Closed-House Conditions and Test Protocols
This domain tests whether the home was operated under the conditions the result is supposed to represent: closed-house conditions, correct duration, and normal occupant activity.
Closed-house conditions
For a short-term test, keep windows and exterior doors closed for at least 12 hours before the test starts and throughout it. Normal entry and exit are allowed, but minimize openings. Operate the HVAC normally; do not run window fans, whole-house fans, attic fans, or other equipment that brings in outside air. Do not tape or seal the house-closed-house is not the same as airtight. Avoid testing during major renovations that generate dust or unusual ventilation.
Duration and protocol
Short-term tests range from 2 to 90 days. Real-estate and many professional tests use a minimum 48-hour measurement, with a CRM recording hourly or a passive device deployed for the stated period. Long-term tests exceed 90 days and better represent annual average exposure. Record start and end times, device serial number, floor/room, HVAC status, and any deviations.
Worked example
A test is to begin Tuesday at 9:00 a.m. The tester should confirm the house was closed by Monday at 9:00 p.m. and remains closed until Thursday at 9:00 a.m. The HVAC may run normally; the whole-house fan may not. A brief exterior-door opening for entry is acceptable, but opening windows "to air out" the house invalidates the closed-house condition and the test should be rescheduled.
Traps
Sealing windows with tape and calling it closed-house; running an attic fan during the test; starting the test only 2 hours after closing the house; testing for 24 hours on a real-estate deadline; and failing to document a protocol deviation such as a window left open.