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- Nyström, Ingrid, 1965, et al.
(författare)
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Energieffektiv bebyggelse och fjärrvärme i framtiden
- 2009
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- I strategisk planering för fjärrvärme i ett framtida energisystem måste hänsyn tas till att fjärrvärmens omvärld står inför stora förändringar. Med fortsatta krav på minskad miljöpåverkan och ökad resurseffektivitet och med samtidig energieffektivisering på användarsidan kommer högre krav att ställas både på beslutsunderlag och analys samt på branschsamverkan med andra intressenter i energisystemet och fastighetsbranschen. Detta projekt inleder en mer framtidsinriktad analys av fjärrvärmens utveckling och bidrar med ny kunskap framförallt rörande energianvändningens utveckling och fjärrvärmens roll för att minska miljöbelastningen från uppvärmning. Särskilt fokus har lagts på betydelsen av energieffektivisering av värmeanvändning i bebyggelsen. Projektet är relativt begränsat i sin omfattning och riktar därför in sig på några särskilda frågeställningar, genom fyra delprojekt:● Klassningssystem för fastigheter och dess inverkan på fjärrvärme (se Delrapport A).● Miljöpåverkan från energieffektiva hus och alternativ värme/el (se Delrapport B).● Analys av energianvändning i miljonprogramsområden (se Delrapport C).● Nya tekniker och ändrade förutsättningar för el- och värmeproduktion (se Delrapport D). I rapportens huvuddel finns en samlande syntes, vilken bidrar med en sammanhållen systemsyn för fjärrvärmens framtida utmaningar såväl på användar- som produktionssidan. Underlaget för denna syntes består av material och resultat från de fyra delprojekten samt diskussioner och bearbetning av branschföreträdare för energi- och fastighetsbransch under projektets workshops. Syntesen är, på grund av projektets omfattning, i första hand kvalitativ och syftar heller inte till att ge några färdiga svar. Den ska i första hand ses som en utgångspunkt för fortsatt analys av fjärrvärmens framtida roll.Projektet lyfter särskilt fram följande slutsatser:• Fjärrvärmebranschen ser kraftigt ändrade förutsättningar framför sig, både vad gäller värmeanvändningens utveckling och tillförselssidan. Det finns därför starka skäl att vidareutveckla och tillämpa metoder för strategisk framtidsinriktad analys, vilket särskilt kräver utveckling av data, datahantering och systemanalytiska metoder avseende utvecklingen av värmeefterfrågan i byggnader och industri.• För att även framåt säkerställa fjärrvärmens roll i ett uthålligt energisystem kommer det att bli viktigare med en transparent och heltäckande miljövärdering av olika typer av fjärrvärmesystem. Miljövärderingen behöver genomföras med hänsyn tagen till det lokala fjärrvärmesystemet, men utifrån generellt tillämpliga, gemensamma, principer.• Från miljösynpunkt står inte fjärrvärme och energieffektiv bebyggelse (”passivhus”) i något motsatsförhållande. Energieffektiva delar som kopplas samman i ett effektivt energisystem ger optimalt utfall.• För att utveckla långsiktigt hållbara fjärrvärme- och byggsektorer krävs fortsatt utveckling av samverkan mellan bland andra fjärrvärmebransch, fastighetsbransch och samhällsplanering. Fjärrvärmebranschen behöver kunskap om sina kunder, ner till aktuell byggnadsstatus och bostadsbolagens åtgärdsplaner, samtidigt som bygg- och fastighetssektorn behöver kunskap om fjärrvärmens förutsättningar och möjligheter att på lång sikt fortsätta att leverera tillförlitlig värme med minsta möjliga miljöpåverkan.
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| 5. |
- Heikkilä, Katarina, 1968, et al.
(författare)
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Indoor Thermal Climate Criteria and the Effects on the Overall Environmental Performance of Air-conditioning Systems
- 2006
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Ingår i: Proceedings of EPIC 2006 AIVC. Technologies & Sustainable Policies for a Radical Decrease of the Energy Consumtion in Buildings.. - 2868341225 ; 1, s. 167-172
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Konferensbidrag (refereegranskat)abstract
- The cooling loads of an office building vary with the desired indoor thermal climate. However, there is a lack of knowledge on how significantly the various indoor climate criteria affects the overall environment performance of the air-conditioning systems. Here, we analyze the environmental consequences of the energy use, as well as the possible midifications of the system design and corresponding use of materials. The analysis is based on a theoretical case study of an air-conditioning system designed for a typical office building situated in Sweden. The environmental performance is evaluated by a life cycle assessment (LCA) method, taking into account the production, the user, and the disposal stages of the life cycle. For the same building, several scenarios of the user stage corresponding with the different requirements on the indoor thermal climate in the building are studied. We conclude that requirements on the indoor climate should be established at appropriate levels, taking into account the environmental performance of the air-conditioning system.
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| 6. |
- Jangsten, Maria, 1989, et al.
(författare)
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A performance assessment method for district cooling substations based on operational data
- 2022
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Ingår i: Science and Technology for the Built Environment. - : Informa UK Limited. - 2374-474X .- 2374-4731. ; 28:10, s. 1472-1488
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Tidskriftsartikel (refereegranskat)abstract
- Many district cooling systems suffer from low delta-Ts due to faults in the substations and buildings. This causes increased pumping costs, congested distribution networks and operation of more chillers. To enable fault detection and further diagnosis of district cooling substations, knowledge about the actual performance is needed. In this paper, a method using performance indicators to assess the performance of individual district cooling substations was developed along with a ranking system for substation comparison purposes. The performance assessment method was tested on 26 substations in a district cooling system by developing an algorithm. The input to the method was historical operational data collected from the substations’ primary and secondary sides from four years. The output summarized the performance of the substation in a few seconds and the ranking indicated which substation is in most need of improvement. The performance assessment can be conducted with only primary data as input but including secondary data from the building system provides additional information about the substation efficiency along with potential improvement measures. The method can be implemented by a utility company to serve as decision support and facilitate continuous follow-up of the substations to subsequently enable fault detection of district cooling substations.
