Consumption of split a/c

Best sources that come to mind - you have some searching to do

www.eere.energy.gov/

www.energy.gov

www.eia.doe.gov

Mike,Insulation quality is only one of the heat generating factors which have to be considered. In order to maintain a set temperature in a space, you have to calculate the incoming heat (outgoing in winter) to the area. Then install an a/c unit of similar capacity to your calculation. The unit will have a rated output in cooling and heating in BTU's or Kw. It will also have an electrical input in Kw. You then calculate the input rating by the hours of operation which will give you Kw/hours, which can then be multiplied by your purchase price of electricity to give you an indication of operting cost. P.S. A good HVAC engineer can acurately calculate your cooling/heating requirement.

Hope this helps

Phil

Hey Mike,

The answer to this question is largely dependant upon the SEER (Seasonal Energy Efficiency Rating) of the unit itself. For example, the average 12.0 SEER unit would have a higher power demand than a 16.0 SEER, and thus would also use more energy that the higher rated unit. Also, most recent improvements in SEER have come through changes in operational control of the fan coil unit inside the conditioned space rather than true reduction in compressor power.

One can reduce the compressor's energy/power consumption by reducing the condensing temperature (and thus the compressor's discharge pressure, which are directly proportional to each other) by such means as condensing in the earth or a cool water reservoir instead of ambient air, and these are typically required considerations at the design stage. Such an earth condenser approach can have SEER values of 18.0 or better.

Assuming your condensing temperature (Amb + 15°F) is ≤ 120°F then you can use a rule of thumb of 1 kWh per ton of AC size. Consider an average electrical: "per ton of AC" value to be 5 amps at 240 VAC (and at .9 PF & .9 Eff of the compressor motor, not the whole system, you get a .81 multiplier) and you come up with ~984 watts/nominal ton of refrigeration. This value will change based on when in the run cycle you measure it. Start up has higher energy draw rate than near the end of the run cycle.

I will ask my question once more.

what do you suppose the AVERAGE value for "compressor on" per hour would be assuming that a good HVAC engineer designed the split unit.

this is a STATISTICAL question, not a computational one. it is to be used for statistical assumptions used in an institution with hundreds of split units, each carefully, even loveingly sized for the room.

that is all...