Energy Performance of Buildings

Climate change in the built environment is described by means of a multi-fold relationship: cities are major contributors to CO₂ emissions; climate change poses key threats to urban infrastructure and quality of life; climate change interacts with urbanization, population aging and socio-economic issues; and how cities grow and operate matters for energy demand and thus for greenhouse gas emissions. This relationship is particularly important since nearly 73 % of the European population lives in cities, and this is projected to reach 82 % in 2050. At the same time, climate change is occurring in Europe, as mean temperature has increased and precipitation patterns have changed. In terms of the Mediterranean area, increasing droughts and extreme climate phenomena (heat spells/heat waves) are key future characteristics that will put the whole region under serious pressure until 2100. They will also directly influence the built environment, including its resilience, and are expected to impact more cities with higher concentrations of vulnerable people, including the elderly, who are considered to be more sensitive to various climatic stress factors as compared to people of working age.

The construction sector consumes significant amounts of natural resources (raw materials, water, energy) during the various phases of its activity that covers construction, operation, and demolition of structures. A large amount of energy is required for the operation of buildings during their overall lives in order to meet their habitats needs—about 40 % of the final energy consumption in the EU in 2012. The EU has set a target for all new buildings to be “nearly zero-energy” by 2020. Considering that construction of new buildings has declined over the last few years and that there is a large stock of old buildings that were constructed without any thermal or energy regulations in several European countries, energy renovation in existing buildings has a high potential for energy efficiency. As environmental issues become increasingly significant, buildings become more energy efficient and the energy needs during their operation decreases, aimed at “nearly zero energy” buildings. Thus, the energy required for construction and, consequently, for the material production, is becoming more and more important. A significant contribution in the efforts to reduce the environmental impacts from construction activities is evaluating their environmental consequences in each stage of their life-cycle. This has led to the development of different “environmental life-cycle” assessment approaches.

The present chapter tries to identify the main advantages of energy conservation measures as well as of the renewable energies on economy and labour. Most of the existing studies foccusing in Southern European climates are presented discussed and analysed.

Over the last few decades, a wide variety of papers have aimed at developing, enhancing, and categorizing the sustainability and energy efficiency indicators. Those efforts assess the economic, social and environmental indicators in isolation to each to other without energy efficiency, material efficiency, and resources sustainability. These studies’ main focus is to provide important information to policy-makers to understand the implications and impacts of various energy programs, alternative policies, strategies, and plans in shaping development within the countries. In fact, indicators—when properly analyzed and interpreted—can be useful tools for communicating data relating to energy and sustainable development issues to policy-makers and to the public, and for promoting institutional dialogue. This research is a first-time effort towards mapping the existing indicators of energy efficiency in the built sector by grouping all the aforementioned indicators into five main parameters. The success of the critical taxonomy is based on the association of sustainable performance indicators with energy sustainability. The link between those parameters provide a structure and clarify statistical data to give better insight into the factors that affect energy efficiency, environment, economics, and social well-being, and how they might be influenced and trends improved. Indicators can be used to monitor the progress of past policies, and to provide a “reality check” on strategies for future sustainable development.

Climatic change, with the increase of ambient temperature, undoubtedly affects the built environment and leads to a significant increase in energy consumption in the building sector—which is already the biggest energy consumer in Europe. Environmental assessment tools provide an effective framework with appropriate indicators for evaluating the environmental performance of buildings and materials for targeting the integration of the sustainable development of a building’s entire life cycle, based on ISO standards and environmental legislation, into the design, construction, and marketing. Direct benefits associated with the building certification schemes include the fostering of energy and CO₂ emissions reductions, as well as broader environmental benefits, increased public awareness of energy and environmental issues, and achieving lower operational costs for users—especially now that the ongoing economic recession has affected so many European countries.

Several treatments that could be implemented in the home environment are evaluated with the objective of reaching a more rational and efficient use of energy. We feel that detailed knowledge of energy-consuming behavior is paramount for the development and implementation of new technologies, services, and even policies that could result in more rational energy use. The proposed evaluation methodology is based on the development of economic experiments implemented in an experimental economics laboratory, where the behavior of individuals when making decisions related to energy use in the domestic environment can be tested.

The greatest potential for energy savings in the EU is in its existing buildings. The concept of “Nearly Zero Energy Building” (nZEB), which represents the main future target for the design of new buildings, is now gaining increasing attention in relation to the renovation of existing buildings as well. This is exceptionally challenging, considering the economic crisis in the EU and, in particular, in the Mediterranean areas, which are currently experiencing high levels of unemployment, poverty, and social exclusion. This chapter presents and discusses some progress in low- and zero-energy research and practice. It contains a brief review of the current policy background and case studies, and a set of demonstration projects containing evaluation and demonstration procedures that consider the technical, economic, and social feasibility of nearly zero energy buildings in the Athens metropolitan area (AMA).

