Estimate the annual electricity cost associated with running your commercial kitchen ventilation system fans and conditioning the makeup air. This calculator helps building owners and operators understand the energy impact of their exhaust and ventilation systems.

How It Works

Fan Motor Power Calculation:
The fan power requirement is calculated using the standard fan law formula:

Motor Power (kW) = (CFM × Static Pressure) / (6356 × Efficiency)

Where:

  • CFM: Total airflow moved by the fan system
  • Static Pressure (in. w.g.): Resistance the fan must overcome (ductwork, filters, hood)
  • 6356: Conversion constant for fan power
  • Efficiency: Combined motor and fan efficiency (decimal, typically 0.60-0.70)

Annual Cost:

Annual Cost = Motor Power (kW) × Annual Hours × Electricity Rate ($/kWh)
Annual Hours = Hours Per Day × Days Per Year

Typical Values:

  • Exhaust fans: 0.5-3.0 in. w.g. static pressure
  • Makeup air fans: 0.5-1.5 in. w.g. static pressure
  • Combined motor/fan efficiency: 50-75%
  • Commercial kitchen operation: 8-16 hours/day, 250-365 days/year

Fan Motor Power Calculation:
The fan power requirement is calculated using the standard fan law formula:

Motor Power (kW) = (CFM × Static Pressure) / (6356 × Efficiency)

Where:

  • CFM: Total airflow moved by the fan system
  • Static Pressure (in. w.g.): Resistance the fan must overcome (ductwork, filters, hood)
  • 6356: Conversion constant for fan power
  • Efficiency: Combined motor and fan efficiency (decimal, typically 0.60-0.70)

Annual Cost:

Annual Cost = Motor Power (kW) × Annual Hours × Electricity Rate ($/kWh)
Annual Hours = Hours Per Day × Days Per Year

Typical Values:

  • Exhaust fans: 0.5-3.0 in. w.g. static pressure
  • Makeup air fans: 0.5-1.5 in. w.g. static pressure
  • Combined motor/fan efficiency: 50-75%
  • Commercial kitchen operation: 8-16 hours/day, 250-365 days/year

FAQ

Q: How much does it cost to run a kitchen exhaust fan?
A: A typical 5,000 CFM exhaust fan running 10 hours/day costs approximately ,000-3,000 per year depending on local electricity rates.

Q: What is static pressure in ventilation?
A: Static pressure is the resistance the fan must overcome. Higher static pressure means more energy consumption.

Q: Can I reduce ventilation energy costs?
A: Yes, use variable frequency drives (VFDs), demand-controlled ventilation, and high-efficiency motors.

References

  • ASHRAE Handbook — HVAC Systems and Equipment (Chapter 21: Duct Design)
  • AMCA International — Fan Application Manual
  • SMACNA — HVAC Systems Duct Design Manual
  • DOE Commercial Building Energy Codes