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Homes & Gardens
Homes & Gardens
Ottilie Blackhall

HVAC Experts Reveal the $1 Incense Trick That's the Secret to Slashing Your AC Bill This Spring

A green green dining room with a jute rug, light wood flooring, and a pale grey table in the centre of the room, surrounded by four green and white patterned chairs. To the right is a white side table, and in the background are large windows with green and white botanical print blinds, with various mismatched plants on the windowsill.

As temperatures rise, so too do air conditioning bills. And, if your windows and doors aren't sealed correctly, you might find them doing so more than usual.

While these costs are an inevitable part of warmer weather, there is one easy and affordable trick you can use to check that your AC is working as efficiently as possible – and all you need is an incense stick.

It's a simple yet effective method that can effortlessly help you to cut energy bills.

Why Drafts Are More Noticeable In Spring, and How to Spot Them

The incense stick trick is simple: Slowly pass a lit stick around window frames on a windy day. If the smoke flickers, you're losing money from failing seals. If you have one of these as part of your home fragrance favorites, then it's easy to get testing. If you don't, you can pick incense sticks very affordably from Amazon, with same-day or next-day delivery.

Josh Mitchell, HVAC Expert and Founder of AirConditionerLab, details that the main reason for new spring drafts stems from winter freeze-thaw cycles.

'Freeze-thaw cycles wear down seals faster than people expect,' he explains. 'During winter, caulk and rubber seals expand during warmer daytime temperatures and contract overnight when temperatures drop below freezing. That repeated movement creates hairline cracks that grow over time. UV exposure from winter sun also dries out sealants, making them brittle.'

'In many homes, especially those over 10 years old, I see seal breakdown within two to four seasons. By early spring, those gaps are already letting conditioned air escape.

'Even small openings around windows can increase cooling load by five to 15 percent, which is why people notice higher AC bills as soon as temperatures start rising,' or struggle to even keep a home cool in the first place.

And, as Patrick Gambel, Owner of General Heating & Air Conditioning, adds, the main issue is, 'Most homeowners don’t catch it right away, but those little openings are what lead to drafts and higher energy bills.'

How to Use the 'Incense Stick' Trick to Identify Drafts

All you need is an incense stick. (Image credit: Future / JONATHAN GOOCH)

'The incense trick works because smoke reacts to even slight air movement,' continues Josh. 'I tell homeowners to turn off ceiling fans and hold a lit incense stick about an inch away from window frames, corners, and trim. Move slowly along the edges.

'If the smoke drifts sideways or gets pulled in a direction, that’s a leak. You can also test on a calm day with the AC running, since pressure differences will still pull air through gaps. It takes about five to 10 minutes to check an entire room and gives a visual result that’s easier to spot than using your hand.'

Most importantly, catching these failed seals early prevents costly repairs, as air leaks spell moisture, mold, and mildew.

'Warm indoor air hitting a cooler window frame can condense inside the wall or around the frame,' adds Josh. 'Over time, that leads to soft wood, peeling paint, and mold.

'Once the frame starts to break down, you’re no longer looking at a seal fix. You’re looking to replace parts of the window or the entire unit, which can cost $500 to $1,200 per window. Fixing the gap early with a $10 to $20 material avoids that progression.'

Jordan Benjamin, HVAC, Plumbing Expert, and the President of Done Rite Services, agrees. 'Catching a failing seal early prevents serious damage from occurring,' he says. 'Gaps in the seal lead to moisture intrusion, which causes wood to rot, insulation to deteriorate, and frames to warp.

'These kinds of issues can be expensive to repair, and if the damage is severe, a full replacement may be needed. It’s much easier and less expensive to replace failing seals as you notice them.'

How to Eliminate Drafts

Identifying gaps and cracks helps to trap air conditioning and keep your home cool. (Image credit: Future / Jonathan Bond Photography)

Once identified, DIY draft proofing is easy.

'For quick fixes, I recommend removable weatherstripping for windows that open and close often,' suggests Josh. Rope caulk [such as the Frost King Fingertip Rope Caulk, available at Amazon] works well for seasonal sealing and costs under $10 per pack.'

If you're not so confident with DIY, you could also go for what Scott Levene, Vice President of Levco, refers to as the 'faster, uglier way' – shrink wrap.

'Shrink-wrap works on not-so-beat-up windows, and it doesn’t require as much precision or near-craftsmanship to install as caulk sometimes can,' he explains. 'It works like a cheaper, temporary storm window, stopping leaks and creating an air pocket with an insulating effect.'

Then, for windows, a door sweep or draft stopper, available at Amazon, blocks airflow at the bottom, where most leaks happen.

'If you find wider gaps, use low-expansion foam labeled for windows and doors,' continues Josh. 'It fills the space without pushing on the frame. A single can can seal multiple windows and costs around $6 to $10.' For this, we recommend the GE Big Gaps & Cracks Insulating Foam, available at Walmart.

'For smaller cracks, acrylic latex caulk is a good option and is easier to control than foam,' he adds. And importantly, Josh warns, don't overlook your outlets and switch plates on exterior walls, or all your attempts to weatherproof your windows will be in vain.

'I’ve tested homes where those spots alone accounted for noticeable airflow,' he says. 'Foam outlet gaskets cost a few dollars and take only a few minutes to install.

'Attic access points and baseboards along exterior walls are also common leak points. When you seal several small gaps, the combined effect reduces how often your system runs and helps maintain stable indoor temperatures.'

What to Shop

Below, you can shop from a selection of expert-approved draft proofing essentials – including caulk, expanding foam, and incense sticks, which you can also use as a quick way to make your home smell nice.

Each is suitable for differing factors, such as the size gap you need to fill, so make sure to assess yours individually before deciding on which will work best for you. Some, like the shrink-to-fit window kit and door sweep, are also conveniently removable, but will work just as well to keep your home warm and trap heat in winter as they will to keep it cool and trap air conditioning this spring and summer.

All prices were correct at the time of publication.

Meet the Experts


Have you considered eco cooling? Discover the greenest ways to stop your home from overheating.

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