Wise Rules

Boilers
Boiler Wise Rule 1. Effective boiler load management techniques, such as operating on high fire settings or installing smaller boilers, can save over 7% of a typical facility's total energy use with an average simple payback of less than 2 years.

Boiler Wise Rule 2. Load management measures, including optimal matching of boiler size and boiler load, can save as much as 50% of a boiler's fuel use.

Boiler Wise Rule 3. An upgraded boiler maintenance program including optimizing air-to-fuel ratio, burner maintenance, and tube cleaning, can save about 2% of a facility's total energy use with an average simple payback of 5 months.

Boiler Wise Rule 4. A comprehensive tune-up with precision testing equipment to detect and correct excess air losses, smoking, unburned fuel losses, sooting, and high stack temperatures, can result in boiler fuel savings of 2% to 20%.

Boiler Wise Rule 5. A 3% decrease in flue gas O2 typically produces boiler fuel savings of 2%.

Boiler Wise Rule 6. Using over fire draft control systems to control excess air can save 2% to 10% of a boiler's fuel use with typical equipment costs of $1,500.

Boiler Wise Rule 7. Using a characterizable fuel valve to match the air/fuel ratios across the load range can save 2% to 12% of a boiler's fuel use at relatively low cost.

Boiler Wise Rule 8. Converting to air or steam atomizing burners from conventional burners can reduce boiler fuel use by 2% to 8%.

Boiler Wise Rule 9. Every 40°F reduction in net stack temperature (outlet temperature minus inlet combustion air temperature) is estimated to save 1% to 2% of a boiler's fuel use.

Boiler Wise Rule 10. Stack dampers prevent heat from being pulled up the stack and can save 5% to 20% of a boiler's fuel use.

Boiler Wise Rule 11. Direct contact condensation heat recovery can save 8% to 20% of a boiler's fuel use, but costs may be relatively high.

Boiler Wise Rule 12. Preheating combustion inlet air can save about 3% of a facility's total energy use with an average simple pay-back of 8 months.

Boiler Wise Rule 13. Minimizing energy loss from boiler blowdown can save about 2% of a facility's total energy use with an average simple payback of less than 1 year.

Boiler Wise Rule 14. Removing a 1/32 inch deposit on boiler heat transfer surfaces can decrease a boiler's fuel use by 2%; removal of a 1/8 inch deposit can decrease boiler fuel use by over 8%.

Boiler Wise Rule 15. Blowdown heat recovery is a proven technology that can reduce a boiler's fuel use by 2% to 5%.

Boiler Wise Rule 16. For every 11°F that the entering feedwater temperature is increased, the boiler's fuel use is reduced by 1%.

Boiler Wise Rule 17. Changing from manual blowdown control to automatic adjustment can reduce a boiler's energy use by 2% to 3% and reduce blowdown water losses by up to 20%.

Steam Systems
Steam Wise Rule 1. An effective steam trap maintenance program can save 3% of a facility's total energy use with an average simple payback of 2 months.

Steam Wise Rule 2. An effective steam trap maintenance program can reduce a boiler's fuel use by 10% to 20%.

Steam Wise Rule 3. Repairing steam system leaks can save 1% of a facility's total energy use with an average simple payback of 3 months.

Steam Wise Rule 4. A single high-pressure steam leak (125 psi) can result in energy losses costing from $660 to $2,200 per year (8,760 hrs). A single low-pressure steam leak (15 psi) can result in energy losses costing $130 to $480 per year (8,760 hrs).

Steam Wise Rule 5. Insulating steam lines can save 1% of a facility's total energy use with an average simple payback of 10 months.

Steam Wise Rule 6. Vapor recompression saves 90% to 95% of the energy needed to raise the steam to the same pressure in a boiler.

Steam Wise Rule 7. Measures to reduce heat loss from condensate in a steam system can save over 1% of a facility's total energy use with an average simple payback of 8 months.

Process Heating
Process Heating Wise Rule 1. Proper heat containment can save about 2% of a facility's total energy use with an average simple payback of 9 months.

Process Heating Wise Rule 2. Insulating a furnace with refractory fiber liners can improve the thermal efficiency of the heating process by up to 50%.

Process Heating Wise Rule 3. Recovering waste heat from furnaces, ovens, kilns, and other equipment can save 5% of a typical facility's total energy use with an average simple payback of 16 months.

Process Heating Wise Rule 4. Recovering waste heat through a recuperator canreduce a kiln's energy use by up to 30%; regenerators can save up to 50%.

Process Heating Wise Rule 5. Each percent of moisture removed by air dryinglumber reduces the kiln's energy use by 50 to 85 Btu per board foot.

Process Heating Wise Rule 6. Variable fan speed control in the lumber industry can reduce dry kiln airflow by 20% and reduce the kiln's energy used during surface drying by as much as 50%.

Process Heating Wise Rule 7. Installing expert systems for kiln secondary control can reduce a cement kiln's energy use by up to 3%.

Process Heating Wise Rule 8. New clinker cooler technologies that optimize heat transfer conditions can reduce a cement kiln's energy use by up to 6%.

Process Heating Wise Rule 9. Direct firing with natural gas in place of indirect steam heating has the potential to save 33% to 45% of process heating energy use. Payback times may range from a few months to 6 years.

Process Heating Wise Rule 10. Direct electric heating (infrared, microwave, or dielectric) can reduce process heating energy use by up to 80% with typical payback periods of 1 to 3 years.

