English

Discusses reasons for making buildings air-tight and the requirements of the swedish building code. Gives examples of design solutions for detached houses and construction details for applying an internal vapour barrier consisting of a polythene sheet. Describes application to seven bungalows, resulting in air change per hour of 0.67 to 0.86. Subsequent measurements of ventilation and air velocity showed that in mechanically ventilated airtight houses the flow of ventilation air can be accurately controlled by the exhaust fan.

Describes the results of an investigation carried out to determine the rate of fresh air infiltration that is experienced during the winter in a modern air conditioned office building. Six different methods were employed to estimate the rate of infiltration through the building, four by direct measurement and two by calculation. The methods of direct measurement were,tracer gas decay, measured air flow through one floor, measured air flow through one air conditioning unit and measured change on power demand.

Reviews existing methods for the prediction of infiltration rates and the factors influencing the pressure difference across buildings. Describes experimental procedure used in tests conducted in wind tunnel. Discusses results and presents prediction technique which enables surface pressures acting on aparticular building situated within an array of similar low rise buildings to be estimated, procedure takes account of the geometrical form of the building spacing parameters describing the array, direction of the wind and the upstream fetch conditions.

Describes the original series of case studies made by Dick and his associates between 1949 and 1951. Reviews current activities, divided by building types and discusses the problems and needs of future work. Recommends research and development projects and project areas.

Describes different methods for sealing joints. Gives method for testing permeability of joints to wind and rain. Concludes that two-stage joint seems to offer the greatest advantages which are long life, lack of need for maintenance, lack of sensitivity to tolerances, extensive lack of sensitivity to faulty installation practice and installation independent of the weather. Tests confirm that the wind permeability of two-stage joints can be practically disregarded in the determination of heat requirements.

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.

Discusses basic physical features of combined energy and moisture flow in porous building material. Discusses mathematical and physical structure of these dynamic processes in terms of local thermodynamic equilibrium, flows induced by gradients in intensive state variables and conservation of energy, moisture and other components. Gives conditions for thermodynamic equilibrium, discusses peculiarities of pore-water tension, and problems concerning energy flow. Deals with the causes of hysteresis and the complications due to hysteresis.

Reviews ideal characteristics of a tracer gas and gives literature review of the subject. Reports tests made on a house in California giving a direct intercomparison between common tracer gases used to measure air infiltration rates in buildings. Results indicate that air exchange rates measured using sulphur hexafluoride are slightly larger than thosemeasured using methane or nitrous oxide. The ratio of air change rates measured using sulphur hexafluoride to air change rates measured concurrently using a lighter tracer gas was found to be 1.10 +/- 0.10

Describes how a family of simulated neutral atmospheric surface layers was used to determine the response of the wind loads on a building model, as well as the associated flowfield near it, to variations in the characteristics of these 'test boundary layers'. Results include the variation in the size of the horse- shoe vortex at the base of the building, spectra of pressure fluctuations, and documented variations in the wake Strouhal frequency with changing boundary layer characteristics.

Refers to earlier work by Mattingly, Peters, Harrje and Heisler which indicated the possibility of reducing air infiltration by using sheltering devices such as fences, neighbouring buildings and trees. Reports use of wind tunnel air infiltration model to explore the effect of trees in a windbreak on a model home. Presents results of tests determining the effect on wind-induced air infiltration of the variation of various windbreak layout parameters. Introduces concept of turbulence generation as the mechanism of tree wind sheltering.