Previous green roof studies have found that planted roofs significantly reduce roof temperatures and roof heat flux, and simulations indicate cooling load reductions of up to 25%. This monitored study evaluates summer and winter energy performance aspects of a green roof on a central Florida university building addition that was completed in 2005.
Analysis of 2005 summer data indicates significantly lower peak roof surface temperatures for the green roof compared with the conventional roof and a significant shift in when the peak temperature occurs compared to the conventional roof. Summer roof heat flux estimates show the green roof to have an average heat flux of 0.39 Btu/ft2 /hr or 18.3% less than the conventional roof's average heat flux rate of 0.48 Btu/ft2 /hr.
Winter data again show significantly lower peak roof surface temperatures and higher nighttime surface temperatures for the green roof. For periods during which the ambient temperature was less than 55° F, the weighted average winter heat flux rate for the green roof is -0.40 Btu/ft2 /hr or 49.5% less than the conventional roof's average heat flux rate of -0.79 Btu/ft2 /hr.
Buildings - Roofs
Florida Solar Energy Center and Sonne, Jeffrey, "Energy Performance Aspects Of A Florida Green Roof" (2006). FSEC Energy Research Center®. 499.