This paper describes the procedures used in residences for rapid grab-sample and time-dependent measurements of the air-exchange rate and radon concentration: the radon source magnitude is calculated from the results of simultaneous measurements of these parameters. Grab-sample measurements in three survey groups comprising 101 US houses showed the radon source magnitude to vary approximately log-normally with a geometric mean of 0.37 and a range of 0.01 to 6.0 pCi/l/h.
The Aardvark automated system has been developed for continuously measuring the air-exchange rate and 222Rn (radon) concentration in an occupied residence. The air-exchange rate is measured over 90 min intervals by tracer gas decay using sulphur hexafluoride as the tracer gas.
A simple means for determining air infiltration rates into homes and buildings for assessment of indoor air quality and energy conservation measures, based on a passive perfluorocarbon tracer (PFT) technique, was evaluated in a well-defined environmental chamber under experimental conditions of 1) constant temperature and ventilation rate, 2) constant temperature, variable ventilation
rate, and 3) variable temperature, constant ventilation rate.
A miniature passive perfluorocarbon tracer system was successfully applied to the determination of air infiltration and exfiltration rates from each zone of a multizoned structure, as well as the air exchange rates between zones inhomes, multiple unit condominiums, naturally ventilated apartment buildings, and large commercial buildings with multiple air-handling systems. Use of the multizone technique in indoor air quality assessments and air-handling system stratification studies appears to be quite feasible with the availability of this measuring system.
The total air infiltration rates can be determined by the tracer gas decay method, but to measure the influence of inhabitants or convective exchanges between rooms, the constant concentration method is more suitable. In order tomeasure these effects, the Compact Equipment for Survey of Air Renewal (CESAR), developed at the LESO, was used to perform an air exchange analysis on data recorded at regular intervals in up to 10 locations simultaneously. Three tracer gas methods were implemented: decay, constant concentration and continuous flow.
A Compact Equipment for Air Renewal Survey (CESAR) has been developed by the Ecole Polytechnique Federale de Lausanne. The device has been designed for simultaneous analysis of up to 10 different inhabited rooms over extended periods of time (days or weeks). The constant concentration tracer gastechnique was used for the first survey done in the South rooms of the LESO building. Mean outdoor to room flow rates of between 1 and 40 m3/h were found.The mean building to room air flow was found to be 5 m3/h for rooms with only one communicating door with the rest of the building.
Modelling houses as two coupled chambers, namely, the living area and basement, predicts more accurately the total indoor radon source flux from building materials and geology than a one-chamber model in houses with disparate radon concentration
Results from a two-box model for calculation of tracer gas concentrations in rooms are given and consequences of different definitions of ventilation efficiency are discussed. Results from three different series of experiments are presented.
As part of a programme to develop measurement methods for determining the ventilation rates of large buildings, we performed two series of tests in a single-celled laboratory with a volume of 600m3. The first series utilised constant concentration, constant emission and rate of decay tracer gas techniques to determine the characteristics of the infiltration pattern in varying winds and external temperatures. We used both discrete and continuous injection and sampling methods.
Login