Life cycle assessment of the semidetached passive house "Röda lyktan" in northern Sweden : A comparison between the construction phase and the use phase

Sammanfattning: This report is a life cycle assessment of a relatively newly built semidetached passive house/low energy house located in Östersund/Jämtland. The analysis concentrates on the building materials in the construction phase and the energy in the use phase for 50 years. The construction phase include frame, foundation, interior and exterior walls, ceiling and roof, middle floor structure, floor coverings, interior and exterior doors, windows, interior staircase with banisters, stove and FTX-ventilation system. The inventory to obtain the volume of each material has been made with the help of blueprints and interviews. The inventory of the use phase has been made using measurements from a parallel study by Itai Danielski of the energy use in the house (Danielski, Svensson & Fröling, 2013). The database Ecoinvent has been used to get a result for the volume and energy values. The inventory data is allocated and the characterization methods GWP, CED (cumulative energy demand) and USEtox are used. The aim of this study was to compare the construction phase with the use phase to see which phase that has the highest energy values ​​and environmental impact. Another goal was to examine which materials in the construction phase that has the highest embodied energy and environmental impact. The result shows that in a comparison between the construction phase and the use phase, and when considering the parameters included in this study, the use phase has the highest values for global warming potentials (around 54 %), cumulative energy demand (around 80 %), ecotoxicity (around 56 %), human non-carcinogenic toxicity (around 77 %) and total human toxicity (around 75 %). The construction phase has the highest values for human carcinogenic toxicity (around 57 %). Even if the use phase has the highest values in most categories the construction phase also has high values. As buildings become more energy efficient and with increasing use of renewable energy, the construction phase becomes more important from an environmental perspective. This means that the material choices which are made in passive houses become increasingly important if passive houses should be considered to be environmentally friendly also in the future. The study also shows that the FTX-ventilation system, some of the insulation materials (with cellular plastic sheets and rock wool in top), metals (with sheet metal roofing of steel in top), glued laminated timber and wood fiber boards  have some of the highest values of environmental impact and the highest embodied energy. These materials should in future buildings be considered, if possible, to be replaced with materials with less environmental impact.