I detta projekt redogörs det svenska pantsystemet för PET-flaskor, sedan undersöks möjlighetentill implementering av ett pantsystem i Storbritannien. Två enkätundersökningar genomfördes isamband med projektet, en i Sverige för att undersöka åsikter kring pantning och hur man skullekunna förbättra systemet, och en i Storbritannien för att undersöka åsikter angående införande avett liknande pantsystem.Rapportens första del behandlar det svenska pantsystemet, hur återvinningsprocessen för PETflaskorsker, för- och nackdelar samt möjligheter till förbättringar av systemet. Sverigespantsystem är en välfungerande metod för att samla in och återvinna PET-flaskor som harresulterat i en hög grad återvunna dryckesbehållare. Vidare presenteras möjligheterna att införaett pantsystem i Storbritannien, samt kostnader som detta skulle medföra.För att realisera en initiering av ett pantsystem i Storbritannien krävs ett aktivt deltagande fråndiverse intressenter. Det behövs ett organ inom regeringen som sätter upp återvinningsmål, ettreturbolag som driver systemet samt att konsumenter och återförsäljare sympatiserar medsystemet.Sammanställning av den svenska enkätundersökningen visade att 9 av 10 pantar sina PET-flaskoroch att mer än hälften skulle fortsätta panta även om det inte betalades ut någon pant. Inte alladeltagare i den brittiska enkätundersökningen hade kännedom om hur ett pantsystem fungerareller vad det var. Däremot upplevde majoriteten en positiv inställning till ett sådant system. Ihelhet konstaterade enkätundersökningarna att en viktig faktor till britternas och svenskarnas viljaatt panta är miljöaspekten, i form av energibesparing och mindre koldioxidutsläpp. / This project declares and explains the Swedish deposit return system (DRS) for PET bottles, aswell brings up suggestions of a possible implementation of a deposit return system in UnitedKingdom. In connection with the project two surveys have been carried out. One aimed forSwedish consumers in purpose of investigating opinions and reasons regarding the deposit returnsystem, in addition, discover possible improvements of the system. The other survey, intendedfor consumers living in United Kingdom, studied the common attitude regarding animplementation of a deposit return system for plastic beverage containers.Initially, the Swedish deposit return system is depicted as well as the process of recycling,advantages and disadvantages of the system and potential improvements. The Swedish depositreturn system is a well functioning organization gathering and recycling PET bottles, which,consequently has lead to a higher rates of return. Henceforth, the opportunities of introducing adeposit return system in United Kingdom are presented and the significant expenses that wouldfollow.In order to actualize an initiation of a DRS in United Kingdom it requires participation fromcertain stakeholders, such as government authority that sets up recycling goals, a central systemand that consumers and retailers sympathize with the system.A conclusion of the results from the Swedish survey demonstrated that 9 out of 10 consumersdeposit their PET bottles and more than half of the participants would continue returning theirbottles although no deposit would be refunded. Furthermore, a summary of the English surveyexpressed that roughly half of the participants had no acquaintance concerning the operation of adeposit return system or what it was. However, the majority expressed a positive approach forsuch a system. In general, one can say that according to the surveys an important factor for Britsand Swedes desire to deposit is the environmental aspect, in the form of energy conservation andreduction of greenhouse gases.

In Sweden, heating accounts for approximately half of the total energy consumption in the residential sector. Houses are often unoccupied during a large part of the day, which reduces demand for comfortable heat- and ventilation levels. Utilizing such a gap in demand, and reducing ventilation and heating during unoccupied hours, could reduce energy consumption by 30-42 %. This possibility raises the need for a robust and accurate way to measure occupancy and control HVAC. There are several techniques, both fully developed as well as those in idea stage, to measure human occupancy and each one of them has unique characteristics in terms of technical properties, accuracy and cost with varying suitability for implementation. This work contributes to the current research on this field by compiling existing literature and comparing different technologies to each other based on a number of aspects. Furthermore, associated privacy concerns associated with some of the covered sensor technologies are discussed and hopefully, this work will serve as the basis for future decisions on what type of sensor technology to be used in some selected projects at KTH.

