A Compact Equipment for Survey of Air Renewal (CESAR) was developed at the Ecole Polytechnique Federale de Lausanne in Switzerland. Controlled by a microcomputer, this apparatus uses tracer gas methods ( decay, continuous flow or constant concentration). Up to ten different locations in inhabited rooms can be monitored simultaneously over extended periods of time, using mainly the "constant concentration" technique. Several air renewal surveys were carried out on different inhabited buildings.
Knowledge of the air change in dwellings under conditions of use is a prerequisite for the calculation of energy consumption and for evaluation of a dwelling's indoor climate. Air change was measured in a total of 25 occupied dwellings over a
Describes a completely automated constant concentration tracer gas technique for measurement of air infiltration. The equipment consists of five components: 1 a controller, 2 a tracer gas analyzer, 3 an injection and sampling unit, 4 special mixing fans and 5 apparatus for the calibration of the tracer gas flow. The system is controlled by a microcomputer.
This paper presents the measurement technique and results of 23 one-week measurements of air change rate in occupied dwellings. The measurements conducted show that the occupants exert a very considerable influence on the total air change rate. The air change rate for occupied dwellings is, on average, 3-4 times greater than the rate in sealed dwellings (with air-escape valves, doors, windows and ventilation system closed). The measurements also reveal a trend towards a higher air change rate in mechanically ventilated dwellings than in naturally ventilated dwellings.
An automated 10-point air sampling network which uses an electron capture detector gas chromatograph to continuously measure changes in sulfur hexafluoride tracer concentration in a residential environment will be described. The injection of the tracer is controlled by a microprocessor which decides to inject sulfur hexafluoride tracer to return its concentration to a preprogrammed set point. Infiltration rates from fan induced pressurization will be compared to the infiltration rates as reported from the replacement of sulfur hexafluoride tracer.
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).
The British Gas 'Autovent' system utilises the constant concentration technique and was developed for measuring ventilation rates in dwellings. It has recently been used in two large open-plan buildings, a school nursery and a factory unit, and the opportunity was taken to carry out special tests to assess its validity in such buildings. The reason why these tests were needed, the nature of the tests and the results obtained form the main content of the paper. The evidence from the tests strongly indicates that the system is suitable.
The Department of Building Technology, the Technological Institute of Copenhagen, have for several years been developing equipment for continuous measurement of air infiltration. It enables continuous measurement of air change rate in up to ten rooms, the constant concentration method with tracer gas is used, and the results are recorded on a computer diskette during measurement. Analysis of possible measuring errors show that the method is accurate and to within plus or minus 5%. Shows the results of measurement of air infiltration in 10 relatively airtight dwellings.
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.
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.
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