English

This article discusses the application of tracer gas methods to industrial hygiene investigations. It introduces the basic concepts necessary to understand the application of tracer gas methods to particular airflow and contaminant movement measurements. It provides an overview of existing methods which can be used to obtain quantitative data on a variety of airflow and contaminant movement related questions which often are of interest to the industrial hygienist.

Tracer gas tests were conducted on a five-storey apartment building to determine the air and contaminant flow patterns within the building. The test method involves the injection of a small amount of tracer gas, SF6, into a selected location to create a single source and monitoring the tracer gas concentrations at locations throughout the building. Based on the rates at which the tracer gas concentrations change at various locations, the air and contaminant flow patterns within the building can be determined. Several such tests were conducted.

The knowledge of IEA-Annex 14 'Condensation and Energy' has been applied to develop a new strategy for humidity control in dwellings. The presented control element assures safe prevention from mould growth at a minimum energy consumption. The advanced humidity control device consists of a surface temperature and an indoor air temperature sensor, from which readings a microcontroller evaluates the appropriate RH setpoint. A humidity sensor then reads the actual RH in the room air and compares it with the momentary setpoint.

This paper reports the design, development, calibration and testing of a fast-response, multi-channel tracer gas concentration measuring instrument. The instrument uses aninnovative application of Infrared Absorption techniques to measure Sulphur Hexafluoride (SF6) concentrations. This approach allows the overall cost of a multi-channel continuous-recording unit to be reduced without sacrificing overall performance. A calibration over the range of 5.0 to 50.0 ppm V SF6 is shown. The current measurement resolution is 0.06 ppm V, and the accuracy is + or - 5.0%.

A new handbook, describing in details the measurement techniques which could be used to better understand the infiltration and ventilation in buildings is presented. This handbook results from the cooperation between Annex 20 and Annex 5 of the IEA ECB program. It presents the techniques for detecting and measuring as well the air leakages as the air flows in buildings and inventilation systems. Methods related to ventilation efficiency and effectiveness, like the measurement of the age of air, are also described.

A new algorithm for the continuous measurement of variable air change rates with tracer gases will be presented. It differs from the constant concentration method by allowing the concentration level to vary according to the air change rate. Also the mixing process of tracer gas within the room under investigation is considered and limited measurement ranges and injection rates of the tracer gas equipment can be accounted for. The new algorithm has a number of advantages, such as quick response to variations in the air change rate and reduced tracer gas consumption.

Field investigations were undertaken on five houses to determine the potential for improved performance and lower costs through the use of a demand controlled ventilation (DCV) systems. All 5 houses were energy efficient, low toxicity construction, and were chosen to reflect a range of mechanical systems consistent with Canada's new ventilation standard (CSA F326). Three of the test houses were extensively monitored and, after 90 days of conventional operation, were converted to DCV using a wide variety of sensors and controls.