Greenroof potential to reduce temperature fluctuations of a roof membrane: A case study from Estonia

This paper analyses the temperature regime of a light weight aggregates (LWA)-based greenroof in comparison with a modified bituminous membrane roof. The measuring period was from June 2004 to April 2005. Both seasonal and daily results showed that in Estonian climatic conditions, an extensive greenroof is sufficiently capable of protecting the roof membrane from extreme temperatures. In the summer period, the 100-mm-thick substrate layer of the greenroof significantly decreased temperature fluctuations compared with the bituminous roof surface. In autumn and spring the substrate layer protected the base roof's membrane from rapid cooling and freezing. It also provided effective thermal insulation in winter. In addition, measurements showed that the surface of the LWA media in the greenroof heats and cools more than the surface of the bituminous roof; however, its influence on temperature in the substrate layer was not considerable. Indexes to characterize greenroof's temperature effects are proposed.