Keywords

Sustainable development; energy production; GHG; energy efficiency; energy retrofitting

1.1 Sustainable Development and Energy Production

Energy production is the main responsible for global greenhouse gas emissions (GHGs). Oil accounts for 32.8%, coal for 27.2% and natural gas for 20.9% (Hook and Tang, 2013). As the source of two-thirds of global GHG emissions, the energy sector is therefore pivotal in determining whether or not climate change goals are achieved. Climate change is the most important problem faced by the human species, being associated to rise in the sea level, ocean acidification, heavy rain, heat waves and extreme atmospheric events, environmental deterioration and wildlife extinction, health problems, and infrastructure damage (Rockström et al., 2009; Williams et al., 2012; Garcia et al., 2014; IPCC et al., 2014).

Since each day there are now about 200,000 new inhabitants on planet Earth (WHO, 2014) this means that the increase in electricity demand will continue growing (King et al., 2015). It is then no surprise to see that the world net electrical consumption is expect to increase from 20.1 trillion kWh in 2010 to 25.5 trillion kWh by 2020 and 35.2 trillion kWh by 2035 (World Energy Outlook, 2013). Unfortunately only 21% of world electricity generation was from renewable energy in 2011, with a projection for nearly 25% in 2040 (World Energy Outlook, 2013). This means that in the next few decades the majority of electric energy will continue to be generated from the combustion of fossil fuels such as coal, oil, and gas releasing not only carbon dioxide but also methane and nitrous oxide. The World Business Council for Sustainable Development estimates that by 2050 a 4- to 10-fold increase in efficiency will be needed (COM (2011a,b) 571). Energy efficiency is therefore very important in this context because efficiency improvements show the greatest potential of any single strategy to abate global GHG emissions from the energy sector (IEA, 2013). Also energy efficiency is the most cost-effective way to improve competitiveness, as well as create employment (COM (2010) 639; Lund and Hvelplund, 2012). This is especially important in the context of the current global economic crisis.

To tackle climate change, the European Union (EU) has agreed on ambitious goals. In the long term (until 2050), the EU has set a goal of reducing by 80–95% its GHG emissions compared with the 1990 emissions level. In the short term (until 2020), GHG emissions in the EU have to be reduced by 20% compared with the 1990 level. Also, energy consumption from renewable resources should be increased by 20% and energy savings of 20% should be achieved (COM (2008) 30). Since the EU has succeeded in cutting its GHG emissions by 18%, between 1990 and 2012, this means that the EU is on track to meet its 2020 GHG emissions target. Unfortunately the same cannot be said concerning the target related to renewable energy or about the energy savings (EU, 2014). As a consequence and according to the latest figures of Eurostat (2015) the annual energy consumption in EU28 (gross inland consumption) is still around 1666 million tonnes of oil equivalent (Mtoe) which basically is the same value of the annual energy consumption of EU28 in 1990 and far from the 371 Mtoe planned savings, being that a substantial amount of that consumption (53%) corresponds to energy imports. This not only constitutes a very important amount of European financial resources of more than 1 billion euro per day, but also raises serious concerns concerning the security of the EU energy supply because almost 70% of EU imports came from just two partners, one being Russia, whose disputes with transit countries have threatened to disrupt supplies in recent years. That is why the recent Communication on the European Energy Security Strategy (COM (2014) 330) among other measures emphasizes the need for a sped-up building energy efficiency and energy-retrofitting rate.

1.2 Building Energy Efficiency and Energy Retrofitting

The building sector is responsible for a high energy consumption and its global demand is expected to grow in the next few decades. Between 2010 and 2050, global heating and cooling needs are expected to increase by 79% in residential buildings (Fig. 1.1A) and 84% in commercial buildings (Fig. 1.1B). These projections are based on a 115% increase in the number of households and on a floor space increase of 94% (Ürge-Vorsatz et al., 2015). Energy efficiency measures are therefore crucial to reduce GHG emissions of the building sector. Recent estimates (Ürge-Vorsatz and Novikova, 2008; UNFCCC, 2013) state that energy efficiency concerning building heating and cooling needs could allow a reduction between 2 and 3.2 GtCO₂e per year in 2020. Other estimates mentioned a potential reduction of around 5.4–6.7 GtCO₂e per year in 2030 (UNEP, 2013).

