Change search
CiteExportLink to record
Permanent link

Direct link
Cite
Citation style
  • apa
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf
System Effects of Improved Energy Efficiency in Swedish District-Heated Buildings
Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences. (Solid State Physics)ORCID iD: 0000-0002-6031-2159
2014 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

To alleviate global warming, European-Union member states must reduce primary energy use, emit less carbon dioxide (CO2), and increase renewable energy use. Buildings constitute a great potential for energy savings, but saving energy in district-heated buildings influences combined heat and power (CHP) production, other electricity generation, and global CO2 emissions.

 

This thesis investigates the system effects from Swedish district heating production caused by district heating demand changes due to energy conservation in buildings. The cost-optimising linear programming modelling tools MODEST and FMS, the latter developed in the context of this thesis, are used to describe present district heating production and to investigate the impact of heat-demand reductions in twelve Swedish district heating systems, four of them representing all Swedish district heating.

 

Energy savings in district-heated, multi-family residential buildings yield a lower, more seasonally levelled district heating demand. These demand changes mainly reduce use of fossil-fuel and biomass for heat production. CHP production is significantly reduced if it supplies intermediate or peak district heating load. The αsystem value (ratio between generated CHP electricity and produced district heating) increases by demand reductions if CHP mainly supplies base district heating load. CO2 emissions due to district heat production depend on the approach used for CO2 assessment of electricity, and are generally reduced with heat demand reductions, unless the share of CHP production is large and the reduced fuel use yields smaller emission reductions than the emission increase from power production that replaces reduced CHP generation.

 

In total, heat demand reductions reduce CO2 emissions due to Swedish district heating, and the district heating systems even constitute a carbon sink at certain energy conservation levels. If saved biomass replaces fossil fuels elsewhere, a lower heat demand reduces CO2 emissions for every studied district heating system.

Place, publisher, year, edition, pages
Uppsala: Acta Universitatis Upsaliensis, 2014. , 91 p.
Series
Digital Comprehensive Summaries of Uppsala Dissertations from the Faculty of Science and Technology, ISSN 1651-6214 ; 1161
Keyword [en]
district heating, carbon dioxide emissions, building energy efficiency, combined heat and power
National Category
Energy Systems
Research subject
Engineering Science
Identifiers
URN: urn:nbn:se:uu:diva-229477ISBN: 978-91-554-8996-0 (print)OAI: oai:DiVA.org:uu-229477DiVA: diva2:736854
Public defence
2014-09-26, Häggsalen, Ångströmlaboratoriet, Lägerhyddsvägen 1, Uppsala, 13:15 (English)
Opponent
Supervisors
Funder
Swedish Energy Agency
Available from: 2014-09-17 Created: 2014-08-08 Last updated: 2017-01-19
List of papers
1. Optimisation of a Swedish district heating system with reduced heat demand due to energy efficiency measures in residential buildings
Open this publication in new window or tab >>Optimisation of a Swedish district heating system with reduced heat demand due to energy efficiency measures in residential buildings
2011 (English)In: Energy Policy, ISSN 0301-4215, E-ISSN 1873-6777, Vol. 39, no 12, 7839-7852 p.Article in journal (Refereed) Published
Abstract [en]

The development towards more energy efficient buildings, as well as the expansion of district heating (DH) networks, is generally considered to reduce environmental impact. But the combined effect of these two progressions is more controversial. A reduced heat demand (HD) due to higher energy efficiency in buildings might hamper co-production of electricity and DH. In Sweden, co-produced electricity is normally considered to displace electricity from less efficient European condensing power plants. In this study, a potential HD reduction due to energy efficiency measures in the existing building stock in the Swedish city Linkoping is calculated. The impact of HD reduction on heat and electricity production in the Linkoping DH system is investigated by using the energy system optimisation model MODEST. Energy efficiency measures in buildings reduce seasonal HD variations. Model results show that HD reductions primarily decrease heat-only production. The electricity-to-heat output ratio for the system is increased for HD reductions up to 30%. Local and global CO(2) emissions are reduced. If co-produced electricity replaces electricity from coal-fired condensing power plants, a 20% HD reduction is optimal for decreasing global CO(2) emissions in the analysed DH system.

