Minimising ventilation for energy conservation in buildings requires that ventilation efficiency be high. The common practice of locating supply outlets and return inlets in or near the ceiling creates an opportunity for air tobypass from the supply to the return without mixing in the occupied space. Equations are derived for calculating efficiency and stratification factor from tracer gas decay measurements.
The paper shows that age analysing techniques are an excellent tool to assess ventilation effectiveness. It is important to differentiate between air exchange effectiveness and contaminant removal effectiveness, having continuous generation of contaminants. Only when a source is homogeneous andpassive, are the age of the air and the contaminants in the room equal. However, the air exchange effectiveness accounts for the removal effectiveness of the contaminant left in the room when the generation stops.
Describes the technique employed, including the mathematical model as well as results from a validation test using an experimental chamber. The model assumes an exponential decay of the tracer gas concentration. The precision of the analytical procedure is estimated at better than 9%, while the error of the measured ventilation rate of the test chamber was 5%.
A tracer method was developed for the evaluation of workplace ventilation. Nitrous oxide or freon was used as the tracer. The concentration of the tracer gas was measured with an infra-red analyser. The versatility of the tracer technique for industrial hygiene applications was improved by the use of a microcomputer for data calculation, display and storage. Three applications are presented: 1. determination of the capture efficiency of a local exhaust hood, 2. the evaluation of the air leakage of a room, and 3. measurement of the local ventilation rates in a large industrial plant.
An accurate determination of air renewal rate and connective exchanges between units was needed for study of the solar units of the experimental building LESO, in both an occupied and empty state. The CESAR compact equipment for tracer gas (nitrous oxide) measurement was developed. This unit uses a microcomputer to perform a simultaneous and periodical gas analysis in 10 locations. Three tracer gas methods can be used: decay, constant concentration, and continuous flow. The device and regulating program work well with low rates of concentration (100ppm of nitrous oxide).
Continuous monitoring of NO, NO2, CO, CO2, and O2 depletion was conducted in 14 residences (13 with kerosene space heaters and one without) in two locations in the residence (room with the heater and bedroom) and outdoors. The continuous monitor
The relation between air infiltration rate and indoor concentrations of radon gas, radon daughters, and formaldehyde has been investigated for both summer and winter conditions in a number of Toronto houses with low rates of natural ventilation.
Defines air change and air penetration. Describes the differential pressure method, the infrasound method, qualitative judgement methods, and acoustic measurement devices for determining air penetration. Explains procedures todetermine air change - the rate of decay method, the constant concentration method, and the constant emission method.
Describes three research programmes measuring tightness of components, of specific areas of a building and of complete buildings. Defines the Belgian standards currently applicable. For air tightness, the area or building is depressurized by 5 to 100 Pa and the flow of air that enters is measured. Thenthe components are made air tight one by one, and each time the new flow rate is measured to give values for the different components. The specific area alone can be depressurized, the specific area plus the whole building or just the whole building.
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