Hello All,

I am working on an energy model for a building which has labs and office spaces. For the lab spaces, we are required by the owner EHS to supply 8 ACH of ventilation air when occupied and drop to 4 ACH during unoccupied hours. The site does not allow recirculation between labs and therefore would typically be conditioned by 100% OA units. In our proposed model, we are utilizing fan coil units to recirculate the air for each individual lab and have a 100% OA unit providing the ventilation. However in the baseline model, it seems that the notes under ASHRAE 90.1 Table G3.1.1A would call for a single unit serving all of these labs. Since they cannot be recirculating between one another, the unit would have to be 100% OA. This results in massive savings which was the design intent.

  1. Is my assumption that the lab unit would have to be 100% OA in the baseline correct? The minimum ventilation is still the same between the baseline and the proposed.
  2. ASHRAE 90.1 baseline calls for me to have 1 unit per floor. Would these lab spaces(which are on all 3 floors of the building) also be broken down by floor or would they all be assigned to one unit? I currently have the baseline broken down to 3 recirculating office units, and 3 100% OA lab units.
  3. For the baseline model would I assign my lab support spaces (storage, lab corridors) to the same system that my office area is assigned to? It would be preferred that these support spaces be 100% OA since a spill in these areas could contaminate the whole building if it were recirculated.