Since buildings are responsible for 38% of the EU’s total CO₂ emissions, higher energy efficiency in new and existing buildings is key for the EU climate and energy strategy (COM (2011a,b) 885/2; JCR, 2015). Residential buildings account for 75% of the total building stock in the EU27 and energy in dwellings is mainly consumed by space heating (68.4%) and the remaining share respects to lighting and appliances (14.1%), hot water production (13.6%) with a minor 3.8% used for cooking (De Boeck et al., 2015). Therefore, in order to achieve such reductions the implementation of building codes associated with a high energy performance must be seen as a top priority.

Over the first decade of the 21st century, several high energy-performance building concepts have been proposed, from low-energy building through passive building and zero-energy building to positive-energy building and even autonomous building (Thiers and Peuportier, 2012). Some authors (Adhikari et al., 2012) use ZEB to mean “net zero-energy buildings” and NZEB to mean “nearly zero-energy buildings.” “Net” refers to a balance between energy taken from and supplied back to the energy grids over a period of time. Therefore, Net ZEB refers to buildings with a zero balance, and the NZEB concept applies to buildings with a negative balance. Rules and definitions for near-zero energy buildings or even zero-energy buildings are still subject to discussion at the international level (Dall’O’ et al., 2013).

The European Energy Performance of Buildings Directive 2002/91/EC (EPBD) was recast in the form of the 2010/31/EU by the European Parliament on May 19, 2010.

If there are no delays in its implementation, this directive could provide the EU with up to 65 Mtoe savings in the buildings sector by 2020 (EU, 2014). One of the new aspects of the EPBD is the introduction of the concept of NZEB. Of all the new aspects set out by the new directive this one seems to be the one with most difficult enforcement by member states. The article 9 of the European Directive establishes that, by December 31, 2020, all new constructions have to be nearly zero-energy buildings; for new public buildings, the deadline is even sooner, i.e., the end of 2018.

Also the EPBD recast (article 4.1; recital 14) obliges Member States to “assure that minimum energy performance requirements for buildings or building units are set with a view to achieving cost optimal levels”. The cost-optimal methodology introduces, for the very first time, the prerequisite to consider the global lifetime costs of buildings to shape their future energy-performance requirements. However, EU regulation and guidelines provide to member states a very large degree of flexibility when selecting the input data for the calculation. Flexibility is also provided for the selection of reference buildings (which represent the typical and average building stock in a certain member state), optional discount, energy cost, equipment and packages, maintenance and labor costs, primary energy factors, and estimated economic lifecycle (BPIE, 2013). Both concepts (cost effectiveness and cost optimality) are related, but still different, the latter being a special case of the first. They are based on comparing the costs and (priced) savings of introducing a particular level of minimum energy-performance requirements for buildings. In general, a measure or package of measures is cost effective when the cost of implementation is lower than the value of the benefits that result over the expected life of the measure (BPIE, 2013). Still some authors (Becchio et al., 2015) mention that nearly zero solutions are far from matching cost-optimal solutions. This is confirmed by Kurnitski (2015), who mentioned that nearly zero-energy or A-class buildings are not yet being offered on the market, because the construction thereof is still considered too expensive. This author also mentioned that calculations made by a research group of Tallinn University of Technology showed that the B-class low-energy buildings can be considered cost effective at the moment while nearly zero-energy buildings need a little more time for development before becoming competitive. Unfortunately, the status of the EPBD implementation in EU countries is disappointing because so far only a minority of countries have transposed the EPBD into their national laws (Antinucci, 2014).

Be that as it may, the fact is that new buildings have limited impacts on overall energy reduction as they represent just a tiny fraction of the existent building stock (Xing et al., 2011). Recent statistics reveal that 14% of EU-27 building stock dates before 1919, and about 12% dates between 1919 and 1945, even if considerable national differences occur (Ascione et al., 2015). Since the first building codes were introduced in the 1970s when almost 70% of the current EU building stock had already been built this means that the majority of the European building stock has low energy-efficiency performance. Existing buildings constitute, therefore, the greatest opportunity for energy-efficiency improvements. This will also help to reduce energy imports in Europe because a major part of gas imports are consumed by the building stock. In 2012, buildings in the Baltic States, the Czech Republic, Bulgaria, and Slovakia were 100% dependent on Russian gas. Buildings were 98% dependent on Russian gas in Hungary, 86% in Romania, and 80% in Poland the same year (JCR, 2015). Besides, new homes use four to eight times more resources than an equivalent refurbishment (Power, 2008), which constitutes an extra and sustainable argument in favor of building retrofitting.