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| 7. |
- Jangsten, Maria, 1989, et al.
(författare)
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Analysis of operational data from a district cooling system and its connected buildings
- 2020
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Ingår i: Energy. - : Elsevier BV. - 0360-5442 .- 1873-6785. ; 203
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Tidskriftsartikel (refereegranskat)abstract
- District cooling systems are likely to become more common as the cooling demands in cities increase. Their performance is often challenged by low temperature differences between the supply and return water, called low delta-T. Few previous studies have investigated low delta-Ts in district cooling systems with heat exchangers separating the distribution system and the connected buildings, which therefore is the objective of this study. The study is based on an analysis of operational data from both district cooling provider and 37 of the connected buildings chilled water systems, collected from the energy transfer stations during spring and summer of 2018. The design delta-T in the district cooling system is 10 °C, while the actual delta-T varies between 6 and 8 °C. The study shows the main causes to the low delta-T are the following: operation in the saturation zone; too low building chilled water return temperature; too low temperature approach of the heat exchanger's supply streams and non-optimized supply temperatures in the buildings. Potential solutions to resolve the low delta-T include adjusting the supply temperature setpoint on the secondary side; restricting the flow on the primary side; providing economic incentives for the district cooling customers and ensuring compliance with the design guidelines.
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| 8. |
- Jangsten, Maria, 1989, et al.
(författare)
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District Cooling – assessment of price models supporting the efficiency
- 2022
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Ingår i: 2022: Proceedings of the 3rd International Conference on Evolving Cities. ; :2022, s. 17-24
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Konferensbidrag (refereegranskat)abstract
- District cooling is an energy efficient cooling supply technology compared to building individual solutions. However, many district cooling systems suffer from low return temperatures, which usually originate from the buildings’ systems and substations andcause increased operating costs for the district cooling company. One potential solution to this problem is to ensure the district cooling price model sufficiently incentivizes the district cooling customers to maintain well-performing substations. The aim of this study is therefore to assess district cooling price models which reward well-performing substations. The study is based on operational data from an actual district cooling system located in Gothenburg, Sweden and 26 of its connected buildings. Four price models were designed based on the existing price model’s components power, energy, and flow along with either a delta-T or a return temperature component. The new price models resulted in lower costs for customers having substations with high delta-Ts compared to the reference price model. The results of this study showed a delta-T, or a return temperature component are more effective in providing economic incentives for customers to maintain well-performing substations compared to utilizing only aflow component. Moreover, it was shown the strongest incentives are realized with both a flow and a temperature component.
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| 9. |
- Jangsten, Maria, 1989, et al.
(författare)
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District cooling substation design and control to achieve high return temperatures
- 2022
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Ingår i: Energy. - : Elsevier BV. - 0360-5442 .- 1873-6785. ; 251
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Tidskriftsartikel (refereegranskat)abstract
- Low return temperatures are a prevailing issue in district cooling systems negatively affecting operating costs and energy efficiency. In this study, three aspects of district cooling substation design and control were investigated with the aim to increase the return temperatures: 1) secondary supply temperature setpoint, 2) primary flow rate and 3) the flow rate relation between the primary and secondary flows. Two different control strategies limiting the secondary setpoint and the primary flow were tested in four buildings supplied by district cooling. Also, the secondary flow was measured along with an NTU analysis and predictions with a heat balance and a support vector regression model. The results showed the control strategies successfully increased the primary return temperature with 0.6–1.6 °C and eliminated flow in the saturation zone. The primary and secondary flows were shown to be unbalanced in fourteen of sixteen substations causing a low heat exchanger temperature effectiveness. The preferred method for predicting the secondary flow was support vector regression. The novelties of this paper are the conducted field tests and measurements with associated analyses, contributing with knowledge about the actual operation of district cooling substations and outcomes when implementing improvement measures to increase the primary return temperature.
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| 10. |
- Jangsten, Maria, 1989, et al.
(författare)
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Field test of active night cooling supplied by district cooling in three commercial buildings
- 2021
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Ingår i: E3S Web of Conferences. - : EDP Sciences. - 2555-0403 .- 2267-1242. ; 246
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Konferensbidrag (refereegranskat)abstract
- Several previous studies have investigated active night cooling strategies to reduce the peak cooling load in buildings, primarily by precooling the building by the ventilation air during the night. In this study, active night cooling is supplied by the use of district cooling, mainly for cooling buildings by hydronic cooling systems, such as chilled beam or fan coil systems, but potentially also to cool the ventilation air if the outdoor air temperature is above the supply air temperature setpoint. A field test with active night cooling by district cooling was conducted during the summer of 2020 in three commercial buildings located in Gothenburg, Sweden. The active night cooling strategy was implemented by changing the time schedule operation of the buildings’ chilled beam systems to twenty-four hours per day for the first half of the summer and changing back to regular time schedules for the second half. The results showed that active night cooling failed to reduce the hourly maximum cooling power. However, the peak cooling load, corresponding to the 100 hours with the highest cooling power, was reduced with 6.5% for one of the buildings. Active night cooling also reduced the daytime energy usage between 0.7 and 4.6%. The field test demonstrated that some buildings and associated cooling systems are more compatible for active night cooling than others. The test also showed it was possible to achieve some cooling power and energy reductions with simple measures. However, providing active night cooling supplied by district cooling will cause additional costs for the building owners unless it is incentivized by the district cooling provider.
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