What condition might affect baseline pressure measurements?

Baseline pressure measurements are crucial for assessing the pressure differential in a building envelope, which impacts airflow and energy efficiency. Wind or a pinched hose in a door or window can create significant disturbances that directly affect the accuracy of these pressure measurements.

The influence of wind introduces variable air pressures due to external conditions, potentially leading to misleading readings. Similarly, if the hose connected to the pressure measurement device is pinched or obstructed, it will not accurately measure the building's internal pressure, thereby distorting results.

In contrast, while high humidity, thermal expansion, and temperature fluctuations can influence the overall conditions within a building, they do not directly impact the baseline pressure readings in the same way that wind or a hose obstruction does. Instead, these factors may contribute more to the comfort levels within the space or long-term structural integrity but do not create immediate discrepancies in the measurements taken at that moment.

Thus, basing pressure measurements on stable and unobstructed conditions is essential for obtaining reliable data regarding the building's air leakage and ventilation characteristics, making wind and hose interference the primary concern when measuring baseline pressures.