**1. Introduction**

We do know today how to design and how to build near-zero-emission buildings. Even plus-energy building performance can be achieved [1] by the integration of highly energy-efficient building design, advanced energy systems and solar energy applications. Under most climate conditions in the world, the annual energy demand and energy generation in buildings can be balanced in the buildings' annual performance, if advanced design principles and technologies are employed, and the ratio between the usable floor area and the solar roof area is not too large [2]. Technically, such performance can be achieved in newly designed, but also in retrofitted buildings. The key technologies are available and technical development

is progressing to make low energy performance buildings more and more feasible in future in all climate zones worldwide.

However, although the global climate crisis is apparent, today only a tiny percentage of buildings is built as near-zero-emission buildings and the existing building stock is not performing anywhere near the required efficiency. In the European Union, at least 75% of the buildings that exist today will still exist in 2050, and only 20–25% will be built new in this period [3]. Therefore, besides the design of new buildings, the retrofit of existing buildings towards zero-emission performance and plus-energy performance is to be pursued throughout the entire building stock worldwide.

While the 2050-building stock is already existing today in the developed countries to a large extent, in other places with currently ongoing urbanisation, new buildings need to be constructed that are able to fulfil the future requirements for low-carbon performance. The low-emission goal is the same, but the starting points and boundary conditions in the various countries are significantly different [4]. Often in rapidly developing economies, where most of the construction activity takes place today, other priorities than the objective to build low-carbon buildings drive this development. Also, the governance framework and the building ordinance are not developed yet, and the local market capacities are not as advanced as necessary to build zero-carbon buildings at the current stage. For example, in many countries, the necessary testing facilities to ensure compliance with high-performance specifications for material, building systems and technical appliances do not exist today [5]. The broad implementation of zero-carbon buildings is also hindered by the available budget for energy-saving investment and other spending priorities. Nevertheless, many clients are aware today that energy prices will rise in the foreseeable future. Also, the connection between fossil fuel consumption for energy services in the building sector and climate change is well known to the clients and the other stakeholders today so that efforts towards advanced performance targets are not hindered by ignorance anymore, but clearly by other barriers.

While a single pilot project is still useful today, the challenge today lies in the implementation of the low-emission performance concepts in the building stock in the markets worldwide. However, there are surely crucial technologies, which continue to be required to be developed, designed and demonstrated in zero-energy building pilot projects in the various contexts around the world. Meanwhile, the effort to transform the global building stock is becoming more process- and policyoriented, rather than being targeted towards the application of specific technologies and the integration of technology systems on building level. Today, the available technologies need to be rolled out for broad application.

#### **2. Contextual conditions**

Technically, the fundamental principles for low energy and zero-energy performance of buildings differ in the various climates. The impact of the various components of the building energy balance will result in different configurations of the physical building systems and the building energy systems depending on the local conditions.

It is also evident that some of these technical configurations while being technically feasible based on international best practice are not economically feasible today and might also overstress the local market capabilities, the skills of the workforce and economic capabilities and the willingness of the local clients to invest in low-carbon design. However, as the building sector is a significant part of all local economies today, with about 30–40% of the national energy demand in

**33**

buildings' life cycle.

*Road-Mapping for a Zero-Carbon Building Stock in Developed and Developing Countries*

most countries, in order to advance the zero-carbon development, especially the building sector must contribute. The building sectors' development in such contexts needs to be guided since there currently is, and there will be, significant pressure from the urbanisation and the parallel socio-economic development in the available time frame. In order to avoid login effects through unsuitable building design and the omission of required technical provisions under these conditions, the design must be prepared with appropriate foresight to achieve the intended performance if

In the assessment of advanced energy concepts besides these conditions of the application of key technologies in each market, also other factors of the market context need to be observed. For instance, under the usual accounting methodology to offset unavoidable emissions, such as for heating in winter or for electricity use in the night with credits for energy generation in times of availability of renewable sources, the assessment will change depending on the change of the emission factors of the delivered energy to the site. Therefore, in a context where clean electricity is supplied by the local grid, building integrated renewable energy systems can contribute less to reduce the carbon account of a building than in a context with

