tracer gas

Describes use of a radioactive tracer for measuring ventilation rates. Finds krypton 85 is the most suitable gas although xenon 133 and argon 41 have been used. Mentions various studies using radioactive tracers made in both France and England. Suggests commercial sources for krypton 85.

Reports air leakage measurements made in a mobile home using sulphur hexafluoride as a tracer gas. The home was located in an environmental chamber where it was possible to measure and control the temperature outside the home. The effect on infiltration rate of inside-outside temperature difference, simulated wind, installation of storm windows, opening of doors and operation of the furnace for was investigated. Also reports pressurization measurements which showed that the installation of storm windows had little effect on air leakage.

Describes air infiltration measurements made in three apartment houses in the Chicago area using SF6 as a tracer gas. Two were in tenement districts and one was suburban. Data were collected in selected apartments in each building, and these data were used to estimate the infiltration rate for the entire building.

Treats investigations in office building where 1) flow rates of supply air, return air and ventilation between main office area and adjacent rooms were measured with an anemometer. Return air rates remained constant but ventilation rates varied widely during measurement periods. 2) CO2 was used as tracer gas to determine ventilation rates in offices. Calculates alterations in gas concentrations in rooms adjacent to stairwell and changes in outdoor air concentrations. During air conditioning, ventilation rates in the room were 4-5 room air changer per hour.

Reports the results of three programmes of measurements of ventilation carried out in one-family houses, which in most cases were of the 'council house' type. The first programme measured ventilation rates using tracer gasin two houses room by room. Wind speed and direction were recorded but no general relation between ventilation and wind was found. The second measured ventilation rate in individual rooms in a house under six different wind conditions. The third measured ventilation rates in three identical homes.

Treats importance of keeping uncontrolled ventilation to a minimum in buildings equipped with balanced ventilation. Provides theoretical and experimental description of leakage of air past windows. Includes comparison between standards of different countries. Discusses effect on building ventilation of variations of wind and outdoor temperature. Considers in conclusion measurement of air flows between rooms in a building. Describes development of tracer gas method based on computer-assisted evaluation.

Describes technique for measuring the volume of air leaving a house through the loft. Two tracer gases are used; nitrous oxide is released in the house and carbon dioxide in the loft. The mean concentration of N2O in the loft gives the volume of house air infiltrating the loft: and the mean concentration of CO2 gives the ventilation rate of the loft itself.< Gives two examples of the use of this technique and gives loft ventilation rate as a function of wind speed for one house.

Presents theoretical model which represents a technique of correlating the easily performed pressurization measurement with the more difficult tracer gas technique. The neutral pressure level is explicitly included to estimate the distribution of openings around the building envelope. Describes model in detail and its application to a number of houses in New Jersey and California.

Presents results of a survey of natural infiltration rates in 2 identical modern homes-one gas fuelled and one electric-over aperiod of a year. Infiltration rates were determined by releasing tracer gas, usually ethane, into the main return duct and measuring concentration every half hour. Discusses results and dependence of infiltration rates on wind speed and direction. Gives preliminary result that wind probably exerts agreater effect on infiltration than any other variable.

Reports measurements of ventilation rates made in a nine-story office building. Two methods were used; tracer gas decay rate using sulphur hexafluoride and a direct method when air flow rates through roof vents and exhaust units were measured. Gives summary of results and finds good agreement between the two methods.