English

Reviews the requirement in building regulations for cavity barriers in roofs. States need for providing ventilation in the cavities of certain forms of roof construction,particularly those with a continuous waterproof vapour barrier to avoid moisture build-up. Examines how adequate air movement can be provided in both new and existing flat roof voids, designed with or having installed cavity barriers.

Presents method for collecting air infiltration data in a large sample of dwellings. The method consists of a tracer gas dilution technique using sulphur hexafluoride and employing air sample bags which are analyzed in a central laboratory. Themethod is easy to perform and inexpensive and will be used in approximately 300 dwellings on 16 sites to give air exchange rates under typical heating season conditions. Presents preliminary data on air infiltration rates in low-income housing in Portland, Maine.

Describes briefly mechanisms and sources by which air infiltration occurs in dwellings. Compares leakage rates through windows and through houses with european standards to illustrate values that can occur in the U.K. Discusses importance of infiltration to both natural and mechanical ventilation and gives examples of the ways in which infiltration can adversely affect the thermal environment in well insulated dwelling. Concludes that more attention should be paid to infiltration through adventitious openings including improving building construction to minimise infiltration.

Summarizes measurements made on a flat. These include inside to outside temperature and pressure differences, infiltration rates using helium as a tracer gas, duration of opening windows and doors and weather conditions. Also describes wind tunnel measurements made on a model of the building with and without obstacles and terrain roughness.

Reports measurements of air pressure differences to determine influence of wind on air flow directions through door and window gaps. Studies measures to prevent air transport between the 4 wings of the cross-shaped hospital and to ensure air flows from the corridors to the rooms on both sides. Pressure differences measured between facades agreed well with wind-tunnel results. Air flow directions measured agreed with results from an electrical analogue ventilation model.

Discusses causes of condensation between the panes of a double window. Treats movement of water vapour by diffusion and by air leakage separately. Describes tests made to determine air flow and vapour diffusion through test windows finds that relative importance of the mechanisms depends largely on the inside to outside pressure difference so that the higher the pressure difference, the greater the importance of air leakage. Suggests venting of windows to overcome condensation.

Reviews wind research prior to 1958, which was based on the simple concept of a smooth air flow resulting in static design loads for most structures. States that research for the past ten years has benefited from three innovations. These are theimplementation of a statistical theory of turbulence, experimentation with turbulent boundary layers and the collection of full-scale measurements to identify and evaluate the real wind structure.

Gives a summary of the work in building thermography in the scandinavian countries, especially Sweden. Deals with the principles of thermography, how to detect thermal resistance deficiencies and air leakage. Discusses applications in building and factors influencing the thermograms. Reviews test requirements in Scandinavia and discusses the results of measurements made on about 500 building projects.

Gives the results of an analytical study of the distribution of pressure differences caused by chimney action in buildings. Gives results of the way in which the pressure differences are affected by various arrangements of excess supply and exhaust air. Suggest ways of controlling stack effect, by pressurization.

Describes three test high-rise buildings and the pressure measurements made on buildings. Gives results of internal to external pressure differences against height within building both with and without the ventilation systems in operation, compared with theoretical predictions. Discusses pattern of pressure differences. Suggests feasibility of pressurizing ground floor to reduce stack effect. NOTE Futher measurements of wind on two of these three buildings are given in 'Pressure differences caused by wind on two tall buildings' Tamura G.T. Wilson. A.G. ASHRAE trans. 74 no 2 p170-181.