Wind tunnel test conducted on a scale model of a classroom show that, provided the test air speed is kept in excess of about 3mph, it is feasible to use models for predicting, with good accuracy, the air-flow conditions in and around full-scale buildings. In the case of low-pitch roofs the height of the stagnant zone set up as a result of flow separation occurring at the windward eaves of a building is influenced by wall height rather than by roof pitch.
Developes a simple procedure for calculating exterior wall pressure differences and air infiltration rates for various wind velocites and direction by applying the pressure data obtained from a wind tunnel model study to a computer model building. Gives separate expressions for air infiltration caused by stack action and by wind and an expression for the combined effect. Gives example of infiltration calculations compared with computer results and finds good agreement.
Describes detailed study of infiltration rates measured with a tracer gas and air leakage rates obtained from fan pressurization in small, 3 - bedroom California house as part of a larger study. Finds surface pressure measurements are an essential step in process of finding a correlation between natural air infiltration and air leakage by pressurization. Measurements also show significant duct leakage and air flow between attic, living space and crawl space.
States that current methods of estimating heat demand of buildings are very inaccurate, and so large safety margins are used which usually result in overestimating the necessary heating plant capacity. Describes computer program developed to improve the accuracy of heat demand calculations. Gives formulae used in the program for calculating heat demand, pressure conditions and air flow within the building. Gives example of the use of the program to calculate the effect of wind on an eight-storey residential building.
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.
Describes experimental techniques used in the low-speed wind tunnels at the Building Research Station when studying air flow around buildings and pressure distribution over their surfaces. Includes flow visualisation both in the stream and in boundary layers over surfaces, velocity measurements around small-scale models, and methods of building models containing pressure tappings. Gives names of suppliers and details of some instruments and equipments. Describes in an appendix how a simply constructed heated-sphere anemometer is made.
Full scale measurements were made of wind pressures on the 177m high post office tower, London. The variation of pressure with height was studied from recordings made at nine different levels between 49m and 168m above ground level. It is suggested that wind speeds of greater magnitude than those at the top of the tower sometimes occurred at lower levels.
Analyses theoretically the natural ventilation of buildings. Derives fundamental formula for the amount of ventilation due to temperature difference from Bernouilli's theorem considering buoyancy. Explains physical meaning of friction loss and theneutral zone, derives pressure distribution due to wind from the shape of buildings and the location of openings. Obtains total expression for amount of ventilation due to both temperature difference and wind.
Describes experiments in a wind tunnel on a model of a tall building of rectangular plan to show the effects of variation in wind velocity with height and the variation of local wind pressures with angle of wind. Discusses the effect of rounding the corners of the building.
Describes measurement of wind pressures on low-rise buildings at Aylesbury. Pressures were recorded simultaneously at over one hundred positions divided between seven houses in an estate and a specially constructed building situated on open ground adjoining the state. The roof pitch of the experimental building could be quickly varied to any angle between 5 and 45 deg. and this was used to investigate the variation of pressure distributions over the surfaces of the building. Data are presented for two skew wind directions. Initial comparisons are made with wind-tunnel tests.
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