Reduced Energy Consumption
Reduces ventilation costs by using heat in outgoing exhaust air to warm incoming fresh air in the winter.
Improved Indoor Environment
Ensures delivery, distribution and circulation of fresh outdoor air throughout the house.
Controls indoor air humidity levels to prevent moisture problems such as condensation on windows and mold growth.
Helps control odours and humidity levels in bathrooms and kitchens.
Dilutes indoor air contaminants.
Provides better comfort by warming incoming ventilation air.
Filters incoming air.
Energy Recovery Ventilators (ERV) can also recover moisture from air to help prevent over-drying of home in the winter.
Reduced Environmental Impact
Reduces energy consumption-related green house gas emissions due to heat recovery that offsets energy otherwise used to heat ventilation air.
Description
HRVs are mechanical devices that exchange stale indoor air with fresh outdoor air (see Figure 1). Heat is transferred from the outgoing air to the incoming air by passing the two air streams through a heat-exchange core. The two air streams are kept separated, and only the heat is transferred to the incoming air, which is then circulated throughout the house. In most cases, fresh air is delivered to bedrooms and the living room, while stale air is removed from bathrooms, laundry rooms, and the kitchen.
HRVs provide energy efficient mechanical ventilation, especially in energy efficient new houses where uncontrolled airflow is minimized. In a well-sealed house, an HRV is much more effective at recovering a large percentage of the heat that would otherwise be lost by means of uncontrolled airflow through the house. HRVs provide ventilation for existing housing as well, especially when energy efficient measures such as air sealing and insulation upgrades have made the building envelope tighter, or when the house is subject to condensation or other indoor air quality problems because there is poor or no air flow in the house.
HRVs have multi-speed settings to deal with varying ventilation needs. Automatic controls are available as well to modulate the operation of the HRV based on time and indoor humidity level.
The ducts bringing fresh air from the outdoors and stale air from inside the home cross by each other in the heat exchange core of the Heat Recovery Ventilator and the heat from one flow of air is transferred to the other. The fresh air is directed into the house while the stale air is exhausted outside.
HRV Schematic — from Heat Recovery Ventilators published by OEE — permission received to use image. Source: "Components of a ventilation system using an HRV", Natural Resources Canada, 2012. Reproduced with the permission of the Minister of Natural Resources Canada, 2014.