The Air Lock Floor and the Pressure Ring are two effective measures for control of air flow directions between rooms or zones in buildings. They create a pressure hierarchy that controls spread of pollutants. Here an example has been given for radon from a crawl space, odours from a bakery into a dwelling above and an isolation chamber with a leaky facade. The Air Lock floor can operate with a 7 W fan and at the same time extractthe normal dwelling ventilation flowrate. Used in the ground floor, the Air Lock Floor results in a warmer floor and contributes to energy savings. The now well ventilated, warmer and dryer crawl-space would make the use of wooden (plywood) floors possible with less risk of wood rot and mould growth.