Heat Recovery Ventilator
We spend so much of our time indoors, especially in Vancouver where 30+ days of rain in a row isn’t uncommon! Therefore, it is vital that we ensure our homes have the very best possible indoor environmental quality. In the past the walls, ceilings, doors, and windows of our homes have been “leaky” enough to allow a good portion of outside air to constantly enter the home. This isn’t very ideal, however, especially since City staff believe that the Program’s increased insulation requirements will significantly reduce the amount of air leakage in new homes.
To ensure that all houses are provided with a constant supply of fresh air, the Green Homes Program requires that a Heat Recovery Ventilator (HRV) be installed in all new homes. An HRV operates continuously, pulling in fresh outside air while at the same time exhausting stale indoor air. The real magic, though, is that the HRV is able to transfer the heat from the warm indoor air to the incoming fresh air, reducing heating requirements for the house. A ventilation machine that recovers the heat from the outgoing air… a Heat Recovery Ventilator!
The Program also includes a few specific requirements as to where the HRV can be located within the house, as well as where the ducting from the unit must run. For example, the HRV must be installed within a heated area in the house (not in the attic) and in an area with good accessibility, since they do need regular care and attention. The fresh air ducts also need to directly supply certain rooms in the house, such as the main living rooms and all bedrooms.
By-law Language:
12.2.2.7. Heat recovery ventilators
1) Each dwelling unit, in the case of a one-family dwelling or two-family dwelling, and each one-family dwelling with secondary suite shall have one heat recovery ventilator.
2) Each heat recovery ventilator shall
a) be designed and tested to meet the CSA International Standard CAN/CSA-F326 M91 (“Residential Mechanical Ventilation Systems”),
b) be installed by persons trained by the Heating, Refrigeration and Air Conditioning Institute of Canada or equivalent,
c) supply outdoor air directly to the principal living area, each bedroom, and any floor without a bedroom,
d) be operated by centrally located manual controls or by automatic controls,
e) not exhaust supplemental exhausts in the kitchens and bathrooms which shall be controlled by a manual switch in the room being served,
f) if a solid-fuel-fired appliance is present, be installed to operate without depressurizing the house in any operating mode,
g) be located within the dwelling unit such that the heat recovery ventilator can be serviced from an area having a minimum headroom clearance of 2 m,
h) have an air intake equipped with a damper or bird screen, and be a minimum of 450mm above finished grade,
i) have an air exhaust equipped with a damper or bird screen, and be a minimum of 100mm above finished grade,
j) have supply-air ducts carrying un-tempered air through heated spaces insulated to at least RSI 0.5 (R-2.9), and
k) have exhaust ducts in unheated spaces insulated to RSI 0.5 (R-2.8).
3) Door under-cuts or transfer grilles shall be installed in doors to rooms where both supply and return air ducts are not located.
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