The household final energy consumption in the EU-28 was 26.2 % of the total (with Serbia achieving almost 37 %) in 2012. According to the International Energy Agency’s (IEA) statistics for energy balance for 2004–2005, the residential sector accounted for 27 % of the final energy use throughout the world. Starting with these average data, a more detailed study is necessary to show the dissimilarities of performance and energy consumption in Mediterranean households, considering concepts such as energy poverty, housing deprivation, and the rate of overcrowding. The analysis is completed by taking into account a wider range of environmental indicators related to the household sector, such as CO₂ emissions and concentration, etc. In addition, the energy efficiency requirements in building codes and policies to achieve net zero energy buildings (nZEBs)—is a technical concept accepted worldwide, put the focus on new building technologies and on the refurbishment of existing buildings. Upgrading the energy performance of homes offers immediate benefits and helps reduce energy poverty. It also expands the potential for providing additional homes in existing communities while saving energy, land, and materials. These topics will be analyzed according to the temperate climatic conditions of the Mediterranean area.

Zero and Positive Energy Buildings are buildings that use their own locally-installed (renewable) energy-generating sources to produce, over a certain period of time (e.g., on an annual basis), more power than they consume. The aim of this chapter is to present the trends and perspectives for office buildings to become zero energy in the coming years. Innovative technologies and energy management practices are presented. The role of case studies and shining examples for the Mediterranean region are revealed.

Hospitals are interesting buildings: they are highly complex, as they comprise a wide range of services and functional units. The prevailing indoor conditions should ensure thermal comfort, air quality, and visual comfort, in order to have a healing effect on patients. At the same time, hygienic regulations are getting tighter and are of obvious importance. Meeting those requirements leads, not unreasonably, to the fact that the energy demand of hospitals is among the highest of non-residential buildings. This was accepted for many years as an unpleasant but inevitable “side effect,” but increased energy costs, cuts in public health budgets, the competition in the private health sector, and growing sustainability concerns have changed this approach. It is therefore interesting to discuss the way in which this complex problem has been addressed over the last few decades and, even more so, the way it is expected to be solved in the coming decades.

The Mediterranean area attracts almost 20 % of the world’s tourism (over 150,000,000 tourists each year) due to its mild and pleasant climate and famous cultural heritage. Tourism-related energy studies generally focus on estimating total energy use and efficiency and comparing the energy consumption regarding various facets of tourism-related activities, mostly hotels. This chapter presents a review of EU projects and papers. There is no doubt that research on tourism and climate change has developed substantially. Recent publications have begun focusing on sustainability—specifically, how climate change will impact tourism and how destinations can be adapted. Considerable attention is also paid to tourism’s role as a contributor to greenhouse gas emissions and how these can be mitigated, due to the fact that the tourism sector has been transformed into an increasing environmentally conscious marketplace where consumers have realized the impact of the behaviors that they have paid for, which are strongly associated with environmental problems. This is the main achievement of recent years, and it certainly represents a qualitative difference in the way that the activity is conducted.

This chapter’s emphasis is on existing school buildings, with an overview of the European and, more specifically, the Mediterranean region. Following the overview of schools in the Mediterranean region, the study focuses on secondary schools in Cyprus. It identifies the prevailing building practices in school construction with specific reference to the schools in Cyprus. The construction and energy consumption details of the secondary school buildings in Cyprus are also presented. Indoor comfort and energy efficiency are analyzed through questionnaires, surveys, interviews, and simulations on specific pilot school buildings. The field studies are conducted to evaluate the indoor thermal conditions during the students’ classes. Further investigation of the energy efficiency of schools is carried out through building simulations. Existing situations, current trends and tendencies of schools provide essential information to facilitate the energy performance assessment of the building stock and to highlight the potential of energy savings and the upgrading of their indoor comfort.

