.


### **8. Covid pandemic issues and other conflicting needs**

The recent global pandemic of Covid-19 has also brought focused attention towards sick building syndromes, or SBS. This phenomenon has been a concern for the past five decades, ever since the widespread acceptance of fully air-conditioned buildings became the preferred typology of built spaces, particularly in the thermally challenged situations found in the tropics. The Covid pandemic resulted in the need to maintain social distancing, and in trying to increase the rate at which interior, potentially infected air, is replaced by purer and infection-free outdoor air. Both these requirements have necessitated a shift in the ways in which interiors are conceived.

As the plan layout of spaces is a vital element in maintaining internet connectivity between the transmitting source and receivers, which may be fixed or moveable, these new considerations will also impact the quality of internet connectivity, and needs to be given due thought hand in hand, in order to ensure human health requirements. When more compartmentalization is the need, for isolating infections, and protecting the occupants, the positioning of partitions, their materials and design, all impact the efficiency of internet connectivity.

Green and sustainable planners also advocate compactness in planning a new development, in order to reduce traffic loads, which can be a valuable energy saver. Compactness also allows increased pedestrian movement and biking between destinations, again an active energy efficient measure, which also promotes health benefits from exercise, an added sustainability feature. Again, this measure may contradict the need to create greater distancing between occupants, a requirement vital to control pandemic spreads. The density of neighborhoods is also likely to affect the internet connectivity issue, creating greater obstructions within smaller pathways, affecting the strength of the signals.

The strongly synergistic connection, between the effects of each and every consideration on suitability, regarding physical distancing and/or compartmentalization, is a phenomenon that is encountered time and again, whenever any requirement is compared to others. For instance, the need for avoiding solar exposure may result in infra-red reflective glass facades, but this conflicts with the need to have uninterrupted internet receptivity within the interiors, as mentioned above.

Much research is now required to address the conflicts between the different needs that a building is designed to serve, whether they be thermal comfort, visual comfort, privacy, security, health and air quality needs, and even inclusivity. It is now becoming vital for designers to address the various requirements, and make intelligent and considered choices regarding each, understanding what and the extent of compromises being made for different design decisions, and whether they are potentially harmful or not. The issue of the health hazards of RF transmissions is also of paramount concern at the moment and needs extensive research.

#### **9. Conclusion**

The wireless connectivity, in a building, is an important aspect of today's lifestyles, without which it is impossible to function and achieve sustainability. This is because it improves the life of building users greatly, while only consuming

#### *Internet Connectivity in Building Interiors: Architecture and Sustainability Considerations DOI: http://dx.doi.org/10.5772/intechopen.95968*

nominal energy, making it a key ingredient of green architecture. Thus, it is essentially providing great services, without destroying fossil fuels, and protecting the future world. And this is being demonstrated increasingly, given the work from home scenario found recently during the Covid pandemic. It is unclear how well the World could have handled the lock-down situation, had internet not reached its present development. This makes it of vital importance in the present World, to ensure the provision of seamless internet connectivity, for even the basics of life to function efficiently.

The discussion has related the objectives of the UN SDGs to the issue of having internet access and connectivity, and their intrinsic link to the architecture of spaces. It is difficult in the present times to think of sustainability in the absence of seamless internet connectivity within building interiors. This combines the expertise of multi-disciplinary teams of Architects and RF Engineers.

From a recent research conducted at BUET relating these disciplines, the various options for wireless services have been listed, particularly since the services are increasing their data rate to 5G levels in the near future. Clearly building interiors need to be designed with focus on the issues of seamless propagation of RF waves. The different architectural measures that can be adopted to make this possible have been mentioned here. The geometry of spaces, their spatial flow and materials, their partitions, and openings, all contribute to the flow of internet connectivity. What remains still unaddressed is the matter of the health and safety issues related to 5G transmission scenarios, which it has been suggested deserves special attention in future research.

This paper has brought out the importance of the different disciplines to collaborate in the design of the environment, in order to ensure seamless and safe transmission of internet connectivity. The collaboration needs to begin at the design phase, so that proper decisions are implemented with an understanding of the consequences holistically. Each of the professionals are experts in their own spheres, but they need to make each other aware of the needs which will best serve the built environment, and help improve user satisfaction, while reducing energy wastage. The participatory approach is the only acceptable way forward.
