BC’s wildfire smoke seasons used to feel like the exception. Not anymore. The province has now seen back-to-back above-average smoke seasons from 2023 through 2025, and the smoke reaches far beyond the communities directly affected by fire, settling over homes across the Lower Mainland and the rest of the province for days or weeks at a time. For homeowners outside the fire zones themselves, the impact is air quality as we continually see the sky turning a murky grey or an eerie shade of orange, along with frequent Air Quality Advisories.
For the majority living outside the wildfire zones, the response is to close the windows to avoid smoke particles. What often goes unexamined is whether a closed window is actually doing its job of keeping smoke out, and what that means for indoor air quality Vancouver homeowners have come to rely on.
This article walks you through what actually determines how well your windows keep smoke out, why BC homes carry a heavier workload than most, and a few simple ways to check where your own windows stand.
Key Takeaways
- Wildfire smoke is now the leading source of fine particulate (PM2.5) pollution in BC, according to the BC Lung Foundation, which means how well your home keeps it out matters more than ever.
- A closed window isn’t automatically a sealed one. How well a window seals is measured by its air infiltration rating, and that performance varies widely between windows, which affects how much of that smoke actually gets in.
- You can spot common warning signs of a failing window seal yourself, including drafts, unusual sounds, and condensation, without needing professional equipment.
- A better-sealed home doesn’t just help during smoke season. It also means fewer drafts, less outside noise, and lower strain on heating and cooling.
Why Closing Your Windows Isn’t the Complete Answer
You already know the drill. The sky turns hazy, the smell of smoke drifts in, and you run to close every window in your home.
Good instinct. But here’s what most of us never stop to ask: how much smoke is actually getting in anyway?
A closed window isn’t a sealed window. Every window has small gaps where the sash meets the frame, and how tight those gaps are depends on the window’s design, its age, and how well it was installed in the first place. Weatherstripping wears down. Caulking dries out and cracks. A window that sealed beautifully ten years ago might be a lot leakier today, even with the latch fully closed.
This matters more in BC than it used to. Wildfire smoke has become the leading cause of fine particulate matter pollution in the province, according to the BC Lung Foundation’s State of the Air report. As one health initiatives manager at the Foundation put it, “this isn’t a one-time-in-a-life exposure anymore. Smoke season has become something BC homeowners plan around, the same way they plan around rain”.
Key takeaway: Closing your windows is the right first move. But if you don’t know how well those windows actually seal, you don’t know how much protection you’re really getting.
So what determines whether a “closed” window is doing its job? That comes down to something called an air infiltration rating, and it’s a lot easier to understand than it sounds.
What “Air Infiltration Rating” Actually Means
Here’s a number most homeowners have never heard of: cfm/ft², short for cubic feet of air per minute, per square foot of window.
Don’t worry, you don’t need to remember what it stands for. You just need to know what it tells you.
An air infiltration rating measures how much air sneaks through a window’s frame when it’s closed, not through the glass, but through the tiny seams where the sash meets the frame. The lower the number, the tighter the seal. Think of it like a rain jacket. A good one keeps you dry in a downpour. A cheap one lets water creep in at the seams, even though it technically covers you.
This is different from the other window numbers you might already know, like U-factor, which measures heat loss, or a DP rating, which measures how well a window holds up to wind and water pressure. Air infiltration is its own category, and it’s the one most directly tied to how much outside air, smoke included, finds its way past a “closed” window.
In Canada, Natural Resources Canada sets the bar for ENERGY STAR certified windows at an air leakage rating of 0.30 cfm/ft² or lower. That’s the minimum a window needs to hit just to wear the label. Plenty of windows on the market meet that number comfortably. Fewer are built to beat it by a wide margin.
So how do you know if your own windows are doing better than the bare minimum, or barely scraping by?
Key takeaway: A lower air infiltration number means fewer gaps for smoke, dust, and drafts to slip through, even with your windows shut tight.
None of this means you need to memorize a spec sheet before your next home project. It just means the number exists, it’s public, and it’s worth asking about the next time someone quotes you a window.
Curious whether your own windows are pulling their weight? Our team can walk through it with you.
Why This Matters More in a BC Home
BC didn’t just start caring about airtight construction because of wildfire smoke. We’ve been building toward it for years, for entirely different reasons.
Here’s the honest answer to why that matters: a BC window is being asked to do two jobs at once. For most of the year, your windows are holding back the coast. Wind-driven rain, damp winters, and condensation that creeps in during a cold snap. That’s always been the job. Now add a second job on top of it: keeping smoke out during a season that shows up more often than it used to. Same seals, twice the work.
Think of it like a boat. A well-built hull doesn’t just keep water out. It also determines how much air gets in when the hatches are shut. BC’s building code has been quietly tightening that hull for years.
The province’s Energy Step Code sets airtightness targets for new homes, and it uses a different measurement than the window rating we just talked about. Where a window’s air infiltration rating looks at one window, the Step Code looks at the whole house at once, using a different number: how many times the air inside gets fully swapped out with outside air in an hour, under test conditions.
