Reviews experimental techniques for determining the infiltration characteristics of buildings. Discusses the use of wind tunnel models to determine surface pressure distributions and ventilation rates. Reviews the measurement of open areas and leakages. Discusses correlation of measured leakage and ventilation. Describes the British Gas method of measuring ventilation rates using tracer gas. The system, known as "Autovent" provides a constant concentration of tracer gas and can be used for the continuous monitoring of ventilation rates.
Describes an automatic measurement system for air infiltration and discusses factors influencing the measurements in single rooms or in a group of connected rooms. The system works on the decay rate method and is controlled by a purpose-designed controller. The test data are evaluated off-line by computer. Discusses in detail the instrumentation and test procedure Gives results of measurements made in a detached house and correlations of the test data with wind and temperature difference data. Gives a comparison with pressurization data.
Presents a survey of tracer gas techniques for measuring air infiltration and includes a theoretical derivation of the equations, a description of each method, and a short description of the experimental procedure. Derives a qualitative error analysis which concentrates on mixing problems and uses it to compare the strengths and weaknesses of each method.< Derives the theory of multi-chamber infiltration measurements in situations involving many interconnected spaces (network type models).
Describes a system which automatically operates a small gas chromatograph and measures parts per billion concentrations of sulphur hexafluoride in air. It samples air on a 10-minute cycle and records the response on a strip chart recorder. When SF6 in distributed in the air of a building, data is obtained from which air infiltration rates may be determined.
Reports experiments using sulphur hexafluoride as a tracer gas to obtain quantitative data on actual residence time distributions in rooms and hallways and contamination caused by reentry of laboratory fume hood exhausts into a building. Defines a factor k which gives a measure of the mixing of fresh withstale air in part of a room. Measured values of k varied from 0.3 to 0.7 insmall rooms without fans. Discusses two experiments to find the amount of exhaust fumes reentering the ventilation system of a building.
Reports measurements of air change rates carried out in the living rooms of 39 flats built during the last 20 years using Freon 12 as a tracer gas. Ventilation rates ranged from 0.3 to 2.9 changes per, hour, the average being 1.3 changes per hour. Air temperature, humidity and wind speed were recorded and the ventilation rates corrected for wind speed and temperature. Notes large ranges in ventilation rates for similar flats.
Suggests use of an electron capture detector for the routine estimation of the SF6 content of a mixture of gases without preliminary chromatographic separation. Gives chromatogram illustrating method.
Discusses the two methods for calculating air infiltration given in the ASHRAE handbook. These are the air change method, a gross estimate based on the number of windows and doors in each room, and the crack method based on measurements of flow through the cracks around windows and doors. Presents comparisons of tracer gas measurements with calculations by both air change and crack methods for test houses in California and Minnesota. Find agreement is adequate for sizing equipment but that the crack method underestimates infiltration at low wind velocity.
Reviews tracer gas methods for measuring ventilation rate and discusses the diffusion of gases. Describes four tracer gas methods; rate of decay, equilibrium concentration, transfer index and constant concentration. Discusses the analysis of results. Describes an experimental room and series of measurements of air change rate using two methods a) rate of decay, where a balloon filled with gas was burst as a point source and b) equilibrium concentration where tracer gas was released continuously at a constant rate.
Reports measurements of natural ventilation and leakage rates in two test rooms in a university building. Describes rooms and instrumentation. Gives results of pressurization tests with windows closed but not sealed, sealed, and weatherstripped. Gives results of measurements of ventilation rate using N2O as a tracer gas. Discusses the analysis of results and experimental errors. Compares measured rates with ventilation rates calculated using crackand ASHRAE methods.
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