Hello,

We are designing a new lab building utilizing low-flow exhaust fume hoods that are able to maintain a sash face velocity of 70 fpm, as opposed to the industry standard of 100 fpm. Due to the lower velocity, these hoods lead to 30% less fume hood exhaust than a traditional 100 fpm hood. These are not industry-standard, and we have had discussions with the Environmental Health and Safety department in an effort to push their standard for this project while ensuring they are comfortable. Since this system is not industry-standard, and is more expensive than a traditional system, it is reasonable to take energy savings credit for the reduced exhaust/makeup requirements. The proposed model should operate with the exhaust (and corresponding makeup air) allowed by the low-flow hoods, while the baseline should operate with the exhaust and makeup air required for the industry-standard 100 fpm hood. Has anyone here done this, and would this need to be an exceptional calc?

Thanks!