The rainscreen principle is not new. It was proposed as early as the mid sixties by researchers of the Division of Building Research of the National Research Council of Canada and the basic principles were developed. It has been applied to certain exterior wall types but it remains largely unknown because of the absence of factual data to support the claims of performance.

Detailed radon measurements and ventilation testing were carried out in five residential premises in Hong Kong. Continuous radon detectors were located in the bedrooms of each site and corresponding C02 decay tests were conducted to estimate the ventilation rate. Four air-conditioning operation modes were used in the measurements. Data obtained from the measurements were used to verify the validity of a simple mass balance model.