By Philip Oldfield
Gardens in the sky
As is obvious to anyone who has sat under a tree on a hot day, vegetation can be a powerful tool in the fight against excessive city heat. Not only does greenery provide shade, it stimulates evapotranspiration, the process by which water evaporating from plants’ leaves reduces the adjacent air temperature.
Many cities recognise the value of parks and trees for urban cooling, not to mention residents’ psychological wellbeing, but few have embraced greenery to the extent of Singapore. The city-state embarked on its ambitious “garden city” plan in 1967 through intensive tree-planting and the creation of new parks. As the population grew and buildings got taller, the focus shifted to include skyrise greenery encompassing “skygardens”, vertical planting and green roofs.
[...]
Reflective roofs
If we are to make cities cooler we must also change the materials they’re built from. Urban areas are dominated by dark and hard materials – concrete, asphalt, paving – most of which absorb, rather than reflect, solar radiation. According to Australia’s Corporate Research Centre for Low Carbon Living, conventional paving can reach temperatures up to 67C and conventional roofs up to 50–90C on a hot day.
[...]
Water: a tool to cool
Water has been used as a tool to cool cities for centuries. The 14th century palace of Alhambra, for example, housed courtyards with pools and arching fountains, stimulating the evaporation of water and cooling the hot, dry Andalusian air.
The contemporary heat-proof city could follow suit, accommodating ponds, pools, fountains, sprinklers and misting systems to cool outdoor spaces.
[...]
Dynamic shades
One of the challenges in keeping the built environment cool is overreliance on fully-glazed facades. Many windows permit desirable natural light and views but can mean buildings trap unwanted heat in summer and don’t retain it in winter. We can easily design shading systems to protect buildings from the sun, but for the best possible results, these shading systems need to move in tune with the local weather and the path of the sun.
[...] 