This chapter identifies the major features of the emerging heat-power nexus in the built environment and suggests the specific energy technologies that will most likely successfully address the new challenges in covering buildings’ thermal loads. These challenges are related in the supply side with the anticipated smart decarbonized grid, and in the demand side with the strict building performance regulations that require Zero Energy Buildings (ZEBs). Heat pumps, solar thermal collectors, photovoltaics and combined heat and power and thermal energy storage (TES) display the energy performance characteristics that can allow buildings to fulfill the ZEB agenda and integrate seamlessly with the smart grid. In the temperate climates of the Mediterranean region, those particular building energy technologies, either for new buildings or retrofits, can increase the flexibility provided by buildings and offer demand response services. For this demand response potential to be significant in high-performance buildings, it needs to be augmented by energy storage technologies. However, to realize the holistic concept of the demand-responsive/smart-grid-ready building, advanced sensoring, controlling, and connectivity infrastructure is required.

Micro-cogeneration is an emerging technology with the potential to—if designed and operated correctly—reduce both the primary energy consumption and the associated greenhouse gas emissions, when compared to traditional energy supply systems. The distributed nature of this generation of technology has the additional advantages of (1) reducing electrical transmission and distribution losses; (2) alleviating the peak demands on the central power plants; and (3) diversifying the electrical energy production, thus improving the security of energy supply. The micro-cogeneration devices are used to meeting the electrical and heating demands of buildings for space heating/hot water production, as well as potentially (mainly for temperate and hot climates) absorption/adsorption cooling systems. Currently, the use of commercial micro-cogeneration units in applications such as hospitals, leisure facilities, hotels, or institutional buildings is well established. The residential cogeneration industry is in a rapid state of development and flux, and the market remains undeveloped, but interest in the technologies by manufacturers, energy utilities, and government agencies remains strong.

The high energy consumption in the building sector, especially for heating and cooling, has promoted new and more restrictive energy policies around the world, such as the new European Directive 2010/31/EU on the energy consumption of buildings. Apart from enforcing stringent building codes that include minimum energy consumption for new and refurbished buildings, the IEA ETP 2012 highlights the necessity of using highly efficient technologies in the envelopes, equipment, and new strategies to address the high energy consumption of the sector. In this context, the use of appropriate thermal energy storage (TES) systems has a high potential to reduce the energy demand for both heating and cooling. The use of TES in the building sector not only leads to the rational use of thermal energy, which reduces the energy demand, but allows peak load shifting strategies, as well as manages the gap between possible renewable energy production and heating/cooling demands. In this chapter, various available technologies are analyzed where sensible, latent, or thermochemical storages are implemented in either active, passive, or hybrid building systems.

This chapter presents an overview of solar thermal systems used to supply energy for domestic hot water provision as well as space heating and cooling of buildings. Solar energy collectors are the main component of solar thermal systems; they play a vital role in converting solar radiation to heat. Water and air heating collectors are the most widely used in either glazed or unglazed configurations, with solar water heating systems the most popular means of utilizing solar energy. Solar water heating systems consist of forced circulation and thermosyphon systems, and solar thermal cooling systems use heat from the sun to drive absorption and adsorption chillers, desiccant and ejector systems to provide cooling in buildings. Solar air heating systems heat ventilation air for buildings and can also provide domestic hot water when connected to a suitable heat exchanger. Solar collectors can be integrated into elements of building envelopes, such as roofs, façades, balconies, and walls.

Photovoltaics (PVs) is an established technology, but there are still potential applications that require further development, and undoubtedly appropriate architectonic integration. This chapter is a short guide for architects and engineers, providing an overview of the main types of PVs and of the alternative ways that PV modules can be integrated into buildings by using various technical arrangements to replace existing construction elements by PV modules in roofs, façades, and other parts of the buildings. Presented are the main types of PV cells—depending on the semiconductor material (single-crystal, multicrystalline silicon, amorphous, thin film), on the type of junction (homojunction and heterojunction), on the method of manufacture (thin film, stacked, vertical multifunction), and on the devices of the system that utilize solar radiation. The main types of PV building integration (roof, façade, sun screening) are discussed at the end of the chapter.

Existing building stock in European countries accounts over 40 % of final energy consumption in the European Union (EU) member states, of which residential use represents 63 % (Hellenic Statistical Authority 2015) of total energy consumption in the building sector. Taking into consideration the significantly low rate of new construction and the implementation of the recasting of the Energy Performance Buildings Directive, the need for energy conservation measures in the existing building stock is of great importance. Consequently, the amelioration of a building’s energy performance can constitute an important instrument towards the alleviation of the EU energy import dependency and comply with the Kyoto Protocol to reduce carbon dioxide emissions. Thermal insulation materials are the appropriate tool towards the mitigation of energy loss. There is a variety of materials based on their technical characteristics that fulfill the requirements of any construction; furthermore, there is great progress in innovative materials (thermo chromic, change face material, cooling). Moreover, the EU enacted legislation ensuring adequate quality for any construction. In this chapter we will investigate all available types of insulation materials, their technical parameters, and the best practices for the most well-known construction elements.

