Building Pressurization with Airflow Control

Building Pressurization is a major part of having a healthy, efficient, better performing building.
Maintaining a net positive or neutral building pressure helps ensure that outdoor contaminants
and moisture do not enter the building through the building envelope and other unintended
locations. Additional benefits include staying compliant with the Americans with Disabilities Act
which requires a certain threshold for door opening force, helping to ensure occupant#s thermal
comfort, controlling isolation zones and preventing wasted energy.
Measuring and controlling airflows is the best method for ensuring compliance with codes and
standards forminimum ventilation and controlling building pressure. Introducing more air into
the building than what is exhausted through the relief air and/or bathroom exhaust is the key to
maintaining a positive building. The main alternative, using a building pressure transducer, has
issues like wind effects on the outdoor reference, locating the indoor reference, pressure
interactions when multipleAHU#s, zones and transducers are involved.
Control diagrams are presented that show how to use airflow measurement to control airflows in
the building.
The links between airflow measurement, building pressurization and LEED 2009 Credits are
discussed. Discussion of the ASHRAE standards are included.
Using airflow monitors to control building pressurization requires accurate, stable devices. The list
of things to consider when specifying airflow monitors is presented.