The True Cost of Cooling by Lekha Patmanathan

In Singapore, we are obsessed with our air-conditioning systems to make us feel cool and fresh in otherwise normally sweltering outdoor temperatures. The Cooling Singapore Symposium held during the World Cities Summit last month (July 2018) in Marina Bay Sands shone a light on the impact of cooling and the resulting phenomenon known as the Urban Heat Island (UHI) effect.

UHI is the increase in temperature in urban environments compared to forested areas.

As a progressively developing nation, we have industrialised our lands where buildings and roads have replaced trees and vegetation. This consequentially leads to an increase in environmental temperature.

Mr Peter Ho, the Chairman of the Urban Redevelopment Authority and senior advisor to the Centre for Strategic Futures delivered the keynote speech where he spoke about the interdisciplinary nature of climate change. It has many contributing factors and every action has a compounding effect. Air conditioning was mentioned as an example, where its purpose it to cool indoor spaces and results in waste heat being rejected outdoors. This vicious cycle means the more we use the air-conditioning the hotter we are making the environment. Mr Ho stressed on the necessity to plan for greenery in the city to reduce UHI effects.

The Cooling Singapore project led by the Singapore-ETH centre is a cross-multidisciplinary team involving academia, research institutes and government agencies. Meticulous research over the past one-year was conducted on Singapore weather data over several decades

Prof Dr Peter Edwards and Prof Dr Gerhard Schmitt, Principal Investigators in the Cooling Singapore project, profoundly presented compelling evidence and a well-articulated analysis on the concept of Urban Heat Island (UHI) affects and its consequences. The quantified impacts of UHI in cities was discovered to be as much as 4°C during the day and up to 7°C at night.

UHI is caused by the storage of solar energy in the urban fabric. This is exacerbated by the loss of surrounding greenery. Plants maintain thermal balance through evaporation and convection. Conversely, metal, concrete and roads, absorb and store heat.

The other cause of UHI is the anthropogenic effect, or how cities are changing the weather. Buildings and the transportation industry are the largest contributors where the heat source comes from combustion engines, industrial equipment and air-conditioning units.

The Cooling roadmap is being developed to reverse the UHI effect. A core strategy is to reduce emissions by using less energy, such as making cooling for efficient. Another technique is to reduce trapped heat with shading technologies and remove them from the system via convection or evaporative cooling. The is a greater need now than ever before to plan for green spaces within cities.

The UHI effect has been undervalued in the past. One of the key revelations now is the magnitude of this problem. Dr Peter Edwards stresses the urgency in implementation of mitigation strategies – it has to begin now. Transition to active mobility – where we walk and cycle more – also plays an important part. We all can plan to contribute to greater physical and psychological outdoor thermal comfort.

More information can be found https://www.coolingsingapore.sg/