As we can assume that the energy mix will move towards a higher percentage of renewable energy sources through the transformation of the national energy infrastructure in many places, the building-related balance calculation needs to be updated regularly over time towards the intended 2050 performance. In case conventional energy sources are used for heating or domestic hot water generation, the results will show that the building's low-carbon performance decreases if the energy consumption is not decreased at the same time, or the building-integrated renewable energy supply is not increased. In other words in situations with emission factors of 600 g/kWh in the local energy mix, 1 kWh renewable energy produced inside the building will off-set double the amount of CO2 emission from fossil energy carriers than in situations with a carbon-emission factor of 300 g/kWh. In consequence, while it is essential to reduce the carbon emission factor of the local electricity grid as a strategy on the national and local municipality level, the zero-carbon strategy on building level must reduce the use of fossil energy carriers for building operation through energy-saving measures and in the last consequence by replacing these fossil applications with clean alternatives in the course of the

The feasibility of such alternatives currently rests with the ability to align the time profiles of energy demand and energy supply from alternative energy sources. As renewable sources depend on environmental processes such as wind and solar radiation, storage technologies are needed. There are three possible solutions to this

1.Installation of energy storage solutions as public infrastructure to buffer clean feed-in energy centrally and then to supply seamlessly back to the end-users.

3.To adjust the users' demand to the available resources and to accept that not all

2.Installation of energy storage applications as part of the building system to buffer available clean energy until it is used inside the building by the end-user.

problem, which differ in their demand for infrastructure and investment:

demands can be met in the building at all times.

*DOI: http://dx.doi.org/10.5772/intechopen.92106*

not now then at least in the long run before 2050.

**3. Development of contextual conditions**

emission-intensive energy infrastructure.

*Road-Mapping for a Zero-Carbon Building Stock in Developed and Developing Countries DOI: http://dx.doi.org/10.5772/intechopen.92106*

most countries, in order to advance the zero-carbon development, especially the building sector must contribute. The building sectors' development in such contexts needs to be guided since there currently is, and there will be, significant pressure from the urbanisation and the parallel socio-economic development in the available time frame. In order to avoid login effects through unsuitable building design and the omission of required technical provisions under these conditions, the design must be prepared with appropriate foresight to achieve the intended performance if not now then at least in the long run before 2050.

## **3. Development of contextual conditions**

*Zero-Energy Buildings - New Approaches and Technologies*

future in all climate zones worldwide.

worldwide.

is progressing to make low energy performance buildings more and more feasible in

However, although the global climate crisis is apparent, today only a tiny percentage of buildings is built as near-zero-emission buildings and the existing building stock is not performing anywhere near the required efficiency. In the European Union, at least 75% of the buildings that exist today will still exist in 2050, and only 20–25% will be built new in this period [3]. Therefore, besides the design of new buildings, the retrofit of existing buildings towards zero-emission performance and plus-energy performance is to be pursued throughout the entire building stock

While the 2050-building stock is already existing today in the developed countries to a large extent, in other places with currently ongoing urbanisation, new buildings need to be constructed that are able to fulfil the future requirements for low-carbon performance. The low-emission goal is the same, but the starting points and boundary conditions in the various countries are significantly different [4]. Often in rapidly developing economies, where most of the construction activity takes place today, other priorities than the objective to build low-carbon buildings drive this development. Also, the governance framework and the building ordinance are not developed yet, and the local market capacities are not as advanced as necessary to build zero-carbon buildings at the current stage. For example, in many countries, the necessary testing facilities to ensure compliance with high-performance specifications for material, building systems and technical appliances do not exist today [5]. The broad implementation of zero-carbon buildings is also hindered by the available budget for energy-saving investment and other spending priorities. Nevertheless, many clients are aware today that energy prices will rise in the foreseeable future. Also, the connection between fossil fuel consumption for energy services in the building sector and climate change is well known to the clients and the other stakeholders today so that efforts towards advanced performance targets

are not hindered by ignorance anymore, but clearly by other barriers.

technologies need to be rolled out for broad application.

