Heat Recovery Ventilators & Energy Recovery Ventilators
Heat Recovery Ventilators (HRVs) are becoming increasingly common in cold climate construction and are almost indispensable in today’s super-insulated, airtight homes. As older homes are getting retrofit and becoming tighter and more insulated, they are also facing indoor air quality issues. HRVs improve the IAQ of your home while using less energy than other types of ventilation.
The main job of the HRV is to supply fresh outdoor air to the house while expelling stale indoor air laden with moisture, animal dander, and gases from combustion appliances and carpets.
At the heart of the HRV is a heat exchanger (called a “core”) where heat is transferred from outgoing stale air to incoming fresh air without the airstreams mixing. Most HRVs recover between 70-90% of heat from exhaust air, depending on the unit and controls, far more efficient than a standard exhaust fan that blows warm air directly outside.
The ducting of an HRV system typically supplies fresh air to bedrooms and living areas while exhausting humid air from bathrooms, kitchens, laundry rooms and crawlspaces. Many systems also include a boost mode in the bathroom to get rid of excess moisture. The HRV does not eliminate the need for a cooking fan, so a range hood should still be the main outlet for greases and smoke above the cook stove.
CCHRC has done extensive research on how HRVs can improve indoor air quality. We developed the BrHEAThe System to improve indoor air quality in homes, which combines an HRV with a high-efficiency boiler to ensure homes receive adequate fresh air.
We also study Energy Recovery Ventilators (ERVs) which recover not just heat but also moisture from exhaust air to temper incoming air, preventing homes from becoming overly dry in the winter. Read about the project here.
|BrHEAThe System Snapshot|
|Department of Energy Ventilation Resources|
|Heat Recovery Ventilators Snapshot|
|HRV Frost Protection Report|
|Jorge and Paul’s Adventure with the Heat Recovery Ventilator|
|Ventilation for Small Homes Report|
|Ventilation for Small Homes Snapshot|