English

Briefly outlines the causes of natural ventilation which are wind and stack effect. Gives calculation of ventilation rates for a simple building. Discusses the effect of a more complex building plan.

Describes the research being undertaken by the British Gas Corporation on adventitious ventilation. Outlines a test house programme which has quantified adventitious areas for both room components and progressively sealed rooms in dwellings of varying age and construction. Describes a model scale approach to natural ventilation aimed at predicting room air movements and ventilation rates. This work is compared with full-scale results and theoretical models.

Gives formula for calculating air-change-rate from decay rate of a tracer gas. Discusses different tracer gases and detecting instruments. Describes portable meter used to measure the concentration of helium. Discusses its performance and describes the experimental procedure.

Examines dependence of measured infiltration rates on wind speed, indoor/ outdoor temperature difference and pressure difference. Gives results in form of graphs of measured values. Calculates air-change-rate from crack length and finds good agreement with measured air-change-rate. Suggests that this is as a result of over-estimating the effect of wind and neglecting stack effect. Finds that stack effect is more important than wind. Comparison of the two houses found that the house shielded by trees and houses had a considerably smaller infiltration rate than that on an open site.

Reports investigation of air infiltration in two residences using helium as a tracer gas. Describes the residences, instrumentation and test procedure. Gives results of decay rate of tracer gas and measured infiltration rates. Summarizes test conditions in tables of temperature, wind speed and direction, internal to external pressure differences and height of the neutral zone. Concludes that in houses with warm-air heating systems a single helium analyzing cell in the return air-stream would provide a satisfactory indication of house infiltration rate.

States that the calculation of transient pressures in buildings requires the estimation of the rate of air leakage through various paths. Gives an expression for infiltration through a wall component. Gives formulae for calculating pressure transients inside a building under forced ventilation with air leaking out of the building under various conditions. Theseformulae also apply when air is leaking into the building. Discusses practical applications and the practical problems for which the formulae are useful.

The overall air leakage of high-rise buildings cannot be measured using a full pressure method because of the large volume involved. Describes a method of conducting small-scale pressurization tests on the exterior walls of apartments in multi-storey buildings. Gives results of measurements in a test building. compares direct method with values obtained by summing the air leakage of individual components. Finds good agreement. Concludes that floor/wall joints, windows and window sills are the three major air leakage sources in exterior walls.

Describes a pressure transducer which was specially developed to measure wind pressures exerted in buildings. The instrument, which gives an electrical output, is suitable for measuring pressure in the range of 1200 n/m2. The frequency response enables pressure fluctuations lasting only 0.1 s to be recorded.

The two-storey house at Aylesbury, England, built by the Building Research Establishment for the full-scale measurement of wind pressures has been modelled at 1:500 scale in a boundary layer wind tunnel to verify the reliability of simulation forlow-rise buildings. Describes wind tunnel tests of buildings models of 5 and 22.5 roof slope. Compares surface pressure measurements with full-scale data for various wall and roof locations. For the model terrain best modelling conditions, the results show agreement which is encouraging.

Describes continuous measurements of wind induced pressure differences across the exterior walls of two schools taken over a period of 8 months. These schools were selected from a total of eleven schools whose air leakage characteristics had been previously studied. Calculates air infiltration rates caused by wind using the measured differentials. Evaluates equivalent pressure differentials caused by wind. Calculates uniform pressure differentials caused by stack action using a computer model.