What is Demand Charge

waterfall

My sister has a condo unit whose building used to have Demand Charge of only 40 Base in 2010. Then suddently the Base became 115 in 2011 up to now. Does anyone have an idea why? The building admin didn't understand why because they are not technical people. Did the power utility increase the power lines levels outside or did they adjust the load or something. What could they have possibly done to make such big Demand Changes? There is no additional load in the building. No one has a clue. Electricity has jump to twice. Why did Demand Charge jumped from 40 to 115 all of a sudden? Thanks.

jambaugh

Try asking google:
https://www.google.com/search?q=dema...on+electricity
(or did you just want to vent your spleen?)

Windadct

IN short - demand charge are what the utility bills you to be able to have the capacity to meet your highest demand. I believe many systems will monitor for the highest usage over a 15 minute period for the whole month. In a condo - if everyone turns their AC on at 5:00PM - I'll bet that is the peak they are seeing.
For example - if you added setback thermostats to all of the condo units - and programmed them the same way (5:00PM )- you will get hammered for a demand charge.

waterfall

What does the utility company usually do to increase one's demand requirement.. do they put higher power lines to the building or do they just replace the meter?

Windadct

Hello Waterfall - Like I said, the 5:00PM surge is tough, so the whole system has to be sized to meet the peak demand. The way you phrase your question - I am not sure what you mean. The Utility does not increase the customer demand requirement, but the utility has to be able to effectively supply power for everyone - so they have to have supply ( generation) on line AND the whole system has to be able to deliver the power.