Thermal-energy and environmental impact of cool clay tiles for residential buildings in Italy

Sustainable solutions for energy saving in buildings are assuming increasing interest both in the research and the industrial community. In this view, cool roof systems demonstrated to be interesting and effective solutions which role in energy saving for cooling and mitigating local and global warming is already acknowledged. In these recent years, several studies were carried out in order to quantify their thermal-energy effect with varying boundary conditions, while global climate analytical models were proposed with the purpose to evaluate the effect of high albedo solutions in terms of radiative forcing and CO2eq offset. This work concerns the combined analysis of thermal-energy and environmental effect of cool roof (high albedo) clay tiles with low visual impact, specifically optimized in order to preserve traditional residential buildings. In particular, dynamic simulation models and field monitoring of a real residential village were developed and the effect of such tiles is analyzed in terms of energy saving for cooling and of CO2eq avoided emissions due to the energy efficient intervention, coupled with the effect in climate change mitigation. This aspect is specifically considered by applying an analytical method elaborated in previous works, where the effect of high albedo surfaces in terms of CO2eq offset is quantified with varying orientation, inclination, solar reflectance and geographical details. The combined analysis showed how an overall annual CO2 emissions' offset is achievable by coupling single-building and global assessment methodologies. In particular, the energy saving contribution saved around 141 tonnes of CO2eq per year, and the global warming analytical model showed that the albedo increase allowed to offset about 772 tonnes of CO2eq per year. This prototypical study showed how local energy analysis should be coupled to global analysis in order to have an exhaustive view of building retrofit strategies' sustainability.