Energy saving policies and low energy residential buildings: a LCA case study to support decision-makers in Piedmont (Italy)

Background, aim and scope A low-energy family house recently built in Northern Italy was selected by Regione Piemonte as an outstanding example of resource efficient building. An economic incentive was awarded to cover the extra costs of the thermal insulation, windows and equipment in order to decrease the yearly winter heat requirement from the legal standard of 109 to 10 kW h/m2, while existing buildings in the study area typically require 200 kW h/m2. As the building was claimed to be sustainable on the basis of its outstanding energy-saving performance, an ex post life cycle assessment (LCA) was set up to understand whether, and to what extent, the positive judgement could be confirmed in a life cycle perspective. Materials and methods After an analysis of the literature on LCA of whole buildings, a detailed life cycle assessment has been conducted by encompassing all the life cycle phases. Emphasis was given on the end-of-life stage, too often disregarded due to lack of data or heavily simplified. Virtually all the materials used in the building structure, finishes and equipment were considered, paying attention to their expected service duration and the recycling potential. In order to increase transparency and therefore credibility and acceptance of LCA in the building sector, an uncertainty analysis was carried out. Results and discussion The dramatic contribution of material-related impacts emerged. Structure and finishes materials represented the highest relative contribution, but maintenance operations also played a major role. The contributions of equipment, construction stage and transportation were minor. The important role of the recycling potential also emerged. Unlike standard buildings, where heating-related impacts overshadow the rest of the life cycle, there is no single dominating item or aspect. Rather, several of them play equally important roles. Conclusions The study confirmed that the initial goal of resource and environmental efficiency was reached, but to a much lower extent than previously thought. In comparison to a standard house, while the winter heat requirement was reduced from 109 to 10 kW h/m2 (10:1 ratio), the life cycle energy was only reduced by 2.1:1 and the carbon footprint by 2.2:1. Recommendations and perspectives The findings emphasise the need for incorporating the life cycle approach in energy-saving policies and economic incentives schemes in the building sector, in Italy and elsewhere, as single-step improvements might not be effective in a life cycle perspective and could even disappoint expectations.