Category: Roof Ventilation

The Advantages and Disadvantages of Whirlybirds

In Australia’s hot and humid summers, a lack of proper roof ventilation can result in heat being held within the roof space. This can cause a multitude of issues, including drying of existing roof timbers, which will eventually lead to their decay. While roof blanket or sisalation is one way to reflect heat, the downside is it seals air and moisture in your roof space, which can encourage growth of fungus. The best way to combat this is a combination of insulation and ventilation.

One of the most popular options for roof ventilation is the commonly seen whirlybird. A whirlybird is a cylindrical dome that spins in the wind, creating a vacuum which extracts warm air from the roof cavity. Whirlybirds are popular because they’re cheap, easy to install, and require little to no maintenance once installed. But you get what you pay for. There are many reasons why you should consider other options for roof ventilation.

The first and most obvious issue is that whirlybirds are dependent on airflow to function properly. If there’s no wind, it won’t spin and is essentially useless. This is especially important in dry summers where there is no wind to make the whirlybird function as intended. Some might consider an electric mechanical whirlybird, but due to the higher price and increased operating costs, it simply makes more sense to consider other options in the same price range, such as a solar vent.

Furthermore, a whirlybird cannot be turned off during winter, which will result in your home losing heat. They tend to be noisy, especially if the wind is very strong on a particular day. And while they’re resistant to rain, they are prone to malfunction because their open design can catch debris, dust, leaves and other foreign objects. While whirlybirds are often considered suitable to be installed and forgotten about, they do in fact require lubrication and cleaning in order to function properly. They’re also not the most durable option, because they’re prone to rust and can be damaged by severe weather.

But by far the most convincing argument to consider other forms of ventilation is that whirlybirds are inherently inefficient when in comparison to other ventilators. A single whirlybird isn’t close to capable of recycling the large mass of air in the ceiling cavity fast enough to prevent it from heating up. They only work if you install enough of them. For the average-sized Australian home, some estimate that it would take at least 10-15 whirlybirds to effectively cool the home. But this will detract from your home’s appearance and can end up making your house look like a factory, not to mention the costs involved. It’s far more sensible to consider other, more modern ventilation options.

Which is best, Whirlybird or Solar Vent?

Whirlybirds are a common form of roof ventilation because they’re cheap, easy to install and you can effectively “set it and forget it”. If you have an adequate number of whirlybirds (one or two won’t be effective unless your home is very small), they may provide an appropriate amount of ventilating and cooling. But if energy efficiency is important to you, we highly recommend considering a solar vent.

For one, whirlybirds remove precious heat during the winter, leaving your home colder, which leads to higher heating costs. Furthermore, they are very inefficient at cooling your home during the summer if it’s not consistently windy. This is especially true in hot and dry climates. This is why it’s more sensible and practical to consider a thermostatically-controlled Solar Roof Exhaust Vent.

A Solar Roof Exhaust Vent contains a small solar panels which powers an exhaust fan inside the frame. It comes with a functioning thermostat and will only function when internal roof temperatures rise above 25 degrees Celsius, so it’s only working when you actually need it to. Our recommended unit also comes with a rechargeable lithium battery which will continue operating the fan for up to four hours even when the solar collector is not receiving direct sunlight (provided the internal roof temperature is still high enough for the Solar Roof Exhaust Vent to be turned on). The next time the solar panels receive direct sunlight, the batteries will be automatically recharged.

A Solar Roof Exhaust Vent does the same job as a whirlybird, but better. It provides ventilation which prevents the accumulation of condensation and moisture, which can severely damage your roof and shingles. Believe it or not, a single Solar Roof Exhaust Vent removes as much hot air as 10 whirlybirds. They’re also quieter than whirlybirds, and operate all-year round. Although they don’t work at night due to the lack of sunlight, this is typically a non-issue because they’re most needed during the day when the sunrays are heating up your roof and attic.

For optimal performance, we recommend installing a Solar Roof Vent at the highest point of your roof. Contact us to learn more about pricing, installation and other considerations to provide the most energy-efficient ventilation option for your home.

Your Options for Roof Ventilation

Have you ever stuck your head into a ceiling cavity during hot weather? If so, it’s no surprise how the space between your ceiling and roof can get.Read More


Roof & Render SA is a family owned business established in Adelaide back in 1921 providing old fashioned customer service and advice. We are Adelaide’s most experienced when it comes to Roofing. We employee all our trades to ensure you a quality finish, back all our work with a 10 year warranty and guarantee our customer service, so you can be confident when choosing Roof & Render SA.

  • Monday to Friday: 8am – 5pm
    Saturday, Sunday & Public Holidays: Closed
  • 2/22 O'Sullivan Beach Road Lonsdale, Adelaide SA 5160
  • 08 8326 9696
  • Email us
Privacy Settings
We use cookies to enhance your experience while using our website. If you are using our Services via a browser you can restrict, block or remove cookies through your web browser settings. We also use content and scripts from third parties that may use tracking technologies. You can selectively provide your consent below to allow such third party embeds. For complete information about the cookies we use, data we collect and how we process them, please check our Privacy Policy
Consent to display content from Youtube
Consent to display content from Vimeo
Google Maps
Consent to display content from Google