When Outside Air (OSA) bring into the building by economizer, space would be pressurized. in order to balance the space pressure, can either use a power exhaust to discharge the equal amount of the incoming outside air to outside or just by installing a barometer damper on the exterior wall to relief the excessive air caused by bringing outside air to the space.
A Barometric Relief damper consist of a few hinged lightweight blades which can allow the air in only one direction such a way that the excessive space air can discharge to the outside in case of space over pressurization but outside air cannot hypothetically enter into the building through the relief blades.