Future projections show that over 500 million people living in Sub-Saharan Africa will be without electricity in 2040 according to IEA, even though UN has set a goal of universal access to affordable, reliable and modern energy services by 2030. This shows that the rate of change is too slow and that there is a need for a greater electrification rate. In an attempt to solve this problem the 12 leverage points framework by Donella Meadows is applied on the SSA energy system to get an overview of different places to intervene in the system and what strength of leverage these hold. The result is a text analyzing leverage points within each of the 12 leverage point categories and high leverage was found in several categories. The results are subjective and the framework is evaluated in the context of these. Finally suggestions on how the framework can be improved are recommended and what types of applications for the framework that are viable. / Framtida projektioner pekar på att över 500 miljoner människor som bor i Sub-Sahara Afrika kommer att vara utan elektricitet 2040 enligt IEA. FN har satt ett mål om universell access till överkomlig, pålitlig och moderna energi tjänster till 2030. Denna diskrepans visar att förändringshastigheten är för långsam och att det föreligger ett behov av en högre elektrifieringstakt. I ett försök att lösa detta problem har 12 Leverage Points ramverket av Donella Meadows tillämpats på SSA energi system för att skapa en överblick över olika platser att ingripa I systemet och hur effektivt man kan ingripa vid dessa. Resultatet är en text som analyserar Leverage Points från de 12 olika Leverage Point kategorierarna och starka möjligheter för effektivt ingripande återfanns I flera kategorier. Slutligen rekommenderas förslag hur ramverket kan förbättras och vilken sorts tillämpningar av ramverket som är praktiskt.

This project is initiated by Engineers without Borders at Kungliga Tekniska Högskolan(KTH) in collaboration with the non-governmental organization Rwanda Village Concept Project at the University of Rwanda. It is funded by KTH Opportunities Fund with an amount of 20 000 SEK. The aim of the project is to design a portable off-grid photovoltaic(PV) system for a typical rural household in Rwanda, more specifically in the village Nyamabuye where there is no access to electricity. The requirements for the system are to have a total cost under 20 000 SEK, a weight under 25 kg and a capacity that meets the energy demand for a rural household. The system consists of PV modules, a battery, a charge controller and a converter. A literature study on off-grid PV systems and the components was conducted. For the case study, an estimation on the energy demand was made based on answers from a survey for locals in Nyamabuye and the current energy situation in Rwanda. To dimension the PV system according to the estimated energy demand, calculations based on a mathematical model for PV systems were conducted in MATLAB. A comparison regarding cost, weight, efficiency etc. of components that currently are available at the market was made. Components could then be chosen to make the system meet the set requirements. The result is a PV system that has a total cost of 10670 SEK and a weight of 13.6 kg. It is dimensioned to meet a daily energy consumption of 1022 Wh. There are several factors that could affect the performance of the system, for example different outdoor temperatures, that were not considered for simplicity. Therefor it is recommended that the system should be tested in different conditions.

