Nearly Zero Energy Building Refurbishment

This chapter starts with an overview on CO₂ emissions and climate change addressing key investigations and important related events. The situation of the European Union concerning energy efficiency is described. A short analysis of the nearly zero-energy building (NZEB) concept is presented. A book outline is also presented.

Buildings in Germany are responsible for more than 40 % of the total final energy consumption. The government already acknowledged the importance of the building sector in the late 1970s and thus started to develop a comprehensive policy framework. On an international level, Germany is especially known for its successful KfW incentive programmes related to energetic refurbishments of buildings that achieved significant reductions in terms of energy and emissions. But these programmes are just one piece of the entire framework. Thus, this chapter describes all parts of the policy framework that relate to the energetic refurbishment of buildings. It starts by describing the current status of a national nearly zero-energy building definition before presenting all relevant strategies and concepts including the targets of the government. After that, the regulatory policies, including the national building code the ‘Energy Saving Ordinance’ and the ‘Renewable Energy Heat Law’, are introduced before having a detailed look at the financial incentive programmes related to energy-related refurbishments and finally describing the most important market instruments.

In order to design and realise an efficient built environment life cycle with focus on climate change mitigation and adaptation, it is necessary to carry out exhaustive investigations of all the decision and processes that form it. The efficiency level of the considered built environment life cycle depends on a great many micro, meso and macro factors. The authors of this paper participated in the different EU projects related with built environment and climate change [Linking European, Africa and Asian Academic Networks on Climate Change (LEAN CC), etc.]. One of the LEAN CC project’s goals was to develop a Model and Intelligent System of Built Environment Life Cycle Process for Climate Change Mitigation and Adaptation. The presented Model and Intelligent System enables one to form up to 100 million alternative versions. Intelligent system allows one to determine the strongest and weakest points of each project and its constituent parts. In order to demonstrate the micro, meso and macro factors that influence the efficiency of the built environment in climate change mitigation and adaptation processes, the Model and Intelligent System will be considered as an example.

Energy and environmental performances of buildings strictly depend on many factors related to the choice of construction materials, HVAC plants and equipment, design, installation and use. By definition, a building interacts closely with its environment. The interactions between building and climate, plants and users have to be taken into account. This aspect is evident in new buildings design process, but it is even more important in the design phase of an existing building renovation, during which actions of energy saving are developed. This chapter summarises the results of the energy and environmental assessment of a set of retrofit actions implemented in the framework of the EU Project ‘BRITA in PuBs’. The main goals were to improve building energy and environmental performances following a life-cycle approach and to support the project partners to select the retrofit actions involving the highest energy saving and the lowest environmental impacts. Synthetic indices, as energy and GWP payback times, and energy return ratio, are defined to better describe the energy and environmental performances of the actions. The use of the life-cycle approach was very successful and potentially transferable to other contexts of building retrofit study.

Building retrofitting projects represent great opportunities to include new energy efficient technologies, already available on the market. However, for many of these technologies, the occupants’ behaviour within the building can weaken the expected return on investment. This is special true in intelligent technologies that try to compensate the lack of user awareness of energy consumption problems. This chapter describes a model for occupant behaviour within the building in relation to energy consumption, along with a building energy consumption model (ECM) is proposed based on stochastic Markov models. The ECM is used to predict possible energy saving gains from building retrofitting projects. The obtained results demonstrate that the proposed ECM learns occupant behavioural patterns from the building. Additionally, it reliably reproduces them, predicts the building energy consumption and identifies potential areas of energy waste. The ultimate objective of the proposed models is the integration in Decision Support Tools to advise the investor on the selection of technologies and evaluate the merits of the investment.

Nearly zero-energy refurbishments provide many of the benefits of nearly zero-energy buildings to the aging building stock and offer an opportunity to make them more resource-efficient and environmentally friendly, with an increased social and financial value. However, high initial costs and uncertainties about the expected benefits characterize this type of investment and affect the building stakeholders’ decision on whether to go ahead with such a project or not. Given the special case of existing buildings and associated challenges to refurbish them to nearly zero energy, this chapter identifies and classifies uncertainties that characterize and make this type of investment a highly uncertain endeavor over the project life cycle. It also provides recommendations about managing these uncertainties during the project evaluation phase. Finally, a new approach to project evaluation based on the option pricing theory is presented along with a case study example.

