We spend a lot of time thinking about insulation, HVAC upgrades, and home efficiency, but ventilation is often the missing piece. Without proper ventilation, stale indoor air can build up, humidity levels can rise, and pollutants can linger, creating comfort issues that no amount of heating or cooling will fix.
If your home doesn’t have a mechanical ventilation system—or if the one you have isn’t delivering consistent results—it might be time to take a closer look. In this guide, we’ll walk through what ventilation does, how to evaluate what your home needs, and how to compare the most common types of mechanical systems.
Ventilation is more than opening a window. A well-designed system improves indoor air quality by removing pollutants, managing humidity, and continuously bringing in fresh outdoor air. It supports healthier indoor environments and allows your HVAC system to perform more efficiently. The core benefits include:
Natural ventilation—air that enters the home through cracks, gaps, and occasional open windows—can offer some airflow, but it’s inconsistent and weather-dependent. It also introduces air from unknown or unfiltered sources.
Mechanical ventilation systems, on the other hand, provide reliable, consistent airflow year-round. They’re designed to bring in fresh air and remove stale air in a controlled, measured way.
Most homes can benefit from mechanical ventilation—especially those that have been air-sealed or recently insulated. There are two ways to evaluate whether your home needs an upgrade:
ASHRAE Standard 62.2 sets the benchmark for how much mechanical ventilation a home should have. It factors in home size, air leakage (from a blower door test), and the presence of spot ventilation (like bath and kitchen fans). This approach is most often used during energy audits and HVAC system design.
Some homeowners track CO2, VOCs, and particulate matter to assess air quality. While helpful, these metrics can fluctuate dramatically throughout the day and don’t always reflect true ventilation needs. A professional energy audit gives a more reliable picture.
The best approach is usually a mix of both: understand what the building needs through measurement, and adjust based on how the home feels and performs day to day.
There are three primary types of whole-house mechanical ventilation systems. Each has its pros and cons depending on your goals and your home’s existing setup.
These systems use a timed bath fan to pull air out of the home, creating negative pressure that draws in outside air through leaks and openings.
Supply systems use a controlled damper and your HVAC fan to draw in outdoor air and distribute it through your home’s ductwork. The HVAC system filters fresh air before entering your living space.
ERV systems bring in fresh air and exhaust stale air simultaneously. They also transfer heat and moisture between the two airstreams to reduce energy loss.
A supply-only system offers the best balance of performance, cost, and control for most homes. It delivers filtered outdoor air, reduces pressure issues, and works well with most HVAC setups.
ERV systems are ideal for homes with tight building envelopes, high energy efficiency goals, or persistent humidity and air quality concerns. Exhaust-only systems are the least expensive but come with tradeoffs that make them less suitable for homeowners focused on performance.
The best way to determine what your home needs is to start with a home energy audit. That gives you a clear picture of how much ventilation your home needs and where it might be falling short. From there, an HVAC professional can help design and install a system that meets those needs efficiently.
If you're looking to improve indoor air quality, reduce humidity, and support the performance of your HVAC system, the right ventilation solution can make all the difference—and we’re here to help you find it.
Atlas Home Energy
