Recommendations for robust renovation strategies of Swiss residential buildings

Abstract Building renovation is urgently required to reduce the environmental impact associated with the building stock. Typically, building renovation is performed by envelope insulation and/or changing the fossil-based heating system. Life cycle assessment and life cycle cost analysis are seen as suitable methods to evaluate the performance of a building in terms of environmental impacts and cost. However, the results are highly affected by uncertainty. The goal of this paper is to provide recommendations for robust renovation strategies considering uncertainties on future evolution of climate, energy grid, user behaviors. The method includes identifying optimal renovation options for the envelope and heating systems for building-representatives from all construction periods that are currently in need of retrofit in Switzerland. Conventional and bio-based materials are examined with inclusion of dynamic carbon storage potential. The results of the analysis show that heating system is a priority for building renovation for all the considered construction periods. The results also show that if only conventional materials are considered for building renovation, optimal solution does not prescribe deep renovation and higher energy consumption during life time is favored. However, when bio-based insulation materials can be used, the opposite conclusion is drawn and synergies between low environmental impact and low energy costs during life cycle are identified. Such renovation strategies pave the way for a just and low carbon transformation of the Swiss building stock.