Microclimate in historic buildings: The role of in-field monitoring in the design of retrofit interventions

Buildings of historical and architectural value face strict preservation regulations that often hinder energy retrofitting, despite their poor energy performance and low comfort levels. Experimental in-field monitoring campaigns are a useful tool, as they allow the identification of site-specific non-invasive retrofit strategies that combine heritage conservation with energy efficiency, sustainability, and comfort. Understanding the microclimatic phenomena's impact on buildings is a pivotal step in choosing effective retrofit solutions, since these parameters can influence the construction hygrothermal behaviour, affecting the overall performance. In this scenario, Villa Farnesina in Rome was monitored to analyse the indoor and outdoor microclimate. The collected data allowed for evaluating: (i) boundary conditions and their correlations with indoor parameters; (ii) the impact of building's characteristics, internal thermal loads, and building management practices; and (iii) the occupants' comfort. Results revealed temperature increases up to 1.8°C due to envelope characteristics and orientations, reductions up to 1.3°C for passive cooling effects and increases up to 2.3 °C from internal thermal loads. Summer comfort was critical with PMV up to 1.8 and PPD up to 70%. This study confirms monitoring campaigns as crucial for supporting suitable retrofit strategies design in historic contexts, enabling the assessment of local phenomena affecting buildings' performance.