Both an Energy Recovery Ventilator (ERV) and a Heat Recovery Ventilator (HRV) move energy from outgoing stale air to incoming fresh air without mixing the streams. The single thing that separates them is moisture: an HRV transfers only heat (sensible), while an ERV transfers both heat and humidity (enthalpy). That one distinction decides which you should specify.
What each one actually recovers
| Property | HRV | ERV |
|---|---|---|
| Transfers heat | Yes | Yes |
| Transfers moisture | No | Yes (partial) |
| Indoor humidity control | None — humidity passes through | Active — balances supply/return humidity |
| Best climate | Cold, dry winters | Hot/humid summers & mixed climates |
| Typical sensible effectiveness | 70–85% | 65–80% |
| Typical enthalpy effectiveness | n/a | 55–75% |
The cold-climate rule
In a heating-dominated climate, exhaust air is warm and humid (showers, cooking, breathing) while outdoor winter air is cold and bone-dry. An HRV recovers the heat but lets that indoor moisture escape — which is exactly what you want, because it stops the house from getting clammy. Adding an ERV in a cold climate can over-humidify the supply in winter unless the core is carefully balanced. So: cold and dry → HRV.
The humid-climate rule
In a cooling-dominated climate the problem flips. Outdoor summer air is hot and muggy; you do not want to import that humidity indoors. An ERV transfers a large share of the exhaust moisture back to the outgoing stream, pre-drying the supply and cutting both the load and the mould risk. So: hot and humid → ERV. See our enthalpy vs sensible guide for the physics.
Commercial and industrial: usually ERV
Offices, schools and labs run high internal moisture loads year-round. An ERV keeps humidity (and thus cooling demand) down, which usually pays back faster than an HRV despite the slightly lower sensible effectiveness. Use our ERV/HRV effectiveness calculator to compare the sensible and enthalpy numbers on your own conditions.
Cost and maintenance
An ERV core (typically a sorbent-coated plate or an enthalpy wheel) costs 10–30% more than a plain HRV plate and needs the same filter discipline. Neither should run without pre-filters — fouling kills effectiveness fast (see cleaning & maintenance).
Quick decision checklist
- Cold, dry winter, vapour barrier tight: HRV.
- Hot, humid summer, cooling-dominated: ERV.
- Mixed climate, noticeable both ways: ERV with balanced core.
- Process exhaust with moisture/odour you must not recirculate: HRV (no moisture transfer) or a run-around coil.
Specifying an ERV or HRV?
Send us your airflow, climate and humidity profile — we will size plate, rotary or heat-pipe recovery to your duty.
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