What is an initial step in preparing for a blower door test?

In preparing for a blower door test, setting gas appliances to pilot mode is crucial to ensure safety and accuracy during the test. When gas appliances are set to pilot mode, it minimizes the risk of gas leaks and combustion issues that could arise if the gas appliances are fully operational and could sense the changes in the air pressure caused by the blower door test. This allows for a controlled environment where the test can accurately measure the leakage rate of the building envelope without interference from operating appliances.

The other options, while they may seem relevant, do not address the specific precautions necessary for safely conducting a blower door test. Keeping doors open, for instance, would not help in isolating the airflow in the building's envelope, which is essential for the test's accuracy. Turning off electrical appliances may not be required and could lead to unnecessary disruptions. Similarly, setting the thermostat to fluctuate does not contribute to the primary goal of a blower door test, which is to assess how well a building is sealed against air leaks.