A South Australian Water Board scientist who worked on the extremely dangerous problem of cooling airport tarmacs, discovered that his airport tarmac solution worked just as well around his own home as the airport. We'll come back to the tarmacs, but it is now official that a healthy lawn will drop the ambient temperature around your home - and reduce your need for air conditioning and fans.
The Adelaide Water Board scientist discovered that by watering the lawn around his house for no more than the equivalent time of a shower most nights, he dropped his home temperature up to a whopping 10°C. It cost a little more in water, but saved a lot more in energy and created a more comfortable home.
When the temperature gets too hot, planes simply can't take off. Even at warmer temperatures, planes need to use more fuel and runway to get the lift needed to take off. Adelaide already has hot, dry summers and in 2019, 12 days in the first three months saw daytime temperatures exceeded 37°C, including a maximum temperature of 46.6°C on January 24. Of course, global warming is set to push temperatures even higher.
An experiment to cool South Australia's airport by growing lucerne to cool the ambient temperature was the brain-child of Greg Ingleton from South Australia Water, who planted a series of grasses at the airport before settling on lucerne - and dropping the Adelaide airport ambient temperature by 3°C. The Adelaide study ran for 3 years and has gone on to be presented to Airport Authorities around the world.
The findings of this work are consistent with what is known about urban streets. Streets with trees and gardens are significantly cooler than those with only road base and concrete. Earth Overshoot Day reports another important point.The power of trees as cooling towers is so great that urban trees are more effective as a climate change adaptation solution than as a mitigation solution. Urban trees can sequester only a fraction of the carbon that cities emit.
"URBAN TREES ARE A VERY EFFECTIVE TOOL TO CREATE COOLER, MORE COMFORTABLE MICROCLIMATES IN AREAS WHERE CITY RESIDENTS GATHER, SUCH AS IN SCHOOL YARDS, AT PARKS, AND ALONG PATHWAYS."
Urban trees contribute not only to the health of the environment and local residents; they also make economic sense. A study of five city tree planting programs shows that the benefits of urban trees are nearly always higher than the costs. The study found that, “although these cities spent $13– 65 annually per tree, benefits ranged from $31 to $89 per tree. For every dollar invested in management, benefits returned annually ranged from $1.37 to $3.09.”
If you have the opportunity to grow lawn or have been thinking about it, you now have the evidence to back your judgement - and cool your own home. Lush greenery of any kind, even pots helps.