**2. Contextual conditions**

local conditions.

While a single pilot project is still useful today, the challenge today lies in the implementation of the low-emission performance concepts in the building stock in the markets worldwide. However, there are surely crucial technologies, which continue to be required to be developed, designed and demonstrated in zero-energy building pilot projects in the various contexts around the world. Meanwhile, the effort to transform the global building stock is becoming more process- and policyoriented, rather than being targeted towards the application of specific technologies and the integration of technology systems on building level. Today, the available

Technically, the fundamental principles for low energy and zero-energy performance of buildings differ in the various climates. The impact of the various components of the building energy balance will result in different configurations of the physical building systems and the building energy systems depending on the

It is also evident that some of these technical configurations while being technically feasible based on international best practice are not economically feasible today and might also overstress the local market capabilities, the skills of the workforce and economic capabilities and the willingness of the local clients to invest in low-carbon design. However, as the building sector is a significant part of all local economies today, with about 30–40% of the national energy demand in

**32**

In the assessment of advanced energy concepts besides these conditions of the application of key technologies in each market, also other factors of the market context need to be observed. For instance, under the usual accounting methodology to offset unavoidable emissions, such as for heating in winter or for electricity use in the night with credits for energy generation in times of availability of renewable sources, the assessment will change depending on the change of the emission factors of the delivered energy to the site. Therefore, in a context where clean electricity is supplied by the local grid, building integrated renewable energy systems can contribute less to reduce the carbon account of a building than in a context with emission-intensive energy infrastructure.

As we can assume that the energy mix will move towards a higher percentage of renewable energy sources through the transformation of the national energy infrastructure in many places, the building-related balance calculation needs to be updated regularly over time towards the intended 2050 performance. In case conventional energy sources are used for heating or domestic hot water generation, the results will show that the building's low-carbon performance decreases if the energy consumption is not decreased at the same time, or the building-integrated renewable energy supply is not increased. In other words in situations with emission factors of 600 g/kWh in the local energy mix, 1 kWh renewable energy produced inside the building will off-set double the amount of CO2 emission from fossil energy carriers than in situations with a carbon-emission factor of 300 g/kWh.

In consequence, while it is essential to reduce the carbon emission factor of the local electricity grid as a strategy on the national and local municipality level, the zero-carbon strategy on building level must reduce the use of fossil energy carriers for building operation through energy-saving measures and in the last consequence by replacing these fossil applications with clean alternatives in the course of the buildings' life cycle.

The feasibility of such alternatives currently rests with the ability to align the time profiles of energy demand and energy supply from alternative energy sources. As renewable sources depend on environmental processes such as wind and solar radiation, storage technologies are needed. There are three possible solutions to this problem, which differ in their demand for infrastructure and investment:


These three strategies can be combined in the building's renovation roadmap. Design in a developing market might first rely on a sufficiency approach (option 3), in which the building design can support the best possible functionality and reduce discomfort, but not guarantee the complete set of performance, which could be achieved when energy would be available at all times. Then, option 1 or 2 could be installed later in the buildings' life cycle as a more functional solution when funds and other capacities are available. Also, in the case of the more extended future where central solutions are developed (option 1), an individual approach (option 2) might only be used as an intermediate solution. In all these cases, the original building design needs to be prepared from the beginning to accommodate the necessary change.

A similar situation can be observed in many developing countries for the installation of room conditioning systems for cooling and heating. Traditionally, the building users are used to free-running conditions. In such situations, the users have to adapt to the climatic conditions in order to find comfort. At a later stage in the buildings' life cycle, the comfort demand changes and technology becomes affordable in the given market. In consequence, the retrofit of conditioning systems becomes necessary. As we can foresee such change of demands, the retrofit should be factored into the design from the beginning. The initial design should include sufficient installation spaces in appropriate locations for the indoor and outdoor units, and airtightness of the building envelope and appropriate zoning of the interior spaces must be prepared.
