Last July, we had about a week and a half of really bad wildfire smoke here in West Michigan. The air was hazy, the smell was terrible, and it got to the point where being outside was genuinely uncomfortable. The smoke burned your nose and throat, and if you were doing any physical work outdoors, you'd quickly find yourself short of breath.
I knew that wasn't the kind of air I wanted coming into our house. For my family, it was uncomfortable and unhealthy, but for some people with allergies, asthma, and similar conditions, air quality this poor is a matter of major health complications and hospital visits.
My home is built to be extremely airtight, using the same high-performance construction principles we follow at R-Value Homes. That gives us a lot of control over how outside air enters the house. But we still need fresh air, and normally our ventilation system handles that automatically.
With the amount of smoke outside, I decided to shut that system off.
What happened next gave me a pretty clear demonstration of why airtight construction, ventilation, and filtration all matter, and why you can't really separate one from the others.
Our custom home has a central ventilation system. In the industry, we call it a heat recovery ventilator, or HRV. It brings fresh outdoor air into the house while exhausting stale indoor air. It also transfers heat between the incoming and outgoing air, which helps us maintain comfortable temperatures without wasting as much energy.
In an airtight house, that fresh-air supply is especially important. We've worked hard to eliminate the gaps and cracks that let outside air leak in uncontrolled, so we need a dedicated system to bring in the right amount of fresh air.
On the morning of July 16, 2026, I turned off our HRV because I didn't want it pulling all that smoky air into the house.
I wasn't trying to run an experiment. The air outside was just that bad.
The problem was that once the HRV was off, we weren't bringing in our normal supply of fresh air anymore.
I use an Airthings air quality monitor in our house to monitor the air quality, including carbon dioxide (CO2), particulate matter (PM2.5), and volatile organic compounds (VOCs).
After I shut off the HRV, CO2 levels started climbing.
That wasn't surprising. We naturally produce CO2 just by breathing, but without the HRV running, we weren't removing the CO2, nor bringing in fresh outdoor air. When the windows are shut, the fresh air system acts like the lungs of our home.
That's actually part of what makes an airtight home work so well. We're not relying on random leaks for fresh air. We have a system designed to bring it in deliberately, in the right amount, and through a controlled pathway. But that system needs to be running.
By July 18, our CO2 levels had climbed to more than 2,600 parts per million (ppm). That's a lot higher than we want to see in our home.
Those readings confirmed that we needed to get the ventilation running again. The challenge was finding a way to do that without bringing all that smoke into the house.
Keeping the smoke out was important, but simply shutting the house up wasn't a long-term solution.
Since our existing HRV didn't have the filtration level we needed for those conditions, I decided to add a filter box to the incoming-air duct.
That would let us get fresh air flowing again while filtering out much of the fine particulate matter in the smoke before it entered the house.
I chose a MERV 13 filter, which was the highest-rated filter I could find for this application. MERV ratings tell us how effectively a filter captures airborne particles, and MERV 13 is particularly effective at capturing the fine particles found in wildfire smoke.
While I was working on the system, I took some photos of the inside of the outdoor-air intake duct. You can see the buildup of material that had accumulated there over time. It wasn't necessarily all from the wildfire, but it's a reminder that outdoor air isn't automatically clean.
By the afternoon of July 18, I had the new filter box installed and the HRV running again.
The difference in our CO2 readings was immediate. Once fresh air started coming back into the house, the levels began dropping.
Now that I'd solved the fresh-air problem, I wanted to make sure we weren't bringing all that smoke into the house along with it.
So I took our Airthings monitor outside to see just how bad the air was. The PM2.5 reading, which measures tiny airborne particles like those found in wildfire smoke, was 107. That's a pretty high reading, since particles this tiny are known to bypass the typical filtration of your lungs and directly enter the bloodstream.
Then I brought the monitor back inside, where the HRV was running with the new filter.
The PM2.5 levels dropped and stayed low, even with the system continuously bringing in fresh outdoor air.
Now, this wasn't a controlled laboratory test. I was moving the same monitor between outdoors and indoors, so I wasn't measuring both locations simultaneously. But seeing the indoor readings stay low while we continued bringing in filtered fresh air was encouraging.
The PM2.5 levels dropped and stayed low, even with the system continuously bringing in filtered outdoor air. I also monitored VOCs (volatile organic compounds), and those readings stayed low throughout the smoke event.
One thing I've learned over the years is that you can't expect one high-performance feature to make up for the rest of the house. Everything has to work together.
The filter I added to our HRV is a good example. It wouldn't have done nearly as much good if our house had been full of gaps and cracks that let smoky air come in around it.
Even with the windows and doors closed, outside air can enter through small openings around windows, plumbing, electrical penetrations, and other parts of the building. When that happens, the air doesn't go through your filter first.
That's why we're so particular about airtight construction at R-Value Homes. We want to control where the air enters the house rather than leave it to chance.
This is something I think more homeowners should understand.
New homes are generally built tighter than they used to be, and building codes require ventilation. But how that fresh air gets into the house makes a big difference.
Some homes rely on exhaust-only ventilation, such as a bathroom fan running on a schedule. When that fan pulls air out, replacement air has to come from somewhere. Depending on how the house is built, it could be coming through gaps connected to your attic, a musty basement, or even your garage.
You may have no idea where that air is coming from or what it's bringing into your home.
R-Value doesn’t want to leave that to chance. We build airtight homes with dedicated ventilation systems so we know where the fresh air comes from, can filter it properly, and can bring in the right amount.
That's what made the difference during the wildfire smoke. Our airtight construction helped limit the smoke entering through uncontrolled leaks, while the filtered HRV allowed us to bring in the fresh air we needed.
Neither one would have worked as well without the other.
This experience reinforced something I've believed for a long time: The way we build homes at R-Value really does make a difference.
We were already installing ventilation systems with MERV 13 filtration in our newer custom homes. My own house has an older system, which is why I needed to add the filter. So this experience didn't change how we're building homes. It confirmed the value of decisions we've already been making for our clients, even before most of them would know to ask about these things.
We've always emphasized airtight construction, controlled ventilation, and energy efficiency. Those aren't necessarily the things homeowners notice when they walk into a finished house, but they have a lot to do with how that house feels and performs every day.
And when outdoor conditions get as bad as they did during the wildfire smoke, they can become especially important.
I could see exactly what happened when I turned off the ventilation and when I brought it back online with better filtration. The readings gave me something tangible to show homeowners, rather than just explaining why these systems matter.
It's one thing to understand the building science. It's another to experience the difference in your own home.
Thankfully, we don't have wildfire smoke hanging over West Michigan all the time. But other situations can still make outdoor air quality less than ideal, from seasonal pollen to regional pollution.
No home can keep out every pollutant. But how you build and ventilate it can give you much more control over the air inside.
Most homeowners probably don't think much about how fresh air gets into their house. But after seeing what happened in ours during the wildfire smoke, I can tell you it matters.
If you're thinking about building a custom home in West Michigan, start here. We'll help you think through your priorities, budget, and the details that matter most in a high-performance home.
If you have any questions, contact us to learn why we pay so much attention to the details that affect your health, comfort, and long-term quality of life.
Jake Vierzen | Founder, R-Value Homes
Jake Vierzen founded R-Value Homes in 2004 after 10 years in commercial concrete construction. With more than two decades of experience building high-performance homes in West Michigan, Jake specializes in ICF construction, airtight building envelopes, and the systems that make homes healthier, more comfortable, and energy-efficient.