Also, energy building retrofitting has important effects on economic recovery. According to Billington et al. (2012) an energy-efficiency program is a more effective way to stimulate the economy, compared to likely alternatives like cutting the value-added tax (VAT) or investing in capital infrastructure projects. For the United Kingdom such a program could have substantial economic benefits, create 71,000 jobs by 2015, and boost gross domestic product (GDP) by 0.20%. Pikas et al. (2015) recently found that in all, 17 jobs per 1 million euro of investment in building retrofitting had been generated per year. These authors also found that a 32% tax revenue would be expected from renovation-related activities, meaning that an official 32% governmental investment would be economically neutral.

Building energy-efficiency retrofitting is also crucial to address an important social problem, energy poverty. This problem affects between 1.3 billion and 2.6 billion people from underdeveloped regions of the world. Between 50 and 125 million people in Europe alone suffer from energy poverty (Atanasiu et al., 2014). This has important health consequences for children and older people, leading to an increase in medical costs. Infants living in energy-poor homes are associated with a 30% greater risk of admission to hospital. Indoor cold is also highly correlated to premature mortality. Between 30% and 50% of excess winter mortality is attributed specifically to energy-inefficient housing conditions. Besides, direct financial help to low-income households or the use of energy subsidies can only address this problem in a partial manner without solving it in the long term, while the funding of building energy-efficiency refurbishment works are also able to generate added value and economic growth (Atanasiu et al., 2014). Renovating existing buildings is a “win–win” option for the EU economy. Energy renovation is instrumental for reaching the EU 2020 goals, and has implications for growth and jobs, energy and climate and cohesion policies (JCR, 2015).

The EPBD Recast does not cover existent buildings except for buildings with a total useful floor area over 1000 m² that undergo major renovation (Article 6). According to the EPBD Recast major renovations includes those

Energy Efficiency Directive (EED) (2012/27/EU) approved by the European Parliament on October 25, 2012, that each member state has had to transpose into national laws by June 5, 2014, addresses the energy-efficiency renovation of existent buildings (Articles 4 and 5). According to Article 4, member states will have to “establish a long-term strategy for mobilizing investment in the renovation of the national stock of residential and commercial buildings, both public and private.” As to Article 5’s content, it requires that “each Member State shall ensure that, as from 1 January 2014, 3% of the total floor area of heated and/or cooled buildings…is renovated each year to meet at least the minimum energy performance requirements.” EED also mentions that the first version of the building-renovation strategy was to be published by April 30, 2014. However, the reported published in November 2014 revealed that only 10 renovation strategy plans were submitted (BPIE, 2014). Of those only the strategies of four member states (Czech Republic, Romania, Spain, and the United Kingdom) were considered acceptable because they met the basic requirements set by Article 4. The strategies of France, Germany, and the Brussels capital region needed to be corrected and resubmitted. The strategies of three countries (Austria, Denmark, and the Netherlands) were rejected because they do not fulfill the basic requirements of Article 4. In January 2015 an addendum was published (BPIE, 2015) showing that only the renovation strategy of Austria remained rejected although its compliance level increased from 28% to 40% and also that the overall compliance level increased from 58% to 63%. This means that much more effort must be put into the building energy-efficiency retrofitting agenda. Also because residential buildings are a complex whole influenced by social, economic, as well as environmental aspects (De Boeck et al., 2015), there is a big challenge to be addressed.

1.3 Financing Aspects Regarding Energy Retrofitting in Europe

Technological innovation to ensure deep retrofitting needs to not only be technically feasible but also economically viable. New building-envelope materials and technologies could increase energy efficiency and energy savings at much lower cost than is possible today (IEA, 2013a) and some of the technologies needed for the retrofitting of the EU’s building stock are already available in the market. However, their diffusion varies across member states due to a lack of market actors’ awareness about the savings potential of the best available technologies. Also the cost of energy retrofitting needs to be made more transparent so that investment needs could be better assessed (JCR, 2015). Of course building-energy cost effectiveness depends on several variables including building-energy performance, climate, and especially electric prices. Friedman (2014) mentioned that in Israel, most of the strategies assessed for energy renovation of the building envelope are not cost effective to the individual homeowner. One of the explanations is that electricity prices in that country are much lower than in European countries.

