Closed Window Summers: Future Home Performance During Wildfire Season in the Midwest.
- Sam De Jonge
- 9 minutes ago
- 6 min read
For generations, summer in the Midwest has been defined by open windows, screen doors, and cool northern breezes moving through the home. In places like northern Michigan, Wisconsin, and Minnesota, opening the house to the outdoors has been part of the seasonal rhythm — a simple connection between architecture and landscape. The smell of pine trees, the sound of birds in the morning, and the cool evening air flowing through a cottage have long represented the escape people seek during the summer months.
But that experience is beginning to change...
This morning, many residents across the Midwest woke to an eerie yellow-grey sunrise. The promise of a clear blue sky disappeared as smoke settled into the region, bringing with it the unmistakable smell of a campfire. Except this time, the source was not a backyard fire or a nearby campsite. The smoke traveled hundreds of miles south from nearly 200 wildfires burning across Ontario, carried into some of the Midwest’s most treasured summer destinations.
This raises an important question for the future of residential design: what happens when the traditional idea of summer comfort — opening the windows and letting nature in — no longer works every day?
Historically, many northern homes and cottages were not designed to control indoor air quality the way we think about it today. Older homes often relied on natural ventilation and the natural leakage of the building itself to exchange indoor and outdoor air. While these homes are often charming and full of character, that same openness means that outdoor air conditions can quickly become indoor air concerns. When wildfire smoke is present, the issue is not just the smell. Wildfire smoke contains extremely fine particulate matter, known as PM2.5, which can travel deep into the lungs and easily enter homes through open windows, doors, and small gaps in the building envelope. A home that allows unwanted air movement during the winter is also allowing uncontrolled outdoor air — including smoke — into the home during summer events. The solution is not to eliminate our connection to the outdoors. Instead, the future of residential design is about creating homes that provide homeowners with control no matter the outside conditions.
How to Handle Existing Homes
For existing homes and cottages, there are several practical improvements that can dramatically improve indoor air quality during smoke events. The first step is understanding your home: it is highly recommended to conduct a proper blower-door test to know what your current conditions are!
Seal the Openings | Weatherstripping older windows and doors, sealing gaps around penetrations, improving attic access panels, and addressing leaks in basements and crawl-spaces can significantly reduce the amount of uncontrolled air entering the home. - Replace older, worn out windows and doors as needed - Caulk any gaps that you can see and reach around the perimeter (AC/plumbing lines) - Sealing on the exterior is more favorable than on the interior only Note: Remember to remove old/worn out sealants first. Check the Attic | Many homeowners overlook the importance of the attic. Openings around plumbing penetrations, electrical fixtures, recessed lights, and attic access doors can create pathways for outdoor air to enter the living space. These small improvements are often some of the most cost-effective ways to improve comfort, energy efficiency, and indoor air quality. - Properly seal all roof penetrations - Locate, Seal or Replace older lighting fixtures leaking through to the attic - Ensure that the attic has the proper amount of venting capacity (gable, soffit, and ridge vents)
Control what You Can | Filtration is another important piece of the solution. Many homes operate with basic HVAC filters designed primarily to protect equipment rather than aggressively clean indoor air. During wildfire smoke events, homeowners should consider whether their system can support a higher-efficiency filter, such as a MERV 13 filter, which can capture much smaller airborne particles. However, filtration only works when the air is actually moving through the filter, making proper HVAC design and maintenance equally important.
- Trace your existing ductwork and tape any leaks to improve performance
- Keep current on your HVAC system maintenance
- Hire a professional to fully clean out your duct work (when was the last time they were cleaned..?)
- Consider installing a seperate HRV system for optimal air exchange and humidity control
For homes without central air systems or advanced ventilation, portable HEPA air cleaners can provide a significant improvement. Placing properly sized units in bedrooms and main living areas can help maintain cleaner indoor air during periods when windows need to remain closed.
Approaches for New Construction
Modern residential construction approaches this challenge differently. High-performance homes are designed with multiple layers that seal the outside . Most new homes feature robust air sealing measures. Instead of relying on uncontrolled air leakage, these homes use intentional air barriers, improved insulation strategies, and carefully detailed building envelopes to reduce unwanted air movement.
Because modern homes are more airtight, fresh air must be introduced intentionally. This is where mechanical ventilation systems such as Heat Recovery Ventilators (HRVs) in northern climates become increasingly important. These systems provide continuous fresh air while recovering energy that would otherwise be lost. They allow homeowners to maintain healthy indoor air without simply opening windows and hoping outdoor conditions cooperate.
Key Considerations for New Construction:
Plan for an HRV or ERV system with high-quality filtration. Mechanical ventilation with appropriate filtration should be considered a standard feature of modern homes, especially in regions affected by wildfire smoke. Note: ERV's are not recommended for predominantly cold climates because they do not address humidity.
Prioritize Air Sealing During Construction. Take the time to properly seal exterior wall assemblies, stud cavities, penetrations, and transitions before they become hidden behind finishes. Consider wall assemblies that incorporate materials designed to reduce uncontrolled air movement, including properly detailed exterior insulation strategies and air-sealing materials.
- Do a thorough walkthrough to ensure sheathing has no air gaps into the stud bays
- Caulk all stud "bucks" at posts, windows, top plates, sill plates - as continuous as possible
- Add a 6 mil vapor/air barrier on the interior of the wall - only when spf insulation is not used
- Consider a double 2x4 stud wall on a 2x6 or 2x8 sill/top plate for additional thermal bridging mitigation
- Limit exterior wall outlets, switches, and boxes - opt for floor outlets is possible - if not, ask your electrician to properly seal boxes off.
Treat Every Penetration as a Potential Air Leak | Electrical wiring, plumbing, and mechanical tubing should not be bundled through oversized openings. Each penetration should be individually sealed to maintain the integrity of the building envelope.
- Each wire/pipe gets it's own respective hole to ensure best sealing (grid your layouts)
Use Advanced Flashing Details Where Appropriate | While ZIP sheathing is in vogue - we do not recommend their application in our cold climate - we will go into detail on this more in another blog post. A quality APA rated CDX plywood or 5/8" OSB sheathing with proper taping and flashing + Polyurethane Spray Foam (spf) has shown to be the most optimal system, at least in northern Michigan. - Use a liquid-applied flashing at critical transitions, seams, and penetrations to improve both air and water control - Apply continuous silicone sealant (2 parallel beads) before foam sill sealer & before the treated sill plate - Properly seal windows and doors on the exterior (to ensure water drainage as well) + foam all small openings larger than 1/4" on the interior.
Select High-Quality Windows and Doors | A beautiful window is not enough — performance matters. Proper installation, flashing, and sealing are critical to preventing unwanted air infiltration.
- Both Marvin / Kolbe & Kolbe make excellent cold weather windows with a range of quality options. Their representation in northern Michigan is also exceptional.
Conclusion
The homes of the future will not be disconnected from nature. Clients will still desire to have large windows, outdoor living spaces, natural materials, and strong connections to the surrounding landscape. But they will also have the ability to protect occupants when outdoor conditions become unhealthy. Robust solutions to maintain indoor air quality should be just as highly considered compared to lighting or bath fixtures.
The northern cottage has always represented escape — a place where the air itself felt different. As wildfire seasons become a more common part of our summers, we may need to redefine what that means. The future cottage may not always be the home with every window open. Instead, it may be the home where, even with the windows closed, the air inside still feels like northern Michigan.
Good design has always responded to the environment around us. The next generation of homes will not only need to respond to temperature, energy use, and comfort — they will need to respond to the quality of the air we breathe.
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