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District heating plays a major role in the Swedish energy system. It is deemed a renewable energy source and is the main provider for multi-family dwellings with 90 %. Although the district heating fuel mix consists of majority renewables, a share of 5 % is provided from fossil fuels. To reduce fossil fuel usage and eradicate CO2-emissions from the district heating system new solutions are sought after. In this project, the potential for shortterm thermal energy storage in buildings is investigated. This concept is referred to as customer flexibility. Demand flexibility is created in the district heating system (DHS) by varying the indoor temperature in 50 multi-family dwellings with maximum 1◦C, without jeopardizing the thermal comfort for the tenants. The flexible load makes it possible to store energy shortterm in the building’ envelope. Consequently, heat load curves are evened in production. This leads to a reduction of the peak load in the DHS. Peaks are associated with high costs and environmental impact. Therefore, the potential benefits of customer flexibility are reduced peak production, fuel costs, and CO2-emissions, depending on the fuel mix in the DHS. The project objective is to examine the techno-economic potential of customer flexibility in a specific DHS. The case study is made in a DHS owned by the company Vattenfall, located in the Stockholm area. To evaluate the potential benefits of implementing the concept, seven key performance indicators are chosen. They are peak power, peak fuel usage, produced volume, total fuel cost, fuel cost per produced MWh, climate footprint, and primary energy. Moreover, an in-house optimization model is used to simulate multiple scenarios of the district heating DHS. Different sets of assumptions about the available flexibility in the DHS and the thermal characteristics of the buildings are made. Customer flexibility is modeled as virtual heat storage that can be charged up or down depending on the speed and size of the available storage at a specific outdoor temperature. Simulation results give a maximum peak power reduction of 10.9 % and annual fuel cost reduction between 0.9-3.6 % depending on the scenario. The results found are comparable to values found in similar studies. However, the environmental key performance indicators generated an increase in CO2-emissions and primary energy compared to the baseline scenarios. The result would have looked different if fossil fuels were used in peak production instead of biofuels. The master thesis also aimed to validate assumptions and parameters made in the input data to the optimization model. This was achieved by using results attained from a pilot in the specific DHS. Therefore results generated from the simulations are deemed accurate and confirm that customer flexibility leads to reduced peak production and DHS optimization. / Se filen

Aging buildings will sooner or later be in need of renovation, which opens opportunities to reduce energy use. Even if economically feasible energy measures or technologies exist, they are not always implemented, leading to an energy efficiency gap. This dissertation deals with how energy measures are handled and why they are enabled or disabled during the planning and design of renovations. During renovations, different kinds of building professionals are engaged, here referred to as middle professionals. The meeting practice of the professionals is investigated, with a focus on how the middle professionals exert influence from the middle-out and to the top and bottom, and how and why they enable or disable measures aimed at energy efficiency or reduction. Three renovation projects are followed in the municipality-owned housing company Stångåstaden, in Linköping, Sweden. The housing company’s goal is to reduce the amount of purchased energy by 25% by 2025. Methods applied during the research are semi-structured interviews, participant observations and document analysis. The conclusions show that energy measures were implemented, but more can be done in renovations. Predefined meeting agendas make the process efficient but not flexible, thus it can be difficult to introduce innovations and alternative ways of thinking into the process. The professionals usually selected measures they had used before. Energy calculations attracted little interest compared to the aggregated knowledge from previous projects, and experience and tacit knowledge were highly valued. This and more lead to a renovation process where it is difficult for energy to enter the current meeting practice. / Byggnader behöver förr eller senare renoveras, vilket ger möjligheter att minska energianvändningen. Existerande energieffektiva och lönsamma åtgärder genomförs emellertid inte i tillräcklig utsträckning, det så kallade energieffektiviseringsgapet. Avhandlingen handlar om implementering av energieffektiviseringsåtgärder vid renovering av flerfamiljshus och varför vissa åtgärder genomförs medan andra väljs bort. I avhandlingen undersöks hur de professionella i mitten av beslutshierarkin, kan påverka implementeringen av energieffektiva åtgärder uppåt och nedåt i en organisation men även utåt, i en horisontell riktning. Undersökningen rör de professionella aktörernas inflytande i planerings- och designfasen, och hur de fattar beslut om att inkludera eller exkludera energieffektiva åtgärder. Studien omfattar tre renoveringsprojekt i det kommunägda bostadsbolaget Stångåstaden i Linköping. Bostadsbolagets mål är att minska mängden köpt energi med 25% till år 2025. Studien bygger på semistrukturerade intervjuer, deltagande observationer och dokumentanalys. Slutsatserna är att även om bostadsföretaget genomför energiåtgärder, kan mer göras i renoveringsprocesser för att förbättra energieffektiviteten. Förbestämda agendor på projektgruppsmötena gör processen effektiv men inte flexibel, och det kan vara svårt att introducera innovationer och alternativa sätt att tänka kring energi. De professionella i mitten valde oftast åtgärder som de tidigare hade använt, energiberäkningar spelade en liten roll och erfarenhetsbaserad kunskap värderades högt. Allt detta och mer leder till en renoveringsprocess där det är svårt att föra in energi i dagens mötespraktik.