Building cool cities for a hot future

thermal_image_house31kRecent media reports have highlighted the bizarre weather patterns in Sydney over January, February and March 2016. Some reports have linked evidence of temperature extremes to urbanisation and the loss of shading and moisture that vegetation provides. This is known as the Urban Heat Island (UHI) effect.

A research collaboration between the UNSW Faculty of Built Environment and the Universities of South Australia and Melbourne has collected further evidence for the highly localised effects of building form, surface materials and street orientation on outdoor microclimate and pedestrian thermal comfort. The aim is to build a solid evidence base to inform design, planning and policy across Australian cities as reported by The Conversation.

Meteorological data collected during the 2015-16 summer in Sydney reveals that air temperatures in the street “canyon” may vary by up to 5℃ from those the Bureau of Meteorology records at Observatory Hill.

Even more worrying are the surface temperatures measured on building facades. These may exceed 70℃ in the sun.

The vertical surfaces of multi-storey buildings account for much of the urban surface in contact with the surrounding air. Hotter surface temperatures elevate nearby air temperatures during the day.

Then, due to the thermal mass of typically dense and dark building materials, building facades continue to emit radiant heat well after sunset. This slows the cooling of local outdoor air temperature.

Without night-time cooling, human thermal discomfort is prolonged. Consecutive nights of elevated air temperatures have severe impacts on human health. This includes increasing heat-related mortality and morbidity.

More extreme heat days projected from climate change on top of localised heating due to urban design elevates the health risks from future heatwaves. To read more click here.

The 9th International Urban Design Conference will be held in Melbourne in November.  To express your interest in the 2016 Conference CLICK HERE.

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