An ERV, or energy recovery ventilator, is a mechanical ventilation device that exchanges stale indoor air for fresh outdoor air while transferring both heat and moisture between the outgoing and incoming air streams, recovering energy that would otherwise be lost through simple exhaust ventilation alone.
This dual heat and moisture transfer capability distinguishes an ERV from a heat recovery ventilator, which transfers only heat, making ERVs particularly well suited to humid climates where managing moisture transfer alongside heat recovery offers genuine additional benefit.
By recovering a significant portion of the energy that would otherwise be lost when exhausting conditioned indoor air and replacing it with unconditioned outdoor air, an ERV allows homes to achieve necessary ventilation with considerably less energy penalty than an unbalanced or non-recovery ventilation approach would incur.
What Does an ERV Involve?
- A core exchanging both heat and moisture between air streams
- Separate ducting for incoming and outgoing air
- Filtration for incoming fresh air
- Balanced airflow between exhaust and supply
Why Are ERVs Important?
The energy recovery capability an ERV provides makes achieving adequate whole-house ventilation considerably more energy-efficient than simple exhaust or supply-only ventilation, offering genuine value particularly in climates with significant heating or cooling demand where unrecovered ventilation losses would otherwise be substantial. This efficiency benefit has made ERVs increasingly standard in high-performance home construction.
In humid climates specifically, an ERV’s moisture transfer capability helps prevent excessive humidity from entering during summer ventilation while also helping retain beneficial humidity during dry winter conditions, offering a genuine climate-specific advantage over heat-only recovery alternatives. This climate-appropriate selection process helps ensure the equipment delivers its full intended benefit.
ERV vs. HRV
An ERV transfers both heat and moisture between air streams, well suited to humid climates. An HRV transfers only heat without moisture exchange, often preferred in drier or colder climates where moisture transfer isn’t as beneficial.