One of our Dorm buildings has a power factor of 80 during the night and drops below 65 in the mornings. We think that the old ballast with the t12 may contribute to this issue. Does anyone know if changing these would make a big difference? Also, do you have any other Ideas on correcting this problem?
I don't think so. Ballasts used in commercial buildings are high power factor and they have a power factor of >0.90.
What are the harmonics? Whats the power factor on other buildings you're maintaining like? There are not many appliances in dorm rooms, but you can bet each occupant has their own computer.
I would guess rectifier front end loads. Computers and TV and I would guess that you have a very high odd harmonics. I'm sure the students leave their computer on 24/7 since they're not paying the power bill and I think that represents a significant portion of the power consumption. Power factor reduction caused by non linear loads can not be corrected with devices that apply corrective kVArs like capacitor banks or synchronous motors.
Given one or two computers per room with a PF of about 0.55 to 0.60, 200W/400VA per occupied room is a fairly good estimate of rectifier front end loads.
When they're back in their room and have their lights on and start using the laundry room, the high power factor ballasts and resistive clothes dryer increases the power factor, because the proportion of technology load relative to building demand is smaller.
What's the kVA demand at night vs morning?
What kind of read outs do you get during breaks when residents are away?
If you identify plug-in loads in rooms as the cause, I would work with the management to encourage residents to avoid leaving their computers on 24/7.