Retrofit of Italian School Buildings. The Influence of Thermal Inertia and Solar Gains on Energy Demand and Comfort

Most of the Italian school buildings were built before the 1973 energy crisis, so they need a retrofit to reduce their primary energy demand and improve the indoor environment quality. Moreover, regardless of age, these buildings have large windows; therefore, it is generally necessary to improve the solar control strategy. The older buildings have heavy masonry; in these cases, the problem is where it is more convenient to place an additional layer of insulation: inside or outside the buildings opaque envelope elements. This work explores, only by means of computer simulations, the effects of various retrofit strategies on energy demand and comfort conditions. The examined strategies are characterized by different positions of the additional insulation and various solar control strategies. The case studies consist of two school buildings of the city of Bologna, in Northern Italy. In order to assess the influence of internal gains and time profile of use, other possible uses for the same buildings, such as offices or dwellings, have been considered. Simulations results show that the external insulation is always the most performing, but the differences with the internal one are not relevant in the case of the classrooms. Differences increase with the reduction of the internal gains and with the extension of the daily use time. Small packable slats inserted between the glasses improve luminous comfort, and reduce energy demand. Larger external slats provide less luminous comfort but better thermal comfort in the cooling period; however, they increase the energy demand.