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Lean & Energy Toolkit: Appendix C

Energy Conversion Resources and Rules of Thumb for Estimating Energy Cost Savings

Energy Metrics Conversion Table

Energy Metrics Conversion Table

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Rules Of Thumb for Estimating Energy Cost Savings

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

Cost Savings Assumptions

  • High pressure steam leaks (125 pounds per square inch gauge [psig]) = $150 to $500 per leak per shift per year.
  • Low pressure steam leaks (15 psig) = $30 to $110 per leak per shift per year.
  • Compressed air leaks (100 psig) = $30 to $90 per leak per shift per year.
  • 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.
  • Typical motor operating cost = $62 per horsepower (hp) per shift per year.
  • High pressure compressed air system reduction (assume 100 psig system):
    • 10 pounds per square inch (psi) compressor discharge reduction = 5 percent reduction in energy consumption.
  • 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.
  • Installing insulation can reduce 90 percent heat loss on a hot, uninsulated surface.
  • Average heating and cooling costs:

 Average heating and cooling costs

  • Combustion efficiency of a typical boiler or furnace is 80 percent.
  • 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.
  • Benefit of fuel switching:
    • Switching from electric heat to natural gas or #2 fuel oil can reduce heating costs by 78 percent.
  • 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.

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