According to ASTM 3158 - 18, what is the recommended wind speed threshold for longer baseline measurements?

The recommended wind speed threshold for longer baseline measurements, as per ASTM 3158 - 18, is 12 MPH. This standard suggests that at this wind speed, the effects of wind on the testing procedure are minimized, allowing for more accurate and reliable measurements of a building's airtightness.

At wind speeds below this threshold, the variability in pressure differentials can lead to inconsistencies in the data collected, potentially skewing the test results. By adhering to the 12 MPH guideline, testers can ensure that any measured leakage rates are more indicative of actual building performance, rather than being influenced by external wind conditions. This is essential for providing valid results that can guide future building improvements or verify compliance with energy efficiency codes and standards.