An Energy Recovery Ventilator (ERV), also known as an enthalpy exchanger, is a mechanical ventilation system that continuously exchanges stale indoor air for fresh outdoor air. It connects to your HVAC system and helps improve ventilation and indoor air quality.
How Does an Energy Recovery Ventilator (ERV) Work?
An Energy Recovery Ventilator exchanges stale indoor air with fresh outdoor air while recovering energy from the exhaust air.
It uses two fans and two air streams through a specialized central core. One fan draws in fresh air while the other blows out stale air. The stale indoor air and fresh outdoor air pass through separate air channels inside the unit, ensuring that the two air streams do not mix.
During this ventilation process, heat and moisture are also exchanged to enhance indoor comfort.
- During summer, the system pre-cools and dehumidifies incoming warm, humid air.
- In winter, ERV recovers heat and moisture from the outgoing air, making your home feel cozy without raising the thermostat.
Calculate Size Requirements for ERV
To calculate the size of the ERV system needed for your home, take the house square footage (including the basement) and multiply it by the ceiling height to get the cubic volume. Then, divide the figure by 60 and multiply by 0.35 to obtain the appropriate size.
- Required Size of ERV = Area of House (including basement) × Height of Ceiling × 0.35 ÷ 60
Energy Recovery Ventilator (ERV) vs. Heat Recovery Ventilator (HRV)
An ERV exchanges both air and moisture, while an HRV only exchanges heat.
ERVs use a moisture-permeable polymer membrane to enable the transfer of moisture. The membrane is designed to be permeable to moisture but impermeable to pollutants such as viruses, bacteria, and mold spores. These contaminants remain on the exhaust air side, preventing them from re-entering the building.
HRVs use non-permeable cores so moisture cannot pass through, and they require an outlet for drainage.
Benefits of Using An Energy Recovery Ventilator
A key benefit of ERV is balanced ventilation, which ensures an equal amount of fresh outdoor air is supplied while an equal amount of stale indoor air is exhausted. This prevents pollutants, allergens, carbon dioxide, odors, and volatile organic compounds (VOCs) from accumulating in tightly sealed homes and contributing to respiratory issues.
It also maintains optimal humidity levels year-round, preventing excessive dryness in winter and reducing moisture buildup in summer, which can lead to mold growth. The result is a consistently comfortable indoor environment with continuous, fresh-air circulation and a stable home climate.
Energy Recovery Ventilator & Energy Efficiency
When integrated with an existing HVAC system, an ERV reduces the workload on heating and cooling equipment, improving HVAC efficiency and reducing energy consumption. Most energy recovery ventilation systems can recover 70-80% of the heat energy and transfer it to the incoming fresh air.
In short, ERV improves overall comfort year-round by retaining heat and moisture in the air in winter and dehumidifying incoming air in summer, creating a perfect home climate year-round.