According to the recent report “Energy Renovation: The Trump Card for the New Start for Europe” (JCR, 2015), in Europe most dwellings were constructed between 1945 and 1980, the worst period from an energy perspective (Fig. 1.2).

This report shows that cost-effective energy renovation will be very unevenly distributed across countries. Deep renovation of post-1945 buildings would be economically feasible only for the countries that have joined the EU since 2004. The report also states that most citizens cannot afford energy renovation, especially in member states with per capita GDPs below the EU average. As a consequence it calls for existing funds to be merged into a well-tailored EU energy renovation fund acting as a risk-sharing pool to provide the initial financing package to support member states’ renovation strategies (JCR, 2015).

Numerous financing instruments exist at the EU level (Fig. 1.3) an important share being devoted to low-carbon investments by the EU, the European Investment Bank (EIB) and various EU stakeholders. Table 1.1 shows the main advantages and disadvantages of several financial mechanisms to promote building energy-efficiency measures.

Štreimikienė (2016) conducted an assessment on the impact of EU structural support in helping the Baltic States to implement energy efficiency and renewable energy development targets set in EU energy policy documents. This author reports that the major impact was related to an increase in energy productivity because of energy savings achieved in refurbishment of residential buildings. Also worth mentioning is the approval of 400-million-euro EIB financing under the European Fund for Strategic Investments (EFSI) in a 800-million-euro project for energy-efficiency retrofitting of residential buildings in France (IP, 2016).

1.4 The Importance of Socioeconomic Aspects

Socioeconomic aspects constitute an important part of any energy-efficiency retrofitting process but these aspects were very often disregarded in the past. Several authors (Banfi et al., 2008) recognized the importance of these aspects to act as barriers for energy-retrofitting decisions. According to Gamtessa (2013) the decision process of energy-retrofitting is influenced by several factors, e.g., the household size, household income, age composition of the household members, and members’ education levels. Stieß and Dunkelberg (2013) mentioned that reaching homeowners not yet aware of the benefits of energy-efficiency improvements constitutes a major challenge that requires the “implementation of coordinated campaigns at the local level with participating energy agencies, consultants, tradesmen, the local authorities, and the local press.” Alberini and Bigano (2014) conducted a survey of over 3000 Italian homeowners and report that each $100 increase in the incentive amount raises the likelihood of replacing the heating system by just 3 percentage points. Friege and Chappin (2014) analyzed 449 peer-reviewed articles and conference proceedings on energy-efficient retrofitting (EER) as well as their 7000 references, concluding that that the literature on EER still lacks a deep understanding of the uncertainties surrounding economic aspects and noneconomic factors driving retrofitting decisions of homeowners. One thing is sure: existing incentives on energy-efficient building retrofitting had so far little success because they exclusively target economic measures.

A commonly identified barrier regarding energy retrofitting is the “information deficit” i.e., the owner not knowing the extent to which they can improve energy performance of their homes or not knowing which actions they should take (Hoicka et al., 2014). That is why energy audits could play an important role in driving retrofitting decisions. However, some authors (Murphy, 2014) who studied a large sample of Dutch households noticed that only 19% of audit recipients of energy-efficient measures mentioned that they were influenced by the audit recommendation. Palmer et al. (2015) analyzed 550 US homeowners in 24 different states who had home energy audits and found that the followup decision to make retrofitting decisions is obviously related to the costs of the operation. However, they found that the strongest determinant of followup is related to idiosyncratic and unobserved factors that affect a homeowner’s satisfaction with the auditor.

