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Energy Efficient Renovation Strategies for Swedish and Other European Residential and Office Buildings
Dalarna University, School of Technology and Business Studies, Energy Technology. KTH, Strömnings- och klimatteknik.ORCID iD: 0000-0002-6722-3220
2017 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

The high energy use in the European building stock is attributable to the large share of old buildings with poor energy performance. Energy renovation of buildings is therefore vital in the work towards energy efficiency and reduced environmental impact in the EU. Yet, the strategies and energy system implications of this work have not been made clear, and the rate of building renovation is currently very low.

The aim of this thesis is to investigate the economic and environmental aspects of energy renovation strategies, with two main objectives:

  • Renovation of Swedish district heated multi-family houses, including life-cycle cost and environmental analysis and impact on the local energy system;

  • Renovation of European residential and office buildings, including life-cycle cost and environmental analysis and influence of climatic conditions.

Buildings typical for the respective regions and the period of construction 1945-1970 were simulated, in order to determine the feasibility and energy saving potential of energy renovation measures in European climates. A variety of systems for heating, cooling and ventilation were studied, as well as solar energy systems, with focus on heat pumps, district heating, low-temperature heating systems and air heat recovery.

Compared to normal building renovation, energy renovation can often reduce the life-cycle costs and environmental impact. In renovation of typical European office buildings, as well as Southern European multi-family houses, more ambitious renovation levels can also be more profitable.

Exhaust air heat pumps can be cost-effective complements in district heated multi-family houses, while ventilation with heat recovery is more expensive but also more likely to reduce the primary energy use. From a system perspective, simple exhaust ventilation can reduce the primary energy use in the district-heating plant as much as an exhaust air heat pump, due to the lower electricity use.

Abstract [sv]

Byggnadssektorn står för omkring 40 % av den totala energianvändningen i EU. Den höga energianvändningen i Europeiska byggnader kan till stor del tillskrivas den stora andelen gamla byggnader med dålig energiprestanda. Energirenovering av byggnader, eller energieffektivisering genom renovering, kan därför anses utgöra en central del i arbetet mot EU:s klimat- och energimål för år 2030. Trots detta är det ännu inte helt klarlagt vilka strategier som ska tillämpas för att uppnå detta och hur det påverkar energisystemet, och i nuläget är renoveringstakten fortfarande väldigt låg.

Målet med denna avhandling är att undersöka ekonomiska och miljömässiga aspekter av strategier för energirenovering, såväl byggnadsskalsåtgärder som aktiva system, för typiska bostads- och kontorsbyggnader i Sverige och i andra Europeiska regioner. Mer specifikt har arbetet följande två inriktningar:

  • Renovering av svenska, fjärrvärmevärmda flerfamiljshus, inklusive livscykelkostnadsanalys och livscykelmiljöanalys samt påverkan på det lokala energisystemet;

  • Renovering av Europeiska bostads- och kontorsbyggnader, inklusive livscykelkostnadsanalys och livscykelmiljöanalys samt påverkan av klimatförutsättningar.

Byggnader typiska för respektive region och byggnadsperioden 1945-1970 modellerades och användes i simuleringar för att fastställa den övergripande möjligheten och energibesparingspotentialen för olika renoveringsåtgärder i Europeiska klimat. En rad system för värme, kyla och ventilation studeras, samt solenergisystem, med fokus på värmepumpar, fjärrvärme, lågtemperaturvärmesystem och värmeåtervinning ur frånluft.

Jämfört med renovering av byggnader utan energieffektiviseringsåtgärder kan energirenovering i många fall minska såväl livscykelkostnaden som miljöpåverkan. Vid renovering av typiska Europeiska kontorsbyggnader lönar det sig mer att renovera ner till ett uppvärmningsbehov på 25 kWh/(m²∙år) än 45 kWh/(m²∙år), då den minskade kostnaden för köpt energi väger upp den ökade kostnaden för isolering. För flerfamiljshus i södra Europa kan mer ambitiösa mål gällande värmebehov också vara lönsamma, medan en mer måttlig nivå är lämplig för småhus.

