tracer gas

Evaluates results from constant concentration tracer gas measurements and fan pressurization measurements in three houses and predicts ventilation rates for longer time periods using the LBL model. Test results show that the best way of both supplying adequate ventilation and conserving energy is to make sure that the building envelope is sufficiently tight and then install a mechanical ventilation system. Shows that it is possible to correlate fan pressurization measurements and infiltration rates.

Carries out measurements of the air infiltration rate of 3 large single cell buildings using the tracer dilution method. The purpose is to determine whether or not there are any special difficulties in using the tracer dilution method in this type of building, prior to emabarking on a more substantial measurement program. Uses nitrous oxide and sulphur hexafluoride as tracers. Finds both to be satisfactory, but concludes that SF6 in conjunction with a portable gas chromatograph performs more reliably when used for on-site measurements.

Discusses the mechanisms available for "single-sided" ventilation - ie when ventilation is achieved by the exchange of air through windows on one side of a space rather than by cross-ventilation. Describes a simple approach to its prediction based upon a combination of theoretical modelling, wind tunnel testing and tracer gas measurements made in full-scale buildings. Describes wind tunnel and full scale measurements which show the effect of degree of opening, window type and combinations of windows on the magnitude of ventilation rate.

A major pathway for loss of conditioned air in east Tennessee homes with externally located HVAC systems is leakage in the ductwork. The effect on infiltration rates, as measured by Freon-12 tracer gas dilution, becomes marked if the central duct fan is operating. Duct fan on and duct fan off measurements of the rate of air exchange gave mean values of 0.41 and 0.78 ach respectively in a total of 31 homes.

Conducts tests over a period of 18 months in a house near Knoxville Tennessee to determine the effect of forced ventilation on the infiltration rate. Uses an outside-vented electric dryer as the power vent. Carries out testing during a variety of weather conditions. Uses SF6 as a tracer gas to measure infiltration rates. Develops a non-linear regression based on measured data relating the change in house infiltration rate to the vent rate.

Presents data on the air infiltration and ventilation rates in 2 large commercial buildings. One building is a 4 storey, 10000m2 office building near Glasgow, Scotland; the other is a 26 storey, 100,000m2 skyscraper in Newark NJ. Collects the data on air infiltration and ventilation rates by a micro-computer based automated air infiltration system which controls the injection of a tracer gas into the various zones of the building and monitors its decay.

A comprehensive theoretical framework is presented, based on the use of moments of concentration histories ie multiplying concentration readings by time of reading and then integrating with regard to time. The concept can be used to characterize either the diffusion of the supplied air or a contaminant released within the room. Results are presentd from about 50 measurements demonstrating the usefulness and practical applicability of the approach for assessing air quality in ventilated buildings. Different experimental procedures have been explored and are discussed.

Describes the general methodology for ventilation measurements by tracer gas, using decay, constant concentration and constant emission methods. Defines ventilation efficiency and the ways in which it can be experimentally determined. Gives the results of a series of lab measurements to determine the accuracy of the decay method under different conditions, and the efficiency of some mechanical ventilation systems.

Reports air tightness measures and variations in 14 low-energy houses in Heimdal, plus testing of energy saving measures for exposed detached houses. The air tightness should be considerably improved according to the regulations. Treats principles of air tightness, pressure measurement, thermography tracer gas measurements and heat loss measurements.

Tests a large office building, consisting of several octagonal towers and other blocks in a boundary layer wind tunnel. Determines the highest suction pressures which are relevant for the fixing of the cladding. Uses a tracer gas method to determine recirculation problems of the ventilation system inlets and outlets resulting from the arrangement of octagonal towers of different heights. Wind velocities on the flat roof of some towers are studied by meansof an erosion technique using flour, checks the accuracy of the method using hot wire measurements.