Basic building life cycle calculations to decrease contribution to climate change – Case study on an office building in Sweden

This study examined whether simplified life cycle-based calculations of climate change contributions can provide better decision support for building design. Contributions to climate change from a newly built office building in Gävle, Sweden, were studied from a life cycle perspective as a basis for improvements. A basic climate and energy calculation tool for buildings developed in the European project ENSLIC was used. The study also examined the relative impacts from building material production and building operation, as well as the relative importance of the impact contributions from these two life cycle stages at various conditions.The ENSLIC tool calculates operational energy use and contributions to climate change of a number of optional improvement measures. Twelve relevant improvement measures were tested. The most important measures proved to be changing to CO2 free electricity, changing construction slabs from concrete to wood, using windows with better U-values, insulating the building better and installing low-energy lighting and white goods. Introduction of these measures was estimated to reduce the total contribution to climate change by nearly 50% compared with the original building and the operational energy use by nearly 20% (from 100 to 81 kWh/m2 yr). Almost every building is unique and situated in a specific context. Making simple analyses of different construction options showed to be useful and gave some unexpected results which were difficult to foresee from a general design experience. This process acts as an introduction to life cycle thinking and highlights the consequence of different material choices