What are energy efficient windows?

Everything you need to know about energy efficient windows

With rising energy prices, unpredictable weather patterns and growing environmental awareness, making the switch to energy efficient windows can be a simple yet highly effective way to improve the efficiency and sustainability of your home or building.

And for buildings with a high ratio of glass, the impact can be significant: up to 87% of a building’s heat is gained through its windows[1], so making a change to smarter, greener window options can lead to considerable savings.

But how exactly do energy efficient windows work? Let's unpack everything you need to know before making a decision on what’s best for your building.

Keeping your cool

Our Australian summers are known for their extreme highs, and if your windows aren’t helping keep the heat out, the cost of keeping your cool is going to become increasingly painful, with predictions that energy costs could go up by 35% in 2023 alone[2]. Ideally, you also want windows that help your home or building maximise the impact of warming winter sun, and to keep your interiors at a pleasant temperature year round. 

So before you reach for the air conditioner controls, consider the benefit of choosing energy efficient glass, which can act as an extra layer of insulation and help regulate indoor temperatures, at any time of year.

Measuring the impact

The Australian Glass and Windows Association has developed a rating system to help you make an informed decision about the energy efficiency of your windows - looking at how readily heat from sunlight flows in through windows, the light transmittance they let in, and the way they conduct heat.

Unfortunately, poorly placed windows without any capacity for energy efficiency can mean an excess amount of heat into your home during summer, and inefficiencies in warming your home during winter.

Consider all of your options - for example, are you retrofitting existing windows or building from scratch? The condition of your frames and fittings is also going to play a part - if they’re letting in drafts during the winter, then energy efficient glass alone aren’t going to cut it. Choosing different window options depending on whether they’re facing north, south, east or west, can also be part of your approach.

Taking steps to get your windows right will be a long-term investment that helps your home or building maintain its temperatures year around. Better for the planet, and better for your bank account.

Tints and coatings

Glass tinting uses tinted glass or coatings to block radiant heat from the sun, and generally the darker the tint, the more direct heat you can block. However, it’s important to remember that going too dark can be counterproductive - if your tint is so dark that you need your lights on during the day, you’ve lost all of the energy efficiencies you were hoping to gain by reducing your home cooling requirements.

Another option for single-glazed windows is to opt for glass which has been treated with a low emissivity (low-e) coating. This is a thin, transparent coating sprayed onto glass during the manufacturing process to prevent non-sun heat transfer through glass - reducing heat loss and heat gain. Low transmission low-e glass is ideal for the Australian climate - it reduces the amount of solar heat gain, while also maintaining good levels of visible light transmission, so your home feels bright and light during the day.

Amazing glazing 

Insulated double and triple glazing is another great option for improving the energy efficiency of windows. It uses an air gap between window panes to reduce heat transfer into and out from the building, and some modern solutions also use gas trapped between window glass panes for even more effective insulation properties.

Combining double glazing with low-e glass means highly effective insulation for your building, as both energy efficiency aspects work hand-in-hand to reduce heat loss and heat gain.

Insulated Glass Units (IGU’s) window options also come with the added benefits of dramatically reducing external noise from traffic, trains, animals and other sources, and improving the security of your building, as the extra glass layers provide redundancy in the event of breakage.

Smart choices for a sustainable future

The windows and glass in your building can make a significant difference to the long-term sustainability and efficiency of your property, providing a long term return on investment in reducing your energy costs and your carbon footprint.