| Parameter | Outdoor | Conditioned (after ERV) |
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Energy Recovery Ventilators: total enthalpy recovery for Canadian climates
An ERV transfers both sensible heat (temperature) and latent heat (moisture) between the exhaust and supply airstreams using a moisture-permeable core, typically an enthalpy wheel or specially coated membrane. This makes it fundamentally different from an HRV, which transfers only sensible heat. The combined sensible and latent recovery is called total enthalpy recovery, and it's the key advantage of an ERV in climates with significant humidity loads.
In summer, an ERV transfers heat and moisture from hot, humid incoming outdoor air back to the cooler, drier outgoing exhaust air, reducing both the sensible and latent cooling load that the air conditioning system must handle. In winter, an ERV transfers some humidity from the moist exhaust air to the dry incoming outdoor air, which can help maintain indoor humidity levels, though this needs careful balance to avoid over-humidifying and creating condensation risk.
Sensible vs latent recovery efficiency
ERV manufacturers report 2 separate efficiency values: sensible recovery efficiency (similar to an HRV) and latent recovery efficiency (moisture transfer). Total enthalpy recovery efficiency considers both. Enthalpy wheels typically achieve higher latent efficiency (60-65%) than fixed-plate membrane cores (50-55%), but enthalpy wheels carry a small risk of cross-contamination between airstreams due to wheel rotation carrying air between channels — a consideration for IAQ-sensitive applications.
Choosing between ERV and HRV for your Canadian climate
For most of Canada's heating-dominated climate, an HRV is the standard and often sufficient choice — indoor winter humidity is already low, and recovering exhaust moisture during heating season isn't usually beneficial. For buildings in southern Ontario, Quebec, and the Maritimes with hot, humid summers and meaningful air conditioning loads, an ERV's latent recovery can measurably reduce cooling energy use. This calculator lets you compare both seasons explicitly: run the summer mode to see cooling load reduction, then the winter mode to verify the ERV doesn't create excessive humidity retention in heating mode.
Always check your specific climate's ASHRAE design conditions for both summer and winter when making this decision. Use the HRV calculator to directly compare a sensible-only system's winter performance against the ERV results from this tool.
Frequently Asked Questions
An HRV transfers only sensible heat, leaving humidity unaffected. An ERV transfers both sensible heat and latent heat (moisture) using a moisture-permeable core like an enthalpy wheel or membrane. In Canadian winters, HRVs are usually preferred since indoor air is already dry. In humid summer climates, ERVs help by transferring moisture from incoming humid outdoor air back outside, reducing latent cooling load. Use the HRV calculator to compare sensible-only performance directly.
ERVs provide the biggest advantage in hot, humid summer climates with significant latent cooling load: southern Ontario, Quebec, and the Maritimes. In drier climates like the prairies or coastal BC with mild summers, the latent benefit is smaller, and an HRV's simpler design without moisture-permeable core cross-contamination risk is often preferred. Run this calculator in summer mode for your city's design conditions to quantify the actual benefit before deciding.