Planning of cost-effective and energy-efficient retrofitting actions: a comprehensive energy audit approach

Buildings in Europe account for 40% of total primary energy consumption and 36% of greenhouse gas emissions. Approximately 40% of Europe’s building stock predates the 1960s (in Italy the percentage increases to 63.8% considering the 1970s), when standards regarding insulation, energy efficiency and indoor comfort did not exist, and the stock is now in dire need of renovation. New construction in Europe represents only about 1% of the building stock, and in the last 15 years, the market of urban refurbishment has constantly increased. Up to now, an accepted and consolidated methodology for refurbishing the existing housing stock is still missing, despite the amount and quality of technologies, components and materials available. Every intervention is considered as specific and subject to a wide range of variables. The purpose of the present study is to present a working approach for optimising the retrofitting process, from an energetic and a cost-effective point of view and considering users’ comfort, through an analysis procedure of the existing building stock, adaptable to different contexts. In particular, this paper refers to the building stock of ITEA SpA, the Social Housing Institute for the Province of Trento (Italy), which manages more than 16,000 housing units. The research can be summarized in four main phases: definition of clusters, in which buildings are similar in terms of age, dimensions, typology, construction system and location within the region Trentino; analysis of building-plant systems solutions and recognition of significant cases for classifying buildings in term of energy class; identification of possible improvements and related cost-benefits; extension of the results to the whole cluster. The aim is to set medium and long term plans taking into account possible benefits on management costs and therefore the effective sustainability of intervention for the controlling body (cost effectiveness) and the final user (energy efficiency and comfort quality).