Regarding energy performance assessment of existing building, the European Standards EN ISO 13790 and EN 15316, adopted at national level in Italy by Technical Standards UNI/TS 11300 (part 1 and 2), allow different approaches and simplification levels for defining some representative input parameters determining uncertainties in the results. Therefore, the reliability of calculated energy performance could be affected. The analysis has been supported applying a set of refurbishment actions on some representative cases of common national residential building stock, comparing the energy performance obtained with different calculation methods allowed by National Technical Standards and laws. The results show how these differences can lead to uncertainties about the class definition.

The majority of energy used in buildings has been traditionally linked to their operation (heating, cooling, lighting, etc.). Much attention has been directed to assess and reduce this energy use, and future refurbishment projects might aim for ‘zero-energy’ buildings. As this goal is progressively approached, buildings generally often employ an increasing amount of materials and systems, to the point that the energy associated with these, the so-called embodied energy, can constitute an important part of the building’s life cycle energy use. For buildings achieving ‘zero-energy’ use in operation, the embodied energy is indeed the only life cycle energy use. Despite this, current building energy assessment methods, and strategies from approaching ‘zero-energy buildings’ or ‘nearly-zero-energy buildings’, frequently ignore the embodied energy component of building life cycle energy use. This chapter presents the concepts and methodology to evaluate life cycle energy performance of buildings, including embodied energy of the different components, systems and processes. It also introduces the concept of ‘net energy ratio’ (NER) to the built environment, presenting it as an indicator to support optimization of building refurbishment strategies from a life cycle energy perspective. A practical application is shown for the refurbishment of an Irish typical house.

The idea of a Net ZEB arises from the development of design criteria and construction methods, addressed to curb the operating energy, increasing the energy efficiency of building equipment and appliances, and of the thermal insulation of envelope components, and enhancing the on-site energy generation, by means of renewable energy sources, to cover the annual building energy loads. In this chapter, the energy and environmental performances of an Italian nearly Net ZEB following a life cycle approach are carried out. Then, a scenario of refurbishment is foreseen in order to shift the studied building from the nearly Net ZEB condition toward the Net ZEB target, and the arising energy and environmental benefits are assessed. The life cycle approach in the energy and environmental assessment of the foreseen retrofit options is necessary to avoid shifting environmental burdens from one step of the life cycle to another. Further, in order to get a deeper description of the energy performance of the retrofit actions and to compare the different alternatives, the energy payback time (EPT) and the emission payback time (EPT) are assessed for the proposed solutions.

Strong increases in energy efficiency in buildings is central to reducing energy consumption and costs, reducing greenhouse gas emissions, tackling climate change, and at the same time, improving energy security. The concept of “nearly zero energy buildings” gives an indication of what is considered achievable, and this has now been widely demonstrated for new buildings of all kinds. However, the large number of buildings that have already been built emphasises the need to carry out extensive energy efficiency upgrades of the existing building stock in order to the “nearly zero energy” concept to achieve its real societal importance. This article highlights retrofits of large buildings using Austrian schools as examples, which have been chosen to illustrate reductions of more than 80 % in heat demand. Key issues are addressed through a multiple-case study of four school retrofits in Austria. All four buildings demonstrate the achievement of the energy efficiency level of the Passivhaus standard for new buildings. They present a paradigm for this form of upgrades and thus validate the Passivhaus standard.

