What is recommended if passive or fan-powered makeup air inlets exist in mechanical rooms during the air tightness test?

When conducting an airtightness test on a building, it is recommended to isolate any passive or fan-powered makeup air inlets in mechanical rooms. This practice is crucial because these inlets can significantly influence the test results by introducing outside air during the testing process. If they are not isolated, the additional airflow can create discrepancies in the measured airtightness of the building envelope, rendering the results inaccurate or misleading.

Isolating the inlets effectively prevents any unintended air exchange from skewing the data collected during the test. This ensures that the measurements reflect the true airtightness of the building’s structure rather than the impact of supplementary air sources. By adhering to this guideline, practitioners can achieve reliable outcomes that accurately represent the building's performance concerning air leakage.

In contrast, including them in the test, using extra fans to filter them, or ignoring them entirely would compromise the integrity of the results and could lead to faulty conclusions about the building's airtightness.