Fönsterareans klimatpåverkan : Jämförelse av koldioxidutsläpp från material- och energianvändning när fönsterarea varieras

Sammanfattning: Right now, the world is facing a challenge of reducing carbon emissions. Existing buildings account for one-third of the world's carbon emissions. The construction and real estate sector in Sweden is facing the challenge of combining a high rate of construction with demands on reduced climate emissions. Energy use in the construction and real estate sector corresponded to about 40 percent of Sweden's total energy use in 2020, where heating in the construction and real estate sector accounts for the largest share. To build more energy-efficient buildings, it is important to insulate them well. In the Swedish National Board of Housing, Building and Planning's building regulations Chapter 9, it is specified that buildings should be designed so that energy use is limited by efficient use of electricity, low heat loss, and low cooling needs. The Swedish building regulations also specifies values for the primary energy factor, average heat transfer coefficient, and installed electrical power for heating. The purpose of the thesis is to investigate the climate impact that follows from choosing a larger window area than the minimum requirements in the Swedish building regulations. This will be achieved through calculations of the climate impact of energy use and materials which are affected by the window area. The method consists of calculations of energy use, daylight simulations, and climate calculations, where four examples of exterior wall designs were compared with each other. Calculations were made on the following exterior wall options: the object's original design, where energy and material use were established. Varying window areas where VIP-Energy was used to simulate energy use. Varied window area with the same amount of concrete even though wall area increases, and an option when a new thickness was calculated for thermal insulation depending on the wall's average heat transfer coefficient. VIP-Energy was used to determine energy use in the object studied, as well as with variations in window and wall area. The climate calculation formed the basis for determining the climate impact of variations in material use depending on the window area. The results show that varying the window and wall areas leads to an increase in climate impact A1-5, which has been determined to have a maximum increase of 8.5 percent, mainly due to the increasing amount concrete which is a result of the window area decreases by 37.3 percent. In the scenario with reduced insulation, the results show that when the window area varies, the thickness of PIR insulation can be reduced by 64 percent. When varying the window and wall areas and assuming the same amount of concrete, the results show a lower climate impact of 8,500 kg CO2-eq per floor, corresponding to 18 percent. In the two cases where material, operation, and insulation vary, it is shown that varying insulation initially results in lower impact with a 25 percent reduction in area. The conclusion is drawn that the material and dimensions of windows affect the building's carbon footprint, although in this case, concrete has the greatest impact.