Hello everyone,
I am modeling a baseline system No. 6 - Packaged VAV with PFP boxes (ASHRAE 90.1-2010) and I would like to confirm some things:
1 - Efficiency for the baseline DX cooling coils is obtained from table 6.8.1A --> Air conditioners, Air cooled based on my autosized capacity, correct?
Moreover, according to G.3.1.1 exception (b) : "If the baseline HVAC system type is 5, 6, 7, 8, 9, or 10 use separate single-zone systems conforming with the requirements of System 3 or System 4 (depending on building heating source) for any spaces that have occupancy or process loads or schedules that differ significantly from the rest of the building. Peak thermal loads that differ by 10 Btu/h⋅ft2 or more from the average of other spaces served by the system or schedules that differ by more than 40 equivalent fullload hours per week from other spaces served by the system are considered to differ significantly."
In my project I have 3 spaces that I believe that must follow this exception, namely a gymnasium, a cafeteria area and a server room, which I modeled in the baseline using a single system 4 – PSZ-HP for each (areas with very different schedules, occupation densities and loads). My questions are:
1 – Where do I get (on Table 6.8.1 ? ) the baseline efficiencies for these systems? I believe that for the server room I need to use table 6.8.1K but I do not understand the concept of “SCOP-127 efficiency”, as Energy plus only allows me to input a gross rated COP. And what about for the system serving the gym and cafeteria areas, wich section of table 6.8.1 should I use?
2 – I also would like to confirm that for system 4 we still calculate fan powers by using Pfan = bhp*746/motor eff and using the CAV formula (CFMs*0.00094+A).
Thank you in advance for your help.
