Actual heating energy savings in thermally renovated Dutch dwellings

The register of the Dutch social housing stock was analysed, containing 300.000 dwellings, renovated between 2010 and 2013. The main objective was twofold: to evaluate the performance gap in these dwellings before and after the renovation and to establish what renovation measures achieve the highest reduction of consumption, particularly in practice (actual savings). The results showed large performance gaps in dwellings with low R and high U values, local heating systems, changes from a non-condensing into a condensing boiler and upgrades to a natural ventilation system. Regarding the actual effectiveness of renovation measures, replacement of old gas boilers with more efficient ones yields the highest energy reduction, followed by deep improvements of windows. Installing mechanical ventilation yields a small reduction compared to other measures, but still much larger than theoretically expected. The paper shows once more that the calculation method currently in use cannot be considered accurate if compared to actual consumption. The study demonstrated that unrealistic theoretical efficiencies of heating systems and insulation values are causing a part of the performance gap. Nowadays, large datasets of buildings thermal performance and actual consumption offer an opportunity to improve these misconceptions.     

Considering user profiles and occupants’ behaviour on a zero energy renovation strategy for multi-family housing in the Netherlands

A number of facade solutions have been developed in recent years to solve the problem of large-scale renovation of housing. In the Netherlands, housing associations have the ambition to achieve an energy-neutral renovation approach, and so, some aim at energy neutrality. However, few address the complexity of multi-family rental dwellings and more importantly, the importance of user behaviour in the actual performance of the buildings. In current approaches, the zero energy target is sought for an average household. In this paper we present an approach to zero energy renovation in which the influence of occupants’ behaviour in building performance is taken into account to eliminate the uncertainties related to energy savings. The results are used to inform the design process regarding the amount of energy production required to reach zero energy performance, and the feasibility of the on-site energy production only with photovoltaic panels. The research showed large statistically significant differences on energy consumption between the different household types, which could contribute to pre-bound effects if these differences are not considered when calculating energy savings and return of investments. When considering scenarios based on behaviour after renovation, the difference between the lowest and the highest heating demand is reduced to 34%.     

Disaggregating the causes of falling consumption of domestic heating energy in Germany

Consumption of domestic heating energy (space and water heating combined) in Germany has been falling in recent years. Official figures indicate it fell by 17 % in 2000–2011, from 669 to 564 TWh (temperature adjusted), while the population reduced by 2 % and the number of occupied dwellings increased by 3.4 %. German policy has strongly promoted deep thermal retrofits through regulation, information campaigns and subsidised loans. An important question is what portion of the reductions are due to progressive energy efficiency upgrade policy and what are due to other, non-technical factors such as demographic and behaviour change. We use national statistics and existing empirical studies to disaggregate the contribution of energy-efficiency improvements and nontechnical factors to the reduction in consumption. Our analysis suggests that around 20 % of the reductions are likely to be due to thermal retrofits of existing dwellings (insulation and new windows), 31 % due to boiler or heating system replacements, 1 % due to replacement of old dwellings with new, energy-efficient buildings, while some 45–50 % of the savings cannot be explained by these technical improvements. Most of these reductions appear to have occurred in non-upgraded, non-new dwellings. Although we do not know what caused these reductions, the finding is robust to very wide inaccuracies in figures for savings through technical improvements in buildings’ energy efficiency. More research is needed to explore the extent to which this implies increasing fuel poverty, increasing skills and motivation among non-poor households to heat more economically, or the effects of demographic and lifestyle changes. Highlights ? German home heating energy consumption fell by 105 TWh in 2000–2011 ? Approximately 31 % of this was due to boiler/heating system upgrades ? Approximately 20 % was due to window replacement and thermal envelope upgrade ? Less than 1 % was due to replacement of old with new stock ? Over 45 % cannot be explained by technical upgrade factors ? This could imply rising fuel poverty or more skilful heating behaviour     

A computer program to study the thermal conditions in retrofitted buildings

A computer program has been developed to check the thermal conditions in retrofit buildings in the different regions of Spain. The actual energy consumption of the building is compared first with the theoretically calculated values and then with the limit rates given by government regulations. At the same time, thermal insulation and quality of design of the installations are checked with regard to the norms. Following this, excessive energy consumption can be detected and the causes diagnosed. Computer output then can give the thermal conditions of buildings, the reasons for excessive consumption and the technical recommendations for reducing the energy waste.     

