Ventilation

Good air ventilation is not so much a tool for reducing greenhouse gas emissions itself as it is an important consideration when doing other energy efficiency upgrades. A house works as a complete system. Changes to insulation and air sealing will have an impact on air flow and ventilation.

Basically, a draughty old house has more than enough air flow. But a well sealed new house or upgraded older house may need controlled ventilation to get rid of indoor pollutants and ensure good air quality.

There are two basic types of controlled ventilation.

Spot ventilation

Kitchen – Install a rangehood vent

Bathroom – Make sure the bathroom has a vent fan, perhaps connecting it to a timer and dehumidistat for best performance

Laundry – Clothes dryers should be vented to the outside

All vents should end up outside, not in the attic where moisture problems can occur.

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Whole house ventilation

For an air tight house, a heat recovery ventilator (or air-to-air heat exchanger) will exhaust stale indoor air while bringing in fresh outdoor air. During the exchange, 60-80% of the heat in the outgoing air will transfer to the indoor air, meaning the furnace needs to do much less work to warm the new air. (1)

Heat recovery ventilators are usually connected to the heating system ductwork in homes with forced air heating. Or, a network of small-diameter outdoor air ducts will be installed for the system in other homes. (2)

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