Development of cool pavement with dark colored high albedo coating

It is considered that the dark surface of buildings and pavements is one of the major heat source causing the urban heat islands, as it absorbs more heat from the sun. In Japan, several kinds of cool pavement have been developed and their cooling effects were investigated. However, they have never been widely used in practice due to a limited effect in mitigating urban thermal environment. Some of the heat island mitigation studies deal with the albedo increase of road and building surfaces (Sailor, 1995). It is not difficult to raise the albedo of the building roof as it can be attained by bright colored painting. For pavements, however, the brighter surface is not allowable for reasons of driving safety and visibility of white line, unless the brightness is less than that of the conventional asphalt and concrete pavements. In this study, a new type of pavement is developed to satisfy both high albedo and low brightness by introducing the paint coating technology. By applying newly developed durable paint coating with high albedo and low brightness to the conventional asphalt pavement, the effectiveness of reducing pavement temperature and sensible heat flux is investigated by field measurements. Then, the impact of introducing high albedo pavement on the overall canopy albedo, canopy surface temperature and energy balance was investigated by applying canopy energy balance model in a real urban canopy setting.