instrumentation

Describes pressure method for testing whole houses for air leakage. States main advantages compared to tracer gas technique are that equipment is inexpensive, easy to handle and so well adapted to routine tests. The house is pressurized using a powerful fan and the flow through the fan is equivalent to the leakage through the building envelope at given pressure. Summarizes measurements made on test houses. and shows use of thermography to detect leaks. suggests use of pressure test to estimate the natural ventilation of a house.

Describes study and operating principles of device allowing a window (or more usually a light-weight cladding unit) to be placed in variable temperature conditions simulating actual summer and winter conditions, in order to determine the airtightness of the window under these conditions. Describes testing of three plastic window frames in the device and supplies the measured values of the airtightness before, during and after the tests, and the corresponding curves.

Examines the use of radioisotope tracers to measure ventilation rates of simple and multiple enclosures. Discusses accuracy of the methods in relation to results obtained in an experimental room with controlled ventilation. Describes an instrument which measures ventilation rates directly, following release of aradioisotope tracer. Demonstrates its accuracy and operating advantages.

Describes method of measuring the air-change rates using sulphur hexafluoride as a tracer gas. The system comprises a highly portable gas chromatograph with an electron capture detector. The system will detect tracer gas without interference from other materials which may be present. The technique takes about six minutes to determine the ventilation rate. Gives practical examples and suggest extensions of the technique for carrying out cross air movements, for example in a hospital.

Gives an account of a method of measuring the ventilation rate of a room using hydrogen as a tracer gas. Describes katharometer used to detect the gas and the experimental procedure. Results agree well with those calculated by orifice plate method.

The measurement systems used at Twin Rivers for determining energy usage are described. These include a weather station, three different systems for the measurement of temperatures and energy-related events in a house, a tracer-gas based air infiltration measurement system and infrared thermography

After discussing briefly the principles of natural ventilation, goes on to describe tracer gas techniques, air movement measurements, and various model techniques including analogues. Advantages and disadvantages of each method are indicated, andtheir suitability for particular applications.

Using nitrous oxide as a tracer, the author made 390 measurements of ventilation rates in seven closed rooms of six houses, in Melbourne, Australia. Half of the observations were taken when the wall ventilators were sealed, in order to explore their influence on room ventilation. Results for each room, grouped in ranges of wind direction and according to whether ventilators were open or closed, are shown as regression curveson plots of ventilation rate against wind speed. The ventilators are shown to have only a slight effect on ventilation.