Evaluation of energy Efficient Refurbishment of Residential Buildings in Southern Europe Based on the Cost-Optimal Methodology

In line with the European Energy Performance of Building Directive (EPBD), this paper aims to calculate the cost-optimal energy performance of a residential building in southern Europe, more precisely in Portugal, taking into consideration thermal and lighting (daylighting and artificial lighting) refurbishment solutions. The economic calculation method used considers the initial investment costs, the running costs (including annual maintenance costs, operational costs, energy costs and periodic replacement costs), greenhouse gas emissions costs and disposal costs. The results obtained for the energy needs allow choosing the cost-optimal package of refurbishment measures. It is shown in this paper the relevance of daylighting and artificial lighting solutions for the users’ indoor comfort, for the building energy consumption and, consequently, for the overall costs during the building life span. From the daylighting and artificial lighting point of view, the most influent factors are the type and solar optical glazing and the shading devices properties. For the adopted reference building under Lisbon climate conditions and a North-South orientation façade, light-coloured external roller blinds and single tinted blue-green glass solutions are the ones that lead, in the majority of cases, to simultaneously lower values of global costs and energy consumptions.