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Whole-House Ventilation

Older Homes: Traditional Ventilation

Without a mechanical ventilation system, the amount of fresh air that enters a home is largely a matter of chance. "Natural ventilation" – the kind you get by opening windows – just doesn't do the best job, because it tends to provide either too much or too little ventilation. In older homes:

  • Air leakage around windows, between floors and up chimneys is typically eight to ten times greater than in an R-2000 home. This is especially true when strong winds or extreme differences between indoor and outdoor temperatures encourage greater air movement.
  • During warmer weather, or on windless days, the level of natural ventilation is low. This causes a problem too, as ventilation levels are insufficient to eliminate moisture and other pollutants. When this happens, your home can be stuffy and uncomfortable.

Newer Homes: Poorly Installed Ventilation

New construction techniques and materials have led to homes that are more tightly built – making proper ventilation all the more critical. If ventilation systems are poorly installed or are being used improperly by the homeowners, the result can be excessively high indoor humidity levels, "stuffy house syndrome," and window condensation in colder weather.

Depressurization – resulting from uncontrolled ventilation – is an even more serious potential problem. Often home heating systems, bathroom fans and kitchen exhaust fans all compete with the home's occupants for fresh air. If more air is exhausted than can leak into the house naturally, the resulting lowered pressure can cause toxic combustion gases to be released from unsealed heating and cooling systems into the house.

R-2000 Homes: State-of-the-Art Ventilation

R-2000 homes avoid ventilation problems by combining tight, well-insulated, leak-free construction with an energy-efficient mechanical heat recovery ventilation (HRV) system.

The HRV system provides a continuous stream of fresh, filtered outdoor air to all living areas of the home. At the same time, it maintains a balance in the home's air by removing an equivalent amount of stale air from the kitchen and bathrooms, where humidity and odours occur. The ventilation system installed in an R-2000 home typically has the capacity to change all the air in the house every three hours.

In addition, the system includes a heat recovery device that uses heat captured from the exhaust air to pre-heat incoming fresh air. This makes ventilation much more cost-effective. Typically, an HRV system recovers 70 to 80 percent of the heat in exhaust air, ensuring that homeowners have fresh air and low energy bills.

R-2000 homes also come with combustion-based heating systems designed to prevent the spillage of toxic gases. This offsets any potential hazards from inadvertent depressurization.

Heat Recovery Ventilator (HRV) (not connected to a forced-air heating system)

house-ventilation

Here are the specifications for a properly installed HRV system:

  1. If the kitchen exhaust is located in a ceiling or wall, it must be within 300 mm (12 in.) of the ceiling. The duct must be accessible for cleaning unless the intake is equipped with a grease filter.
  2. Supplemental exhausts in the kitchens and bathrooms are not exhausted by the HRV but are controlled by a manual switch in the room being served.
  3. Door under-cuts or transfer grilles allow air movement from supply-air grilles to exhaust grilles.
  4. If a solid-fuel-fired appliance is present, the HRV must be installed to operate without depressurizing the house in any operating mode.
  5. Supply-air ducts carrying untempered air through heated spaces must be insulated to at least RSI 0.5 (R-2.9).
  6. Exhaust ducts in unheated spaces must be insulated to RSI 0.5 (R-2.8).
  7. The HRV supplies outdoor air directly to:
    • the principal living area
    • each bedroom
    • any floor without a bedroom
  8. The HRV is operated by centrally located manual controls or by automatic controls.

R-2000 is an official mark of Natural Resources Canada.