Another important social issue concerning energy retrofitting is related to the rebound effect. The rebound effect is used to describe the situation in which money saved from the installation of an energy-efficient technology is then used to heat more floor space (spatial rebound) or to extend the heating period (temporal rebound). Rosenow and Galvin (2013) mentioned that this behavioral change can occur after building retrofitting. More recently Winther and Wilhite (2015) study 28 Norwegian homes, confirming the occurrence of both spatial and temporal rebound. This study also confirmed that the fact that very few homeowners use program functioning and were reluctant to learn how to program the heat pump controller increased the rebound effect. Other authors (Peffer et al., 2015) mentioned that although some homeowners install programmable thermostats to save energy, they can use more energy than those controlled manually depending on how or if they are used. Occupants’ inability to operate complex new system controls properly was also reported by Walker et al. (2014). This shows the important influence of homeowner behaviors on building energy efficiency. Garde et al. (2014) has even stated that the best-designed building in the world can consume more than a conventional building if users are not informed and supported in the use of the building. This view confirms that occupant behavior is now widely recognized as a major contributing factor to uncertainty of energy building performance. These behaviors include occupants’ interactions with operable windows, lights, blinds, thermostats, and plug-in appliances (Yan et al., 2015).

Recent investigations show that occupant behaviors significantly affect the energy demand of buildings, ranging from 1.2 to 2.84 times when comparing identical buildings (Schakib-Ekbatan et al., 2015). As technical performance standards ratchet tighter, behavioral factors gain relative importance (Hong et al., 2015). Also Frederiks et al. (2015) mentioned that a growing body of evidence shows that consumer behavior is driven by cognitive biases and other irrational tendencies very far from traditional economic models that predict that people make decisions that yield the optimal result given budget constraints. This helps to explain why some homeowners are reluctant to adopt energy-saving measures even if they are cost effective. This means that although cost effectiveness is a crucial step, energy-efficient building retrofitting is not a silver bullet capable of triggering major changes in the building sector. Those changes also require innovative government incentives tailored to target specific socioeconomic conditions of homeowners.

1.5 Outline of the Book

This book provides an updated state-of-the-art review on cost-effective energy-efficient building retrofitting. The first part encompasses materials and technologies (see Chapters 2–6).

Chapter 2, Methodologies for Selection of Thermal Insulation Materials for Cost-Effective, Sustainable and Energy-Efficient Retrofitting, concerns methodologies for selection of thermal insulation materials. The classification of thermal insulation materials based on their composition, as well as on their physics of performance, was implemented. Comprehensive methodologies for the environmental and cost assessment of insulation materials suitable for the energy upgrade of building materials was also discussed. An optimization model was applied, in which the impact of different parameters that affect the appropriate insulation thickness for existing buildings was interpreted.

Chapter 3, Phase Change Materials for Application in Energy-Efficient Buildings, reviews commercial state-of-the-art products found on the market and shows some of the potential areas of use for phase change materials (PCMs) in building applications. Examples of how PCMs can be integrated into buildings, and also building materials and projects using PCMs that have already been realized, have also been reviewed. Furthermore, future research opportunities have been explored and the challenges of the technology as of 2016 have been discussed.

Chapter 4, Reflective Materials for Cost-Effective Energy-Efficient Retrofitting of Roofs, discusses the cost effectiveness of reflective materials when installed in buildings roofs (cool roofs). Net savings (NS) over a 10-year lifecycle cost analysis are obtained for a building prototype located in different cities. Finally two emerging technologies, retroreflective and thermochromic, which are not cost effective yet but promising for future applications, were described.

Chapter 5, Solar Air Collectors for Cost-Effective Energy-Efficient Retrofitting, is concerned with solar collectors. It presents an economic study of both unglazed transpired solar air collector (UTSAC) and back pass solar air collector (BPSAC) systems, taking into account the internal rate of return and installation cost, based on large-scale test setups and measured performance data.

Chapter 6, Building Integrated Photovoltaics for Cost-Effective Energy-Efficient Retrofitting, covers the performance of building-integrated photovoltaics (BIPV). It investigates potentialities and challenges of the use of BIPV in cost-efficient energy retrofitting, through market analysis and photovoltaic products analysis.

Optimization constitutes the subject of Part II (see Chapters 7–12).

Chapter 7, Measurement and Verification Models for Cost-Effective Energy-Efficient Retrofitting, provides a review of the main protocols and standards used in the construction industry for measurement and verification (M&V) of retrofit projects. Various M&V options are reviewed. Key drivers for and barriers against M&V are also discussed.

Chapter 8, A Cost-Effective Human-Based Energy Retrofitting Approach, discusses how to describe and take advantage of people’s behavior in building thermal-energy assessment issues. Finally, the literature dealing with the possibility to trigger energy-conscious behaviors and further cost-effective energy-savings opportunities, i.e., the human-based energy retrofit, is discussed.

