The heat load of detached residential buildings in warm and hot climates is predominantly driven by
the interaction of the external environment with the building envelope. Because of its large surface
area in relation to building volume and its high exposure to direct and indirect solar radiation, the roof
is the key building structure that allows or limits heat flow into internal spaces of one and two storey
single family houses in Australia. The energy balance of a roof is determined by incoming solar
radiation, the reflectance and absorptance of the roof surface, heat transfer, roof structure and internal
and external temperatures [2,3]. While light coloured roofs have long been used in many hot regions as
a means of providing a cooler internal space, modern ‘cool roof coatings’ use advanced chemistry to
increase both the solar reflectance and infrared emittance of the roof. For over two decades researchers