Peak Demand Calculator Formula

Understand the math behind the peak demand calculator. Each variable explained with a worked example.

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Formulas Used

Peak Demand

peak_demand = peak_kw

Monthly Demand Charge

monthly_charge = peak_kw * demand_rate

Annual Demand Charge

annual_charge = peak_kw * demand_rate * 12

Demand Factor

pct_of_connected = demand_factor

Variables

VariableDescriptionDefault
total_connected_kwTotal Connected Load(kW)50
demand_factorDemand Factor(%)70
demand_rateDemand Charge Rate(USD/kW)12
peak_kwDerived value= total_connected_kw * demand_factor / 100calculated

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.

total_connected_kw = 50demand_factor = 70demand_rate = 12
  1. 01Peak demand: 50 * 0.70 = 35 kW
  2. 02Monthly charge: 35 * $12 = $420
  3. 03Annual charge: $420 * 12 = $5,040

Ready to run the numbers?

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