Natural airflows between roof, subfloor and living spaces.

This paper is concerned with natural air flows between major construction cavities in New Zealand houses. A two tracer technique was developed to measure infiltration rates in the subfloor (crawl space), the living space and roof space, together with air flow rates connecting these zones. Five experimental houses were chosen to represent expected extremes in air flow resistance between subfloor and roof space. Two were clad in brick veneer over timber franie walls, allowing possible air leakage paths through the wall cavities, and the other three were clad in weatherboards with little likelihood of air leakage paths through the wall cavities. Subfloor to roof space air flows of around 30% of the roof space ventilation rate were nreasured in the brick clad houses while in the weather board examples it was only 7%. Air flows connecting subfloor and roof space with living space were generally in the range 1-30 m³/h with a general tendency for upward flows to exceed downward flows. Interzone flows involving the living space were not obviously clependent on the type of building or on wind speed and zone temperature differences.