17 Jun 2019

This report outlines the key outcomes of research project RP1037u1 ‘Above-Roof Temperature Impacts on Heating Penalties of Large Cool Roofs in Australian Climates’, an extension to project RP1037 ‘Driving increased utilisation of cool roofs on large-footprint buildings’. The research has been focused on two key aspects of roof thermal performance that had, up until the time of writing, not been taken into account in most investigations into cool roof technology:

09 Jul 2018

The implementation of ‘cool’ roofing materials, with high solar reflectance and infrared emittance, has received significant attention in recent years, as a method to mitigate the urban heat island effect and reduce building cooling energy requirements. The effect of ‘cool’ roofs on heat transfer through the roof structure has been investigated by many researchers. However, the air temperature field above roofs and the influence of elevated above-roof air temperatures on the performance of rooftop air-conditioning equipment and photovoltaic panels have not been studied in depth.

Conference paper
07 Mar 2018

Light, reflective surfaces can have a dramatic impact in cooling the surrounding air – in cities, but in the countryside too. Whitewashed walls, arrays of photovoltaic cells, and stubble-filled fields can all provide local relief during the sweltering decades ahead. But policymakers beware. It doesn’t always work like that. There can be unintended consequences, both on temperature and other aspects of climate, like rainfall. Even local geoengineering needs to be handled with care.

22 Sep 2017

This document presents the mitigation study for the CBD area of Darwin, performed by the High Performance Architecture Group of UNSW, Faculty of Built Environment.The first part of the report includes the methods and the results of the terrestrial and aerial monitoring campaign, the evaluation of the magnitude of the Urban Heat Island (UHI) and finally the main conclusions on the climatic context characterized with the monitoring.

01 Feb 2018

This report provides an in-depth analysis of the costs and benefits of applying a set of smart surface solutions1 , including cool roofs, green roofs, solar PV, and permeable and reflective pavements and road surfaces across three cities: El Paso, Philadelphia and Washington, D.C. The report demonstrates that cities can strengthen resilience, improve health and comfort, expand jobs and slow global warming through smart surface strategies while securing billions of dollars in net financial benefits.

01 Jan 2015

A novel material open to warm air stays below ambient temperature under maximum solar intensities of mid-summer. It is found to be 11 °C cooler than a commercial white cool roof nearby. A combination of specially chosen polymers and a silver thin film yields values near 100% for both solar reflectance, and thermal emittance at infrared wavelengths from 7.9 to 13 μm.

Journal article
01 Jan 2014

Cities experience the effect of extra heat compared to their rural surroundings. This phenomenon is known as the Urban Heat Island (UHI) effect. Urban geometry, land cover, landscape and metabolism have been cited as the main contributors to the UHI effect. This paper compares the UHI mitigation strategies of the contemporary development of Dubai Marina (United Arab Emirates) with historical cities of Sana’a (Yemen) and Bushehr (Iran).

Journal article
22 Nov 2016

Problem: Roofs receive the most intense solar heat load among all building envelope surfaces in Equatorial-region. Solar heat gain through roof contributes to a significant portion of building heat load. In tropics where building cooling is needed all-year-round, passive methods to reduce heat gain through roof could provide significant cooling energy-savings.
Approach: Currently, the most widely adopted practices to curb the heat flux through roof include using thick building material-layer (30-40 cm-thick concrete) or insulation (5-10 cm-thick). This study investigates the thermal performance of emerging methods: cool roof and green roof. Cool roof works by applying a coating-layer having high-solar-albedo. Green roof works by adding a soil-layer and vegetation. This study numerically compares the heat curbing performances of these technologies under the tropical climate using an experimentally-calibrated EnergyPlus model.
Results and discussion: Cool roof performs best in reducing annual net heat gain in tropical climate of Singapore, which receives abundant irradiation. Cool roof reduces heat gain during day-time and promotes heat loss during night-time. Insulation and green roof are effective in curbing heat gain during day-time but they prevent heat loss during night-time.
Research limitations: This paper reports the investigation on a flat concrete roof as the base. Investigations on other roof base materials, e.g., metal roof, will be reported in future.
Originality: This is the first study that compares performances of cool roof, green roof and insulation against original concrete roof in tropical climate.

Conference paper