From the numbers you gave and seeing that you have reduced lighting power use and taken away some electric stoves, it looks to me as if you can safely allow each tenant one 6000 BTU air conditioner.
You can take applications for this summer and see how things go, power usage wise.
If not all tenants put in air conditioners and pay you the energy surcharge you specify, you should still collect data and make allowance for each apartment to have one air conditioner before granting permission for second air conditioners.
"Demand" refers to the number of amperes (not kilowatt hours) being drawn at any moment. If you do upgrade your service it is possible that you would have to go into a different rate category that includes a "demand charge" based on the highest spike in demand each month (or maybe the highest 4 or 5 spikes, one each week) even if the spike occurred for only fifteen seconds. The demand charge is in addition to the other charges on your bill.
Thanks for that, and I agree that slowly adding machines and monitoring the results is the best route to take.
I do not anticipate a huge demand, and indeed aside from the five that were installed last year no one has requested permission. So notwithstanding that a warmer than normal summer is predicted I expect that only one or two more would be added this year, which would permit me to gradually collect more and better data.
I appreciate the difference between usage and demand. Indeed, when I purchased the property in 1997 our utility charged a separate demand charge to its commercial accounts. However, although this property ought to have been treated as a commercial account it had been misclassified as residential (and therefore not subject to a demand charge) so part of my motivation to be rid of electric stoves was in anticipation of the utility correcting this error. Of course, had I been paying the demand charge I would have been aware of the peak demand.
Subsequently the utility went to time-of-use pricing and discountinued the demand charge, and now charges residential and small commercial users the same rates.
Nonetheless, I assume that peak demand is unlikely to be more than double the average hourly demand, particularly when the number I’ve been referring to is the highest hourly usage ever recorded in the summer. That is, if our hourly usage has never topped 6.75 KW (or about 60 amps) I’ll assume that at no time during that hour… between 9:00 pm and 10:00 pm… would demand have exceeded 120 amps. Five more air conditioners would add 20 amps to that, even if they were all running at the same time.
I still have not made it down to the propert to inspect the service properly but may have a chance this weekend.