Heat Recovery Ventilation (HRV) and Energy Recovery Ventilation (ERV) are often used as if interchangeable. The difference is what they recover: an HRV moves only sensible heat, while an ERV (also called an enthalpy recovery ventilator) moves both heat and moisture.
What each transfers
| HRV | ERV | |
|---|---|---|
| Sensible heat (temperature) | Yes | Yes |
| Latent heat (moisture) | No | Yes |
| Best climate | Cold, dry winters | Mixed / humid |
| Humidity control | None | Active (both directions) |
| Typical core | Sensible plate or heat pipe | Enthalpy wheel or membrane plate |
Cold, dry climates
In a cold dry winter, indoor air is warm and humid relative to outside. An HRV retains that humidity (good) while recovering heat. An ERV would also transfer some moisture outward, which can be acceptable but is less necessary.
Humid summers
In a humid summer, an ERV rejects incoming moisture to the exhaust stream, cutting the cooling and dehumidification load. An HRV recovers only temperature, so the AHU must remove all incoming humidity mechanically.
How to decide
If your design goal is moisture control or you operate in a humid climate, specify an ERV. If you only need to cut heating load in a dry climate, an HRV is simpler and cheaper.