Lower is still better, and the industry shorthand for it is ACH50. Step 3 is currently the provincial minimum for most residential construction at 2.5 ACH50, with the province working toward a net-zero-ready Step 5 target of 1.0 ACH50. Two different numbers, one shared idea: BC has been steadily tightening the bar on how much outside air is allowed into a home.
BC Housing’s own guidance points out that an airtight building enclosure improves energy efficiency, durability, and a homeowner’s control over indoor air quality. That last part is the whole answer. A seal built to keep BC’s rain out is the same seal deciding how much smoke gets in. It was never just a weather feature. It’s been doing double duty all along, and most homeowners have never had a reason to think about it that way until now.
Key takeaway: BC windows carry a heavier workload than windows in drier climates. The same seal fighting off coastal rain all winter is the one standing between you and wildfire smoke every summer.
How to Get a Sense of Where Your Own Windows Stand
You don’t need a professional blower door test, where a technician measures exactly how much air leaks from your home, to start figuring this out. A few honest minutes walking around your house will tell you a lot.
Here’s what to check:
- Age: Original windows from the 80s or 90s are running decades-old seal technology. Weatherstripping wears out, and vinyl and rubber components get brittle over time.
- Drafts: Stand near a window on a windy day and see if you can feel air moving, even with it fully latched. A steady draft is a pretty clear sign the seal isn’t doing its job anymore.
- Sound: A whistling or humming sound during a storm usually means air is finding a gap somewhere in the frame.
- Condensation: A little bit on the inside of the glass on a cold morning is normal. But condensation between the panes, or fogging that won’t clear, points to a seal that’s already failed.
- Window type: Sliding windows rely on a brush seal, similar to what you’d find on the bottom of a screen door. It works, but it wears down faster than the compression seal on a casement or awning window, which presses tight every time you latch it shut.
We go into more detail on how these seal types compare in our Passive House guide.
Key takeaway: Age, drafts, sound, and condensation are all clues your windows are leaving for you. None of them require a professional visit to notice, just a little attention.
None of this replaces a proper assessment. But it’s a reasonable place to start before deciding whether that’s worth doing. And if you’re weighing a bigger project down the line, installation quality matters just as much as the window itself, something we cover in detail in our guide to 5 critical decisions that determine cost and quality.
Where A1 Fits Into This Picture
We’re not going to tell you that new windows are the answer to wildfire smoke. They’re not, and anyone who tells you otherwise is overselling it. Air purifiers, indoor air monitors, and a good plan for smoke season all still matter. What we can tell you is that your windows are part of that plan too, whether you’ve thought about them that way or not. And if you’re going to rely on a piece of your home to do that job, it should be one built with that responsibility in mind from the start.
That’s really the whole philosophy behind how we build. We’re a local manufacturer, right here in Burnaby, which means we’re not choosing between quality and accountability. We do both, because we’re the ones who stand behind it.
Our installation teams follow the BC Housing Best Practices Guide on every job. It’s how we make sure a window’s seal is only as good on day one as it is five years later, through BC’s rain, wind, and yes, its smoke seasons too.
If everything you’ve read here has you wondering how your own windows stack up, that’s a fair question, and not one you need to answer alone.
Frequently Asked Questions
Do I need to replace all my windows to protect against wildfire smoke?
Not necessarily. If your home is a mix of newer and much older windows, the older ones are usually where you’ll find the biggest gaps in performance. A gradual, room-by-room approach can make sense for a lot of homeowners, rather than treating it as an all-or-nothing decision.
Should I just get an air purifier instead of worrying about my windows?
An air purifier and well-sealed windows aren’t competing solutions, they work together. A purifier cleans the air that’s already inside your home. Better seals reduce how much smoke gets in to begin with. Most homes benefit from both, not one instead of the other.
How do I find out my current windows’ air infiltration rating?
If your windows are relatively new, the rating may be listed on the original spec sheet or the NRCan energy label that came with them. For older windows, that documentation is often long gone, which is where a visual check like the one we walked through earlier, or a professional assessment, becomes the more realistic option. If you’re curious about window performance ratings more broadly, our guide to energy efficient windows in Vancouver covers a few others worth knowing.
Does a tighter seal help with anything besides smoke?
Yes. The same seal keeping smoke out also cuts down on drafts, outside noise, and the kind of temperature swings that make your heating and cooling system work harder. Smoke season is one reason to care about it, but far from the only one.
Conclusion
Closing your windows during smoke season will always be the right instinct. What most homeowners miss is that the windows themselves determine how much that instinct actually protects you. Between age, seal type, and simple wear, two “closed” windows can perform very differently, and BC’s own building standards reflect just how much that difference matters.
The good news is you don’t need special equipment to start figuring out where your own home stands. A walk around your house on a windy day, paired with a look at your windows’ age and condition, tells you more than you might expect.
If your walk-around turns up a draft, a whistle, or a window that’s fogging between the panes, that’s worth a second look. Our team can help you figure out what it means for your home.
Written by Brandon P., Sales Manager at A1 Windows.
Credentials: With 25+ years in the local window installation sector, Brandon leads our residential and commercial installation teams, providing transparent, no-pressure guidance to BC homeowners.