Keyword
Low-energy residential buildings, District heating, Energy efficiency measures
National Category
Engineering and Technology
Identifiers
urn:nbn:se:uu:diva-169246 (URN)10.1016/j.enpol.2011.09.031 (DOI)000298363400036 ()
Available from: 2012-02-27 Created: 2012-02-24 Last updated: 2017-12-07Bibliographically approved
2. Sensitivity of district heating system operation to heat demand reductions and electricity price variations: A Swedish example
Open this publication in new window or tab >>Sensitivity of district heating system operation to heat demand reductions and electricity price variations: A Swedish example
2012 (English)In: Energy, ISSN 0360-5442, E-ISSN 1873-6785, Vol. 41, no 1, 525-540 p.Article in journal (Refereed) Published
Abstract [en]

In the future, district heating companies in Sweden must adapt to energy efficiency measures in buildings and variable fuel and electricity prices. Swedish district heating demands are expected to decrease by 1-2% per year and electricity price variations seem to be more unpredictable in the future. A cost-optimisation model of a Swedish local district heating system is constructed using the optimisation modelling tool MODEST. A scenario for heat demand changes due to increased energy efficiency in buildings, combined with the addition of new buildings, is studied along with a sensitivity analysis for electricity price variations. Despite fears that heat demand reductions will decrease co-generation of clean electricity and cause increased global emissions, the results show that anticipated heat demand changes do not increase the studied system's primary energy use or global CO2 emissions. The results further indicate that the heat production plants and the fuels used within the system have crucial importance for the environmental impact of district heat use. Results also show that low seasonal variations in electricity price levels with relatively low winter prices promote the use of electric heat pumps. High winter prices on the other hand promote co-generation of heat and electricity in CHP plants.

Keyword
District heating, CHP, Building energy efficiency, CO2 emissions, Primary energy use, Electricity price variations
National Category
Engineering and Technology
Research subject
Engineering Science
Identifiers
urn:nbn:se:uu:diva-175624 (URN)10.1016/j.energy.2012.02.034 (DOI)000304076800058 ()
Available from: 2012-06-12 Created: 2012-06-11 Last updated: 2017-12-07Bibliographically approved
3. Large-scale introduction of new residential district-heating loads to increase renewable electricity generation in CHP plants
Open this publication in new window or tab >>Large-scale introduction of new residential district-heating loads to increase renewable electricity generation in CHP plants
2012 (English)In: Proceedings of the World Renewable Energy Forum 2012, Denver, Colorado, USA, May 13-17, 2012, 2012, 2407-2414 p.Conference paper, Published paper (Refereed)
Abstract [en]

Combined heat and power (CHP) plants enable an efficient use of low-grade energy carriers, such as domestic waste and biomass, for co-generation of district heating (DH) and electricity. Expected future building energy-efficiency improvements reduce the demand for space heating and may limit the possibilities to cogenerate electricity. The use of DH for new applications, such as household appliances, can improve conditions for co-generation of electricity. This paper investigates the future potential to increase DH demand and co-generation of electricity due to large-scale implementation of household appliances that use DH instead of electricity. The analysis is applied to the DH system in Uppsala, Sweden. Results show that co-generation of electricity and total fuel use increase with implementation of household appliances connected to a building hot water circuit (HWC). The impact on CO2 emissions depends on DH fuel mix and electricity assessment approach.

National Category
Energy Systems
Research subject
Engineering Science with specialization in Solid State Physics
Identifiers
urn:nbn:se:uu:diva-174620 (URN)978-162276092-3 (ISBN)
Conference
World Renewable Energy Forum 2012, Denver, Colorado, USA, May 13-17, 2012
Available from: 2012-05-22 Created: 2012-05-22 Last updated: 2015-01-22Bibliographically approved
4. Development, validation and application of a fixed district heating model structure that requires small amounts of input data
Open this publication in new window or tab >>Development, validation and application of a fixed district heating model structure that requires small amounts of input data
2013 (English)In: Energy Conversion and Management, ISSN 0196-8904, E-ISSN 1879-2227, Vol. 75, 74-85 p.Article in journal (Refereed) Published
Abstract [en]