Chapter 9, An Overview of the Challenges for Cost-Effective and Energy-Efficient Retrofits of the Existing Building Stock, aims to identify the optimal cost-effective energy-retrofitting strategy. A holistic retrofitting scenario has been considered, which includes reduced energy consumption, cost savings, capital investments, emissions, technology behavioral change, and comfort indexing along with sustainability concerns incorporating geometry and envelope construction while considering various uncertainty parameters and risk factors.

Chapter 10, Smart Heating Systems for Cost-Effective Retrofitting, discusses smart heating systems. The chapter aims to provide a picture of the most recent advances in hydronic heating systems, which can be applied in case of retrofits. After the description of the technological features of the smart devices that can be applied at the various levels, the applications in retrofit are discussed and evaluated in terms of cost optimality.

Chapter 11, Artificial Neural Networks for Predicting the Energy Behavior of a Building Category: a Powerful Tool for Cost-Optimal Analysis, considers an original methodology that employs artificial neural networks (ANNs) to predict the energy behavior of all buildings of an established category. The final aim is a reliable assessment of the global cost for space conditioning as well as of the potential global cost savings produced by energy retrofit measures for each category’s building. Beyond the presentation of the methodology, this is applied to the office building stock of South Italy, built during the period 1920–70.

Finally, Part III presents several case studies (see Chapters 12–19).

Chapter 12, Cost-Effective Retrofitting of Swedish Buildings, presents cost-effective potentials for energy conservation through energy retrofitting of existing Swedish buildings, including residential and nonresidential buildings. Ten individual energy-conservation measures and six packages of measures were considered. The chapter also presents how the cost effectiveness depends on energy prices, discount rates, and the assumed investment costs for the different measures.

Chapter 13, Cost-Efficient Solutions for Finnish Buildings, presents Finnish case studies of cost-efficient retrofitting. The first case study shows how multiobjective simulation can be utilized for selecting the most cost-efficient renovation measures. The second case study presents a real pilot building where cost-efficient renovation has been successfully implemented. The last case study presents the economic and environmental advantages of an ambitious nearly zero-energy level renovation compared to a traditional renovation.

Chapter 14, Cost-Effective District-Level Renovation—A Russian Case Study, analyzes the costs of adapting three different holistic energy renovation concepts both in the buildings and at the corresponding residential district in Moscow. In the buildings, the estimated costs included both mandatory less-energy-efficient repairs and suggested energy-efficiency improvements, focusing on reducing heating and electricity demands, reducing water use, and improving ventilation.

Chapter 15, Cost-Effective Energy and Indoor Climate Renovation of Estonian Residential Buildings, uses the methods of large-scale field studies as well as computer simulations to analyze the energy performance of dwellings in Estonia.

Chapter 16, Cost-Effective Energy Refurbishment of Prefabricated Buildings in Serbia, addresses the case of two prefabricated buildings of different typology, in New Belgrade, Serbia. Economic analyses were performed for each building type, after several energy-efficiency improvement measures were implemented, looking for the optimal solution, considering present economic situation in Serbia and availability of funds for refurbishment.

Chapter 17, Cost-Effective Refurbishment of Residential Buildings in Austria, represents a study of cost-optimal building renovation based on typical Austrian residential buildings with different building ages and therefore different constructions.

Chapter 18, Cost-Effective Energy Retrofitting of Buildings in Spain: An Office-Building of the University of the Basque Country, focuses on an energy renovation of a nonenergy-efficient and nonsustainable office building located in northern Spain. It presents the highlights of the energy-retrofitting project, describes the designed monitoring study and shows the assessment of expected achieved targets, taking into account both energy simulations and monitoring studies.

Chapter 19, Cost-Effective Refurbishment of Italian Historic Buildings, closes Part III with two studies on the energy refurbishment of historic buildings in South Italy. An educational ancient palace built beginning in the 12th century and, as an existing building, a railroad station, located in the same city. In both cases, replacement of components of the thermal envelope and active energy systems were applied, by evidencing that, based on the building peculiarities, technologies, architectural values, and kind of loads, different boundary conditions imply different cost-optimal energy-conservation measures.