openings

Retrofitting of older buildings brings about a noticeable drop in air supply. Fireplaces in buildings need sufficient combustion air. Tight windows may cause insufficient air supply. Therefore an adequate combustion air flow for the fireplace may not be attained and poor combustion will take place. In this study data on length, tightness, etc of windows, doors and other openings in buildings of the last 30 years have been collected.

Investigates a rational method of utilizing recent improvements in wind tunnel techniques and meteorological data, to estimate potential wind-generated air flow through housing in hot humid climates. The method uses mean pressure differences obtained from solid wind tunnel models together with appropriate discharge coefficients for rectangular openings. Changes in pressure distributions due to typical openings through models indicated that the use of pressure data from solid models results in errors similar to those associated with the local wind data.

Describes method for calculating the adventitious ventilation of a building using information from a pressurization test. The method requires a knowledge of the surface pressures on a building, calculated from wind speed and direction, the inside-outside temperature difference, and the distribution and characteristics of openings in the building shell. Applies formulae to threebuildings and finds a great dependence of infiltration on wind direction. Discusses the effect of wind and stack effect, separately and combined.

Gives equations and charts for the calculation of heat and moisture flow due to natural convection through openings in vertical partitions separating spaces at different air conditions. Finds that heat and moisture transfer coefficients depend on the Grashof number and to some extent on the ratio of opening height to thickness. Also gives chart and equations for flow across an opening in a horizontal partition when the higher density air is above the opening.

States that application of further thermal insulation to house structures increases importance of ventilation heat loss, from around 20% to nearly 50% of total design heat requirement. Any further energy savings will be by minimising ventilation components. On basis of British Gas research results and others, illustrates sources and mechanisms of infiltration to give an insight into problems it may cause in future housing. Treatseffect of weather, ventilation rates. Among conclusions states increasing attention will have to be paid in future toinfiltration.

Reviews the main mechanisms giving rise to natural ventilation of spaces with openings to outside air on one wall only. These are temperature difference, pressure fluctuation, mean pressure difference, turbulent diffusion and the "vane" effect. Derives expressions for the magnitude of the ventilation rates caused by each of these mechanisms. Reports wind tunnel studies of the ventilation rate in a small test chamber ventilated through one opening only. Air change rates were measured using a tracer gas.