Embodied and operational energy of rural dwellings in India

On a global scale, buildings are responsible for significant energy consumption. While the energy intake of urban buildings has been studied well, there are barely any studies on rural dwellings. The current paper examines the embodied energy (EE), operational energy (OE) and life-cycle energy (LCE) of 27 rural dwellings spread across four climate zones of India. It is found that these rural dwellings use locally available least-processed natural materials with very low EE. However, with the advent of modern transportation, manufactured energy-intensive construction materials have reached rural areas. From the analysis it is seen that the EE ranges from 0.002 to 2.8?GJ/m², the annual OE from 0.006 to 0.053?GJ/m² and the LCE from 0.77 to 4.05?GJ/m² for the rural dwellings studied, with mass ranging from 1.13 to 3.6?t/m².     

Germany's path towards nearly zero-energy buildings—Enabling the greenhouse gas mitigation potential in the building stock

On 19 May 2010, the European Union adopted a Directive stipulating that by the end of 2020, Member States must ensure that all newly constructed buildings consume ‘nearly zero’ energy. In Germany, drastic reductions of energy demand for space heating have already become a policy target over the last decade, both for new and existing dwellings. In this article, we evaluate the impact of past and future policies on the development of buildings with a very high energy performance (VHEP) and on their primary energy demand and emissions. These dwellings account for 4% of all dwellings which have been constructed since 2001 and 1% of the total building stock. We have defined different policy scenarios, all of which assume a gradual increase of requirements for new and existing buildings and a continuation of the support policies that stimulate both new constructions and ambitious refurbishments. In the most ambitious scenario, the proportion of VHEP dwellings will increase by up to 30% of the total stock in 2020 and the share of nearly zero and zero-energy dwellings will then make up 6%. This will lead to emission reductions of over 50% of the 1990 level and primary energy reductions of 25% compared with today.     

Policy measures to overcome barriers to energy renovation of existing buildings

Even though there is great potential to reduce greenhouse gas emissions from existing buildings, most political effort in Korea has been focused on the construction of new buildings; few concrete measures have been taken to limit greenhouse gas emissions from existing buildings. This study examined the potential to reduce greenhouse gas emissions from existing residential buildings as a means to cope with global warming. Additionally, several barriers to improving the energy performance of existing dwellings instead of constructing new dwellings were explored. The major barriers to improving the energy performance of existing residential buildings are: (1) a lack of awareness; (2) financial reasons; (3) insufficient information; and (4) the absence of regulatory systems. To overcome such barriers, systems adopted and implemented in developed European countries were considered and their feasibility was verified so that political measures could be suggested to improve the energy performance of existing dwellings in Korea.     

Will energy regulations in the Gulf States make buildings more comfortable – A scoping study of residential buildings

Building envelope impacts upon energy consumption and indoor environment. The relationship between envelope components and indoor environment has become increasingly important, especially with the new emphasis on visual comfort, thermal comfort and indoor air quality. This paper examines the interaction between occupant thermal comfort and envelope component regulations in the Gulf States. The country chosen for this study is the Kingdom of Bahrain, the smallest country in the Gulf region. Simulation results and comparative studies were employed to investigate the impact of the current envelope component regulations on the internal environment. The paper focuses on residential buildings and concludes that the envelope component regulations contribute positively to the internal thermal performance. Although these envelope components are not generally the primary elements that impact upon internal thermal comfort there are circumstances when the components become very warm and occupants positioned close to them will experience discomfort. This paper shows that the thermal insulation regulation makes a small impact on thermal comfort, whereas the window regulation, particularly glazing, is more influential and that for most window areas, solar impacts are generally large.     