The retrofit of a building involves not just the fulfillment of functional requirements, but also considerations such as investment costs, energy consumption, environmental impact, and occupant well-being. Careful long-term decisions in the retrofit and operation of buildings can significantly improve their thermal performance and thus reduce their consumption of energy. Moreover, they can improve indoor environmental quality in buildings. Alternative building energy conservation measures, standards compliance, and economic optimization can be evaluated using available energy analysis and decision-aid techniques. These may range from simplified energy analysis methods for approximate energy use estimates to detailed computerized hourly simulation coupled with decision-aid techniques. This chapter reviews the research and development in the decision support processes in building retrofit. Special attention is devoted to the methodologies using multi-objective optimization and genetic algorithms. Accordingly, the decision methodologies are broadly separated into two main categories: approaches in which alternatives are explicitly known a priori and approaches in which alternatives are implicitly defined by an optimization model. The advantages and drawbacks of the various methods in each category are also discussed.

For a broader application of the life cycle of energy-efficient built environment in the practice of various countries, more attention needs to be paid not only on the selected most rational processes and solutions, the interest level of the stakeholders, but also on the micro-, meso- and macro-level factors. The authors of this article developed the life cycle of energy-efficient built environment model and different decision support systems over the course of two international projects (IDES-EDU and LEAN CC). Based on this model, professionals involved in design and realization of life cycle of energy-efficient built environment can develop a lot of the alternatives as well as assessing them and making the final choice of the most efficient variant. The model and two systems (Energy Efficient House DSS for cooling and decision support system for assessment of energy generation technologies) are briefly described in this chapter.

Indoor air quality (IAQ) has become an issue of interest, since people spend most of the time indoors. This chapter reviews main indoor pollutants and their sources. Considering existing World Health Organisation (WHO) guidelines for IAQ and toxicity, the pollutants considered here are asbestos, biological pollutants, benzene, carbon monoxide (CO), formaldehyde, naphthalene, nitrogen dioxide (NO₂), particulate matter (PM), polycyclic aromatic hydrocarbons (PAHs), radon, tetrachloroethylene and trichloroethylene. As key factors for the improvement of IAQ, management of indoor emissions and ventilation improvement in buildings are discussed.

This chapter reviews literature on radon as a source of indoor air contamination. It shows that post-construction remediation like soil depressurization systems (SDS) seems to be more cost-effective than the use of protection measures installed during construction like radon-barrier membranes which have a significant failure rate. Since radon concentration is very dependent on the air change rate (ACH), it is important to maintain adequate air ventilation. However, in some situations, the cost of additional heating to eliminate the heat losses would exceed the total costs of remediation by soil ventilation as much as eightfold. This chapter also shows that there are optimum temperature and relative humidity which minimize radon levels.

This chapter will focus on the performance of ventilation, both in reducing adverse effects of indoor air on building occupants and in reducing the energy required for this. The first section of the chapter elaborates on the adverse effects stemming from airborne pollution: why do we need fresh air? The next section than explores the specific merits and limitations of ventilation as a strategy to renew air, while the last section focuses on the different ventilation concepts and their performance. The main focus in that section is on technologies that allow to reduce ventilation heat loss without increasing the exposure of occupants to airborne pollutants, more specifically air-to-air heat exchangers, exhaust air heat pumps (EAHP) and demand-controlled ventilation.

Vegetable fibres are finding increasing applications in building industry due to their economic, energy and environmental sustainability. In view of utilization of insulation materials made from vegetable fibres for near zero energy buildings, this chapter presents a summary of physical, mechanical and chemical characteristics of vegetable fibres incorporating building insulating properties with recommendations and suggestions. Subsequently, relevant issues of the raw materials and the manufacturing processes that lead to certain common characteristics are highlighted. The greatest challenge in working with vegetable fibres is their large variations in thermal properties and characteristics dependent on their complex architectures of geometrical structures. Mathematical models are of great importance in understanding and predicting the thermal performances of the fibres and their global responses in the building system. Coupled heat and mass transfer through a fibrous insulation in buildings is therefore studied. The most important vegetable fibrous composites, properties of the composites and their applications in buildings are briefly reviewed also. The chapter provides a guide to the fundamentals and latest developments in building insulation technology for vegetable fibrous materials.