Användningen av solenergi har ökat väsentligt under de senaste åren. Den främsta förklaringentill detta ligger i att solenergi enligt vissa källor nu är billigare att producera än olja. Solenergiär en förnybar energikälla till skillnad från olja. Detta driver företag och vetenskapsmän att hittaalternativa lösningar för att lösa klimatfrågan.Studien omfattar en teoretisk granskning över vilka förbättringar som kan göras och vilkaåtgärder som redan har vidtagits till att utnyttja solenergi mer hållbart ur tre aspekter; socialt,ekologiskt och ekonomiskt. Den sociala aspekten kommer att beröra ansvaret som tas av diverseintressenter som forskare, politiker och finansanalytiker i strävan om att göra solenergin merkonkurrenskraftig på den globala marknaden. Finansanalytiker förutspår att solenergi kan bliden ekonomiskt mest fördelaktiga energikällan i 80 procent av världen i slutet på 2017, menfrågan är komplex och påståendet har ifrågasatts. Vidare kommer tekniken bakom solfångareoch solceller att beskrivas. Ur ett ekologiskt perspektiv kommer energieffektiva lösningar attdiskuteras som exempelvis energilagring och hur mer lättillgängliga material kan användas istörre omfattning. Ur en ekonomisk aspekt, kommer det fallande priset på solpaneler attdiskuteras och hur denna energiresurs står sig i jämförelse med fossila bränslen som allt merblir en begränsad energikälla. Analys av dessa aspekter kommer gemensamt att hjälpa till attbesvara frågorna som finns avseende hur det kan skapas mer konkurrenskraftiga,energieffektiva och tillförlitliga solceller och solfångare på den globala marknaden.Slutsatser som kan dras av denna studie är att framtidsprognosen för solenergin ser ljus ut.Priser på solpaneler pressas ständigt och mer lättillgängliga material börjar användas som ettresultat av framgångsrik forskning och ledande teknik. Dessvärre kan solenergi i nuläget inteersätta fossila bränslen eftersom lagring av energi under en längre tidperiod inte är möjlig, menpotentiella lösningar är på gång. Omfattande forskning pågår kring att öka verkningsgraden hossolpaneler och genom högre produktionskapacitet och enklare material kan detta förverkligas. / The use of solar energy has increased substantially over the last couple of years. The fast-pacedincrease in the use of solar energy is driven by the fact that solar power according to somesources is now cheaper to produce than oil. Energy provided by the sun is a renewable energysource in comparison to oil. This stimulates companies and scientists to find alternativesolutions to solve the climate issue.This study covers a theoretical examination of the possible improvements that are required andthe actions that already have been made to utilize solar energy more sustainably from threeaspects; social, environmental and economical. The social aspect will cover the responsibilitytaken by various stakeholders such as scientists, politicians and financial analysts in the questof making the solar energy more competitive on the global market. Financial analysts predictthat solar energy can be the most economically beneficial source of energy in 80 percent of theworld by the end of 2017, but the issue is complex and the prediction has been questioned.Furthermore, the technology behind solar collectors and solar cells will be described. From anecological point of view, energy-efficient solutions will be discussed, such as energy storageand how more accessible materials can be used. From an economic point of view, the decreasingprice of solar panels will be discussed and how this energy resource stands in comparison tofossil fuels. Analysis of these aspects will commonly help to answer the questions about howto create more competitive, energy efficient and reliable solar cells and solar collectors on theglobal market.The conclusions that can be drawn from this study is that the future prediction for solar energylooks bright. Prices for solar panels are constantly being reduced and more accessible materialsare being used because of successful research and improved technology. Unfortunately, for thetime being solar energy cannot replace fossil fuels at present, as energy storage over a longperiod of time is not possible, but potential solutions for this are under way. Extensive researchis ongoing aiming at increasing the efficiency of solar panels, with higher production capacityand more accessible materials this can become reality.

