There’s an ongoing debate in the construction industry about whether modern homes can become “too airtight.” Many people wonder if tightly sealed homes are unhealthy or if they lack proper fresh air circulation. At Clay Construction, we believe the answer comes down to one key factor: proper ventilation design.
On a recent project in Delta, we achieved an impressive 0.48 air changes per hour (ACH) — exceeding even Passive House standards. But what does that actually mean, and is it healthy for homeowners?
Understanding Air Changes Per Hour (ACH)
Air changes per hour measure how often the air inside a home is replaced with outside air.
- Older homes often measure between 10–15 ACH, meaning they are very drafty and leak air constantly.
- A half dozen years ago, the average new home in Vancouver tested around 5.5 ACH.
- Current building code requirements in British Columbia are approximately 2.5 ACH.
- High-performance homes today are often achieving 1 ACH or lower.
Our featured home achieved 0.48 ACH, which is even tighter than the Passive House benchmark of 0.6 ACH.
At first glance, some homeowners may think a tightly sealed home sounds unhealthy. However, airtight construction is only one part of the equation.
Why Airtight Homes Need Proper Ventilation
An airtight home prevents uncontrolled drafts, moisture, pollen, insects, noise intrusion, and energy loss. However, because less outside air naturally leaks into the home, proper mechanical ventilation becomes essential.
This is where an HRV (Heat Recovery Ventilator) plays a critical role.
What Is an HRV?
n HRV is a ventilation system specifically designed for modern airtight homes. Its purpose is to continuously provide clean, fresh, filtered air while improving energy efficiency.
An HRV performs three important functions:
1. Filters the Air
HRV systems contain filters that remove airborne particles from incoming fresh air.
- Larger particles such as dust and pollen are captured first.
- Additional filters, such as MERV-8 filters, help remove smaller particles and improve indoor air quality.
This results in a cleaner and healthier indoor environment for homeowners.
2. Conditions the Air
One of the most important functions of an HRV is heat recovery.
As stale warm air is exhausted from bathrooms and kitchens, the system transfers much of that heat energy to the fresh incoming air. This allows the home to maintain comfort while reducing heating costs and improving overall efficiency.
3. Controls Airflow
HRVs actively remove warm, moist, and contaminated air from areas such as:
- Bathrooms
- Kitchens
At the same time, they deliver filtered fresh air into primary living areas and bedrooms.
This controlled airflow helps:
- Reduce humidity buildup
- Improve indoor air quality
- Prevent condensation and mold risks
- Create a more comfortable living environment
The Future of Healthy High-Performance Homes
Airtight construction is not unhealthy when paired with properly designed ventilation systems. In fact, homes built to higher performance standards often provide:
- Better comfort
- Improved energy efficiency
- Cleaner indoor air
- More controlled humidity levels
- Less intrusion of dust, pollen, insects
- Quieter homes
At Clay Construction, we focus on building homes that are not only energy efficient, but also healthy and comfortable for homeowners year-round.
Modern construction is evolving, and properly designed HRV systems are a key part of creating high-performance homes that truly work for the people living inside them.
— Larry Clay
The Clay Way
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