| 1. |
- Dodoo, Ambrose, 1979-, et al.
(författare)
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Final energy savings and cost-effectiveness of deep energy renovation of a multi-storey residential building
- 2017
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Ingår i: Energy. - : Pergamon Press. - 0360-5442 .- 1873-6785. ; 135, s. 563-576
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Tidskriftsartikel (refereegranskat)abstract
- In this study we present a method for analysis of cost-effectiveness of end-use energy efficiency measures and demonstrate its application for modelling a wide range of energy renovation measures for a typical 1970s multi-family building in Sweden. The method integrates energy balance and bottom-up economic calculations considering total and marginal investment costs of energy efficiency measures as well as net present value of total and marginal savings of the measures. The energy renovation measures explored include additional insulation to basement walls, exterior walls, and attic floor, improved new windows, efficient electric appliances and lighting, efficient water taps, glazed enclosed balcony systems, and exhaust air ventilation heat recovery systems. The measures are analysed first individually and then designed to form economic packages. Our results show that improved windows give the biggest single final energy savings while resource-efficient taps is the most cost-effective measure for the building. We find that the cost-effectiveness of the energy renovation measures is sensitive to real discount rates and energy price increases. Cost-optimal final heat savings varies between 34% and 51%, depending on the choice of real discount rate and energy price increase. The corresponding electricity savings varies between 35% and 43%. This study shows a method and the significance of various technical and economic-related parameters in achieving deep energy savings cost-efficiently.
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| 2. |
- Dodoo, Ambrose, 1979-, et al.
(författare)
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Influence of simulation assumptions and input parameters on energy balance calculations of residential buildings
- 2017
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Ingår i: Energy. - : Elsevier. - 0360-5442 .- 1873-6785. ; 120:1, s. 718-730
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Tidskriftsartikel (refereegranskat)abstract
- 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.
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| 3. |
- Dodoo, Ambrose, 1979-, et al.
(författare)
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Life cycle primary energy use of nearly-zero energy building and low-energy building
- 2017
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Ingår i: ECEEE 2017 Summer Study. - : European Council for an Energy Efficient Economy (ECEEE). ; , s. 1075-1081
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Konferensbidrag (refereegranskat)abstract
- Energy legislations are increasingly driving towards buildings with very low operation final energy use as part of efforts to reduce energy use and climate impact of the built environment. In this study we analyse the life cycle primary energy use of a recently constructed Swedish conventional 6-storey apartment building and compare it to variants designed as nearly-zero energy building or as low-energy building with a combination of improved thermal envelope and passive design strategies. We maintain the architectural design of the constructed building and improve the thermal properties of the envelope to achieve a low-energy building and also nearly-zero energy building including solar thermal collectors. We consider scenarios where the building variants are heated with renewable energy using cogenerated district heating, also complemented with solar heating system. We follow the life cycle of the building versions and analyse their total primary energy use, considering the production, operation and end-of-life phases. The results show that the relative significance of the production phase increases as buildings are made to achieve very low operational energy use. The production phase accounts for 17 % of the total primary energy use for production, operation and demolition of the constructed building for a 50-year lifespan. The corresponding values for the nearly-zero energy and low-energy building variants ranges between 30 to 31 %. Overall, the life cycle primary energy use for the nearly-zero energy and low-energy building variants are about 30–35 % lower compared to the constructed building.
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| 4. |
- Dodoo, Ambrose, 1979-, et al.
(författare)
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On input parameters, methods and assumptions for energy balance and retrofit analyses for residential buildings
- 2017
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Ingår i: Energy and Buildings. - : Elsevier. - 0378-7788 .- 1872-6178. ; 137, s. 76-89
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Tidskriftsartikel (refereegranskat)abstract
- 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.
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| 5. |
- Tettey, Uniben Yao Ayikoe, 1979-, et al.
