Peak Demand Calculator Formula
Understand the math behind the peak demand calculator. Each variable explained with a worked example.
Formulas Used
Peak Demand
peak_demand = peak_kwMonthly Demand Charge
monthly_charge = peak_kw * demand_rateAnnual Demand Charge
annual_charge = peak_kw * demand_rate * 12Demand Factor
pct_of_connected = demand_factorVariables
| Variable | Description | Default |
|---|---|---|
total_connected_kw | Total Connected Load(kW) | 50 |
demand_factor | Demand Factor(%) | 70 |
demand_rate | Demand Charge Rate(USD/kW) | 12 |
peak_kw | Derived value= total_connected_kw * demand_factor / 100 | calculated |
How It Works
How to Calculate Peak Demand
Peak demand is the maximum power draw at any point, measured in kilowatts (kW).
Formula
Peak Demand (kW) = Connected Load * Demand Factor
Monthly Demand Charge = Peak kW * Rate per kW
Demand factor accounts for the fact that not all equipment runs simultaneously. Typical factors are 60-80% for commercial buildings.
Worked Example
A building with 50 kW total connected load, 70% demand factor, and $12/kW demand charge.
- 01Peak demand: 50 * 0.70 = 35 kW
- 02Monthly charge: 35 * $12 = $420
- 03Annual charge: $420 * 12 = $5,040
Frequently Asked Questions
What is peak demand?
Peak demand is the highest rate of electricity consumption at any moment, measured in kilowatts. Utilities charge for peak demand because they must maintain enough generation capacity to meet it.
How can I reduce peak demand?
Stagger equipment start times, use battery storage for peak shaving, shift loads to off-peak hours, and improve equipment efficiency to reduce simultaneous power draw.
What is a demand factor?
Demand factor is the ratio of actual peak demand to total connected load. It is always less than 100% because not all equipment runs at full power simultaneously.
Ready to run the numbers?
Open Peak Demand Calculator