Solvärme- eller solelsystem kan användas för att minska byggnaders miljöpåverkan. Utan subventioner eller inmatningstariff för överskottsel kan det bli svårt att få lönsamhet i dessa system för kontorsbyggnader i Nord- och Centraleuropa samt för småhus. För flerfamiljshus kan solenergisystem dock sänka den totala livscykelkostnaden, såväl i södra som i norra Europa.

Värmeåtervinning och lågtemperaturvärmesystem visade sig båda ha större inverkan i kallare klimat. Lågtemperaturvärmesystem förbättrar värmefaktorn för värmepumpar, i synnerhet när uppvärmningsbehovet är stort i förhållande till varmvattenbehovet. Vid renovering av byggnader med vattenburna radiatorer kan konvertering till tilluftsradiatorer sänka framledningstemperaturen i värmesystemet.

I svenska flerfamiljshus kan frånluftsvärmepump vara ett kostnadseffektivt komplement till fjärrvärme, medan från- och tilluftsventilation med värmeåtervinning är dyrare men mer sannolikt att ge en minskad primärenergianvändning. I ett systemperspektiv kan frånluftsventilation utan värmeåtervinning minska primärenergianvändningen i fjärrvärmeverket lika mycket som en frånluftsvärmepump, tack vare den lägre elanvändningen.

Place, publisher, year, edition, pages
Stockholm: KTH Royal Institute of Technology , 2017. , 73 p.
Keyword [en]
Energy efficiency, renovation, low-temperature heating, air heat recovery, district heating, heat pump
Keyword [sv]
Energieffektivitet, renovering, lågtemperaturuppvärmning, värmeåtervinning, fjärrvärme, värmepump
National Category
Energy Engineering Building Technologies Environmental Analysis and Construction Information Technology
Research subject
Energy, Forests and Built Environments
Identifiers
URN: urn:nbn:se:du-25726ISBN: 978-91-7729-401-6 (print)OAI: oai:DiVA.org:du-25726DiVA: diva2:1130461
Public defence
2017-06-15, B1, Brinellvägen 23, Stockholm, 13:15 (English)
Opponent
Supervisors
Projects
iNSPiRe
Funder
EU, FP7, Seventh Framework Programme, 314461]
Available from: 2017-08-09 Created: 2017-08-09 Last updated: 2017-08-09Bibliographically approved
List of papers
1. Energy performance comparison of three innovative HVAC systems for renovation through dynamic simulation
Open this publication in new window or tab >>Energy performance comparison of three innovative HVAC systems for renovation through dynamic simulation
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2014 (English)In: Energy and Buildings, ISSN 0378-7788, E-ISSN 1872-6178, Vol. 82, 512-519 p.Article in journal (Refereed) Published
Abstract [en]

In this paper, dynamic simulation was used to compare the energy performance of three innovativeHVAC systems: (A) mechanical ventilation with heat recovery (MVHR) and micro heat pump, (B) exhaustventilation with exhaust air-to-water heat pump and ventilation radiators, and (C) exhaust ventilationwith air-to-water heat pump and ventilation radiators, to a reference system: (D) exhaust ventilation withair-to-water heat pump and panel radiators. System A was modelled in MATLAB Simulink and systems Band C in TRNSYS 17. The reference system was modelled in both tools, for comparison between the two.All systems were tested with a model of a renovated single family house for varying U-values, climates,infiltration and ventilation rates.It was found that A was the best system for lower heating demand, while for higher heating demandsystem B would be preferable. System C was better than the reference system, but not as good as A or B.The difference in energy consumption of the reference system was less than 2 kWh/(m2a) betweenSimulink and TRNSYS. This could be explained by the different ways of handling solar gains, but also bythe fact that the TRNSYS systems supplied slightly more than the ideal heating demand.

