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Heat demand profiles of buildings' energy conservation measures and their impact on renewable and resource efficient district heating systems
Mälardalen University, School of Business, Society and Engineering, Future Energy Center. (Reesbe)ORCID iD: 0000-0003-3530-0209
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.
Series
Mälardalen University Press Licentiate Theses, ISSN 1651-9256 ; 236
Keyword [en]
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
Identifiers
URN: urn:nbn:se:mdh:diva-31495ISBN: 978-91-7485-266-0 (print)OAI: oai:DiVA.org:mdh-31495DiVA: diva2:925612
Presentation
2016-06-10, Delta, Mälardalens Högskola, Västerås, 10:00 (English)
Opponent
Supervisors
Funder
Knowledge Foundation
Available from: 2016-05-03 Created: 2016-05-02 Last updated: 2016-06-03Bibliographically approved
List of papers
1. Impact on carbon dioxide emissions from energy conservation within Swedish district heating networks
Open this publication in new window or tab >>Impact on carbon dioxide emissions from energy conservation within Swedish district heating networks
Show others...
2014 (English)In: Energy Procedia, ISSN 1876-6102, E-ISSN 1876-6102, Vol. 61, 2132-2136 p.Article in journal, Meeting abstract (Refereed) Published
Abstract [en]

The 100 largest Swedish district heating (DH)-networks were studied on how DH conservation measures impacts CO2-emission rates taking both direct and indirect (i.e. displaced electricity) emissions into account, applying six different methods for the indirect emissions assessment. When the marginal electricity approach is applied on low CO2-emitting DH-networks with a high share of cogenerated electricity, it resulted in assessments that imply that DH conservation leads to higher CO2 emissions. This was not the case with the efficiency method.

Keyword
District heat, CO2 emissions, marginal electrcity, efficiency method, energy conservation
National Category
Energy Engineering
Research subject
Energy- and Environmental Engineering; Energy- and Environmental Engineering
Identifiers
urn:nbn:se:mdh:diva-27510 (URN)10.1016/j.egypro.2014.12.092 (DOI)000375936100475 ()2-s2.0-84922357043 (Scopus ID)
Conference
6th International Conference on Applied Energy
Projects
Reesbe
Funder
Knowledge Foundation
Available from: 2015-02-12 Created: 2015-02-12 Last updated: 2017-12-04Bibliographically approved
2. SEASONAL DEPENDENT ASSESSMENT OF ENERGY CONSERVATION WITHIN DISTRICT HEATING AREAS
Open this publication in new window or tab >>SEASONAL DEPENDENT ASSESSMENT OF ENERGY CONSERVATION WITHIN DISTRICT HEATING AREAS
2014 (English)In: Proceedings from the 14th International Symposium on District Heating and Cooling, September 7th to September 9th, 2014, Stockholm, Sweden / [ed] Anna Land, Stockholm: Swedish District Heating Association , 2014Conference paper, Published paper (Refereed)
Abstract [en]

When housing companies plan for energy conserving renovations, costs and amount of saved energy are usually estimated with yearly mean values. Yet the fuel mix varies widely depending on heat demand of district heating system, often with higher cost and CO2 emission rates during winter than summer.

Instead of comparing different energy conserving measures’ potentials with yearly mean values, it would be beneficial to examine them in a higher resolution, e.g. on daily or monthly basis, to identify real effectiveness of different measures in reducing CO2-emissions and primary energy consumption.

In this study, three energy conserving measures are put into a building simulation model to obtain results of hourly energy consumption reduction, which is then fitted into a district heating optimization model to analyze the impact on district heating system.

This study also discuss the correlation between energy cost for the customer and different measures’ environmental impact under new circumstances: seasonal energy price models of district heating, a price model which introduce price fluctuation throughout a year. This new factor provides a more comprehensive incitement to the property owners to encourage them to make environmental friendly decisions when planning for energy conserving renovations.

Place, publisher, year, edition, pages
Stockholm: Swedish District Heating Association, 2014
Keyword
District heating energy conserving price model co2 evironmental optimazation
National Category
Energy Systems
Research subject
Energy- and Environmental Engineering
Identifiers
urn:nbn:se:mdh:diva-27507 (URN)ISBN 978-91-85775-24-8 (ISBN)
Conference
The 14th International Symposium on District Heating and Cooling, September 7th to September 9th, 2014, Stockholm, Sweden
Projects
Reese
Funder
Knowledge Foundation
Available from: 2015-02-12 Created: 2015-02-12 Last updated: 2017-02-07Bibliographically approved
3. Heat demand profiles of energy conservation measures in buildings and their impact on a district heating system
Open this publication in new window or tab >>Heat demand profiles of energy conservation measures in buildings and their impact on a district heating system
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.

Keyword
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
Identifiers
urn:nbn:se:mdh:diva-29430 (URN)10.1016/j.apenergy.2015.10.024 (DOI)000366063100023 ()2-s2.0-84945219207 (Scopus ID)
Available from: 2015-11-06 Created: 2015-11-06 Last updated: 2017-12-01Bibliographically approved

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