COOL ROOFS: MONITORING A RETROFIT PROJECT IN ROME, ITALY

摘要

The paper presents the results of a monitoring campaign, performed in the course of last summer, on a building, used as a Senior Citizens recreational center, retrofitted with a "cool roof' material. A research group of Roma Tre University, in cooperation with ENEA, the Italian Agency for Energy and Environment, decided to experiment the use of "cool roof' strategies to improve the unsatisfactory internal thermal comfort conditions and to save energy. ENEA had already studied and tested several materials, to be used as coatings for roofs and walls. Such materials need to present very high reflectances in the visible-near infrared spectrum (solar radiation), while having high emissivities in the far-infrared range. An Italian company manufactures materials of this kind, which come in rolls and can be easily glued to existing flat surfaces. The building has been provided with temperature sensors, measuring air and surface temperatures. In addition to that, a pyranometer has been installed to measure solar radiation. All sensors were linked to a data acquisition system, which collected and stored all data. Measures were taken before and after installing the cool roof material. That allowed the analysis of surface and indoor air temperatures with and without the cool roof material, thus enabling the comparison of the two situations. Finally, the building has been simulated using TRNSYS in both situations, first without air conditioning, to check the correspondence between measures and simulation, then assuming continuous air conditioning operation. The first exercise shows the degree of thermal comfort improvement, the last exercise provides an valuation of the energy savings, associated with the adoption of cool roof strategies. The paper presents the main results of the study, which show a significant improvement both aspects.