The difference between an HRV and an ERV is moisture: both recover heat from exhaust air, but only an ERV also transfers water vapor, making climate zone the primary factor in choosing one over the other.
What Both Units Do
A heat recovery ventilator (HRV) and an energy recovery ventilator (ERV) solve the same problem: modern airtight homes trap stale air, CO2, and pollutants inside, yet opening windows wastes the energy used to condition that air. Both units continuously exhaust stale indoor air and bring in fresh outdoor air, passing the two airstreams through a heat exchanger core so they transfer energy before separating. Typical models recover 70–85% of the energy that would otherwise be lost.
The difference is what “energy” means in each case.
How recovery ventilators work
HRV: Sensible Heat Only
An HRV core is made from aluminum or polypropylene. It transfers temperature (sensible heat) between airstreams but blocks moisture. Cold outdoor air enters warm, and warm exhaust air is cooled, but the humidity of each stream stays separate.
Best fit: Climate zones 5–7 (cold, dry winters). In these regions, indoor air already tends toward low relative humidity in winter. Adding moisture from a humid exhaust stream would encourage condensation in ducts and on windows. An HRV prevents over-humidification while still recovering 70–85% of heating energy.
If you run a whole-house humidifier in winter, an HRV lets you control indoor RH precisely rather than having the ventilator add uncontrolled moisture.
ERV: Sensible Heat Plus Latent Energy
An ERV core uses a hygroscopic (moisture-permeable) membrane or enthalpy wheel. It transfers both temperature and water vapor between airstreams. In summer, the hot humid outdoor air transfers moisture to the drier exhaust air before entering the home, pre-dehumidifying the supply. In winter, it transfers moisture from the humid indoor exhaust to the dry incoming outdoor air, reducing how much humidification load the HVAC system carries.
Best fit: Climate zones 1–3 (hot, humid summers). An ERV reduces the latent load on the air conditioner, lowering runtime and energy use. It is also a strong choice in very tight cold-climate homes where indoor RH drops below 30% in winter and occupants cannot tolerate the dry air even with a humidifier.
Side-by-Side Comparison
| Feature | HRV | ERV |
|---|---|---|
| Sensible heat recovery | Yes | Yes |
| Moisture (latent) transfer | No | Yes |
| Best climate zone | 5–7 (cold/dry) | 1–3 (hot/humid) |
| Winter indoor RH impact | No change | Retains indoor moisture |
| Summer indoor RH impact | No change | Reduces incoming humidity |
| Typical core material | Aluminum / polypropylene | Hygroscopic membrane |
| Typical sensible effectiveness | 70–85% | 70–80% |
| Risk of winter frost in core | Higher (no moisture transfer) | Lower |
HRV vs ERV side by side
How Sensible Effectiveness Is Calculated
ASHRAE 84 defines sensible effectiveness as:
Effectiveness = (T_supply_outlet - T_supply_inlet) / (T_exhaust_inlet - T_supply_inlet)Example: Outdoor air enters at 10°F, indoor exhaust air is at 70°F, and the supply stream leaves the core at 55°F.
Effectiveness = (55 - 10) / (70 - 10) = 45 / 60 = 75%Manufacturers publish rated effectiveness at 0°C (32°F) and at -25°C (-13°F). Always compare at the colder condition if you are in a zone 5–7 climate, because effectiveness drops as the temperature differential increases and frost risk rises.
Sensible effectiveness formula
Sizing to ASHRAE 62.2
ASHRAE 62.2 sets the minimum whole-building ventilation rate for residential buildings:
CFM = (0.03 x floor area in sq ft) + (7.5 x (number of bedrooms + 1))Example for a 2,000 sq ft, 3-bedroom home:
CFM = (0.03 x 2,000) + (7.5 x 4) = 60 + 30 = 90 CFMThe unit you select must be rated at or above this flow at the external static pressure of your duct system. Most residential HRVs and ERVs are rated between 60 and 200 CFM. Manufacturers publish performance curves — verify the CFM at actual system resistance, not just at free air.
Balanced operation (supply and exhaust within 10% of each other) is required for the effectiveness rating to hold and to avoid pressurizing or depressurizing the conditioned space. Units with adjustable fan speeds on each side make balancing straightforward.
Typical Costs
Equipment costs for a residential unit range from $700 to $2,000 depending on capacity, brand, and features such as demand-controlled ventilation inputs or integrated defrost controls. Installation adds $500 to $1,500 depending on whether ductwork needs to be run or the unit integrates into an existing forced-air system. Total installed cost typically falls between $1,200 and $3,500.
Operating cost is low — most residential units draw 30 to 100 watts, adding roughly $30 to $100 per year in electricity at average U.S. rates.
Use the Free Calculator
HRV / ERV Effectiveness Calculator — get your exact answer in seconds.
FAQ
Does an HRV remove humidity?
No. An HRV transfers sensible heat only. Its core material does not allow water vapor to pass between the supply and exhaust airstreams. Indoor humidity is unaffected by the ventilator. If your goal is to reduce indoor humidity in summer, you need either an ERV or a standalone dehumidifier.
Do I need an HRV or an ERV?
Use an HRV if you are in a cold dry climate (IECC zones 5–7) and your winter indoor RH is already adequate or you use a humidifier. Use an ERV if you are in a hot humid climate (zones 1–3) where summer dehumidification is the primary concern, or if you are in a cold climate but your home is extremely tight and indoor winter RH falls below 30% without supplemental humidification.
What is sensible effectiveness and why does it matter?
Sensible effectiveness is the percentage of the maximum possible sensible heat that the unit actually transfers. A unit rated at 80% effectiveness at 0°C recovers 80% of the heating or cooling energy in the exhaust air. The remaining 20% is lost. Higher effectiveness means lower operating costs and more comfortable supply air temperatures.
How much does an HRV cost installed?
Installed cost for a residential HRV typically ranges from $1,200 to $3,500. The unit itself costs $700 to $2,000 and installation adds $500 to $1,500. ERVs fall in the same price range. Quotes vary by region, duct complexity, and whether the unit ties into existing HVAC or requires dedicated distribution ductwork.
Can I use an HRV in a hot climate?
You can, but it is not the right tool. In a hot humid climate, an HRV will bring in outdoor air at close to outdoor humidity levels, increasing the latent load on your air conditioner. An ERV pre-dehumidifies that incoming air using the drier exhaust air, reducing cooling system runtime. In climate zones 1–3, an ERV is the correct choice.