How demand is measured
Your TDU records demand in 15-minute intervals. The single highest interval reading in the billing month sets your demand charge for that month, multiplied by the demand rate (typically $5-$25/kW depending on TDU and rate class).
Why demand charges hurt
A facility that runs steady at 50 kW most of the time but peaks at 200 kW for one 15-minute window during a startup gets charged at 200 kW. On a $10/kW demand rate, that single peak adds $1,500 to the bill — even though average usage was 50 kW.
How to manage demand
Peak shaving (shifting non-essential loads off-peak), demand controllers (automated load curtailment), battery storage (discharge during projected peaks), and process scheduling (stagger HVAC and equipment startups) are the big four. Many large commercial accounts hire energy management consultants for this specifically.
