Rating System

LEED BD+C: New Construction, LEED O+M: Existing Buildings, LEED ID+C: Commercial Interiors, LEED BD+C: Core and Shell, LEED BD+C: Schools

Rating System Version

v3 - LEED 2009, v3 - LEED 2008, v2 - Schools 2007, v2 - LEED 2.2, v2 - LEED 2.0

Inquiry

Our facility\'s HVAC system consists of high-efficiency, packaged, direct-fired \'Cambridge\' Unit heaters, passive intake louvers and powered exhaust fans. There is no ducted air distribution system. We propose to install airflow devices at each of the exhaust fans, instead of the intakes. We feel that this makes sense because the exhaust fans will always be \'on\', whereas the \'Cambridge\' Unit heaters will not, when heat is not required. Furthermore, it follows that measuring air being discharged from the building would be equivalent to measuring fresh air being induced into the building, since fresh air will necessarily replace exhaust air in an equal amount. Considering that this building type can be somewhat porous (when the loading dock doors are open) and, per industry norms, always under negative pressurization, it is most logical to measure air where it is being exhausted (since this necessarily will happen in a controlled way at specific locations), rather than where it is being brought in (which would be variable and would happen throughout the building). In accordance with the requirements of this credit, the airflow metering devices will be tied to alarms to alert building occupants if the prescribed airflow pattern ever fails. Finally, the minimum outside air rate (OAR) will be considerably higher than the minimum prescribed by ASHRAE 62.1-2004. The standard prescribes a minimum OAR of 0.06 cfm/sf for this building type. The specified design OAR of 3 complete air changes per 8 hour interval exceeds this minimum by a factor of 3.66. This will also allow us to achieve EQc2 - Increased Ventilation. Is this allowed?