Does opening the garage door help to keep your house cool?

When dealing with extreme heat, we are open to trying just about anything to help keep our homes cool. Given that our garages are often poorly insulated, they heat up like ovens when temperatures rise – and some of this heat makes its way into adjoining areas of the home.

Some claim that opening the garage door just a crack will keep your garage cool in hot weather, and in turn help keep the temperature down in adjacent rooms, but is this nothing but a heatwave myth?

We turned to heating and insulation specialists to find out.

Does opening the garage door help to keep your house cool?

'Opening the garage door a crack may allow for some airflow, but it's usually not an effective way to cool down the home significantly,' says Josh Mitchell, HVAC specialist from Air Conditioner Lab. Below, we explain the potential pitfalls and what to do instead.

Josh Mitchell

Josh is an HVAC expert and the owner of the Air Conditioner Lab with years of experience tackling the challenge of home cooling. Josh has explored various innovative methods to cool down living spaces during hot weather.

Why you shouldn't open the garage door in hot weather

Leaving your garage door partially open will, of course, increase the ventilation – but is unlikely to cool down your home enough to outweigh the potential hazards.

1. It may attract pests

A garage door left open is likely to invite bugs and other pests inside, which could cause damage to items stored in the garage. Ryan Ratkowski from Rustic Decorating shares a personal anecdote: 'During a blistering heatwave, I decided to leave my garage door slightly open, only to discover later that my space had been hijacked by raccoons,' he says. 

'Not to mention dust and other environmental elements can easily invade your space through an open garage. The temptation is big during summer, but spending hours trying to get rid of raccoons was not part of my summer to-do list.'

Pet food may attract mice, and other insects, such as spiders and ants, are more likely to enter if the door is open. This could be remedied by adding a garage door screen, at Amazon, but it would need to be carefully sealed.

2. It also poses potential security risks

We would be most likely to open our garage doors while the air is cooler, either early in the morning or at night, which are also the times that pose the biggest security risk in terms of break-ins and theft. If you have any valuable tools, equipment or any other items stored on your garage shelving or in boxes, be cautious of leaving them unattended.

'Some garage door systems do allow for partial opening without being able to be opened from the outside, which can reduce the security risk a bit,' comments Thomas Scharpf, founder of Schartec, a company that manufactures and sells garage doors, door openers and home improvement devices.

3. It could also damage your garage door

Keeping the garage door open a crack could also put a strain on the door if yours hasn't been replaced for many years. Instead of opening the door, take note of ways to cool down a room, and if doing DIY and decorating in the garage, consider investing in an air purifier to keep air quality healthy and comfortable. Wind and rain could also make its way inside, potentially damaging the door and items you are storing.

4. It may cause air-conditioned air to escape

There's also energy efficiency to consider. If you have air conditioned rooms near to the garage, opening the garage door could allow this cool air to escape, making the interior feel warmer and resulting in you spending more to keep your home cool. 

Tips for creating a cross breeze

Andrew Johnson, owner of Texas-based Prime Seamless Gutters & Roofing argues that under certain conditions, leaving the garage door slightly open can help to cool the house down, especially early in the morning or in the evening and more crucially when the outdoor temperature is lower than indoors.

'When you open the garage door during such times, you may still have to open a side door/window for proper ventilation or cross breeze,' he explains. 'This method even works in removing the choking smell of paint or stains. 

'However, it's important to be mindful of potential pests that may come in through the garage door. As much as you want to be comfortable, you must bear security in mind,' Andrew advises. 

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