Addressing historic buildings' energy efficiency. A methodology based on building operation.

In Europe, more than 14% of the whole building stock dates from before 1920, but this percentage reaches over 50% in several urban centres. Therefore, historic buildings are fundamental to reach the current Europeans CO2 emissions’ reduction targets. Historic buildings’ energy retrofit is relevant not only from an environmental point of view; since most of these buildings host human activities (often different from the original ones), it is important to provide adequate indoor environmental conditions for occupants’ comfort and wellbeing, but also for the preservation of eventual decorations or artworks within the building. Moreover, a reduction of the energy consumption represents an important opportunity for reducing the operational costs of these buildings. However, historic buildings’ energy retrofit entails some controversial aspects due to the necessity of preserving their architectural evidence. For instance, interventions on the building fabric are usually forbidden, especially if they alter the external appearance of the facades. In this framework, actions aimed at optimizing the way the building is operated become crucial. This paper presents a methodology elaborated to investigate the potential energy savings and enhancement of environmental comfort conditions by acting only on the way the historic building is operated by building managers (or technicians) and occupants. The methodology, conceived with a pre-test and post-test design approach, is flexible and allows the adoption of different retrofit strategies depending on the different case studies’ necessities. Limitations of the methodology consists on the impossibility of establishing its efficacy ex-ante, due to the fact that the strategies’ application rely on users and technicians’ willingness to engage in the experimentation.