DIMENSIONERING OCH LIVSCYKELANALYS : EN JÄMFÖRELSE MELLAN EN STÅL- OCH TRÄKONSTRUKTION

Sammanfattning: The purpose with this report was to do an alternative design with timber as constructional materialfor a reference building designed with a structure in steel. The load-bearing structure of thealternative building have been designed and compared to the reference building with climateimpact and energy needed in consideration. The timber construction has been designed by usingmanual calculations and with computer programs. The timber construction has also been designedby using provided drawings for the reference building.  The result of the design showed that it was possible to use timber as framing material for thereference building, despite the size of the building. The result also showed that the cross sectionsof the timber construction become larger than the cross sections of the steel construction. Horizontal stabilization with cross-laminated timber panels for the roof and with diagonal bars forthe walls is a possible method to use for achieving full horizontal stabilization for the timberconstruction. The external height of the ceiling becomes approximately one and a half metershigher for the timber construction compared to the reference building, assumed that the internalheight of the ceiling stays the same.  Calculations of the climate impact is made by using 3D-modelling tools and computer programsfor environmental calculations. Carbon dioxide equivalents were used when calculating theclimate impact. The result of the accomplished Life cycle assessment shows that the element thatcauses the most climate impact for the building with the steel construction is the load-bearingconstruction, for the timber construction the roof causes the most climate impact. It can also beseen that the phase that causes the most climate impact is the use stage, this turns out to be true forboth designs. The construction stage contributes to 35 % of the climate impact for the steelconstruction and 6 % for the timber construction. The use stage accounts for about 65 % of theemissions for the steel construction and for the timber construction the use stage accounts foralmost 93 % of the emissions with the product specific data.  Calculations of the use stage for the building shows that the building envelope of the timberconstruction has a lower impact on the climate and needs less energy than the building envelope ofthe steel construction. The result also shows that the building envelope for the steel constructionhad a 27 % higher energy consumption than the timber construction. The report also shows thatthe total emissions of the steel construction is greater than the emissions of the timberconstruction.