Excessive negative pressure in the building enclosure is said to cause which of the following?

Excessive negative pressure in a building enclosure can lead to various issues, one of which is the potential production of carbon monoxide (CO). When a building operates under significant negative pressure, it can result in combustion appliances, such as gas water heaters or furnaces, drawing air from within the building instead of receiving it from outdoors. If these appliances lack proper ventilation, this can cause incomplete combustion, leading to an increase in CO levels, which is hazardous to the occupants.

The relationship between negative pressure and CO production is critical because it highlights the importance of balanced air pressure within a building. Ensuring that airflow is properly managed helps prevent backdrafts and ensures that combustion appliances operate efficiently and safely.

Decreased airflow, increased humidity, and structural damage can also result from negative pressure; however, they do not pinpoint the immediate concern of CO production as a direct consequence. Instead, they represent broader issues that might arise under certain conditions of negative pressure but are not as clear-cut or immediate as the risk of carbon monoxide generation in improperly vented systems. This is particularly important in understanding building performance and indoor air quality, as safety is a paramount concern when it comes to the effects of combustion appliances on occupants.