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Primary energy use of residential buildings: implications of materials, modelling and design approaches
Linnaeus University, Faculty of Technology, Department of Built Environment and Energy Technology. (Sustainable Built Environment Research)ORCID iD: 0000-0003-2111-806X
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. , 60 p.
Series
Linnaeus University Dissertations, 281/2017
Keyword [en]
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: urn:nbn:se:lnu:diva-61470ISBN: 978-91-88357-66-3 (print)OAI: oai:DiVA.org:lnu-61470DiVA: diva2:1083055
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
List of papers
1. Effects of different insulation materials on primary energy and CO2 emission of a multi-storey residential building
Open this publication in new window or tab >>Effects of different insulation materials on primary energy and CO2 emission of a multi-storey residential building
2014 (English)In: Energy and Buildings, ISSN 0378-7788, Vol. 82, 369-377 p.Article in journal (Refereed) Published
Abstract [en]

In this study, we analyzed the implications of various insulation materials on the primary energy and CO2emission for material production of a residential building. We modeled changes to the original design ofthe building to achieve reference buildings to energy-efficiency levels of the Swedish building code of2012 or the Swedish Passivhus 2012 criteria. We varied the insulation materials in different parts of thereference buildings from mineral rock wool to glass wool, cellulose fiber, expanded polystyrene or foamglass. We compared the primary energy use and CO2emission from material production of functionallyequivalent reference and optimum versions of the building. The results showed a reduction of about 6–7%in primary energy use and 6–8% in CO2emission when the insulation material in the reference buildingsis changed from rock wool to cellulose fiber in the optimum versions. Also, the total fossil fuel use for onlyinsulation material production was reduced by about 39%. This study suggests that enhancing materialproduction technologies by reducing fossil fuel-use and increasing renewable energy sources, as wellas careful material choice with renewable-based raw materials can contribute significantly in reducingprimary energy use and GHG emission in the building sector.

Place, publisher, year, edition, pages
Elsevier, 2014
Keyword
Insulation material; Primary energy; CO2 emission; Energy-efficiency; Fossil fuel; Residential building
National Category
Building Technologies
Research subject
Technology (byts ev till Engineering), Civil engineering
Identifiers
urn:nbn:se:lnu:diva-36878 (URN)10.1016/j.enbuild.2014.07.009 (DOI)000343781400035 ()
Available from: 2014-09-11 Created: 2014-09-11 Last updated: 2017-03-20Bibliographically approved
2. On input parameters, methods and assumptions for energy balance and retrofit analyses for residential buildings
Open this publication in new window or tab >>On input parameters, methods and assumptions for energy balance and retrofit analyses for residential buildings
2017 (English)In: Energy and Buildings, ISSN 0378-7788, E-ISSN 1872-6178, Vol. 137, 76-89 p.Article 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
National Category
Building Technologies Energy Systems
Research subject
Technology (byts ev till Engineering), Civil engineering
Identifiers
urn:nbn:se:lnu:diva-58941 (URN)10.1016/j.enbuild.2016.12.033 (DOI)000393260000007 ()
Available from: 2016-12-13 Created: 2016-12-13 Last updated: 2017-03-20Bibliographically approved
3. Influence of simulation assumptions and input parameters on energy balance calculations of residential buildings
Open this publication in new window or tab >>Influence of simulation assumptions and input parameters on energy balance calculations of residential buildings
2017 (English)In: Energy, ISSN 0360-5442, E-ISSN 1873-6785, Vol. 120, no 1, 718-730 p.Article in journal (Refereed) Published
Abstract [en]

In this study, we modelled the influence of different simulation assumptions on energy balances of two variants of a residential building, comprising the building in its existing state and with energy-efficient improvements. We explored how selected parameter combinations and variations affect the energy balances of the building configurations. The selected parameters encompass outdoor microclimate, building thermal envelope and household electrical equipment including technical installations. Our modelling takes into account hourly as well as seasonal profiles of different internal heat gains. The results suggest that the impact of parameter interactions on calculated space heating of buildings is somewhat small and relatively more noticeable for an energy-efficient building in contrast to a conventional building. We find that the influence of parameters combinations is more apparent as more individual parameters are varied. The simulations show that a building's calculated space heating demand is significantly influenced by how heat gains from electrical equipment are modelled. For the analyzed building versions, calculated final energy for space heating differs by 9-14 kWh/m(2) depending on the assumed energy efficiency level for electrical equipment. The influence of electrical equipment on calculated final space heating is proportionally more significant for an energy-efficient building compared to a conventional building. This study shows the influence of different simulation assumptions and parameter combinations when varied simultaneously. (C) 2016 Elsevier Ltd. All rights reserved.

National Category
Civil Engineering
Research subject
Environmental Science, Environmental technology
Identifiers
urn:nbn:se:lnu:diva-58638 (URN)10.1016/j.energy.2016.11.124 (DOI)000395953000062 ()
Available from: 2016-12-05 Created: 2016-12-05 Last updated: 2017-05-22Bibliographically approved
4. Primary energy implications of different design strategies for an apartment building
Open this publication in new window or tab >>Primary energy implications of different design strategies for an apartment building
2016 (English)In: Energy, ISSN 0360-5442, E-ISSN 1873-6785, Vol. 104, 132-148 p.Article in journal (Refereed) Published
Abstract [en]

In this study, we explored the effects of different design strategies on final and primary energy use for production and operation of a newly constructed apartment building. We analysed alternatives of the building “As built” as well as to energy efficiency levels of the Swedish building code and passive house criteria. Our approach is based on achieving improved versions of the building alternatives from combination of design strategies giving the lowest space heating and cooling demand and primary energy use, respectively. We found that the combination of design strategies resulting in the improved building alternatives varies depending on the approach. The improved building alternatives gave up to 19–34% reduction in operation primary energy use compared to the initial alternatives. The share of production primary energy use of the improved building alternatives was 39–54% of the total primary energy use for production, space heating, space cooling and ventilation over 50-year lifespan, compared to 31–42% for the initial alternatives. This study emphasises the importance of incorporating appropriate design strategies to reduce primary energy use for building operation and suggests that combining such strategies with careful choice of building frame materials could result in significant primary energy savings in the built environment.

Keyword
Building orientation, Design strategies, Material production, Primary energy, Space heating and cooling, Windows
National Category
Building Technologies
Research subject
Technology (byts ev till Engineering), Civil engineering
Identifiers
urn:nbn:se:lnu:diva-50901 (URN)10.1016/j.energy.2016.03.071 (DOI)000377727000013 ()2-s2.0-84971324184 (ScopusID)
External cooperation:
Available from: 2016-03-17 Created: 2016-03-17 Last updated: 2017-03-20Bibliographically approved

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