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Heat demand profiles of energy conservation measures in buildings and their impact on a district heating system
Mälardalen University, School of Business, Society and Engineering, Future Energy Center.ORCID iD: 0000-0003-3530-0209
Mälardalen University, School of Business, Society and Engineering, Future Energy Center.ORCID iD: 0000-0003-4589-7045
2016 (English)In: Applied Energy, ISSN 0306-2619, E-ISSN 1872-9118, Vol. 161, 290-299 p.Article in journal (Refereed) Published
Abstract [en]

This study highlights the forthcoming problem with diminishing environmental benefits from heat demand reducing energy conservation measures (ECM) of buildings within district heating systems (DHS), as the supply side is becoming "greener" and more primary energy efficient. In this study heat demand profiles and annual electricity-to-heat factors of ECMs in buildings are computed and their impact on system efficiency and greenhouse gas emissions of a Swedish biomass fuelled and combined heat and power utilising DHS are assessed. A weather normalising method for the DHS heat load is developed, combining segmented multivariable linear regressions with typical meteorological year weather data to enable the DHS model and the buildings model to work under the same weather conditions. Improving the buildings' envelope insulation level and thereby levelling out the DHS heat load curve reduces greenhouse gas emissions and improves primary energy efficiency. Reducing household electricity use proves to be highly beneficial, partly because it increases heat demand, allowing for more cogeneration of electricity. However the other ECMs considered may cause increased greenhouse gas emissions, mainly because of their adverse impact on the cogeneration of electricity. If biomass fuels are considered as residuals, and thus assigned low primary energy factors, primary energy efficiency decreases when implementing ECMs that lower heat demand.

Place, publisher, year, edition, pages
2016. Vol. 161, 290-299 p.
Keyword [en]
Building energy simulation, District heating, Energy conservation, Energy system assessment, Typical meteorological year, Weather normalisation, Buildings, Gas emissions, Greenhouse gases, Heating, Heating equipment, Historic preservation, Meteorology, Thermal load, Building energy simulations, Combined heat and power, Energy conservation measures, Energy systems, Multi-variable linear regression, Normalisation, Primary energy efficiencies, Energy efficiency
National Category
Energy Engineering
URN: urn:nbn:se:mdh:diva-29430DOI: 10.1016/j.apenergy.2015.10.024ISI: 000366063100023Scopus ID: 2-s2.0-84945219207OAI: diva2:867801
Available from: 2015-11-06 Created: 2015-11-06 Last updated: 2017-12-01Bibliographically approved
In thesis
1. Heat demand profiles of buildings' energy conservation measures and their impact on renewable and resource efficient district heating systems
Open this publication in new window or tab >>Heat demand profiles of buildings' energy conservation measures and their impact on renewable and resource efficient district heating systems
2016 (English)Licentiate thesis, comprehensive summary (Other academic)
Abstract [en]

Increased energy performance of the building stock of European Union is seen as an important measure towards mitigating climate change, increasing resource utilisation efficiency and energy supply security. Whether to improve the supply-side, the demand-side or both is an open issue. This conflict is even more apparent in countries such as Sweden with a high penetration of district heating (DH). Many Swedish DH systems have high share of secondary energy resources such as forest industry residuals, waste material incineration and waste heat; and resource efficient cogeneration of electricity in combined heat and power (CHP) plants. When implementing an energy conservation measure (ECM) in a DH connected building stock, it will affect the operation of the whole DH system. If there are CHP plants and the cogeneration of electricity decreases due to an ECM, and this electricity is valued higher than the fuel savings, the consequences of the ECM would be negative. 

These complex relationships are investigated by conducting a case study on the Eskilstuna DH system, a renewable energy supply system with relatively high share of cogenerated electricity. Heat demand profiles of ECMs are determined by building energy simulation, using recently deep energy retrofitted multifamily buildings of the “Million Programme”-era in Eskilstuna as model basis. How implementing ECMs impact on the DH system’s heat and electricity production under different electricity revenue scenarios has been computed and evaluated in terms of resource efficiency and CO2 emissions. 

The results show that different ECMs in the buildings impact differently on the DH system. Measures such as improved insulation level of the building’s envelope, that decrease the heat demand’s dependence to outdoor temperature, increase the amount of cogenerated electricity. While measures such as thermal solar panels, which save heat during summer, affects the absolute amount of cogenerated electricity negatively. Revenues from cogenerated electricity influence the amount of cost-effectively produced electricity much more than the impact from ECMs. Environmental benefits of the ECMs, measured in CO2 emissions and primary energy consumption, are quite small in DH systems that have high share of forest residual fuels and electricity cogeneration. The consequences can even be negative if ECMs lead to increased need of imported electricity that is produced resource inefficiently or/and by fossil fuels. However, all studied ECMs increase the relative amount of cogenerated electricity, the ratio between amount of cogenerated electricity and the heat load. This implied that all ECMs increase the overall efficiency of the Eskilstuna DH system.

Place, publisher, year, edition, pages
Västerås: Mälardalen University, 2016
Mälardalen University Press Licentiate Theses, ISSN 1651-9256 ; 236
district heating, energy conservation, weather normalisation, typical meteorological year, building energy simulation, system analysis
National Category
Energy Engineering Energy Systems Other Civil Engineering
Research subject
Energy- and Environmental Engineering
urn:nbn:se:mdh:diva-31495 (URN)978-91-7485-266-0 (ISBN)
2016-06-10, Delta, Mälardalens Högskola, Västerås, 10:00 (English)
Knowledge Foundation
Available from: 2016-05-03 Created: 2016-05-02 Last updated: 2016-06-03Bibliographically approved

Open Access in DiVA

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