The complex issues of air movement, internal moisture and insulation in New Zealand houses.

An airtight building envelope helps prevent hot air from escaping and can significantly reduce the costs of heating a building.

Unlike vapour barriers, intelligent airtightness and vapour control layers have a humidity-variable function, ensuring protection from mould and moisture damage.

A wall is not a ventilation system, therefore airtightness is not the enemy.

The requirements for airtightness in a passive house are an important factor when looking at energy efficiency and comfort.