(författare)
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Design strategies to minimise heating and cooling demands for passive houses under changing climate
- 2017
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Ingår i: ECEEE 2017 Summer Study. - : European Council for an Energy Efficient Economy (ECEEE). ; , s. 1185-1195
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Konferensbidrag (refereegranskat)abstract
- In this study, we analyse the heating and cooling demands of a multi-storey residential building version, designed to the passive house criteria in Southern Sweden and explore various design strategies to minimise these demands under different climate change scenarios. The analysis is performed for recent (1996–2005) and future climate periods of 2050–2059 and 2090–2099 based on the Representative Concentration Pathway scenarios, downscaled to conditions in South of Sweden. Design strategies include efficient household equipment and technical installations, bypass of ventilation heat recovery unit, window solar shading, building orientation, window size and properties, besides mechanical cooling. Results show that space heating demand reduces, while cooling demand increases as the risk of overheating under the future climate scenarios. The most important design strategies are efficient household equipment and technical installations, solar shading, bypass of ventilation heat recovery unit and window u-values and g-values. Total annual final energy demand decreased by 40–51 % and overheating is avoided or significantly reduced under the considered climate scenarios when all the strategies are implemented. Overall, the total annual primary energy for operating the building versions decreased by 49–54 % This study emphasises the importance of considering different design strategies and measures in minimising the operation energy use and the potential risks of overheating in low-energy residential buildings under future climate scenarios.
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| 6. |
- Tettey, Uniben Yao Ayikoe, 1979-, et al.
(författare)
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Energy use implications of different design strategies for multi-storey residential buildings under future climates
- 2017
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Ingår i: Energy. - : Elsevier. - 0360-5442 .- 1873-6785. ; 138, s. 846-860
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Tidskriftsartikel (refereegranskat)abstract
- The effects of climate change on the final and primary energy use of versions of a multi-storey residential building have been analysed. The building versions are designed to the Swedish building code (BBR 2015) and passive house criteria (Passive 2012) with different design and overheating control strategies under different climate scenarios. Future climate datasets are based on Representative Concentration Pathway scenarios for 2050–2059 and 2090–2099. The analysis showed that strategies giving the lowest space heating and cooling demands for the Passive 2012 building version remained the same under all climate scenarios. In contrast, strategies giving the lowest space heating and cooling demands for the BBR 2015 version varied, as cooling demand became more significant under future climate scenarios. Cooling demand was more dominant than heating for the Passive 2012 building version under future climate scenarios. Household equipment and technical installations based on best available technology gave the biggest reduction in total primary energy use among considered strategies. Overall, annual total operation primary energy decreased by 37–54% for the building versions when all strategies are implemented under the considered climate scenarios. This study shows that appropriate design strategies could result in significant primary energy savings for low-energy buildings under changing climates.
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| 7. |
- Tettey, Uniben Yao Ayikoe, 1979-, et al.
(författare)
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Impacts of parameter values interactions on simulated energy balance of residential buildings
- 2017
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Ingår i: 11th Nordic Symposium on Building Physics, NSB2017, 11-14 June 2017, Trondheim, Norway. - : Elsevier. ; , s. 57-62
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Konferensbidrag (refereegranskat)abstract
- In this study we use dynamic simulation to explore the interactive impacts of different uncertain parameter values in energy balance modelling of existing and improved variants of a Swedish multi-storey residential building. We modelled variations as well as interactive influence of different simulation assumptions and parameters encompassing outdoor microclimate, building thermal envelope and technical installations including household equipment. The results indicate that the interactive influence of the parameters on calculated space heating of buildings seems to be small and relatively more evident for a low-energy building than for a conventional building. The influence of the interactions between the parameter combinations becomes more evident as several parameters are varied simultaneously. The results also indicate that calculated space heating demand of a building is noticeably influenced by how heat gains from household equipment and technical installations are modelled. The calculated final energy for space heating for the analysed building versions varied between 13-43% depending on the energy efficiency levels for household equipment and technical installations as well as their interactions with other parameter values variations. This study shows the importance of appropriate input parameters and assumptions for building energy balance calculation.
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| 8. |
- Tettey, Uniben Yao Ayikoe, 1979-
(författare)
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Primary energy use of residential buildings : implications of materials, modelling and design approaches
- 2017
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- 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.
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