Mitigating temperature increases in high lot density sub-tropical residential developments

Residential developments built with houses that use passive design features can have significantly reduced energy requirements for thermal comfort. In the context of global warming, this can reduce greenhouse gas emissions. The current trend towards higher lot density in residential developments and the resulting increase in thermal mass increases the associated heat island effect. Designers of future residential developments face the dual challenges of heat island impacts and any future global warming. Resource efficient house designs combined with approaches that mitigate the outdoor heat load must be considered and addressed from the design of the initial subdivision layout. Some land sub-division and house design initiatives are proposed for sub-tropical climatic conditions as prevailing in south-east Queensland, Australia. Computer simulations that account for heat island and global warming effects are used to estimate the indoor thermal performance of display houses constructed by a large scale property developer for current climate conditions and scenarios that may occur in the future. The use of north-south orientation of narrow building lots combined with high albedo house surfaces and the increased strategic use of shade trees for reducing the heat island effect of high density residential developments are presented. The cooling requirements of houses with high-energy rating (5 star or more) are found to be significantly superior to those with low rating (3.5 star) in scenarios of global warming.