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In recent years there has been a widespread adoption of high reflectance (cool) roofing materials in hot climates to reduce a building's cooling load and energy use. While a cool roof can reduce the building's cooling load during warm months, it may regrettably increase the heating load in cool months thus reducing their overall effectiveness. One potential solution to preserving high cooling load savings without accruing a large heating load penalty is to implement a switchable roof reflectance technology; allowing a low reflectance roof during the heating season and a high reflectance roof during the cooling season. This paper organizes and summarizes the literature on cool roofs and switchable roofing materials as a tool for energy savings in buildings. It presents a review of material properties and advancements, energy savings and penalties, current codes, additional benefits and limitations, and recommendations for future research. Finally, the paper summarizes comparative analysis results of the energy performance for both static and switchable cool roofs. [ABSTRACT FROM AUTHOR]

To benchmark the contributions of building retrofits to the National Energy Efficiency Action Plans (NEEAPs) of the Member States (MS) of the European Union (EU) and to identify potential improvements to the general EU methodology, this paper presents homogenous mapping of the potential for energy savings and associated effects on CO 2 emissions for the building stocks of five selected MS: France, Germany, Spain, Sweden, and the United Kingdom. The mapping is created using a verified building stock modeling methodology, and includes results related to technical and techno-economical improvements for ten energy conservation measures (ECMs) and six ECM packages. These results are compared to the corresponding estimates in the NEEAPs, as well as those in the literature. Although both our results and those in the literature show high variability for the cost-efficiency of the ECMs between the five national building stocks, the potential application of complete ECM packages generally appears to be more profitable than the application of individual ECMs. Certain challenges must be overcome before this potential can be realized. The energy savings for Year 2020 projected in the NEEAPs appear to be overly optimistic when one considers the efficiency trends, current regulatory framework, and techno-economical potential detailed in this study. Furthermore, the NEEAPs are not in full compliance with the requirements of the EU Energy Efficiency Directive. These requirements could be defined more specifically, so as to address the identified information gaps, thereby facilitating the implementation and monitoring of energy savings in existing buildings. [ABSTRACT FROM AUTHOR]

In residential sector, air conditioning system takes the biggest portion of overall energy consumption to fulfil the thermal comfort need. In addressing the issue, thermal insulation is one efficient technology to utilize the energy in providing the desired thermal comfort by its environmentally friendly characteristics. The principle of thermal insulation is by the proper installation of insulation using energy-efficient materials that would reduce the heat loss or heat gain, which leads to reduction of energy cost as the result. This paper is aimed to gather most recent developments on the building thermal insulations and also to discuss about the life-cycle analysis and potential emissions reduction by using proper insulation materials. [ABSTRACT FROM AUTHOR]

Abstract: This paper analyzes the thermal and energy behaviour of apartments in three-story block buildings located along a NE-SW axis (azimuth=120°) in a temperate-cold climate (latitude: 36°57′; longitude: 64°27′) in the city of Santa Rosa, La Pampa, central Argentina. Four apartments had been monitored during May and June 2009. Three of them are located in Block 126. Two of these apartments face South: 15 and 23 on the SE end, ground and first floor, respectively; 18 faces N on the second floor. Finally apartment, 12 is located in Block 374, on the first floor, faces N and shows a carpentry-closed balcony. The purpose of this work is – to study the evolution of the indoor temperature in each apartment; to analyze energy consumption and comfort conditions; to study energy potential and energy intervention in order to reduce energy consumption; to analyze bioclimatic alternatives feasibility and the possibility to extrapolate results to all blocks. On the basis of the analysis of natural gas historical consumption records, results showed that regarding heating energy consumption during the period May–June, Apartment 12, facing N, with its only bedroom facing NW and its carpentry-closed, transparent glass balcony, presented a mean temperature of 21.2°C, using a halogen heater for 6h/day between 9pm and 2am (0.16kWh/day/m2). Apartment 15, on the SE end, first floor of the block consumed 22.5kWh/day (0.43kWh/day/m2) (mean temperature=22.2°C). Apartment 23, located on the second and top floor (on top of Apartment 15) with higher energy loss, consumed 28kWh/day (0.54kWh/day/m2) (mean temperature=23.7°C). Apartment 18, also on the second floor and facing N, located in the centre and with its only bedroom facing SE, consumed 18.8kWh/day (0.48kWh/day/m2) (mean temperature=22.3°C). Apartment 23, with higher thermal loss through its envelope, but with heat transfer from the apartment located below, is the one that showed the highest level of consumption/m2. Closing the balcony with carpentry produced an important reduction of energy consumption while reaching comfort conditions. The analysis of the experimental results allowed: (a) to determine through analysis of historical consumption of natural gas prior to the year 2009 that the owner lived under conditions of comfort, (b) to evaluate possible interventions in the building that would lead to saving heating energy. Thermal insulation of roof and envelope appears as the most feasible alternative whereas closing balconies constitute a very good design option in winter. [Copyright &y& Elsevier]

Abstract: Hong Kong is located in a typical subtropical region. The buildings in Hong Kong are subjected to high cooling demands for their air-conditioning systems throughout most of the year, and their contribution toward the total energy consumption is about 40%. Therefore, energy efficiency in buildings is essential to reduce the global energy use and improve the local environmental sustainability. This paper provides an overall review of the building energy research and efforts in Hong Kong over the last decade. Various aspects and energy saving measures, including energy policy, energy audit, design, control, diagnosis, building performance evaluation and renewable energy systems, studied or used to enhance the energy efficiency in buildings are reviewed. A brief introduction of the Hong Kong Building Energy Codes (BEC) and Hong Kong Building Environmental Assessment Method (HK-BEAM) are also provided to present the efforts of the local government and community on energy efficiency in buildings. This review aims at providing building researchers and practitioners a better understanding of buildings energy saving opportunities and approaches in cities particularly in subtropical regions and taking further proper actions to promote buildings energy efficiency and conservation. [Copyright &y& Elsevier]