Place, publisher, year, edition, pages
Elsevier, 2014
Keyword
Energy performance, Dynamic simulation, HVAC, Micro heat pump, Heat recovery, Ventilation radiator, TRNSYS, MATLAB Simulink, Renovation
National Category
Energy Engineering
Research subject
Energy, Forests and Built Environments, iNSPiRE
Identifiers
urn:nbn:se:du-15163 (URN)10.1016/j.enbuild.2014.07.059 (DOI)000343781400050 ()
Projects
iNSPiRe
Funder
EU, FP7, Seventh Framework Programme, 314461
Available from: 2014-09-04 Created: 2014-09-04 Last updated: 2017-12-05Bibliographically approved
2. Techno-economic analysis of energy renovation measures for a district heated multi-family house
Open this publication in new window or tab >>Techno-economic analysis of energy renovation measures for a district heated multi-family house
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2016 (English)In: Applied Energy, ISSN 0306-2619, E-ISSN 1872-9118, Vol. 177, 108-116 p.Article in journal (Refereed) Published
Abstract [en]

Renovation of existing buildings is important in the work toward increased energy efficiency and reduced environmental impact. The present paper treats energy renovation measures for a Swedish district heated multi-family house, evaluated through dynamic simulation. Insulation of roof and façade, better insulating windows and flow-reducing water taps, in combination with different HVAC systems for recovery of heat from exhaust air, were assessed in terms of life cycle cost, discounted payback period, primary energy consumption, CO2 emissions and non-renewable energy consumption. The HVAC systems were based on the existing district heating substation and included mechanical ventilation with heat recovery and different configurations of exhaust air heat pump.Compared to a renovation without energy saving measures, the combination of new windows, insulation, flow-reducing taps and an exhaust air a heat pump gave up to 24% lower life cycle cost. Adding insulation on roof and façade, the primary energy consumption was reduced by up to 58%, CO2 emissions up to 65% and non-renewable energy consumption up to 56%. Ventilation with heat recovery also reduced the environmental impact but was not economically profitable in the studied cases. With a margin perspective on electricity consumption, the environmental impact of installing heat pumps or air heat recovery in district heated houses is increased. Low-temperature heating improved the seasonal performance factor of the heat pump by up to 11% and reduced the environmental impact.

Keyword
Air heat recovery, District heating, Heat pump, LCC, Low-temperature heating, Primary energy
National Category
Civil Engineering
Research subject
Energy, Forests and Built Environments
Identifiers
urn:nbn:se:du-21620 (URN)10.1016/j.apenergy.2016.05.104 (DOI)000380623900010 ()2-s2.0-84969776538 (Scopus ID)
Available from: 2016-06-08 Created: 2016-06-08 Last updated: 2017-11-30Bibliographically approved
3. Primary energy use in buildings in a Swedish perspective
Open this publication in new window or tab >>Primary energy use in buildings in a Swedish perspective
2016 (English)In: Energy and Buildings, ISSN 0378-7788, E-ISSN 1872-6178, Vol. 130, 202-209 p.Article in journal (Refereed) Published
Abstract [en]

The building sector accounts for a large part of the energy use in Europe and is a sector where the energy efficiency needs to improve in order to reach the EU energy and climate goals. The energy efficiency goal is set in terms of primary energy even though there are different opinions on how to calculate primary energy. When determining the primary energy use in a building several assumptions are made regarding allocation and the value of different energy sources. In order to analyze the difference in primary energy when different methods are used, this study use 16 combinations of different assumptions to calculate the primary energy use for three simulated heating and ventilations systems in a building. The system with the lowest primary energy use differs depending on the method used. Comparing a system with district heating and mechanical exhaust ventilation with a system with district heating, mechanical exhaust ventilation and exhaust air heat pump, the former has a 40% higher primary energy use in one scenario while the other has a 320% higher in another scenario. This illustrates the difficulty in determining which system makes the largest contribution to fulfilling the EU energy and climate goals.

