Emission factors and methods used in climate impact assessments of energy use in Swedish heated buildings - Assessing district heating and electricity as energy source

Sammanfattning: When the property- and building industry moves towards new solutions targeting reduced climate impact, this puts pressure on the building owners and companies to calculate the climate impact of buildings. It may seem easy, but there are various methods and guidelines to navigate around. This study addressed the issue of which emission factors for district heating and electricity are used in climate calculations of heating buildings today and how a climate calculation can have different results, depending on system boundaries and method guidelines that are followed. To be able to answer the research questions, evidence was gathered through a pre-study, literature study and interviews with key people in the industry. Interviews were held to examine the problem more comprehensively. The material collected from interviews is presented in the result, together with a complication of the literature study findings. To discuss differences and similarities in the climate calculation methods and between the emission factors presented during the literature study and compilation of results, two case studies on district heating and electricity were conducted on a building with a heating need of 80 kWh/m2, yr. In the district heating case study, three locations – Hässleholm, Linköping and Stockholm – were calculated to give a broader range of different fuel mixes. For electricity, the case study was grid-based. The study showed differences in emission factors and methods based on the collected material. For emission factors related to district heating, it emerged from the discussion that there are differences in the weighting of global warming potential, allocation when combusted, presentation and names of the fuel, and different system boundaries. For the emission factors related to electricity, the study shows differences depending on included countries in the average mix. Emission factors for specific electricity sources, such as solar, wind, hydro, or nuclear power, differ significantly. The methods used for the climate calculation vary between if the method follows bookkeeping- or/and consequence perspectives, different scenarios for the future, how to present data and when the year of the data sources. There are inconsistencies in the methods, system boundaries, and recommended emission factors for calculating module B6, resulting in ambiguity. Currently, there is no nationally accepted methodology for calculating the climate impact assessment, and there is a demand for standardized guidelines, according to this study.