True or False: In an envelope test, all windows and doors must be closed and locked.

In an envelope test, it is essential that all windows and doors are closed and locked to ensure accurate measurement of the building's airtightness. This requirement is in place because any gaps or openings could significantly influence the test results by allowing air to flow in or out of the building. When windows and doors are properly closed and locked, it creates a controlled environment that reflects the building's true performance under normal operating conditions.

The purpose of this procedure is to identify and quantify leaks in the building envelope, which is crucial for understanding the building's energy efficiency and overall performance. A thorough and reliable assessment can only be achieved when the test is executed under the correct conditions, meaning that every potential pathway for air exchange must be sealed appropriately. Therefore, having all windows and doors closed and locked ensures that the test accurately represents the building's airtightness.