Energibesiktning och energiklassificering har genomförts på en bostad på Bolkavägen 18, Norrtälje. Byggnaden sattes i undertryck med hjälp av en Blowerdoor, som genom ett automatiserat program estimerade husets luftinfiltration. Som komplement användes en IR kamera för att lokalisera värmeflöden genom bostadens klimatskal.Data på fastighetens värme- och elanvändning har i kombination med klimatdata från SMHI använts för att fastställa husets UA-Värde. Vidare beräknades byggnaden energiprestanda till 200kWh/m2. Vilket motsvarar 222% mer än rekommendationen vid nybyggnation och ger fastigheten energiklass F.Byggnaden värms huvudsakligen av fjärrvärme och är försedd med två vedkaminer. Sedan tidigare har fastighetsägaren borrat en energibrunn med avsikt att installera en bergvärmepump. Med dessa förutsättningar beräknades lönsamheten att installera bergvärme- eller luft/vattenvärmepump. Avbetalningstiden för dessa hamnar på 8 respektive 11 år.De mest energieffektiva åtgärderna för bostaden är att isolera vindsbjälklagret och installera en bergvärmepump. Åtgärderna skulle sammantaget minska energianvändningen med 14 300 kWh per år. Vilket ger en total energiförbrukning för fastigheten, baserat på de senaste 3 åren, på 14 000 kWh per år. Det motsvarar en halvering av tidigare energiförbrukning och skulle ge en energiprestanda på 107 𝑊𝑊𝑚𝑚2⁄ och innebära energiklass D.För att fastställa en byggnads UA-Värde och termiska tröghet genomfördes 2013 ett termiskt responstest på bostaden. Genom att visa att UA-värdet från det termiska responstestet överensstämmer med det UA-värde som framställts ur klimatdata från SMHI påvisas relevansen och precisionen av denna typ av test. / An Energy inspection and energy classification has been carried out at a residence on Bolkavägen 18, Norrtälje. The building was suppressed by a Blowerdoor, which, through an automated program, estimated the amount of air infiltration. In addition, an IR camera was used to locate heat flows through the building envelope.Data on the property's heat and electricity usage has been used in combination with climate data from SMHI to determine the house's UA value. Furthermore, the building was estimated to have a power usage of 200 kWh/m2. This corresponds to 222% more energy use than what is recommended for a new construction. This places the property in energy class F.The building is heated mainly by district heating and is equipped with two wood burning stoves. Previously, the property owner has drilled an energy source with the intention of installing a ground source heat pump. With these conditions, the profitability was calculated to install a ground source or air/water heat pump. The payoff period for these alternatives ends in 8 and 11 years respectively.The most energy-efficient measures for the building are to isolate the windbreaker and install a ground source heat pump. These measures would reduce energy consumption by 14,300 kWh per year. This gives a total energy consumption of the property, based on the last 3 years, of 14,000 kWh per year. This corresponds to half of the previous energy consumption and would provide an energy performance of 107 𝑊𝑊𝑚𝑚2⁄ and mean energy class D.In 2013, a thermal response test was carried out at the residence. This is a method for determining a building's UA value and thermal inertia. By showing that the UA value from the thermal response test complies with the UA-value produced from the SMHI climate data, the relevance and accuracy of this type of test is demonstrated.

Affordable and reliable electricity can provide a mean to reduce poverty, improve health care and decrease local pollution. Nevertheless, about 950 million people living in Africa and developing Asia did not have access to electricity in 2016. Renewable sources pose as keys for the implementation of smaller and adjustable power systems, especially in developing countries, since they require lower investment. Furthermore, biomass has the advantage of being widely available and its use for power generation can be scheduled, which makes it a suitable alternative to traditional fuels. Despite the strategies put in place by the Ugandan government, the country still has an electrification rate of only 10% and most of its population lives in rural areas, without any access to the electric grid. Agriculture remains the main sector, even though Uganda faces large problems regarding food security. There is a strong need to evaluate and map the country's resources, to identify opportunities for small-scale off-grid generation without compromising food production. In this study, the electricity generation potential of selected crops was evaluated and mapped. Parts of Jatropha Curcas, Maize, Oil Palm and Sugarcane were considered in the analysis. This approach ensured that the crops could be used for other uses, such as food or ethanol production. Food security was also taken into consideration by disregarding the areas currently used to produce the main staple crops of the country. Four technologies were analysed – combustion, gasification, pyrolysis and anaerobic digestion – and different engines were also included for each technology. The results obtained show that combustion and gasification are the most promising technologies in terms of electricity generation potential, due to their maturity level and straightforward approach. In addition, it was possible to conclude that using the silage obtained from a hectare of cultivated maize in an anaerobic digestion facility with a gas engine, enough electricity for 39 people could be generated. This result strengthens the idea that biomass is a suitable alternative to fossil fuels since the population density in most of the country is 0.03 people per hectare.

