The thermal effect of an innovative cool roof on residential buildings in Italy: Results from two years of continuous monitoring

• The year-round thermal performance of an innovative cool clay tile is investigated.
• The proposed cool roof is applied on a traditional residential building in a temperate climate zone in Italy.
• The thermal effect of the cool roof is assessed through two years of continuous monitoring.
• The proposed cool roof produces important cooling benefits in summer and relatively small penalties in winter.

Cool roofs represent an innovative and relatively inexpensive technique to reduce building energy requirements for cooling and to improve indoor thermal comfort conditions. These applications primarily consist of high-reflectance and high-emissivity coatings or membranes commonly applied to the flat roofs of non-residential buildings located in both hot and mild climates. This paper discusses the possibility of applying an innovative “cool roof” solution, consisting of a prototyped cool clay tile, on a traditional residential building in central Italy to improve the thermal conditions of the indoor environment that is adjacent to the roof. In particular, the results of a two-year continuous monitoring campaign are presented. The building was monitored for an entire year in the original configuration and for another entire year in the optimized configuration, with the final objective of quantifying both the summer benefits and the winter penalties of such a solution in residential buildings in temperate climate conditions. The year-round analysis shows that the proposed cool roof solution produces a maximum effect of decreasing summer peak indoor overheating of the attic by up to 4.7 °C. The corresponding winter maximum overcooling reduction is 1.2 °C. These experimental results show that this innovative cool roof solution can be implemented on traditional sloped roofs with a clay tile covering, producing substantial benefits in summer and relatively small penalties in winter for residential buildings, even in temperate climates.