Vegetalized Complex Partition (VCP): Impact of a Green Roof under a Humid Tropical Climate, Comparison between Hong Kong and Reunion Island

The aim of this paper is to present the experimental results of a specific vegetated complex partition (VCP) and discuss the conclusions found from an interesting study case in Hong Kong, especially the presence of a strong upward heat flux in winter. The experimented VCP configuration have never been tested in Reunion Island. It is located on a small scale building with a sloped roof covered with steel foil and under a humid tropical climate. From March to August, the extensive VCP reduced the global average heat flow by 91.61% and the ceiling temperature by 9.3°C, with a maximum average reduction of 18.9°C at noon. Compares to the results from Hong Kong, three of the four conclusions have been observed or deduced from the experimented VCP's results. The fourth conclusion (about heat flow loss in winter) have not been observed. But, based on the results, a precision of the explanation of its origin is proposed: the evaporation process act like an heat loss amplifier.