Plant shade trees to naturally cool your garden and home

Trees make the best shade. Known as nature’s air-conditioners, trees are essential for reducing energy consumption, which is even more important now with rising interest rates and three in every four households across Australia reported to have either refrigerated air conditioning or evaporative cooling (ABS, 2014) to provide relief from the heat.

Where space permits, large deciduous shade trees positioned on the north-west of your house can have a huge impact on naturally cooling your home. They will not only shade the roof, walls and windows from direct sunlight, but also cool the ambient air that enters your home. This can have an economic benefit by reducing energy costs, as less artificial cooling is required, as well as health benefits by providing a more pleasing outdoor area in which to take respite from the hot summer sun.

While it is widely accepted that trees and other plants (including lawns) help to cool the environment, how much do they help?

According to the EPA, surfaces shaded by trees may be 11–25°C cooler than the peak temperatures of unshaded materials. This is achieved by lowering both surface and air temperatures through shading and the act of evapotranspiration (a direct result of photosynthesis).

On a 40°C day in our Heronswood garden we took temperature readings from around the garden and found the temperature of the turf grass to be 15°C cooler than the ambient air temperature.

There is an opposite side to this equation where summer shade is essential for cooling, while winter sun is required for natural heating. Maximising shade in summer and sunlight in winter gives us the best of both worlds. Deciduous shade trees provide both summer shade, and then allow the warm winter sunlight to penetrate when it is needed most. They also provide the added benefit of ample leaf litter for compost bins.

Getting the balance right

To naturally maximise cooling, aim to have at least 20%-50% of your outdoor space shaded by a large deciduous shade tree (preferably on the north-west side of your home), clothe your walls and fences with green insulating climbers, and opt for lawn over paving to create your own green oasis.

We have many shade trees, groundcovers, and climbers that you can add to your garden to help naturally cool your garden and home.