English

Discusses the mechanisms which govern natural ventilation. These are wind speed, flow, characteristics of openings in buildings and pressures generated at building surfaces by wind and temperature difference. Gives formulae for simple cases. Outlines ways of determining natural ventilation rates. Gives brief account of the effect of turbulence and openings in one wall only.

States that aim of research project is to develop a method of testing entire buildings for air infiltration. Suggests apressure method using a powerful fan to pressurize or depressurize the house and measuring air flow through the fan and internal pressure to give a figure for air infiltration.

Discusses variations in the test results which occur with the laboratory procedures for assessing the air and water penetration attributes of windows. Presents data for windows examined under British Standard BS 4315 : part 1 "Methods of test for resistance to air and water penetration - windows and gasket glazing systems". Considers the implications of thesetests for the development of performance levels for use in standards and procurement documents, and proposes a two-stage statistical procedure, based in the first instance on tests on five windows.

States that ventilation needs can be identified from a study of people's behaviour. Reports results of regular systematic observations of open windows in a group of scottish houses which confirmed earlier work in Britain. Finds that the number of open windows is a direct function of outdoor temperature or moisture content and was also influenced by air speed with a smaller number of windows being opened in windy weather. Large families opened their windows more frequently than small families. Suggests that moisture control may be the main motivation for opening windows.

Describes adaptation of photo-electrical optical technique to measure ventilation rates in wind tunnel models. Illustrates probe photographically and diagrammatically. It comprises essentially a light-emitting diode and a hybrid photodiode-amplifier detector. Compares technique with conventional tracer gas technique using helium and a katharometer and finds good agreement. Considers optical probe has considerable potential for measurements in small and multi-celled models where conventional techniques are not feasible.

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.