A facility can use the same number of kilowatt-hours in two months and receive different electric bills. The reason may be demand: how much power it draws at once. For many commercial tariffs, the highest measured interval in a billing period sets a demand charge. One overlap between major loads can therefore matter long after the equipment cycles off.
The first step is to separate energy from demand. Energy, measured in kilowatt-hours (kWh), accumulates over time. Demand, measured in kilowatts (kW), describes the average rate of consumption during a defined interval. If a facility uses 862.5 kWh during a 15-minute interval, its average demand for that interval is 862.5 ÷ 0.25 = 3,450 kW. The relevant interval may be 15, 30, or 60 minutes depending on the meter and tariff; match your analysis to the utility’s billing definition.
What could one peak cost?
Consider an illustrative hospital whose usual high demand is 2,800 kW. At 2:15 p.m., cooling equipment, air handlers, and another large load operate together. The billed peak reaches 3,450 kW. At a hypothetical non-coincident demand rate of $18 per kW, the difference is:
(3,450 − 2,800) kW × $18/kW = $11,700 for that billing month.
That number is the potential difference in one demand-charge component if the facility could keep its billing peak at or below 2,800 kW. It is not a guaranteed saving. The facility may have another near-peak interval, a time-of-use demand charge, a minimum bill, or a ratchet based on earlier months. Changes to equipment scheduling can also alter kWh charges. Read the actual tariff and bill before assigning a value to an intervention.
A demand ratchet can make a peak especially consequential: some tariffs determine billed demand using the greater of the current peak and a percentage of a prior peak. Other charges depend on the facility’s load during a grid or system peak rather than its own highest interval. These mechanisms require different strategies. Shifting a chiller start may lower a facility’s monthly maximum without changing its contribution during the utility’s system peak.
Investigate the peak before changing operations
Pull at least a year of utility bills and interval data if available. Confirm the meter, time zone, billing start and end dates, interval length, and whether the bill reports actual or ratcheted demand. Then examine the ten highest intervals, not just the single maximum. Are they clustered on hot afternoons, Monday mornings, or after planned maintenance?
Overlay the building total with the relevant submeters and equipment status. A 650-kW rise could be a predictable seasonal pattern, a startup sequence, a one-time test, or an instrumentation problem. Look at chillers and cooling towers, air handlers, electric heat, imaging or process loads, EV charging, and central plant equipment. If onsite generation is involved, distinguish gross building load from utility import demand.
One useful measure is load factor: monthly kWh divided by (monthly peak kW × hours in the billing period). A low load factor may indicate that a facility pays for a high peak it uses only briefly. It is a clue for investigation, not proof that the peak can safely be removed.
Choose the right action for the cause
If several discretionary loads start together, stagger their start times. If EV charging overlaps a predictable facility peak, apply managed charging within vehicle readiness limits. If pre-cooling or thermal storage is feasible, evaluate whether it shifts demand without causing a rebound peak. A battery can discharge across a billing interval, but its economics must include charging, efficiency losses, controls, and all tariff components. Demand response is a separate opportunity that may compensate a facility for reducing load during called events.
For critical facilities, operational constraints come first. A hospital should not curtail essential ventilation, clinical equipment, or required redundancy to improve a billing metric. Set a demand target around controllable loads, test the sequence, and compare future billing peaks with a suitable weather and operations baseline.
Where NovaVue fits
NovaVue brings interval and device data into a common view, supports energy and capacity dashboards, and provides reporting that can help teams locate when a peak occurred and examine the associated equipment loads. Its estimated utility cost report can support an internal screening view; the utility tariff and invoice remain the authority for billed charges. The value is a repeatable process: find the peak, identify its contributors, take a safe action, and verify the result.
Read next: Part 2 builds an energy balance so the loads behind both monthly consumption and short peaks become visible.