A collective self-consumption project defines a community made of different electricity consumers that gather around a decentralized distributed energy generation system in order to supply part of their electric demands through self-consumption of the decentralized electricity produced. Solar photovoltaic (PV) technology is the most used decentralized energy generation system. Thanks to the falling price of renewable energy technologies due to the development of research, and political regulations towards the sustainable development goals, new ways of producing energy have emerged and collective self-consumption projects are part of them. France stands as one of the few Europeans countries having specific regulatory framework for such projects. However, strong barriers prevent from their deployment. These are mainly: a low retail electricity price, high taxes and network tariffs, and a regulation with heavy administrative processes. Besides, the majority of the studies made on collective self-consumption projects are mostly on blockchain technology for the local energy market created by them. The few techno-economic analyses on collective self-consumption are essentially commercial and not research oriented. Therefore, the aim of this study is first, to analyze typical system designs for a collective self-consumption project and set an example of a reference PV system for such project. The objective is also to find most critical barriers for a collective selfconsumption project through an analysis of their impact on the project’s economics. Finally, the aim is to investigate possible policies that could be set by the French Government, regarding its budget, in order to develop PV collective self-consumption projects in the future. A community made of diverse electricity consumers and located in Montpellier, was defined for the purpose of this study. Each consumer’s annual electric load was directly collected from the national open data platform and the sum constituted an input for the system design and modeling in SAM (System Advisor Model), the software used. Techno-economic optimizations were performed both in SAM and a specific built-in economic tool to find an optimal PV system based on the key performance indicators (KPIs) defined. Two main business models were looked at: prosumer and third-party business models. The former corresponds to the case where the PV system is owned by the community itself. The latter is associated to a situation where a third-party which can be a developer, or a utility owns the PV asset and sells the electricity to the community. The impact of barriers to collective self-consumption on the project’s economics are analyzed through the different business models. Critical barriers are found and an analysis on possible policies favoring State initiatives for collective self-consumption is held. This study defines a collective self-consumption project with a techno-economic optimized system design based on fixed key performance indicators (KPIs). The most important KPI is the solar fraction (SF) corresponding to the ratio of the local energy self-consumed by the community over its load. A PV system of 35 kWp with a SF of 34% was found for the city of Montpellier. This study also confirms the fact that collective self-consumption projects are not profitable in France. The CSPE is mainly the tax component that prevent such projects from being profitable regardless of the business model. Besides, the VAT on local electricity consumption weakens the project’s profitability in the prosumer business model. In terms of budget, removing the CSPE costs less to the State (with 19 027 €) than subsidizing direct PV investment cost at 638 €/kW (with 22 330 €) for a project having a third-party business model within the found PV system. For a project having a prosumer business model, a subsidy of 511 €/kW on the direct PV investment cost is preferable for the State (with 17 885 €) than removing both the CSPE and the VAT on local electricity consumption which causes a shortfall of 29 732 €. In conclusion, a collective self-consumption project is not economically profitable in France within the current legislation. To allow the deployment of such projects, the French state should allocate a minimum subsidy of 40% in the direct PV investment (511 €/kW for a PV system of 35 kWp) for projects with a prosumer business model. For the ones with a third-party business model, the CSPE should be removed. / I ett projekt för kollektiv självkonsumtion definieras en gemenskap som består av olika elkonsumenter