Improving the thermal efficiency of the existing building stock is one of the key measures to deliver a substantial contribution to reduce CO₂ emissions of our society. Novel high-performance insulation materials with superior low thermal conductivity values offer several advantages in comparison with conventional insulation products. Following a brief introduction of the principles of heat transfer in thermal insulations, two classes of superinsulations will be discussed in detail: vacuum insulation panels (VIP) and microporous thermal insulations. The special features of these thermal insulations will be pointed out and best practice examples are presented. Finally, a general summary and a discussion on future trends in R&D for thermal insulation will complete this topic.

Energy, the lifeline of all activities is highly regarded to be conserved at every step of the growing engineering and the stupendous technological activities for ensuring the congruent economic development of a country. The gap present between the energy generation and the energy consumption keeps expanding with a precipitous increase in the demand for the energy, especially in the infrastructure and construction sectors. From this perspective, the incessant value-added engineering designs from the scheme inception to the construction are to be primarily necessitated, for enhancing the energy savings potential and energy efficiency in the new as well as in the refurbishment of building structures. Albeit there are several measures available to minimize the net energy consumption in buildings, there is still a need for an efficient system which can shift the thermal load demand during the on-peak to off-peak conditions, without losing energy conservative potential. In this context, the thermal energy storage (TES) systems are primarily intended for enhancing the performance of the cooling and heating systems in terms of storing and releasing heat energy on short-term or diurnal or seasonal basis, depending on the thermal load requirements experienced in buildings. The incorporation of renewable energy-based seasonal TES systems can collectively contribute for achieving enhanced energy performance on a long term, which would take forward the new and the existing building refurbishment designs towards the nearly zero-energy concepts.

Phase-change materials have a very big potential as a tool for energy demand reduction in buildings, and therefore, their use in nearly zero energy buildings refurbishment is clearly an option. Nevertheless, there are little examples where PCM have been used for such application. This chapter shows examples where PCM have been used in research for new buildings, highlighting the more appropriate options for refurbishment.

This chapter deals with the application of highly energy-efficient windows and skylights with silica nanogel as a strategy in the building refurbishment. Aerogel windows seem to have the largest potential for improving the thermal performance and daylight in fenestration industry, because of very low conductivity, density, and a good optical transparency. A state-of-the-art review of nanogel windows in building applications is firstly presented. Then, the proprieties of nanogel glazings in terms of thermal, lighting, and acoustic insulation solutions are discussed. Finally, the potential of the nanogel windows for energy saving in order to achieve a nearly zero-energy building is described, thanks to the results of a case study.

Switchable electrochromic glazings employ multilayer devices with a basic resemblance to thin-film electrical batteries and color/bleach upon electrical charging/discharging. The transmittance of visible light and solar energy can be varied reversibly and persistently between widely separated extrema, which makes it possible to regulate solar energy inflow for energy savings as well as visible light level for comfort reasons. This chapter outlines the basics of electrochromic glazing technology and its implementation in buildings. Device designs and component materials are discussed in some detail. Several practical electrochromic glazing designs are introduced with focus on a foil-type construction applicable as a lamination material between glass panes. Electrochromic glazing has been discussed for many years and has many unfulfilled promises; it is argued here that today’s developments are likely to change this situation so that electrochromic glazing will be able to take its proper place as an important energy savings and comfort enhancing technology for near-zero-energy building refurbishment as well as for new buildings.

In this chapter, the global market potential of solar thermal, photovoltaic (PV) and combined photovoltaic/thermal (PV/T) technologies on current stage and near future was overviewed. The concept of PV/T technology and the theory behind the PV/T operation were briefly introduced. Evaluation standards for technical, economic and environmental performance of the PV/T systems were individually addressed. A comprehensive introduction of the R&D achievements and practical applications of the PV/T technology was illustrated. The PV/T technologies were critically analysed in terms of type and research methodology. Opportunities for further improvement in PV/T technology were identified. This chapter helps to bring forward the barriers remaining in PV/T field, untangle the practical applications of PV/T technology in building retrofitting, establish the standards of PV/T design/installation, identify new research directions and promote its market penetration throughout the world.