Influencing factors in energy use of housing blocks: a new methodology,based on clustering and energy simulations,for decision making in energy refurbishment projects

In recent years, big efforts have been dedicated to identify which are the factors with highest influence in the energy consumption of residential buildings. These factors include aspects such as weather dependence, user behaviour, socio-economic situation, type of the energy installations and typology of buildings. The high number of factors increases the complexity of analysis and leads to a lack of confidence in the results of the energy simulation analysis. This fact grows when we move one step up and perform global analysis of blocks of buildings. The aim of this study is to report a new methodology for the assessment of the energy performance of large groups of buildings when considering the real use of energy. We combine two clustering methods, Generative Topographic Mapping and k-means, to obtain reference dwellings that can be considered as representative of the different energy patterns and energy systems of the neighbourhood. Then, simulation of energy demand and indoor temperature against the monitored comfort conditions in a short period is performed to obtain end use load disaggregation. This methodology was applied in a district at Terrassa City (Spain), and six reference dwellings were selected. Results showed that the method was able to identify the main patterns and provide occupants with feasible recommendations so that they can make required decisions at neighbourhood level. Moreover, given that the proposed method is based on the comparison with similar buildings, it could motivate building occupants to implement community improvement actions, as well as to modify their behaviour.     

Analysis of variables that influence electric energy consumption in commercial buildings in Brazil

Air conditioning systems in commercial buildings in Brazil are responsible for about 70% share of their energy consumption. According to BEN 2009 (The Brazilian Energy Balance), energy consumption in the residential, commercial and public sectors, where most buildings are found, represents 9.3% of the final energy consumption in Brazil. This paper aims to examine design factors that could contribute to greater reductions of electric energy consumption in commercial buildings, with emphasis on air conditioning. Simulations were carried out using shades and different types of glass, walls, flooring and roofing. The VisualDOE 2.61 was used as a simulation tool for calculating energy consumption of the analyzed building. This paper shows that the energy performance of the building is considerably influenced by the façade protection and shows, through tables, the impact that decisions related to the top-level and façades have on the energy consumption of the building. The authors concluded that the results confirm the importance of taking energy use into account in the very first design stages of the project, since appropriate choices of types of glass, external shading and envelope materials have a significant impact on energy consumption.     

The influence of the Energy Performance Certificate: The Dutch case

All European Union Member States require an Energy Performance Certificate (EPC) when buildings are constructed, sold and rented. At its introduction the EPC was considered a pioneering instrument, one that would help overcome an information deficit hindering consumer interest in energy efficient dwellings. Now that the EPC has been implemented for several years it is possible to examine its impact. This research draws on data from ex-ante and ex-post assessments of the EPC in a number of countries and presents the results of a survey of Dutch private dwelling purchasers. This survey was based on two sample populations, one received an EPC during property transaction and another did not. Differences were sought between the two samples in a number of areas relating to the adoption of energy efficiency measures. Results show that many projections about the impact of the EPC have fallen short. The EPC was found to have a weak influence, especially pre-purchase. The potential of the EPC in driving energy efficiency improvement in the existing stock is doubted especially if it continues to act independent from a mix of instruments designed to tackle multiple barriers. It is argued that the energy saving potential of existing dwellings, applauded in climate change policy, will remain unexploited if it continues to be assessed subjectively by householders.     

Success factors of energy performance contracting (EPC) for sustainable building energy efficiency retrofit (BEER) of hotel buildings in China

Hotel building is a type of high-energy-consuming building and most existing hotel buildings need energy efficiency improvement in China. Energy performance contracting (EPC) is considered a win−win mechanism to organize building energy efficiency retrofit (BEER) project. However, EPC mechanism has been introduced into China relatively recently and many EPCs have not been successful in building energy efficiency retrofit projects. This research aims to develop a set of critical success factors (CSFs) of EPC for sustainable energy efficiency retrofit (BEER) of hotel buildings in China. Semi-structured interviews and a questionnaire survey with practitioners and other professionals were conducted. The findings reveal the relative importance of the 21 number of identified success factors. In order to explore the underlying relationship among the identified critical success factors (CSFs), factor analysis method was adopted for further investigation, which leads to grouping the 21 identified CSFs into six clusters. These are (1) project organization process, (2) EPC project financing for hotel retrofit, (3) knowledge and innovation of EPC, sustainable development (SD), and M&V, (4) implementation of sustainable development strategy, (5) contractual arrangement, and (6) external economic environment. Finally, several relevant policies were proposed to implement EPC successfully in sustainable BEER in hotel buildings.     