Vernacular architecture in the Mediterranean area has some peculiarities; one of them is the use of light colors for the building envelope to reduce solar gains during the hot summer period. Cool materials merge ancient concepts and new technological solutions in modern buildings. Cool materials can be used for the building skins and for urban applications. They are characterized by high thermal emissivity and higher solar reflectance than that of conventional construction and building materials, thus reducing the heat released to the ambient air by convection and to the built environment through conduction. The various technologies available on the market, as well as innovative technologies still in the research phase, are described. Potentialities and limits of the technology for building and urban applications are presented via numerical analyses; case studies of cool roof application are also presented.

Shading can have an impact on both building’s energy balance affecting not only annual energy consumption but peak loads as well. In addition influences  users’ visual  and thermal comfort. Proper selection of shading system is a key factor for reducing unwanted solar gains satisfying simultaneously daylight adequacy and  aesthetic desires. With today’s pressing problem of global warming, optimization of building façade in terms of daylighting/solar radiation control can be considered as a corner stone strategy for low-energy building design. This chapter present basic information on the parameters that affect the selection of shading & daylighting systems. This includes a review of metrics used to characterize these systems according various European norms and energy codes. Antagonistic phenomena are discussed in detail together with synergies with glazing selection. In addition a number of selected systems are presented along with their operational principles.

In temperate climates, lighting represents a significant part of the consumed end-energy of a building; considering the primary factor, it is very often the biggest part. Modern lighting techniques, especially the groundbreaking LED technology, offer a great variety of energy-conscious solutions. Replacing antiquated and inefficient lighting installations by energy-efficient techniques is a huge energy-saving potential, and, in parallel, the lighting quality could be significantly improved. By doing so, we should not lose sight of the primary goal of the system: to lighten a space according to architectural, visual, and biological requirements. LEDs as a digital light source offer completely new technical possibilities for fulfilling these special needs.

There are several important challenges facing the construction sector and among them, achieving low energy buildings is the first step towards the attainment of “nearly Net Zero Energy Buildings.” For this purpose it is necessary that architects and designers use adequate design strategies especially in early stages of the project. Without a correct interpretation of climatic, geographic and location parameters, meeting the goals in a project a posteriori would be very difficult. For decades, climogramas (or bioclimatic charts) and sun charts have been widely used for the microclimatic analysis of the built environment. However, the interpretation of results, the definition of strategies and design-integration is still the most difficult issue. For this purpose, this chapter aims to provide valuable design strategies and architectural solutions for the case of temperate climates. Furthermore, 21 cities in 10 countries will be studied in more detail.

Microclimatic improvement can be defined as the mitigation of microclimatic conditions on a local scale, and it produces, together with the quality of the building envelope, comfortable interior spaces, sheltered from the inclemencies of climate. From this point of view, the mild Mediterranean climate offers very interesting features to explore. Its warm winters and mild, dry summers allow for designing open spaces as buffer zones, close to the building envelope. This favorable climatic condition is not exclusive to southern Europe and North Africa, but extends to parts of California, Chile, South Africa, and Australia. The open areas designed to mitigate climate also blur the boundaries between inside and outside. Since they fall inside the comfort zone most of the year, they can be considered an extension of the living rooms, suggesting a rich interplay between interior and exterior spaces. This chapter introduces some basic notions about microclimate, and illustrates some relevant examples to investigate the fundamental design topics related to microclimatic improvement. From Moorish architecture until the present, the idea of mitigating climate through the design of open spaces inside or around the building has produced a vast array of configurations that feature both proven efficiency and an imposing spatial quality. All these architectural spaces can be considered efforts to tame the energy fluxes flowing through the site and make them part of a spatial concept, improving and enriching the quality of space. The result is an exploration of the complex relationship between inside and outside, a study on the continuity of artifice from the enclosed volume to the outer space, and a different point of view of one of the fundamental questions of architecture: the act of enclosing.

These days, urban design of open spaces is strongly related to bioclimatic techniques and practices. In this chapter we present the procedure of such bioclimatic studies by the use of simulation tools. Outdoor spaces that are characterized by decreased human thermal comfort conditions during the summer, especially in areas under temperate climatic conditions, justify a bioclimatic intervention. Modelling has contributed to the understanding of both the limitations and benefits of specific interventions that should be made in the open space in order to succeed at the predefined thermal related improvement. Also, it shows how these interventions affect buildings’ operations.