Fume Hood Ventilation

The Jacobsen Lab in Harvard University's Mallinckrodt Building uses Mott variable volume fume hoods to help save energy by reducing the volume of air being exhausted (and as a result reducing the fresh air brought into the space that needs to be heated or cooled) as the hood sash is closed. The hoods are saving additional energy by having air movement with 80 feet per minute face velocity entering the hood, reduced from the typical 100 fpm or higher in most hoods (the hood was tested and demonstrated safe containment at 60 fpm). To ensure occupant safety, each hood has a digital display indicating the face velocity, with an alarm sounding if it were to go too low and a purge button that allows the occupant to increase volume to 300% of normal if there is a spill. Occupants are educated about the hoods' operations and then provided with large digital displays at the entrance to the lab that indicate total volume of air being exhausted in cubic feet per minute. Lab users know what the volume should be if all hoods are closed and can quickly assess whether a hood was left open and is unnecessarily wasting energy (as Philip Kreycik is doing in the pictures above and below). The newly renovated Jacobsen lab is pursuing a Gold rating from the US Green Building Council's Commercial Interior rating system and has integrated a number of sustainable design elements into the project.