Demand Charge & TOU Bill Estimator
Commercial bills have two meters in one: energy (kWh) and demand (your single highest kW). See how the pieces combine — and what shaving the peak is worth.
peak kW × $/kW
TOU-weighted
demand + energy
per year at scenario
Results update live as you type. For planning and field-check estimates — always verify against applicable standards and equipment ratings.
The bill inside the bill
Commercial and industrial tariffs bill two different things. Energy charges pay for the kWh you consume, usually split into on-peak and off-peak time-of-use windows. Demand charges pay for capacity: the utility takes your single highest average draw over any 15-minute interval in the month and multiplies it by a $/kW rate — commonly $10–30. One clumsy half-hour, three motors starting while the HVAC runs flat out, can set the demand charge for the entire month.
For many facilities, demand is 30–50% of the bill, which makes peak management the highest-leverage efficiency work available. The playbook, in rising order of capital: stagger equipment starts and interlock large loads so they can't coincide; shift flexible processes into off-peak windows; add controls that monitor interval data and shed load as the building approaches a new peak; and finally, batteries that discharge briefly during peak events — an application where storage often pays back faster than in any residential use.
The starting point is your interval data — most utilities provide 15-minute load profiles on request. Knowing exactly when and why your peaks occur turns demand charges from a mystery line item into a controllable one, and it's the first artifact to bring to any tariff-optimization or storage conversation.