tracer gas

Based on current concerns regarding indoor air quality and energy use, there is a need for in situ techniques for evaluating buildings' infiltration and ventilation characteristics. The U.S. National Bureau of Standards has developed and employed equipment and techniques for such evaluation. The measurement of whole building leakage and ventilation rates has been reported on previously. Additional procedures are presented here for a more complete evaluation of the ventilation system operation and the distribution of air within the building.

Describes the development of an automated air sampling equipment to measure air infiltration and interzonal air flows. A new matrix analysis method has been developed to calculate single zone infiltration and interzonal air flow rates from measured data. A number of multi-zone experiments have been carried out in the PCL solar heated house at Peterborough, and several single zone infiltration rate measurement experiments have been carried out in a widevariety of buildings. A grab-tube method has been developed for assessing air change rates.

The air change rate and the volume of heated air of the villa were measured by the constant concentration tracer gas method during a period of 11 days. The total volume of the villa is 1000 m3 and the heated volume 530 m3. It is built on six half-levels. The occupants continued their normal lifestyle during themeasurements. The Compact Equipment for Survey of Air Renewal (CESAR) was used with nitrous oxide as tracer gas at a concentration of 100 ppm. The mean global air change rate was 0.50/h.

The typical infiltration load for a residential building has been found to range from one-third to one-half of the total space conditioning load. However, most infiltration measurements have been made on single-family houses. 

The various meanings of ventilation efficiency are briefly summarised. The residual life time of a released tracer gas is chosen as the most meaningful and convenient basis for local efficiency measurements in large, occupied, mechanically ventilated buildings. Measurements were carried out in ten public swimming pool halls. Sulphur hexafluoride tracer gas was released from a 20 ml syringe at various locations around the pool hall and the integrated concentration with respect to time was measured at the exhaust air duct. This was extrapolated to infinite time using the measured decay rate.

Air infiltration flows into different zones of a building can be measured with the constant concentration technique by injecting a metered amount of tracer gas t o hold the concentration of the gas constant. The control and estimation algorithm used to calculate the injection rate is designed using classical transform and optimal estimation methods. The ability of the control algorithm to keep the concentration constant and to accurately measure time varying infiltration flows is demonstrated using digital computer simulations and laboratory experiments.

The R-2000 Super Energy-Efficient Home Program is a cooperative industry/government initiative sponsored by Energy, Mines and Resources Canada (EMR) and delivered by the Canadian Home Builders Association. The program supports building industry development, training of builders and the construction of energy-efficient houses incorporating high levels of insulation, a well sealed air barrier and mechanical ventilati on systems with heat recovery. In 1983, with assistance from the Buildings Energy Conservation Sub-Committee (B.E.C.S.

For more than two years a series of detailed air infiltration measurements have been conducted over the complete yearly weather cycle on two identical side-by-side test houses in Gaithersburg, Maryland, USA. These measurements have been part of a broad study of the interaction of air infiltration , indoor air quality and energy in tightly constructed, well-insulated homes. The standard method of collecting air infiltration data throughout the study has been tracer gas decay. Operation of the duct air circulation fans has transformed each house into a single well-mixed cell .

Pacific Power and Light Company and Battelle PNW Laboratories have completed a project which investigated residential ventilation rates. The results presented in the report discuss evaluation of methods used to measure ventilation rates, the behavior of ventilation rates in residences and the comparison of ventilation rates among home construction types. The perfluorocarbon tracer gas decay technique for measuring ventilation rates was concluded to be the best method used during the testing.

This paper describes a preliminary investigation of the validity of a means of calculating the ventilation rate of a large enclosure from experimental data. It was assumed that the air in the enclosure is not perfectly mixed. The measurement method selected was tracer gas concentration decay. Thecalculation of ventilation rate was performed by "least squares" fitting of a model to the observed tracer gas concentrations. Simulations of tracer gas concentration decay measurements were performed with varying initial distribution of tracer gas.