Keyword
Primary energy; Primary energy factors; Energy efficiency; District heating; Heat pump; Air heat recovery
National Category
Energy Engineering
Research subject
Energy, Forests and Built Environments, Reesbe företagsforskarskola
Identifiers
urn:nbn:se:du-23047 (URN)10.1016/j.enbuild.2016.08.026 (DOI)000385323900019 ()
Funder
Knowledge Foundation
Available from: 2016-09-08 Created: 2016-09-08 Last updated: 2017-11-21Bibliographically approved
4. Environmental impact of energy refurbishment of buildings within different district heating systems
Open this publication in new window or tab >>Environmental impact of energy refurbishment of buildings within different district heating systems
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2017 (English)In: Applied Energy, ISSN 0306-2619, E-ISSN 1872-9118Article in journal (Refereed) Epub ahead of print
Abstract [en]

The refurbishment of existing buildings is often considered a way to reduce energy use and CO2 emissions in the building stock. This study analyses the primary energy and CO2 impact of refurbishing a multi-family house with different refurbishment packages, given various district heating systems. Four models of typical district heating systems were defined to represent the Swedish district heating sector. The refurbishment packages were chosen to represent typical, yet innovative ways to improve the energy efficiency and indoor climate of a multi-family house. The study was made from a system perspective, including the valuation of changes in electricity use on the margin. The results show a significant difference in primary energy use for the different refurbishment packages, depending on both the package itself as well as the type of district heating system. While the packages with heat pumps had the lowest final energy use per m2 of floor area, air heat recovery proved to reduce primary energy use and emissions of CO2-equivalents more, independent of the type of district heating system, as it leads to a smaller increase in electricity use.

Keyword
District heating; Primary energy; Energy refurbishment; Building simulation; Multi-family house
National Category
Civil Engineering
Research subject
Energy, Forests and Built Environments
Identifiers
urn:nbn:se:du-25709 (URN)10.1016/j.apenergy.2017.07.022 (DOI)2-s2.0-85026287103 (Scopus ID)
Available from: 2017-08-07 Created: 2017-08-07 Last updated: 2017-12-04Bibliographically approved
5. Economic and environmental analysis of energy renovation packages for European office buildings
Open this publication in new window or tab >>Economic and environmental analysis of energy renovation packages for European office buildings
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2017 (English)In: Energy and Buildings, ISSN 0378-7788, E-ISSN 1872-6178, Vol. 148, 155-165 p.Article in journal (Refereed) Published
Abstract [en]

A large share of the buildings in Europe are old and in need of renovation, both in terms of functional repairs and energy efficiency. While many studies have addressed energy renovation of buildings, they rarely combine economic and environmental life cycle analyses, particularly for office buildings. The present paper investigates the economic feasibility and environmental impact of energy renovation packages for European office buildings. The renovation packages, including windows, envelope insulation, heating, cooling and ventilation systems and solar photovoltaics (PV), were evaluated in terms of life cycle cost (LCC) and life cycle assessment (LCA) through dynamic simulation for different European climates. Compared to a purely functional renovation, the studied renovation packages resulted in up to 77% lower energy costs, 19% lower total annualized costs, 79% lower climate change impact, 89% lower non-renewable energy use, 66% lower particulate matter formation and 76% lower freshwater eutrophication impact over a period of 30 years. The lowest total costs and environmental impact, in all of the studied climates, were seen for the buildings with the lowest heating demand. Solar PV panels covering part of the electricity demand could further reduce the environmental impact and, at least in southern Europe, even reduce the total costs. © 2017 Elsevier B.V.

Keyword
Energy renovation, LCA, LCC, Office buildings, TRNSYS
National Category
Energy Engineering
Research subject
Energy, Forests and Built Environments
Identifiers
urn:nbn:se:du-25094 (URN)10.1016/j.enbuild.2017.04.079 (DOI)000404705000013 ()2-s2.0-85019454202 (Scopus ID)
Available from: 2017-06-05 Created: 2017-06-05 Last updated: 2017-11-06Bibliographically approved

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