Impact of climatic conditions on the thermal effectiveness of an extensive green roof

Publication date: September 2013
Source:Building and Environment, Volume 67
Author(s): Bau-Show Lin , Chin-Chung Yu , Ai-Tsen Su , Yann-Jou Lin
The density of urban development has been the source of a number of environmental issues, and in urban areas with large quantities of stereoscopic space, roof greening has become an important strategy for land compensation and environmental quality improvement. In particular, with the intensification of urban heat island and the global warming phenomena, the effective regulation of the microclimate by building a green roof becomes more attractive. Because a green roof is closely related to the climate and the environment, the main purpose of this study is to explore the impact of climatic conditions on the thermal effectiveness of an extensive green roof. The experimental cases of an extensive green roof were individually established in urban areas with both sub-tropical and tropical island climates, and synchronous observations were made. The research results show that it can reduce the increase of outdoor temperature by approximately 42% and the increase of the indoor temperature by 8% during the daytime. During the night, it can maintain 17% of the temperature in the outdoor environment, stabilizing the temperature change. The thermal effectiveness of an extensive green roof is closely related to the climate. The daytime cooling effectiveness was relatively high in the tropical island climate in summer, and the nighttime insulation effectiveness was more pronounced in the sub-tropical climate. Rainfall reduced the thermal effectiveness of an extensive green roof.