Energy Recovery Ventilator [ERV]
An Energy Recovery Ventilator (ERV) is a mechanical ventilator that exchanges stale indoor air with fresh outdoor air and transfers heat and moisture from one air stream to the other. The pre-heated or pre-cooled, fresh outdoor air is then circulated throughout the house. They are similar to Heat Recovery Ventilators (HRVs), which transfer only heat.
ERVs are preferable over HRVs in two climate conditions: (1) dry, winter climates where it is desirable to retain moisture in a house. (2) hot, humid climates in a house with air conditioning (because an air conditioner removes moisture from the air). If you would otherwise need a humidifier in your house in winter, an ERV could be advantageous.
Consider Energy Star rated models first - this means, models that have lower energy usage and higher sensible efficiency in the heating season.
There are three ways an ERV can be integrated into your home, especailly if you already have a central heating system:
- Direct duct for each room, with dedicated ductwork for exhausting air from kitchens and bathrooms.
- Through a forced air heating system, and directly ventilating bathrooms and kitchen.
- Connected to an existing forced air heating system - used generally to provide indoor-outdoor air exchange.
Maintenance considerations:
- You'll want to make sure the intake and exhaust and intake are properly balanced for airflow - something that is done upon install and periodically thereafter by a professional.
- The unit's filter and heat recovery core are crucial components of the ERV, and should be cleaned thoroughly at the beginning of each heating season. This is something that can be performed by the homeowner by following the manufacturer's directives.
In a well-sealed and insulated home, an ERV is effective at recovering a large percentage of heat that would otherwise be lost to the outdoors during winter months. Likewise, they can remove heat and moisture from incoming hot, humid outdoor air during the summer months. ERVs are ideal in retrofits just as much as new builds, especially when air sealing and insulation upgrades have made the building envelope tighter.