Reducing the energy use of buildings is an important part in reaching the European energy efficiency targets. Consequently, local energy systems need to adapt to a lower demand for heating. A 90% of Swedish multi-family residential buildings use district heating (DH) produced in Sweden’s over 400 DH systems, which use different heat production technologies and fuels. DH system modelling results obtained until now are mostly for particular DH systems and cannot be easily generalised. Here, a fixed model structure (FMS) based on linear programming for cost-optimisaton studies of DH systems is developed requiring only general DH system information. A method for approximating heat demands based on local outdoor temperature data is also developed. A scenario is studied where the FMS is applied to six Swedish DH systems and heat demands are reduced due to energy efficiency improvements in buildings. The results show that the FMS is a useful tool for DH system optimisation studies and that building energy efficiency improvements lead to reduced use of fossil fuels and biomass in DH systems. Also, the share of CHP in the production mix is increased in five of the six DH systems when the heat demand is reduced.

National Category
Energy Systems
Research subject
Engineering Science with specialization in Solid State Physics
Identifiers
urn:nbn:se:uu:diva-211824 (URN)10.1016/j.enconman.2013.05.032 (DOI)000326661400009 ()
Available from: 2013-12-02 Created: 2013-12-02 Last updated: 2017-12-06Bibliographically approved
5. Investigating the impact of heat demand reductions on Swedish district heating production using a set of typical system models
Open this publication in new window or tab >>Investigating the impact of heat demand reductions on Swedish district heating production using a set of typical system models
2014 (English)In: Applied Energy, ISSN 0306-2619, E-ISSN 1872-9118, Vol. 118, 246-257 p.Article in journal (Refereed) Published
Abstract [en]

The European Union (EU) aims at reducing its CO2 emissions and use of primary energy. The EU also aims to improve the energy efficiency in buildings and promote the use of combined heat and power (CHP) plants in district heating (DH) systems. Due to significant differences among DH systems regarding fuel use and heat production units, results for one individual DH systems are not generally valid for other DH systems. Therefore, there is a need to generally describe entire DH sectors in a way that considers the heat production plant merit-orders of the individual DH systems. Here, four models of typical DH systems are defined to represent the Swedish DH sector. A scenario for stepwise heat demand reductions due to building energy efficiency improvements is studied. The results show that heat demand reductions in Swedish DH systems generally reduce global CO2 emissions and mainly reduce the use of biomass and fossil fuels, while the use of waste and industrial waste heat (IWH) is less influenced. The results further show that in order to maximise the reduction of CO2 emissions by energy conservation in buildings, the heat production technologies of the DH system should be considered. A large share of CHP production with a high electricity-to-heat output ratio decreases the possibilities to reduce global CO2 emissions through heat demand reductions.

Place, publisher, year, edition, pages
Elsevier, 2014
Keyword
district heating, heat demand, Building energy efficiency, CO2 emissions, Combined heat and power
National Category
Engineering and Technology
Research subject
Engineering Science with specialization in Solid State Physics
Identifiers
urn:nbn:se:uu:diva-219717 (URN)10.1016/j.apenergy.2013.11.077 (DOI)000332435000025 ()
Funder
Swedish Energy Agency
Available from: 2014-03-05 Created: 2014-03-05 Last updated: 2017-12-05Bibliographically approved

Open Access in DiVA

fulltext(1862 kB)485 downloads
File information
File name FULLTEXT01.pdfFile size 1862 kBChecksum SHA-512
e0ad1ee704e12186c14e2bc93847634923837a3c84e75c347e7d1b8579f7ea635947e346e41416a68507d02e6cf36d6a261bbc8a98e51f7b61af448620f4eaa0
Type fulltextMimetype application/pdf
Buy this publication >>

Search in DiVA

By author/editor
Åberg, Magnus
By organisation
Department of Engineering Sciences
Energy Systems

Search outside of DiVA

GoogleGoogle Scholar
Total: 485 downloads
The number of downloads is the sum of all downloads of full texts. It may include eg previous versions that are now no longer available

isbn
urn-nbn

Altmetric score

isbn
urn-nbn
Total: 738 hits
CiteExportLink to record
Permanent link

Direct link
Cite
Citation style
  • apa
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf