A Passing Number From a Test That Should Not Have Been Run
A whole-building pressurization test is performed on a 40,000 ft2 envelope: 28,000 ft2 of wall, 9,500 ft2 of roof, and 2,500 ft2 of exposed floor over open parking, with the ground-contact slab excluded by the specification. The measured leakage is 15,400 cfm50. The draft report divides by the wall area alone and states 0.55 cfm/ft2 at 75 Pa against a 0.40 cfm/ft2 limit. Conditions during the test: sustained wind of 10 m/s gusting to 16 m/s, zero-flow baseline pressure differences swinging between -5 and +6 Pa, and single 5-second readings at each test point. Two combustion appliances in the building remained connected and operating during the test. The client wants the report filed as a failure so remedial work can be justified.
1. Recompute the metric and determine whether the reported conclusion is correct.
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The area basis is wrong. Dividing 15,400 cfm50 by the 40,000 ft2 envelope area gives 0.385 cfm/ft2 at 75 Pa, which is below the 0.40 limit; dividing by the 28,000 ft2 of wall alone inflates the result by about 43% and produces the 0.55 figure. As computed, the report is not describing the specified metric.
Correcting the arithmetic does not make the test valid, however. A zero-flow baseline that swings from -5 Pa to +6 Pa means the driving pressure across the envelope is of the same order as the signal being measured, and single 5-second samples cannot average out gust-induced noise. Under those conditions the reported leakage value carries uncertainty larger than the 0.015 cfm/ft2 margin between 0.385 and 0.40, so neither a pass nor a fail can be asserted. The honest conclusion is that the test is inconclusive and must be repeated under acceptable wind and baseline conditions.
2. What must be corrected in the test setup before a valid retest, and how should the retest be planned?
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Address three things. First, intentional openings and combustion equipment: open combustion appliances must be taken out of service and their flues sealed, and any designed openings such as exhaust or make-up air dampers must be temporarily sealed and recorded, otherwise their flow is counted as envelope leakage and cannot be separated afterward.
Second, conditions: schedule the retest for a period with sustained low wind and stable indoor-outdoor temperature difference, and monitor baseline zero-flow pressure for a suitable period before and after the test series, rejecting the run if stability criteria are not met.
Third, method: use multiple test points with averaged pressure and flow readings rather than single short samples, and record fan configuration, calibration date, and instrumentation. The auditor should also reject the draft narrative that the building failed, since that conclusion is not supported, and should flag the area-basis error as a template defect affecting other reports from the same office.
3. The client insists on a failure finding so remediation is funded. How should the auditor respond?
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The auditor cannot manufacture a finding to fit a funding outcome, even a sympathetic one. Reporting a failure that the data do not support is a misrepresentation, and it would expose both the auditor and the client to challenge if the report is used for a contract claim or a code compliance filing.
The workable path is to report what is actually known: the arithmetic error, the invalid test conditions, and specific observed defects from the site audit, such as the parapet continuity issues documented during the walkthrough. Those observations can justify remedial work on their own merits. The auditor should recommend the retest, offer the corrected computation as an interim statement clearly labeled as unaudited, and put the client's request and the auditor's refusal in the file. If the client pressures further, escalate internally and notify the program before any report is issued.