Air conditioning calculation

[cubdh]

Hi, I have the 2008 NEC code book.
I have an office and a hospital which has a certian amount of AC tonnage.

When choosing a transformer for these, the NEC tells me how to calculate the lighting factor, the receptacle factor, but i cannot find the AC factor for these in the book.
I only find that in dwellings, the AC is at 100% of the rating

I dont want it in terms of VA/sq ft.
does anyone know where i can find the factors in the NEC for non- dwellings such as office and hospitals??

I am guessing it would be 100% but maybe not because i know the capacity might be overkill??? Or i am just guessing it might be the 6VA/sq ft. or 100%, if the 100% of nameplate rating is less than then 6VA/sq ft.
That is just a guess

Any help would be appreciated

Thanks

 

[topgone]

Demand factors

Demand factors

Capacity design for transformers and main cables supplying electrical equipment significantly depends on the demand factor, which varies with the load and operation patterns of the equipment. If the demand factor is unknown, the demand factors defined in some design standards has often been used (demand factor tables), which, as you said, you can't find as of now.
Keep in mind that the demand factor depends on the use and operation pattern of the equipment. That means, you need to know the maximum HVAC system consumption for a period and divide it by the maximum HVAC system consumption assuming all HVAC components are ran at the same time for the same period of time (it may not be the same time interval). That will be your demand factor.
In many cases, the capacities of electrical installations are designed larger because of the combined effects produced by specific application situations. That is, the capacities of electrical installations tend to be designed on the safe side in case of the future expansion of load equipment.
To make the story shorter, any overcapacity you may do, should put you on the safe side of the design situation. You may say it's an overkill, but think about taking all the hassles of redoing a job that should have been easy using your common sense.