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Building hygrothermal performance, indoor air quality and energy consumption depend heavily on envelope airtightness. Over the last three decades, single-family dwellings have been amply studied in this respect by researchers in North Europe, the United States and Canada. However, very few studies have been conducted on airtightness in multi-family housing in warm climates such as Mediterranean Europe. This paper aims to enhance the understanding of building airtightness in early twenty-first-century multi-family buildings in southern Spain. Blower Door tests were conducted in 45 units in seven such buildings. The main airtightness parameter values found are reported and compared to the data for other buildings in southern Europe. The paper includes a statistical analysis of the findings, characterises building types and describes the protocol used to identify and quantify air leakage pathways. The conclusion drawn is that although a rough predictive model can be developed, the results are widely scattered due to the impact of the random component of manual construction, even in buildings with identical construction characteristics and types. The values recorded are nonetheless consistent with the findings for other European surveys. [ABSTRACT FROM AUTHOR]

This paper proposes a novel Case Based Reasoning (CBR) application for intelligent management of energy resources in residential buildings. The proposed CBR approach enables analyzing the history of previous cases of energy reduction in buildings, and using them to provide a suggestion on the ideal level of energy reduction that should be applied in the consumption of houses. The innovations of the proposed CBR model are the application of the k -Nearest Neighbors algorithm (k-NN) clustering algorithm to identify similar past cases, the adaptation of Particle Swarm Optimization (PSO) meta-heuristic optimization method to optimize the choice of the variables that characterize each case, and the development of expert systems to adapt and refine the final solution. A case study is presented, which considers a knowledge base containing a set of scenarios obtained from the consumption of a residential building. In order to provide a response for a new case, the proposed CBR application selects the most similar cases and elaborates a response, which is provided to the SCADA House Intelligent Management (SHIM) system as input data. SHIM uses this specification to determine the loads that should be reduced in order to fulfill the reduction suggested by the CBR approach. Results show that the proposed approach is capable of suggesting the most adequate levels of reduction for the considered house, without compromising the comfort of the users. [ABSTRACT FROM AUTHOR]

Windows are central for the development of liveable nearly zero-energy homes and require careful consideration. Various studies have indicated that the effect of windows on energy consumption may change significantly with improved building insulation levels. Current guidelines on windows may therefore not apply in very well-insulated buildings, and more up-to-date information is needed about window solutions that are appropriate for the new conditions. This study maps the effect of multiple combinations of window size and basic glazing—and frame properties on energy, daylighting and thermal comfort in nearly zero-energy houses located in the European cities Rome and Copenhagen. The aim was to identify options that can support the easy and robust design of future homes with typical use of roof and façade windows. Hourly daylight levels were calculated in DAYSIM, while space heating demand and operative temperatures were calculated in EnergyPlus. The results support previous findings on the limited ability of nearly zero-energy buildings to utilise solar gains. It was found that U -values are becoming increasingly important for the energy performance of windows. The paper sketches the increased flexibility and related possibilities that may appear with improved roof window frame constructions and glazing U -values far lower than currently standard levels. [ABSTRACT FROM AUTHOR]

Abstract: Energy efficiency in buildings is essential for economic, social, and environmental reasons. Under current European legislation, buildings have to be certified with an energy efficiency index. To provide a fair comparison of the energy performance in buildings we need a global and unified representation. In this paper we propose the Energy Efficiency Ontology (EEOnt) to provide a foundation upon which this requirement can be built. EEOnt extends the applicability of other ontological models of buildings incorporating energy efficiency data and knowledge that can be calculated with high spatial and temporal resolution in what we call an Energy Efficiency Landscape (EELB). These EELB''s provide significant information which allows a detailed diagnosis of the energy efficiency within the building. Consequently, EEOnt is capable of representing buildings and energy efficiency in a unified way. Furthermore, it supplies a tool for managing the energy efficiency in buildings and constructing national inventories. These two features link the global and particular needs of governments and users, thus becoming key to both improve the energy efficiency in buildings and to implement viable certification schemes. [Copyright &y& Elsevier]

Abstract: The age of European existing building stock and the very low growth rate make energy retrofit a critical issue at the moment. The spreading of good practices is strongly hampered by their cost effectiveness. National legislation thermal requirements for retrofitting works play a fundamental role. If they are too strict, the initial economic investment could be too high if compared with energy savings achievable. The paper refers to a case study of improving fabric thermal performance of stone masonry buildings located in Cagliari – Italy. They were built in 1950s. The economic feasibility of different energy efficiency retrofits is evaluated. Two different scenarios are analyzed: the former according to the earlier Italian legislation (valid from 2006 to 2008), the latter according to the latest and strictest measures (valid from 2010). The results show that heavy thermal performance upgrades, even though compulsory, are not completely cost-effective in a mild Mediterranean climate area as far as payback time is concerned. National subsidy policies can improve the economic return on the investment. The impact of present Italian incentives has also been evaluated. [Copyright &y& Elsevier]

Abstract: Cool roof technology is an energy efficient, financially viable and sustainable solution for mitigating heat islands and reducing building energy consumption for cooling. An EU supported project called Cool Roofs has achieved to promote this technology in the EU by the implementation of an Action Plan. The work is developed in four axes, technical, market, policy and end-users. The Action Plan is steered by the development of the European Cool Roof Council that brings together all related stakeholders. The main results of the project include the creation of the European Cool Roof Council (ECRC), five cool roof pilot studies, a database of cool roofing materials, a handbook and a toolkit to assist the better understanding of the technical aspects of the technology, a market promotion plan, a proposal for a successful strategy to overcome possible policy barriers and engage with key stakeholders who could support and accelerate the creation of an EU policy and regulatory friendly environment to cool roofs, the organization of workshops and seminars and other actions of dissemination. This paper presents the main achievements at EU level regarding the establishment of cool roofs as heat island mitigation strategy and a measure for reducing cooling loads. [Copyright &y& Elsevier]

Abstract: A big amount of final energy in Europe is used in buildings (about 50%). Thermo insulating investments in the building sector can have a great impact on the improvement of the energetic efficiency of buildings and the reduction of the use of final energy in this sector. In the paper there were presented properly modified indicators for the economic assessment of the investments which is based on the thermal insulation of external walls of the building, such as: net present value, profitability indicator and payback period. For the ecological assessment the following indicators were introduced: ecological net present value, ecological indicator of profitability and ecological payback period. LCA technique was used in ecological indicators. For different variants of external walls, sources of heat and thermo insulating materials, the assessment of investments due to economic and ecological indicators was conducted. Ecological payback periods were obtained within 0–6 years. [Copyright &y& Elsevier]

Abstract: Indoor air pollution has a negative impact on human health, comfort and productivity. Emissions, however, are often related to essential functions of the indoor environment and cannot be eliminated with source control. Ventilation is then used to dilute these pollutants to acceptable concentrations. Due to recent crises in the energy markets and the subsequent quest for higher efficiency in energy use, heat recovery ventilation has gained capstone status in sustainable building concepts. However, along with a reduction of ventilation heat loss, operating a heat recovery unit increases the pressure drop and fan power consumption in the system. These aspects are rarely traded off against each other and even more scarcely for a broad range of operating conditions. This paper addresses this trade-off based on primary energy, carbon dioxide emission, household consumer energy price and exergy frameworks for the different climates in Europe. The results presented here demonstrate that, for the moderate climate region of middle Europe, natural ventilation, simple exhaust mechanical ventilation and heat recovery ventilation have no clear advantage over each other as far as operating energy is concerned. Realistically low specific fan power will make heat recovery ventilation advantageous in virtually all tested conditions. [Copyright &y& Elsevier]