'The benefits are massive': how to upgrade your home to keep it cool during summer

As temperatures edge higher across the country, home owners may be dreading the prospect of another long, hot summer sweltering indoors, or a scary power bill after blasting the airconditioner.

Fortunately, there are alternatives. Identifying the main problem areas of a home and investing even small amounts to address these issues can prevent heat build-up, keep the home cool and reduce the need for airconditioning.

While various cooling strategies are most effective when implemented while building a home or undertaking a major renovation, homes can still be upgraded in many ways to minimise heat gain.

Understand your building

The key to affordably cooling a home is diagnosing why the building is hot, according to architect and Envirotecture director Andy Marlow.

“Normally, it’s because you’ve got poor shading over the windows,” he says. “The sun getting into the building has a huge impact.”

Marlow says windows are a major source of heat gain into a home, and protecting these surfaces from direct heat is the upgrade that delivers the most bang for buck for home owners.

“Fundamentally, the aim is to keep the sun off the windows in summer. It’s the single most cost-effective thing you could do.”

Options for shading windows include fixed or retractable awnings, shutters and blinds, but exterior protection is best.

“Blinds are much more effective when they’re outside the glass than inside the glass,” he says. “Once the heat passes through the glass, it’s inside your building.”

Marlow says home owners should also investigate the quality of their windows and doors, and replace ineffective components that are letting heat in.

“There is a gulf between good windows and the windows people may have in their houses.”

Archicentre director Peter Georgiev says eaves are important to include when designing a building or an extension, but are often overlooked on many modern homes.

“It’s the simplest thing to put on a building and the benefits are massive,” he says. “It gives a degree of protection to the window, the thermally weakest part of a building.”

Other cost-effective upgrades include insulation in the roof space, as well as verandah blinds and pergolas to help shade openings.

Owners of old homes need to understand that there are multiple ways to upgrade a home to deal with summer heat, many of which don’t involve a complete redesign, Georgiev says. In many cases, it will mean using airconditioning and offsetting the cost by installing solar power.

“You can keep your piece of heritage and your charming leadlight that doesn’t work thermally and acknowledge in this case that you have to go active,” he says. “Look at photovoltaics and batteries and spend your money there.”

Thermal massing

Home owners aiming to cool their homes more effectively need to understand the principle of thermal massing.

In a nutshell, dense materials such as brick, stone and concrete take a long time to heat up and can store a lot of heat, which radiates into the home even after the sun has gone down.

Exposing these surfaces to sunlight can be very useful in winter when warmth is desired. But in summer, keeping sunlight off the thermal mass is the key.

“In a well-designed building thermal mass can be really helpful,” Marlow says. “If you can make that thermal mass cool, a concrete floor for example, that will act as a thermal buffer.

“If it cools down at night, you can open your windows and cool down the thermal mass.”

Smart planting

Shading the home with plants is a long-term approach. Well-positioned deciduous trees can block direct sunlight in summer and allow light penetration in winter, but not all trees and shrubs are suitable for planting next to buildings, Marlow says.

“You really need to think about the geometry of how large that plant needs to be to shade the building,” Marlow says.

Additionally, some trees have roots that can interfere with plumbing or foundations, and excess vegetation near buildings can increase the risk of property damage from bushfires.

Georgiev says plants can also cool outdoor areas. “Plants in your garden can deliver shade and give you a form of evaporative cooling,” he says, adding home owners can use rainwater tanks to keep gardens moist.