In the past years the need has grown for a sensitive flowrate meter with a very low pressure drop. Such a device can be used to measure flowrates of airflows through the grilles of mechanical ventilation systems with low duct pressures. Another application would be the measurement of flowrates through the different rooms of a dwelling during a blower door test. A prototype was developed based on the very simple principle of a throttled fan. The prototype proved to be accurate and capable of measuring flows on ducts with natural ventilation.
Looks at some studies that have been done to see if the retrofits have actually changed indoor air quality and changed pollutant concentrations. The first study (1981) of 18 homes in Washington state used the house doctor technique. The second study was of two homes in Medford, Oregon and one in Cranbury, New Jersey, all monitored for two weeks. The third study was of two identical houses in Rockville, Maryland, monitored over a year. One of them was retrofitted using the house doctor technique, as a result of which air leakage dropped by 40%. A fourth study of fifty houses is mentioned.
The airtightness of 82 passive solar homes located throughout the United States was studied using tracer gas measurements of air infiltration and pressurization testing. The air infiltration measurements employed the tracer gas decay technique in a low-cost mode employing air sample bags and off-site infiltration determination. The infiltration rates measured under natural conditions ranged from about 0.05 to almost 2 air changes per hour (ACH). The pressurization test results ranged from 1 to more than 30 ACH at 50 Pa, with an average of about 10 ACH.
Describes a calibration technique to relate the air flow rate through a blower door to the fan speed and pressure difference across the door. To obtain an accurate and well-documented calibration of pressurization devices, a facility was designed and constructed at the US National Bureau of Standards. This accurately determines the flow rate through the fan as a function of fan speed, air density and pressure difference across the fan.
Describes the installation and use of the Gadzco blower door, as part of a house doctor's program for identifying source of air leakage before retrofitting. Discusses advantages and drawbacks of this particular type of blower door.
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