Large, multicelled, and naturally ventilated buildings pose many inherent difficulties for the measurement of overall infiltration rates using tracer gases.
Air exchange rates were measured in the National Archives Building under various combinations of temperature and wind speed. The average air exchange rate under normal operation of the HVAC system was 0.9 h-1 for an average temperature difference.
This paper deals with a new computer program, MOVECOMP, which calculates the in- and exfiltration and the airflows between the rooms of a multicell building. The calculations are made due to wind and thermal forces and the characteristics of the leakage openings. MOVECOMP was developed to be user friendly: input data are limited and output data are very flexible. The userchooses which output he wants from a menu. The building is described with asystem of pressure nodes, connected to each other through flow-pressure difference functions.
Fan pressurization techniques are being employed by an increasingly large number of contractors and auditors to determine the leakage characteristics of structures. In this study, a large data base of flow exponents and flow coefficients are compiled to determine the degree of correlation that exists between flow parameters. The resulting empirical relationships are then used to determine the feasibility of predicting these flow parameters directly from a single pressure difference test. On the basis of these correlations, a new pressure independent tightness parameter is proposed.
Air leakage is the single most important quantity in the determination of air infiltration in residential structures. Air leakage is most commonly measured using the fan pressurization technique (ASTM standard E779): the data gathered with this method is often used to determine a leakage constant and a flow exponent. In this report, data gathered from measurements in the USA and Canada is compiled into a list of leakage constants and flow exponents, and the variability of these values over climate and housing types is examined.
Several different ratings of building airtightness are used to report the results of fan pressurization tests. These are generally based on airflow rates at specific reference pressures, predicted by curve fits to the test data. The statistical
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.
An energy-efficient residence in Mt. Airy, Maryland, USA, was monitored for aldehydes and radon in order to develop relationships between air infiltration rates and contaminant levels. One fifth of the measured formaldehyde concentrations were in the range that may cause health concerns. These concentrations were measured under very low air infiltration rates. Increased ventilation was effective in reducing high concentrations. Use of the heat exchanger led to an increase in the air infiltration rate which resulted in a substantial reduction of formaldehyde levels.
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