som samlar sig kring ett decentraliserat system för energiproduktion för att tillgodose en del av sina elbehov genom självkonsumtion av den producerade decentraliserade elen. Solcellsteknik är det mest använda decentraliserade energiproduktionssystemet. Tack vare det sjunkande priset på teknik för förnybar energi på grund av forskningens utveckling och politiska bestämmelser för att uppnå målen för hållbar utveckling har nya sätt att producera energi kommit fram och kollektiva projekt för självkonsumtion ingår i dessa. Frankrike är ett av de få EU-länder som har särskilda rättsliga ramar för sådana projekt. Stora hinder hindrar dock från att de sätts in. Dessa är huvudsakligen följande: Ett lågt elpris i detaljistledet, höga skatter och nätavgifter och en förordning med tunga administrativa förfaranden. Dessutom handlar de flesta studier som gjorts om projekt för kollektiv självkonsumtion främst om teknik för att blockera den lokala energimarknad som de skapar. De få tekniska-ekonomiska analyserna om kollektiv självkonsumtion är huvudsakligen kommersiella och inte forskningsinriktade. Syftet med denna undersökning är därför först och främst att analysera typiska systemutformningar för ett kollektivt självkonsumtionsprojekt och föregå med gott exempel på ett referenssolcellssystem för sådana projekt. Målet är också att hitta de viktigaste hindren för ett kollektivt projekt för självkonsumtion genom en analys av deras inverkan på projektets ekonomi. Slutligen är syftet att undersöka möjliga politiska åtgärder som den franska regeringen skulle kunna fastställa när det gäller dess budget, för att utveckla kollektiva projekt för solcellsanvändning i framtiden. I denna studie definierades ett samhälle som består av olika elkonsumenter och som är beläget i Montpellier. Varje konsuments årliga elbelastning samlades direkt från den nationella öppna dataplattformen och summan utgjorde en inmatning för systemutformning och modellering i SAM (System Advisor Model), den programvara som användes. Teknikekonomiska optimeringar utfördes både i SAM och ett specifikt inbyggt ekonomiskt verktyg för att hitta ett optimalt solcellssystem baserat på de nyckelutförandeindikatorer som definierats. Två huvudsakliga affärsmodeller granskades: företagsmodeller för konsumenter och tredje part. Det förra motsvarar det fall där solcellssystemet ägs av samhället självt. Det senare är förknippat med en situation där en tredje part som kan vara en utvecklare, eller ett företag äger solcellstillgången och säljer elen till samhället. Effekterna av hinder för kollektiv självkonsumtion på projektets ekonomi analyseras genom de olika affärsmodellerna. Kritiska hinder finns och en analys av möjliga politiska åtgärder som främjar statliga initiativ för kollektiv självkonsumtion genomförs. I denna studie definieras ett kollektivt projekt för självkonsumtion med en tekniskt-ekonomisk optimerad systemdesign som baseras på nyckelutförandeindikatorer (KPI). Den viktigaste nyckelutförandeindikatorn är den solfraktion (SF) som motsvarar förhållandet mellan lokalbefolkningens egen energiförbrukning och dess belastning. Ett solcellssystem på 35 kWp med en standardtäckningsgrad på 34 % hittades för staden Montpellier. Denna undersökning bekräftar också att kollektiva projekt för självkonsumtion inte är lönsamma i Frankrike. CSPE-bolaget är i huvudsak den skattekomponent som hindrar sådana projekt från att vara lönsamma oavsett affärsmodell. Mervärdesskatten på lokal elförbrukning försvagar dessutom projektets lönsamhet i konsumentens affärsmodell. När det gäller budgeten är det mindre statens kostnader att ta bort CSPE (med 19 027 euro) än att subventionera direkta kostnader för solcellsinvesteringar till 638 euro/kW (med 22 330 €) för ett projekt som har en affärsmodell från tredje part inom det befintliga solcellssystemet. För ett projekt som har en konsumentaffärsmodell är en subvention på 511 euro/kW på kostnaden för direktinvesteringar i solcellssektorn att föredra för staten (med 17 885 euro) än att ta bort både CSPE och momsen på lokal elförbrukning, vilket leder till ett underskott på 29 732 euro. Sammanfattningsvis är ett kollektivt projekt för självkonsumtion inte ekonomiskt lönsamt i Frankrike inom ramen för den nuvarande lagstiftningen. För att sådana projekt ska kunna genomföras bör den franska staten anslå ett minimibidrag på 40 procent i direktinvesteringen i solcellssektorn (511 euro/kW för ett solcellssystem på 35 kWp) till projekt med en konsumentaffärsmodell. För de som har en affärsmodell från tredje part bör CSPE-bolaget tas bort.

