How do I work out an electrical, estimated load calculation?
First, figure the lighting load. Assuming all the lights in the building are on, how much power do they draw? (Use the wattage figures on the bulbs; if the fixtures are fluorescent, add 20% for the ballast loss.) Now add the computers; there should be rating plates on all the computer gear which give some idea of how much power they draw. (If you can’t find this, use 250 watts per computer, which should be close enough.) Add this up and set the number aside. Now, figure the load for air conditioning: take the electrical load number, add 200 watts per person in the building, and allow 0.3 watts of air conditioning power per watt. Now add enough to this to take care of the heat coming through the walls (there are web sites that can help), convert wall and ceiling BTU/h to watts by multiplying by 0.293, and divide this by 2.5 because an air conditioner can move several watts of heat per watt of input power. (You can use the EER of the A/C to get a more precise value.) Add this number of w
