Is it required for all dampers to be closed before testing according to ASTM E779 - 19?

The correct answer highlights the importance of ensuring that all dampers are closed prior to conducting airtightness testing based on the ASTM E779 - 19 standard. Closing all dampers is essential to achieve accurate test results because any open damper could introduce additional airflow pathways that can alter the pressure dynamics within the building.

If dampers are left open, the test may indicate a higher level of air leakage than is truly present, leading to misleading data that can affect assessments of energy efficiency and building performance. The standard establishes clear protocols to ensure that testing conditions accurately reflect the airtightness of the building envelope without interference from unmonitored airflow.

In summary, the requirement for all dampers to be closed reinforces the integrity of the testing process and helps ensure that the outcomes genuinely reflect the building's performance characteristics.