There is ongoing work related to the energy efficiency of residential buildings in the subarctic regions in northern Sweden. The focus is often on the reduction of energy usage and the economic aspects for the property owners. With the introduction of new technology and changes to the existing building, the indoor thermal climate is affected. While these measures not necessarily create a negative impact on the occupants’ experience, it is essential to understand the outcome of various energy efficiency measures on an indoor thermal climate point of view. It is also crucial to explore used software, methods and how to interpret the outcome of projected simulations. The present thesis investigates residential buildings subjected to energy efficiency measures in the subarctic region of Sweden, primarily from an indoor thermal climate point of view. Both typical residential buildings in the region and a new pilot building with unconventional approaches were included. The goal of the present thesis was to establish important aspects of energy efficiency measures to improve the knowledge for the region. Along with measurements in the buildings, the building energy simulation software IDA Indoor Climate and Energy (IDA ICE) and the computational fluid dynamic (CFD) software ANSYS CFX were used in the present thesis. A comparison showed that the IDA ICE software and the CFX software gave different results when predicting the indoor thermal climate, mainly attributed to the thermal radiation. Due to the nature of CFD, the CFX was able to identify the variation of velocities, temperatures and thermal radiation in the whole volume, which also affected the results. Further, CFX could detect potential problems of the interior that could be crucial, that building energy simulation software such as IDA ICE could not. The results also demonstrate how CFD is an essential tool when evaluating the indoor thermal climate. When it comes to making a fair assessment of changes, it is important to consider the thermal parameters, the occupied zone and the time spent in that zone. Without considering the occupants’ experience or adequately pay attention to heating and ventilation systems, energy efficiency measures could lead to the rebound effect. It is, therefore, important to consider and evaluate the thermal climate and properly adjust heating and ventilation systems after energy efficiency measures.

With the increasing awareness of the impact of climate change, there has been more intention to reduce greenhouse gas emissions and achieve carbon neutrality targets. However, as one essential element for human well-being, residential heating remains a major contributor to global greenhouse gas emissions. The complex, interdependent, and sometimes contradictory nature of factors influencing residential heating choices makes it a difficult problem to address. Multiple actors with different goals and priorities further complicate the decision-making process. Moreover, given the current energy crisis, selecting an appropriate heating system for residential areas has become even more crucial. Therefore, there is a need for decision support tools that can consider multi-dimensional factors and heating alternatives, which usually have a long-term impact involved in residential heating choices.   Thus, this thesis aims to improve the understanding of what influences decisions to choose a heating technology alternative and how decision support tools can sup-port these decisions. Among the decision-making techniques, multi-criteria decision-making (MCDM) methods have been chosen because they are capable of considering a wide range of factors and are simple to understand and use, taking into account data availability and capability. A systematic literature review is conducted to understand the criteria and MCDM methods commonly used in the field. Two appended papers applied different approaches of MCDM methods to support the Danish residential heating transition. These applications also act as case studies to address the research questions.    This thesis highlights financial, technical, and environmental factors for decision-making on heating technologies and addresses common problems that might occur during the decision-support process. Specifically, it suggests considering financial costs, environmental emissions, technical efficiency and lifetime when choosing a heating technology and using distance-to-ideal MCDM combining other methods. Furthermore, the thesis reflects on the complexity of MCDM applications in decision support and presents a publicly available online decision support tool based on the research (https://api.flexsus.org/MCDM). This thesis contributes to knowledge for academics and fills gaps in residential heating decision-making. For practitioners, a useful tool is provided for improving the quality of decision-making in residential heating, offering a practical and scientific perspective for making informed decisions without consuming extra resources. By increasing the under-standing of influencing factors and decision-support methods for heating technologies, this thesis helps facilitate the heating transition.