I have a real nice equest model of a hotel that looks great, produces
very believable annual energy profiles BUT has about 75% of zones listed
as many thousands of unmet load hours, both cooling and heating.
We are using mostly PTACs with a few fan coil units (HW/DX).
Any obvious reasons why this many unmet load hours is happening?
Must be something simple but I am new to this program and cannot find it
Thanks in advance for any assistance!
Peter LeMessurier, P.E.
Try making your thermostats reverse acting and increase the deadband
between heating and cooling.
And send us the .INP and .PD2 if you would like us to review your
inputs.
We are all professional here, so it is just an offer to help.
John R. Aulbach, PE, CEM
Peter,
Something else that can cause a lot of unmet load hours is too much of a nighttime setback. If it takes a long time for the system to warm-up or cool-down in the morning, that time can really add up.
Also check to make sure that the PTACs are allowed to "cycle at night." If the heating and cooling equipment is not allowed to run during unoccupied mode, that can cause a long morning warm-up or cool-down.
Another thing to check is the location of the thermostat for zones with different load characteristics. For example, a storage room next to an occupied room might be on the same temperature control zone, but if the thermostat is in the main room, the storage room may not get what it needs and have unmet load hours.
Keith Swartz, P.E., LEED AP