a b s t r a c t
Statistics have confirmed that a lawn placed on a roof top can reduce the cooling load. In this study, the
VISUAL DOE 4.0 energy simulation program was used to determine the effects of roof lawn gardens (RLG)
on the annual energy required for cooling, and annual electrical usage in an experimental model. The
overall heat transfer coefficient (U-Value) of the RLG was estimated by using data from site measurements
and the effect of the RLG on the building’s energy consumption was calculated by the simulation
program. The effect of different thicknesses of soil was also investigated. From the field measurements, it
was confirmed that the RLG could reduce building heat gain. Thus, an experiment was set up to find the
energy benefits of the RLG. With evaporative cooling by the RLG, it was found that the consumption of
energy in a building with a RLG with 0.20 m of soil was 37.11% less than in a building with a bare roof
surface (without evaporative cooling). Moreover, a building with 0.10 m of soil in the RLG consumed
31.07% less energy than a building with a bare roof surface. The results show that an increase in the
thickness of the soil layer reduces the building energy consumption