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This paper is focused on the energy performance of buildings containing massive exterior building envelope components. The effect of mass and insulation location on heating and cooling loads is analyzed for six characteristic wall configurations. Correlations between structural and dynamic thermal characteristics of walls are discussed. A simple one-room model of a building exposed to periodic temperature changes is analyzed to illustrate the effect of material configuration on the ability of a wall to dampen interior temperature swings. Whole-building dynamic modeling using DOE-2.1E is employed for the energy analysis of a one-story residential building with various exterior wall configurations for six different US climates. The best thermal performance is obtained when massive material layers are located at the inner side and directly exposed to the interior space.

Abstract ETFE (ethylene tetrafluoroethylene) cushion integrated flexible photovoltaics (PV) is an extension of building integrated photovoltaics into membrane structures, which could be near zero-energy, sustainable and environmental-friendly buildings. This paper focused on a two-layer ETFE cushion integrated flexible photovoltaics with experimental study and theoretical analysis. Field experiments on a prototype were carried out to investigate temperature distribution and characteristics. It is found that temperature distribution was the result of solar irradiance, incident angle and surface curvature of ETFE cushion and that solar irradiance had an essential effect on temperature distribution. The theoretical thermal model was developed based on energy balance equation and the corresponding differential equation was solved by the Runge-Kutta method. Maximum temperature difference of 3.3 K between experimental and numerical results demonstrated that this thermal model could predict PV temperature appropriately. Furthermore, a modified equation to determine heat transfer coefficients was proposed and average heat transfer coefficients of PV and ETFE foil were 4.89 W/(m 2 K) and 4.39 W/(m 2 K). In general, this study could provide basic values and observations for investigating thermal performance of ETFE cushion integrated flexible photovoltaics.

Abstract Solar thermal technology is a promising key strategy for future renewable energy production. Various concepts exist that use solar collectors and heat mirrors, built from rigid materials, to gather thermal energy from solar radiation. A new approach is the utilization of textile materials to build solar thermal collector systems with flexible material properties, lightweight design and improved material-efficiency. A solar collector, based on a multi-layer arrangement of technical textiles and foil membranes, has been realized by the ITV Denkendorf (Institute of Textile Technology and Process Engineering Denkendorf). The proposed collector system allows transparent insulation in textile-based buildings while gathering thermal energy simultaneously. The system is inspired by the transparent insulation and heat harvesting strategies of polar bear fur and can inform textile-based envelopes of future transparent buildings. In this study, different material arrangements and the influence of different parameters on the temperature distribution along the collector were tested. Air temperatures up to 150 °C (302 °F) could be generated inside the collector system. Furthermore, a closer look at the polar bear fur and other related principles in nature delivered additional concepts for energetic optimization.

Abstract There are approx. 5.5 million residential buildings in Poland including 5 million single-family houses, 90% of which were built before 2002. Most of the existing single-family houses are not energy-efficient and a large amount of energy is wasted. It is therefore essential to develop, experimentally validate and then disseminate strategies for thermal modernization of the existing single-family houses, including strategies for ventilation systems renovation. In two-storey single-family houses with sloping roofs it is possible to locate a ventilation heat recovery (VHR) unit and ventilation ducts in the unheated roof space. The paper presents the results of tests of combined ventilation systems: mechanical ventilation with heat recovery in rooms on the second floor and stack ventilation in the rooms on the first floor. On-site measurement of the efficiency of ventilation heat recovery was performed, the airtightness of the house was measured twice before and after its improvement. The results of the experimental tests of the hybrid system were used to estimate the ventilation airflow in the house and the energy demand for ventilation. The ventilation airflow was calculated using the software CONTAM. The estimated heat demand for the tested ventilation system was 37.4 kWh/m2/season; though it seems possible to reduce it below 20 kWh/m2/season.

Abstract The paper concerns thermal energy consumption in residential buildings. Heat consumption data of 2280 buildings are compared. Special attention is given to compare heat consumption in identical buildings. Heat consumption variability analysis enables to evaluate inherent heat consumption for space heating dissipation which exists even if design and construction requirements are met. The attempt is made to find the numeral value of heat consumption dissipation caused by design and construction allowances. The analysis of multiflat panel sister-buildings annual heat consumption reveals that minimal value of maximal and minimal heat consumption ratio in identical panel buildings reaches 1.22 (95% confidence level). Data scatter testify erratic quality of construction works, in other words, maximal and minimal heat consumption ratio trend reflects quality of construction works as a whole. On the other hand awareness of inherent unavoidable heat consumption difference in similar houses may strengthen residents’ and policy makers’ confidence in energy saving tools and enhance thermal renovation of residential buildings.

Abstract Energy-efficiency of sustainable constructions and buildings are evaluated based upon the heating and cooling demands, but also according to the primary-energy demand, CO2 savings potential, and the ecological properties of building materials. To meet increasingly rigorous requirements, the demand for natural building materials is growing rapidly. The research objective of the here presented study is to stabilize soils with natural straw fibres to produce a composite, sustainable, non-toxic and locally sourced building material. The material appropriateness was determined by establishing the thermal conductivity of a selection of unfired earth bricks that were identified as potential new natural building materials. The thermal conductivity is an essential material characteristic to achieve the required insulation level and for market success as a new product. The earth bricks consist of soil, cement, gypsum and straw fibres. Straw was applied as fibre reinforcement for unfired bricks. Two fibre types were used: wheat and barley straw. The results indicated that the thermal conductivity of all investigated variants decreased with increasing fibre content while increasing with higher cement and gypsum contents. They also show that barley straw fibre reinforced bricks exhibited the highest thermal insulation values. The addition of fibre positively improves both, thermal and static properties.

Abstract This article presents the results of the research project financed by the Polish Ministry of Science and Higher Education (N N309 078138) and coordinated by the Wood Technology Institute in Poznan. A key point of this project was LCA study performed for four detached single-family dwellings with a particular emphasis on the use stage. The life-cycle assessment involved various types of activity made within a hundred years of use and related to: operation (energy and water consumption), replacements and repairs, renovations and maintenance, land occupation, waste transport and waste management. Two of the four analyzed buildings met passive house standards and their energy demands in the use stage were several times lower than those of their conventional counterparts. The aim of the studies was to demonstrate whether lower nominal energy consumption is sufficient to get the best results of the environmental impact of passive buildings, or whether a type of energy used to cover the demand also plays an important role.