https://www.mdu.se/

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.

District heating (DH) is considered to be an efficient, environmentally friendly and cost-effective method for providing heat to buildings, since electricity is usually co-generated in biomass fuelled combined heat and power (CHP) plants. This gives it an important role in the mitigation of climate change. Swedish district heating companies are currently facing multiple challenges, and are in urgent need of new price models to increase transparency and maintain their competitiveness.

This thesis describes a survey carried out to understand the structure of the present price models and subsequently proposes and compares two restructured price models with the most commonly used price model. This work also investigates the impact of restructured price models on users who would encounter a significant cost increase if the restructured price models were to be introduced. The district heating costs of different price models are compared with three alternative technical solutions.

The results show that price models based on the consumption pattern of users can reflect district heating companies’ cost structure. Meanwhile, adopting a pricing strategy based on users’ consumption patterns increased the incentives to reduce the peak load.

Consequently, users with high load factor (flat consecutive load curve) were able to reduce costs whereas users with low load factor (steep consecutive load curve) faced possible cost increases, when the load demand cost was changed to daily or hourly peak demand based methods. Further, the most economically preferable option for the invested district heating user was to combine district heating with direct electrical heating or with a ground source heat pump.

Fjärrvärme anses som ett effektivt, miljövänligt och kostnadseffektivt sätt för att leverera värme eftersom kraftvärme blir vanligare i fjärrvärmesystem, där elektricitet produceras tillsammans med värme. Den spelar en viktig roll i att begränsa klimatförändringen. Svenska fjärrvärme företag står inför flera utmaningar nu för tiden, och är i akut behov av nya prismodeller för att öka öppenheten och behålla konkurrenskraften.

I denna avhandling, genomfördes en undersökning för att ta reda på strukturen av de nuvarande prismodellerna. Därefter föreslogs två omstrukturerade prismodeller, vars påverkan på kostnaden av fjärrvärme konsument analyserades jämför med den nuvarande modellen.

Detta arbete undersökte också effekten av omstrukturerade prismodeller på konsument som skulle drabbas på signifikant kostnadsökning i samband med införande prismodeller. Kostnaden av fjärrvärme under olika prismodeller har också jämförts med tre olika tekniska lösningar.

Resultatet visade att prismodeller som baserar sig på konsuments förbrukningsprofil kunde återspegla fjärrvärme företagens kostnadsstruktur; Samtidigt medförde prissättningsstrategi baserad på användarens förbrukningsprofil högre incitament för att minska spetseffekt.

Följaktligen kommer att konsumenter med stabila konsumtionsprofiler att spara kostnader, medan konsumenter med spetsiga konsumtionsprofiler kommer att drabbas av kostnadsökning. Och för den investerade fjärrvärme konsument, den ekonomiska bättre val var att kombinera fjärrvärme med elpanna eller bergvärmepump.