A multi-criteria approach for the assessment of housing renovation strategies

The building sector is well known to be one of the key energy consumers worldwide. The majority of the current European housing stock was built during 1940-1970s, with low standards especially with regard to energy performance. The challenge now is to act in this stock. In this paper, a multi-criteria methodology is proposed for the comparative analysis of retrofitting solutions. First, environmental impacts and financial costs are evaluated via a life cycle approach. Secondly, Life Cycle Assessment (LCA) and Life Cycle Cost (LCC) are combined through the Pareto optimization method. For this, environmental impacts are expressed in monetary values. To illustrate the applicability of our approach, a case study has been selected: the renovation of a representative housing block from the 60s located in Madrid. Three scenarios have been proposed for the analysis of energy saving measures: scenario 1, where typical solutions used in Spain are applied; scenario 2, where strategies to achieve energy requirements fixed by Spanish regulation are assumed; and scenario 3, where Passive House standard is achieved. Energy saving measures are therefore defined for each scenario considering roof, facade and windows. Results show how housing renovation involves important benefits, not only from the environmental point of view but also from the financial perspective. For the building typology analysed, located in Madrid, the current retrofitting strategies are not optimal from an environmental point of view. The necessary extra investment for the improvement of the envelope with a higher insulation thickness (8%) is arguable taking into account the extra environmental and financial savings (45% and 87% respectively).status: publishe