90.1 Reference building basic PSZ questions

edit

Thanks for your comments! A follow-up to #4. The formula in 6.5.3.1.1.A requires "CFMs".

How do I get CFM of the auto-sized equipment? Do I take the output from the SIM file after I run a simulation? Or do I follow G3.1.2.9.1? If so, how do I go about doing that?

Appreciate it!

I would just look at the SVA report when you do a preliminary run. You can manually calculate it : cooling capacities / (1.08) ( 20 degrees delta T) to get your supply cfm.

Thanks again, really appreciate your clarity. I want to push you a bit further in this. If I make an hourly report of my systems, I can see their auto-sized cooling capacities and CFMs. If I use your formula above (standard heat formula), I get a different CFM from the cooling capacity.

Do I enter this CFM (the one I manually calculated) in the Air-side HVAC tab for my systems?

There are several factors affecting the auto-sizing in the model such as the Design Ventilation Rates, minimum flow rate (0.4 cfm/sf), and the sizing factor depend on whether you specified it. I'm using 20 delta degrees based on G3.1.2.8 in the standards. I would use the eQuest autosize. You're just using the supply CFM to calculate the fan power or rate W/cfm, right? Additional references here and here for other opinions.

You are awesome! Yes I'm trying to calculate the W/cfm <-- what cfm do you use? Autosized or manually calculated?

Thanks for the links too