Air leaks through exhaust fans, vented skylights and
fireplaces should also be prevented. Some exhaust
fans are now available with built-in automatic shutters
or dampers to stop air leaks. It is also possible to fit
lightweight hinged lids over the outlet of a conventional
exhaust fan; the lid is blown open when the fan is
switched on and falls shut when the fan stops.
Make sure that exhaust fans are vented to the outside and not into the roof space or wall cavity, as the vapour in the exhaust air
may condense within the construction and damage
wall or ceiling linings.
Permanently vented skylights
allow the warm air near the ceiling to escape, so
they should not be installed in heated areas. Vents
in an existing skylight may be blocked off, or a sheet
of clear acrylic installed under the skylight unless it
is the only means of ventilation in the room.
A fireplace is designed to extract air from the house. It does this even if there is no fire. Fireplaces should therefore be blocked off when not in use. A damper can be placed at the throat or at the top of the chimney, as long as it is not forgotten when a fire is lit. Alternatively, a close fitting panel may be placed across the front of the fireplace when it is not in use.