Résumé

Following the Fukushima accident in 2011, Switzerland decided to start turning off the electricity coming from nuclear power plants as a part of an ambitious “Energy Strategy 2050” including better energy savings and efficiency of buildings and the development of renewable energies. In this new framework, one of the measures concerns the replacement of direct electric heating systems. It has been discussed in some Swiss cantons and increases the pressures on building tenants that use direct electricity as energy carrier e.g., for heating. However, from an environmental and economic point of view it is not clear yet whether it is better to renovate the building envelope, the electric heating systems or a combination of both. As several alternatives exist during a building renovation, the objective of this paper is to conduct an integrated economic and environmental assessment of four representative scenarios using the Life Cycle Assessment and Life Cycle Cost methodologies based on Swiss standards and cost data collected from manufacturers. From an economic point of view, results showed that the renovation of the electric heating system by a heat pump, solution often promoted by Swiss cantons, enables to get similar costs compared to the existing building. This solution is more interesting than the building envelope renovation or the switch to another heating system for which a technical room needs to be created. From an environmental point of view, the building envelope renovation is fundamental to lower the impacts. The partial renovation of the building envelope while keeping the direct electric heating system gives equivalent results compared to the only replacement of the electric heating by an air-to-water heat pump. Finally, this study shows that it is not always possible to be below the indicative values of the SIA 2040 standard “Energy Efficiency Path” (intermediate goals of the 2000-Watt Society) for the “Construction” and “Operational” aspects for building renovation.

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