Klimatsmart betongbyggande

Sammanfattning: One of the main sustainability goals in Sweden is to reduce the nations greenhouse gas emissions to a net-zero level by 2045. This is a national implementation of the Paris- Agreement. To achieve this goal measures need to be taken in all industrial sectors. The construction and real-estate sectors are responsible for about 22 % of Sweden’s yearly territorial greenhouse gas emissions. The cement industry alone accounts for 5 to 7 %. About half of the emissions during a modern apartment-buildings lifecycle come from material and energy-demanding processes during the construction-phase. The other half is generated throughout the operational lifetime of the building. The purpose of this master’s thesis has been to identify and analyze measures taken to minimize the emission of CO2,equivalents from the concrete structure in a specific apartment building, Kv. Kungsörnen in Helsingborg. The different participants in the concrete-part of the project and their ability to affect the emissions of the project have also been analyzed. Through interviews with people involved in the project, a review of the blueprints and a visit to the construction site an overview of the project was achieved, and the measures taken by the participants were identified. The result on the carbon footprint from the measures taken were put in relation to general cases representing the emissions of a standard apartment building. The environmental impact of the different cases were calculated with “Byggsektorns miljöberäkningsprogram”. The following standard reference cases where investigated and compared to the actual project: • Concrete-recipes • Concrete-dimensions • Amount of reinforcement • Sound class C • Reduced productiontime • Impacts depending on time of the year A reference scenario was summarized based on the individually studied reference cases. The calculated carbon footprint from this reference scenario corresponds well with generic data of similar modern structures. The results show that the carbon footprint from Kv. Kungsörnen has been reduced by about 40% compared to the reference scenario. Additionally, a calculation of the carbonatization of the concrete in Kv. Kungsörnen was done and a comparison between carbon footprints from different methods of heating in the production phase were made. This case study indicates the importance of collaboration between the different actors in an early stage of the construction process. The most important factor identified in the project was the chosen concrete. Primarily it is important to use concrete with optimized strength and dimensions, this was achieved in the project by separate calculations on each concrete element. When the chosen concrete was discussed with the concrete supplier further changes were made to make it possible to use the climate reduced concrete, without compromising the performance of the concrete in the finished building.