I'm modeling a 6-story hotel. Baseline is PTAC. I set up the baseline to
have outside air at each PTAC with the fans running continuously. The
Proposed Case is watersource heat pumps. Outside air is through dedicated
units at the corridors. I've set (at least I am trying to set) the heat
pump fans to cycle on the thermostat. I've set the heat pumps to 0 CFM
outside air. When I run the two models, the ventilation fan energy is
nearly identical. I expected to see some fan energy savings with the heat
pump fans cycling. When I look at the detailed output report, the SS-C for
the heat pumps seems like it is showing fans running continuously. I say
this because the "hours floating" are less than the "hours fans on", and the
"hours fans cycle on" is zero. This implies to me that the fans are running
continuously. However, when I look at the reports that show fan energy
consumption, the months with floating hours show significantly reduced fan
energy, which to me implies that they are cycling. The total fan kW in the
proposed model is about twice that of the baseline, so from that standpoint
maybe the kWh being about the same is correct. I set up the PTAC units at
.3 watts/CFM per ASHRAE. I set up the heat pumps fans with a static
pressure input from the design drawings rather than input the fan motor
sizes (used .2" w.g. Static).

Also, my space cooling energy is higher in the proposed case than the
baseline, even though the envelope is better, the watersource heat pumps
have a lower EIR and the design lighting power density is 30% lower. I
haven't dug into that yet because I'm still trying to verify my fan cycling
is working.

My questions are, can anyone explain how to interpret the SS-C reports in
terms of fan cycling, or point me to which report I should look to really
verify the fans are cycling? And anyone modeled a similar comparison, and
if so, what type of results did you get with respect to cooling energy and
fan power consumption? Seems like I should be seeing savings.