1. Introduction
Environmental problems, especially in urban areas, have
become a serious issue. The increasing numbers of buildings in
cities causes a loss of green areas, resulting in the Urban Heat Island
effect (UHI), which makes temperatures increase and causes
uncomfortable conditions for human living [1,2]. The reduction of
heat coming into buildings is very important with respect to
thermal comfort and saving energy. Thus the need for vegetation in
urban areas is increasing.
There are many ways to change internal thermal comfort conditions,
such as: the use of mechanical equipment, environmental
factors or vegetation. However, while vegetation does not consume
energy,mechanical equipment consumes a largeamountof energy [3].
The roof lawn garden has become accepted as a viable option to
increase thermal comfort and reduce energy consumption. Many
researchers have tried to improve the performance of green roof
technology. However, research into the incorporation of green roof
technology to local contexts is still in its infancy phase. This is the
first study in use of roof lawns for the prevention of solar heat gain
in Thailand.
N.H.Wong et al. [4] found that plants can absorb a large amount
of solar radiation through their biological functions. Thus, the
remaining solar radiation which affects the internal temperature of
a building is much less than one with a bare roof.