Dynamic characteristics and energy performance of buildings using phase change materials: A review

Thermal energy storage (TES) systems using phase change material (PCM) have been recognized as one of advanced energy technologies in enhancing energy efficiency and sustainability of buildings. The use of PCMs in buildings provides the potential for a better indoor thermal comfort for occupants due to the reduced indoor temperature fluctuations, and lower global energy consumption due to the load reduction/shifting. A good knowledge on dynamic characteristics and energy performance of buildings using PCMs is essential for building researchers and practitioners to better understand building temperature response characteristics and economic feasibility of using PCMs and take further proper actions to fully utilize PCMs to enhance indoor environmental quality and overall energy efficiency of buildings. This paper presents an overview of the previous research work on dynamic characteristics and energy performance of buildings due to the integration of PCMs. The research work on dynamic characteristics and energy performance of active and passive building applications is reviewed, respectively. Since the particular interest in using PCMs for free cooling and peak load shifting, the specific research efforts on both subjects are reviewed separately. A few useful conclusive remarks and recommendations for future work are presented.     

A comparative study of the design and construction process of energy efficient buildings in Germany and Sweden

Reducing the energy consumption of buildings is an important goal for the European Union. However, it is therefore of interest to investigate how different member states address these goals. Countries like Sweden and Germany have developed different strategies for energy conservation within the building sector. A longitudinal comparison between implemented energy conservation key policy instruments in Sweden and Germany and a survey regarding the management of energy requirements in the building process shows that:

• –No evidence is found that energy consumption is of great importance for producing competitive offers, either for Swedish or German clients.
• –The Swedish market-driven policy has not been as successful as the German regulation policy in decreasing the energy consumption of new buildings.
• –Building standards and regulations regarding energy performance affects how professionals are educated and the way energy requirements and demands are managed throughout the building process.

In conclusion, the client's demand will govern the development of energy efficient buildings. Therefore, in order to use market-driven policies, the desired parameters must be of concern for the customer to influence the majority of building projects to be more energy efficient than is specified in national standards and regulations.     

A comparison of the accuracy of building energy analysis in Bahrain using data from different weather periods

Weather data are important in building design and energy analysis. In Bahrain, the weather data currently used are based on far past climatic information. Climate variability during the last few decades has raised concern over the ability of these data to provide accurate results when analysing the energy performance of buildings. This study discusses issues related to climate variability and evaluates its impact on the performance of weather data used in building simulation. An evaluation was performed using two methods: firstly, a comparison of measured climatic elements and secondly, a comparison of the thermal performance of two statistically based weather data files. With respect to their impact on typical Bahraini building thermal systems, the comparison was carried out between simulation results and the actual energy consumption of two case studies. This paper shows a 14.5% difference between simulation results based on far past data and present electricity consumption and concludes that the prediction of present and future performance based on recent updated data gives better results.     

Statistical analysis of residential building energy consumption in Tianjin

To analyze the effect of energy conservation policies on energy consumption of residential buildings, the characteristics of energy consumption and indoor thermal comfort were investigated in detail in Tianjin, China, based on official statistical yearbook and field survey data. A comprehensive survey of 305 households indicates that the mean electricity consumption per household is 3215 kWh/a, in which annual cooling electricity consumption is 344 kWh/a, and the mean natural gas consumption for cooking is 103.2 m³/a. Analysis of 3966 households data shows that space heating average intensity of residential buildings designed before 1996 is 133.7 kWh/(m²·a), that of buildings designed between 1996 and 2004 is 117.2 kWh/(m²·a), and that of buildings designed after 2004 is 105.0 kWh/(m²·a). Apparently, enhancing the performance of envelops is effective in reducing space heating intensity. Furthermore, the results of questionnaires show that 18% of the residents feel slightly warm and hot respectively, while 3% feel slightly cold in winter. Therefore, the electricity consumption in summer will rise for meeting indoor thermal comfort.     

