What is a Heat Recovery Ventilator (HRV)?

An HRV, also known as an Energy Recovery Ventilator (ERV), is a controlled ventilation system that reduces high humidity, pollutants and odours by replacing stale air with fresh air. Its main function is to provide acceptable indoor air quality all year long.

Exhaust air is not only stale and damp, but warm.  It is this warmth that is used to pre-heat fresh air as it enters the building.  All HRVs have two fans and an in-built “Air to Air” heat exchanger, which transfers heat from the exhaust air stream to the cold fresh air supply. By the natural laws of physics, whenever cold air is warmed, humidity is reduced, and condensation control is the result.  The two air streams are 100% separated at all times. The fresh air introduced into the building is warm and dry and provides a permanently fresh, healthy, indoor environment.


An HRV can recover up to 5 times more energy than it costs to operate. This level of efficiency is unmatched by any other domestic appliance.  Unlike other condensation control devices, HRVs perform best, when conditions are at their worst. HRVs ventilate, 24 hours a day, every day.

Do HRVs provide heat to buildings?

The HRV is not a heater or a heat pump.   It does not generate heat.  It captures and recycles heat (or cooled energy) from other sources, for example, gas heaters and furnaces, electric heaters, heat pumps, hot water heaters & boilers, radiant heating, etc.   Whatever the heat source, the HRV will recover the heat from the exhaust air stream and recycle this heat directly back into the building.

HRV unit

The HRV is a most effective method to control condensation, as well as providing a healthy environment, because the only air entering your home is fresh outdoor air which has been warmed and dehumidified.

At the same time, humid warm indoor air, which has absorbed moisture, and contains other indoor air pollutants, is exhausted, and carries with it, the moisture and pollutants.  As the exhaust air passes through the HRV, the exhaust air heat is captured by the heat exchanger, and then directly heats the incoming outdoor cold air.

How do HRVs work during the summer months?

In air conditioned buildings, indoor air will be cooler than outdoor air, and the HRV recycles cooled energy, in exactly the same way as it recycles heat.  The cooled energy is captured by the heat exchanger and used to cool the warm outdoor air as it is introduced into the building. This reduces the load on the air conditioning system while providing 100% fresh air ventilation.

Most air conditioners simply recirculate the same stale, polluted indoor air.  Very few air conditioners have any provision to ventilate the air conditioned space with fresh outdoor air.  Thus most air-conditioned spaces require ventilation.  The HRV saves summer “cool energy”, just as it saves winter “heat energy”.

What if there is no air conditioning in the building?

The HRV can only dehumidify outdoor air (that is being supplied to the building) when the outdoor air is colder than the inside air.  If the indoor air is warmer, no dehumidification will occur.  What does occur is that the HRV continuously exhausts indoor stale humid air and replaces it with fresh outdoor air.

In some buildings without air conditioning, it is possible for the indoor air temperature to be several degrees cooler than outdoors.  In this case, the HRV will cool the incoming fresh air by recycling the “cool” energy that is retained indoors and using this energy to cool the outdoor air as it is introduced into the building.

If the outdoor air is warmer than indoors, the HRV will supply fresh outdoor air at whatever temperature and humidity the outdoor air may be.  At the same time, it will exhaust warm, humid indoor air.  The overall effect may not be very noticeable but the indoor air quality is safe and healthy to breathe.  Also, normal indoor activities will increase indoor humidity.  Ventilation by the HRV with outdoor air that is slightly drier than indoor air will provide some dehumidification.

The only practical way to dehumidify and cool a building in summer is to install an air conditioning unit and the HRV will continue to provide indoor air quality, while reducing the cooling load that the air conditioner has to handle.

How much do HRVs cost?

For residential applications, a whole-home HRV system can range anywhere from $500 to $1,500+ with installation, but the average cost of a unit is typically in the $500 to $900 range. You can also get smaller single-room units for between $350 and $450.

HRV systems for commercial spaces are typically priced per square foot of space and vary greatly by region. The average cost is $2-3 per square foot but we strongly recommend that you consult your local HVAC professionals for an accurate quote.