Urban Heat Island Mitigation Using Green Roof Approach

Abstract

In urban environments, vegetation has largely been replaced by impervious and often dark surfaces. These conditions contribute to an Urban Heat Island (UHI) effect. This phenomenon is demonstrated in many cities and produced effects such as higher atmospheric temperatures, intensive precipitation, excessive solar radiation and increasing air pollution. Therefore, reducing the surface temperature of roofs in a building may play an important role in improving the conventional roof surfaces with green roofs that offer much lower temperatures throughout a day to reach their thermal performance and reduce the absorption of solar radiation. Thus, this study is focused on determining the effectiveness of the existing green roof in reducing the ambient temperature and humidity of the air above it by comparison with conventional open roof top without vegetation. This study also aims to evaluate the potential of green roof to reduce the air pollutants in improving air quality in urban cities. As a result, by adopting green roof system, it has reduced temperature during the hottest hour in a day at 1230 hour (hr) by 4.3°C when compared to open roof. Green roof has also recorded higher percentage of humidity compared to open roof. Most importantly, it was proven through this study that green roof has the potential of absorbing pollutants in the air by reducing the concentrations of Sulphur dioxide (SO2), Ammonia (NH3), Nitrogen dioxide (NO2), Ozone (O3) and Carbon monoxide (CO) compared to open roof. Thus, green roofs can be considered to be one of the effective methods to mitigate UHI effects in urban cities.

Evaluating the potential of persistent luminescence in counteracting urban overheating

“…To address UHI, sustainable urban planning and design are crucial, including the use of green infrastructure and cool materials [3]. Sohaili et al [4] have shown that green roofs can reduce surface temperatures by 4.3 °C compared to traditional dark roofs. Additionally, green roofs can lead to a 3.7 °C reduction in average air temperature and an 8.46% reduction in relative humidity compared to standard bitumen roofs [5].…”

Growth and development of succulent mixtures for extensive green roofs in a Mediterranean climate

“…‘Green roofs’ or ‘living roofs’, comprising roofs which are partially or wholly covered by vegetation [ 7 – 9 ], can be considered one such technology. The ability of a green roof to reduce the effects of the urban heat island (with energy saving benefits), to improve the quality of the air, to manage stormwater runoff and to help increase urban biodiversity is widely recognized [ 10 – 21 ]. The effectiveness of a green roof on the environment strongly depends on the local climate, the design of the green roof and the characteristics of the building.…”