A Rapid Roof Modeling Tool - the MIT Design Advisor Roof Module

TitleA Rapid Roof Modeling Tool - the MIT Design Advisor Roof Module
Publication TypeConference Paper
Year of Publication2011
AuthorsStephen D Ray, Leon R Glicksman
Conference NameCanadian Conference on Building Science and Technology
Date Published07/2011
Conference LocationWinnipeg, Manitoba, May 10-13, 2011

Previous studies suggest potential for energy savings through cool and green roofs, but do not always consider the many factors that affect potential savings or the relative advantages of different technologies. To further investigate these factors, a tool has been developed and introduced into the existing MIT Design Advisor to allow architects the ability to quickly assess the energy-saving potential of different roof systems. A first principles heat transfer model has been developed for each of the roof technologies, with particular care for green roof heat and mass transfer. Experimental data from Japan and Florida validate the models by predicting roof surface temperature. Example simulations are run with the tool to show that potential energy savings are highly sensitive to many parameters, particularly roof type, climate, and amount of insulation. To illustrate these dependencies, simulations show that a one-story building in Toronto with a modified-bitumen roof and 1 m2K/W roof insulation can save 24% in cooling and heating energy by adding 4 m2K/W insulation, whereas only 3% if a green roof with is installed instead. However, in Phoenix, the same additional amount of roof insulation to the same building results in 24% savings, while the installation of a green roof results in a 29% reduction.