IAQ Building Education and Assessment Model (I-BEAM)
Visual Reference Modules
Mouse over the animated pictures below to see messages which are referenced in more detail below.
Pressure relationships between rooms is designated at the bottom of each room (with a plus for positive and minus for negative pressure).
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| 1. Normal Flows with Exhaust Fan |
- [GARAGE] Exhaust fans in the garage are fully operational during significant use periods to insure that all garage contaminants are fully exhausted to the outside. Exhaust fans may be in partial use during slack periods. Sometimes carbon monoxide sensors are used to control fan operations. In any case, the garage should be maintained UNDER NEGATIVE PRESSURE relative to the building at all times.
- [VESTIBULE] The vestibule is acting as a buffer between the garage and the occupied spaces in the building. It may be subject to slight depressurization because of a stack effect up the elevator shaft and stairwell which draws some air, and because of the exhaust fans in the garage. However, some ventilation air is supplied through a supply air duct to neutralize this effect. Some air flows up the elevator and stairwell, and some flows from the vestibule into the garage. But garage pollutants do not enter the vestibule.
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| 2. Inadequate Pressure Control |
- [GARAGE] Exhaust fans are not operating, and a strong wind at the garage entrance pressurizes the garage. This allows garage contaminants to enter the vestibule.
- [VESTIBULE] Garage contaminants are entering the vestibule. At the same time, the stack effect is drawing a column of air up the elevator shaft and the stairwell and into the building. Building occupants are subject to carbon monoxide and other garage contaminants. GARAGE FANS SHOULD BE OPERATING DURING HEAVY USE PERIODS. Pressure relationships between the garage and the vestibule should be checked under different operating conditions.
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