In an effort to highlight and tackle heat issues in Darwin, CLOUSTON Darwin has been working with the NT Government Architect Professor Lawrence Neild and heat mitigation world expert Mat Santamouris (Professor of High Performance Architecture, UNSW) on landscape and building interventions to reduce temperatures throughout Darwin’s CBD.

Research undertaken by Mat has indicated that global temperature increases of 2 degrees can be multiplied by urban heat island effect’s resulting in temperature increases in tropical cities of over 10 degrees! Tree canopy cover and landscape solutions are a key aspect of the integrated solution and will play a major role in reducing surface temperatures that can be as high as 45-67 degrees in the wet season (November to April). These high surface temperatures have a significant impact on human comfort.

Figure 1. Surface temperature in the central CBD area of Darwin exceeds 60°c

Combined with other heat mitigation techniques it has been shown that Darwin’s city wide temperatures could be reduced by 2 degrees, cool noted ‘hotspots’ by as much as 6 degrees and reduce surface temperatures by up to 35 degrees. Preliminary financial modelling has indicated that savings in power costs associated with air-conditioning in Darwin CBD could ‘pay’ for the intervention works within 7 years!

The extensive research and modelling undertaken to date will inform a number of streetscape trial projects to be implemented in 2018. It is anticipated that this work, a first for a tropical city, will have widespread applications in other cities throughout tropical and equatorial regions.

Figure 2. Classification of the cost per degree of temperature drop for each of the considered mitigation technology
The blue zone corresponds to the technologies presenting a low specific cost per degree of temperature drop, while the red zone represents all technologies having a high relative cost. As shown, all considered mitigation technologies, except of the green roofs, are suitable for implementation in the Darwin CBD area.