Energy and environmental assessment of two high energy performance residential buildings

The «positive energy building» concept combines energy saving and electricity production using renewable resources, aiming a positive primary energy balance on a yearly basis. Compared to other concepts of high energy performance buildings, it is very ambitious on an energy point of view, but more materials and components are used, this is why the environmental relevance of this concept has to be questioned. In order to contribute to answer this question, a life cycle assessment (LCA), including the fabrication of components, construction, operation, maintenance, dismantling and waste treatment, has been used to evaluate the environmental impacts of two high energy performance buildings: a renovated multi-family social housing building and two passive attached houses. Both buildings are located in North of France. For the purpose of this study, renewable energy production has been assumed to achieve nearly positive energy balances. For these buildings, four different heating solutions have been studied: an electric heat pump, a wood pellet condensing boiler, a wood pellet micro-cogeneration unit, and district heating. Modeling and simulation have been performed using the building thermal simulation tool COMFIE, to evaluate the heating load and thermal comfort level, and the LCA tool EQUER to evaluate twelve impact indicators. The results show the level of performance as well as the influence of the choice of the heating system on the environmental impacts considered in this assessment.