Government regulation as an impetus for innovation: Evidence from energy performance regulation in the Dutch residential building sector

The recent implementation of energy performance policy as a way to tackle energy consumption in the building sector in Europe draws attention to the effect it has on the development and diffusion of energy-saving innovations. According to innovation system literature, government regulation through norms and standards is one of the factors stimulating innovation. This paper concentrates on the role of stricter government regulation as an incentive to innovation in the Dutch residential building sector. Innovation in this sector is predominantly a process of applying incremental modifications to comply with new and stricter government regulations and standards. Energy performance policy in its current shape will therefore not contribute to the diffusion of really new innovation in energy techniques for residential buildings in the Netherlands. If diffusion of really new innovation is an explicit aim of energy performance policy then the European wide introduction of this scheme needs reconsideration.     

Low energy consumption in Swedish single-family houses

In Sweden, as well as in many other countries, the energy consumption in residential buildings is a burning question.Due to this, the thermal insulation and the tightness of new buildings gradually has been increased.A well defined ventilation is because of this even more important, and the minimum level is given in regulations prescribed by the National Board of Housing, Building and Planning.To fulfil the regulations it is almost necessary to use mechanical ventilation. Since an ordinary ventilation causes a substantial energy loss it is of vital interest to reduce this.The most efficient way of reducing the ventilation loss, is to use an exhaust air heat pump which recovers energy from the exhaust air and supplies it to heating and hot water.In Sweden there have been about 100.000 units installed in single family houses until today.The paper will describe the regulations, the ventilation system, the exhaust air heat pump and the results achieved when installed in single family houses.     

Market response to the public display of energy performance rating at property sales

Energy labels have generally received positive response from consumers and have moved the market for white goods and cars in the direction of more energy-efficient products. On the real estate market, it was expected that an energy label, rating the energy performance of a property based on a national energy performance certificate (EPC) might receive similar response. However, in Denmark no response to the energy performance rating was observed for 15 years. This was a surprise considering that Denmark was the first country to implement an A to G rating of the energy performance of buildings. A statistical examination of data on property sales prices and energy performance ratings was carried out. All relevant property transaction data from 2007 till 2012 were examined and they showed that energy performance ratings had an impact on property sales prices. However, before June 2010, the impact was modest, whereas after June 2010 the impact of energy performance ratings on property sales prices increased significantly as a result of an EU requirement to display the energy performance rating in connection with property sales. On this background, it was concluded that a public display of the energy performance rating is fundamental for market response.     

Potential of energy and water efficiency improvement in Abu Dhabi's building sector – Analysis of Estidama pearl rating system

Energy and water infrastructure in Abu Dhabi provides a strong example of the interconnection between energy and water, where the majority of its electricity and water demand is jointly produced from cogeneration plants. The total cost of fuel used for cogeneration plants are heavily depending on the efficiency level of end-use energy and water consumption. Buildings are the major electricity and water consumers with 84.6% and 92.2% respectively from the entire demand. The aim of this study is to analyze the energy and water consumption reduction by implementing Estidama pearl regulations and compare it with Business as Usual -the normal execution of things as they always do-for three sample buildings (villa, multistory residential and office building). For energy assessment, eQUEST software was used to examine the energy performance of the chosen buildings and to evaluate the energy saving potential after applying Estidama requirements. While for water assessment; Estidama and LEED calculation tools were used to do the same. The results of energy simulation and water analysis of the chosen buildings showed a potential of electricity reduction between 31% and 38% and a potential of water reduction between 22% and 36% depending on building type and other parameters. Also, a total monetary savings of 19 Billion AED can be achieved cumulatively over ten years period (2011–2020) after Estidama regulations have been applied. In addition, a reduction of 31.4 Million ton of CO₂eq cumulatively can be achieved.