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On input parameters, methods and assumptions for energy balance and retrofit analyses for residential buildings
Linnaeus University, Faculty of Technology, Department of Built Environment and Energy Technology. (SBER)
Linnaeus University, Faculty of Technology, Department of Built Environment and Energy Technology. (SBER)
Linnaeus University, Faculty of Technology, Department of Built Environment and Energy Technology. (SBER)
2017 (English)In: Energy and Buildings, ISSN 0378-7788, E-ISSN 1872-6178, Vol. 137, p. 76-89Article in journal (Refereed) Published
Abstract [en]

In this study we explore key parameter values, methods and assumptions used for energy balance modelling of residential buildings in the Swedish context and analyse their effects on calculated energy balance of a typical multi-storey building from 1970s and on energy savings of energy efficiency retrofit measures. The parameters studied are related to microclimate, building envelope, occupancy behaviour, ventilation, and heat gains from electric appliances and persons. Our study shows that assumed indoor air temperature, internal heat gains and efficiency of ventilation heat recovery units have significant effect on the simulated energy performance of the studied building and energy efficiency measures. Of the considered microclimate parameter values and assumptions, the outdoor temperature, ground solar reflection and window shading have significant impact on the simulated space heating and cooling demands. On the contrary, the simulated energy performances are less affected by the variations in air pressure outside and the percentage of wind load that hits the building. We found that input data and assumptions used for energy balance calculations and energy saving analyses vary significantly in the Swedish context. These result in significantly different calculated final energy performance of buildings and energy efficiency measures. To inform accurate analysis of energy performance of building and energy saving measures, input parameters used in simulation models need to be appropriate.

Place, publisher, year, edition, pages
Elsevier, 2017. Vol. 137, p. 76-89
National Category
Building Technologies Energy Systems
Research subject
Technology (byts ev till Engineering), Civil engineering
Identifiers
URN: urn:nbn:se:lnu:diva-58941DOI: 10.1016/j.enbuild.2016.12.033ISI: 000393260000007OAI: oai:DiVA.org:lnu-58941DiVA, id: diva2:1055715
Available from: 2016-12-13 Created: 2016-12-13 Last updated: 2017-11-29Bibliographically approved
In thesis
1. Primary energy use of residential buildings: implications of materials, modelling and design approaches
Open this publication in new window or tab >>Primary energy use of residential buildings: implications of materials, modelling and design approaches
2017 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

Buildings can play an essential role in the transition to a sustainable society. Different strategies, including improved energy efficiency in buildings, substitution of carbon intensive materials and fuels, efficient energy supply among others can be employed for this purpose. In this thesis, the implications of different insulation materials, modelling and design strategies on primary energy use of residential buildings are studied using life cycle and system perspective. Specifically, the effects of different insulation materials on production primary energy and CO2 emission of buildings with different energy performance are analysed. The results show that application of extra insulation materials to building envelope components reduces the operating primary energy use but more primary energy is required for the insulation material production. This also slightly increases the CO2 emissions from material production. The increases in primary energy use and CO2 emissions are mainly due to the variations in the quantities, types and manufacturing processes of the insulation materials. Thus, choice of renewable based materials with energy efficient manufacturing is important to reduce primary energy use and GHG emissions for building material production.

Uncertainties related to building modelling input parameters and assumptions and how they influence energy balance calculations of residential buildings are explored. The implications on energy savings of different energy efficiency measures are also studied. The results show that input data and assumptions used for energy balance simulations of buildings vary widely in the Swedish context giving significant differences in calculated energy demand for buildings. Among the considered parameters, indoor air temperature, internal heat gains and efficiency of ventilation heat recovery (VHR) have significant impacts on the simulated building energy performance as well as on the energy efficiency measures. The impact of parameter interactions on calculated space heating of buildings is rather small but increases with more parameter combinations and more energy efficient buildings. Detailed energy characterisation of household equipment and technical installations used in a building is essential to accurately calculate the energy demand, particularly for a low energy building.

The design and construction of new buildings present many possibilities to minimise both heating and cooling demands over the lifecycle of buildings, and also in the context of climate change. Various design strategies and measures are analysed for buildings with different energy performance under different climate scenarios. These include household equipment and technical installations based on best available technology, bypassing the VHR unit, solar shading of windows, combinations of window u- and g-values, different proportions of glazed window areas and façade orientations and mechanical cooling. The results show that space heating and cooling demands vary significantly with the energy performance of buildings as well as climate scenarios. Space heating demand decreases while space cooling demand and the risk of overheating increase considerably with warmer climate. The space cooling demand and overheating risk are more significant for buildings with higher energy performance. Significant reductions are achieved in the operation final energy demands and overheating is avoided or greatly reduced when different design strategies and measures are implemented cumulatively under different climate change scenarios.

The primary energy efficiency of heat supply systems depends on the heat production technology and type of fuel use. Analysis of the interaction between different design strategies and heat supply options shows that the combination of design strategies giving the lowest primary energy use for space heating and cooling varies between heat supply from district heating with combined heat and power (CHP) and heat only boilers (HOB). The primary energy use for space heating is significantly lower when the heat supply is from CHP rather than HOB. Operation primary energy use is significantly reduced with slight increase in production primary energy when the design strategies are implemented. The results suggest that significant primary energy reductions are achievable under climate change, if new buildings are designed with appropriate strategies.

Place, publisher, year, edition, pages
Växjö: Linnaeus University Press, 2017. p. 60
Series
Linnaeus University Dissertations ; 281/2017
Keywords
primary energy use, material production, simulation, input parameters, design strategies, climate change, overheating, residential buildings
National Category
Building Technologies
Research subject
Technology (byts ev till Engineering); Technology (byts ev till Engineering), Civil engineering
Identifiers
urn:nbn:se:lnu:diva-61470 (URN)978-91-88357-66-3 (ISBN)
Public defence
2017-03-15, Södra-salen, M1083, Hus M, Linnaeus University, Växjö, 13:00 (English)
Opponent
Supervisors
Available from: 2017-03-20 Created: 2017-03-20 Last updated: 2017-04-28Bibliographically approved

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Dodoo, AmbroseTettey, Uniben Yao AyikoeGustavsson, Leif

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