Heat Recovery & Cogeneration

Heat Recovery/Cogen Wise Rule 1. Recovering waste heat can reduce a typical facility's total energy use by about 5% with an average simple payback of 16 months.

Heat Recovery/Cogen Wise Rule 2. Reducing net stack temperature (outlet temperature minus inlet combustion air temperature) by 40°F is estimated to reduce the boiler's fuel use by 1% to 2%.

Heat Recovery/Cogen Wise Rule 3. Preheating furnace combustion air with recovered waste heat can save up to 50% of the furnace's energy use. Heat Recovery/Cogen Table 1 summarizes typical fuel savings for a natural gas furnace.

Heat Recovery/Cogen Wise Rule 4. Using an economizer to capture flue gas waste heat and preheat boiler feedwater can reduce a boiler's fuel use by up to 5%.

Heat Recovery/Cogen Wise Rule 5. Removing a 1/32 inch deposit on boiler's heat transfer surfaces can reduce a boiler's energy use by 2%; removing a 1/8 inch deposit can reduce a boiler's energy use by over 8%.

Heat Recovery/Cogen Wise Rule 6. Gas turbines with heat recovery equipment typically cost from $600 to $1,000/kW. Larger gas turbines may be available for half the cost per kW.

Heat Recovery/Cogen Wise Rule 7. A typical cogeneration project may reduce primary energy consumption (including fuel inputs at off-site powerplants for purchased electricity) for steam and electricity generation by 10% to 15%.

Heat Recovery/Cogen Wise Rule 8. Cogeneration systems can save about 9% of a typical facility's primary fuel inputs for on-site energy use (i.e., including fuel savings at off-site powerplants for purchased electricity) with an average simple payback of 34 months. (Savings are calculated by dividing total energy savings, including powerplant inputs, by total facility energy use.)

Compressed Air Systems
Compressed Air Wise Rule 1. Efficiency improvements can reduce compressed air system energy use by 20 to 50%.

Compressed Air Wise Rule 2. Efficiency improvements to compressed air systems can save approximately one-half percent of a facility's total energy use.

Compressed Air Wise Rule 3. Using cooler intake air for compressors can reduce compressed air system energy use by 1% per 5°F reduction in intake air temperature. The payback period for this measure is usually less than two years.

Compressed Air Wise Rule 4. Using cooler intake air for compressors can save almost one-half percent of a facility's total energy use with an average simple payback of 5 months.

Compressed Air Wise Rule 5. Installing or adjusting unloading controls can reduce compressed air system energy use by about 10%.

Compressed Air Wise Rule 6. Upgrading controls on screw air compressors can reduce a facility's total energy use by about 1% with an average simple payback of 8 months.

Compressed Air Wise Rule 7. Reducing air compressor pressure can reduce a facility's total energy use by about one-half percent with an average simple payback of 4 months.

Compressed Air Wise Rule 8. Reducing air compressor pressure by 2 psi can reduce compressor energy use by 1% (at 100 psi).

Compressed Air Wise Rule 9. Eliminating or reducing compressed air usage for certain activities can reduce a facility's total energy use by more than one-half percent, with an average simple payback of 6 months.

Compressed Air Wise Rule 10. Repairing air leaks can reduce compressed air system energy use by 30% or more.

Compressed Air Wise Rule 11. Repairing air leaks can reduce a facility's total energy use by about one-half percent, with an average simple payback of 3 months.

Compressed Air Wise Rule 12. It takes approximately 2.5 to 5.0 kWh to compress 1,000 ft 3 of air to 100 psi. Each psi reduction in compressed air loss from the distribution system (at 100 psi), reduces the compressor's energy use by more than one-half percent.

Compressed Air Wise Rule 13. Air compressor waste heat recovery can reduce a facility's total energy use by about 1.8% with an average simple payback of 10 months.

Compressed Air Wise Rule 14. For every 1 psi increase in air compressor pressure gained by periodic filter changes, air compressor energy use is reduced by about 0.5%. Changing dryer filters at 8 or 10 psi drop per filter can eliminate this waste.

Compressed Air Wise Rule 15. For every 11°F decrease in air compressor working temperature, gained by careful maintenance of intercoolers, air compressor energy use will decreased by 1%.

Process Cooling
Process Cooling Wise Rule 1. Installing energy efficient chillers and refrigeration systems can save 1.2% of a facility's total energy use with an average simple payback of 23 months.

Process Cooling Wise Rule 2. "Free cooling" with cooling tower water can reduce a facility's total energy use by about 1 percent with an average simple payback of 14 months.

Process Cooling Wise Rule 3. Free cooling can reduce cooling system energy use by as much as 40% depending on location and load profile.

Process Cooling Wise Rule 4. Increasing chilled water temperature by 1°F reduces chiller energy use by 0.6% to 2.5 (See Process Cooling Table 1 for data on specific chiller types.)

Process Cooling Wise Rule 5. Reducing condenser pressure by 10 psi can decrease refrigeration system energy use per ton of refrigeration (kW/ton) by about 6%.

Process Cooling Wise Rule 6. For each 1°F decrease in condenser cooling water temperature, until optimal water temperature is reached, there is a decrease in chiller energy use byup to 3.5%.

Process Cooling Wise Rule 7. Eliminating heat losses from leaks and improper defrosting can reduce refrigeration system energy use by 10% to 20%.

Process Cooling Wise Rule 8. Freezing products in batches rather than continuously can reduce freezing process energy use by up to 20%.

Process Cooling Wise Rule 9. Installing variable speed drives in place of constant speed systems can reduce cooling system energy use by 30% to 50%, depending on load profile.