joesinger12
commented
3 years ago CEC - I’m almost inclined to not allow the modeling of a process space in core and shell because if the designer knows it’s a process space, then theoretically the HVAC could be designed for it. If they know a space will be a future commercial kitchen (or computer room or lab) they could model it as Unleased Tenant Area in the core and shell run to capture the shell. And since what you propose below would be proposed=baseline, it wouldn’t affect the compliance. Or is that information necessary for some mechanics in E+?
Original comment by: joesinger12
DR - I’m reviewing a few things I fixed in the core and shell rules, and have a question on default behavior for shell ‘Commercial Kitchen’ spaces.
Currently, If the user identifies the space as a “process” space, i.e. indicating it would fall under 140.9(b), we would model it as such using the use- defined vent/exhaust flows but baseline assumptions for the HVAC system type/performance. A few questions:
• By definition, a shell space is undesigned, so should we allow modeling of user defined kitchen vent/exhaust flows for these spaces? We often see shell spaces that are intended to be for a restaurant, and are built with shaft/ducting to exterior installed for a future Type I/II hoods, so there is typically some idea of what the possible kitchen exhaust would be. However, I’m interested to hear if you all think we should model whatever the user specifies; keeping in mind it would be proposed = baseline.
• If we do continue to allow this, should the default kitchen HVAC system OA be the code minimum for the space (0.15 cfm/ft2), or match the kitchen exhaust exhaust rate? 140.9(b)2 limits conditioning make-up air to hood flow minus available transfer air, which in a NewMechanical case, is up to the designer to figure out. The current default behavior for 2019.1.3 core kitchen spaces is to use user inputs for OA/exhaust flows, with a default to code minimums flows for both; the default does not include any logic to ensure there is sufficient make-up OA (either direct to zone or by transfer from other zones). However, I could easily revise the default behavior to track the exhaust flow, which would be worst-case in terms of energy. Ultimately, the intent would be proposed = baseline, so not sure we need to get too detailed on this.
Reported by: joesinger12
Original Ticket: cbecc-com/tickets/3225