Jump to main content.

The Lean and Energy Toolkit

« Back to Toolkit Homepage

Appendix C: Energy Conversion Resources and Rules of Thumb for Estimating Energy Cost Savings

 

Energy Metrics Conversion Table
Energy Unit Energy Equivalent
1 kilowatt-hour (kWh) 3,412 British Thermal Unit (Btu)
1 Therm 100,000 Btu
1 cubic foot of Natural Gas 1,000 Btu*
1 gallon #2 Oil 140,000 Btu*
1 gallon #4 Oil 144,000 Btu*
1 gallon #6 Oil 152,000 Btu*
1 gallon propane 91,600 Btu*
1 ton coal 28,000,000 Btu*
1 boiler horsepower (hp) 9.81 kW
1 horsepower 746 W
1 ton refrigeration 12,000 Btu/hr

Rules Of Thumb for Estimating Energy Cost Savings(1)

The following rules of thumb are a useful resource for understanding the potential cost savings of energy conservation and waste minimization efforts.

Cost Savings are Based on the Following Assumptions
  1. High pressure steam leaks (125 pounds per square inch gauge [psig]) = $150 to $500 per leak per shift per year.
  2. Low pressure steam leaks (15 psig) = $30 to $110 per leak per shift per year.
  3. Compressed air leaks (100 psig) = $30 to $90 per leak per shift per year.
  4. Submetering an evaporative cooling tower can result in sewage treatment savings (assume 1 percent water loss to evaporation), including:
    • $9 per ton per shift per year based on size of tower in tons.
    • $3 per gallons per minute (gpm) per shift per year based on gpm of water through tower.
  5. Typical motor operating cost = $62 per horsepower (hp) per shift per year.
  6. High pressure compressed air system reduction (assume 100 psig system):
  7. Cost of heat lost through hot, uninsulated pipes:
    • 25 psig steam: $375 per 100 feet per shift per year.
    • 50 psig steam: $430 per 100 feet per shift per year.
    • 75 psig steam: $480 per 100 feet per shift per year.
    • 100 psig steam: $515 per 100 feet per shift per year.
  8. Installing insulation can reduce 90 percent heat loss on a hot, uninsulated surface.
  9. Average heating and cooling costs:

      Comfort Cooling Costs (per ft2 / year) Comfort Heating Costs (per ft2 / year)
    Michigan $0.12 $0.26
    Tennessee $0.30 $0.35
    Texas $0.52 $0.24

  10. Combustion efficiency of a typical boiler or furnace is 80 percent.
  11. Upgrading to an energy-efficient motor can result in savings of about 5 percent over the operating costs of a standard motor. A typical standard motor has an efficiency of 90 percent.
  12. Benefit of fuel switching:
  13. Cost savings for demand reduction (or load shifting):
    • Move operating shift to off-peak times: $75 per hp per year.
    • Move “other electric equipment” to off-peak: $120 per kW per year.
Footnotes

1. Adapted from: Office of Industrial Productivity & Energy Assessment. Useful Rules of Thumb for Energy Conservation and Waste Minimization. Rutgers, the State University of New Jersey. July 9, 1996.
 

« Appendix B | Toolkit Homepage »

Lean Home | Top of Page

Local Navigation

Jump to main content.