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• Fluorescent Lamps are the predominant type used in commercial and industrial spaces in the U.S. They are relatively efficient, have long lamp lives, and are available in a variety of styles. The four foot T-12 lamp is the most common fluorescent lamp used in offices today, but they are being rapidly replaced by T-10 and T-8 lamps. Energy efficient T-8 lamps are more expensive than the T-12 lamps, however they provide 98% as much light and use about 40% less energy when installed with an electronic ballast.
• Electronic Ballasts - When replacing standard fluorescents with the more energy efficient T-8s, it is necessary to replace the existing electromagnetic ballasts with the electronic ballasts, which operate at higher frequencies and convert power to light more efficiently. Energy saving electromagnetic ballasts can cut fluorescent lighting energy consumption by as much as 10%. The life of these ballasts is approximately twice that of their conventional counterparts.
• High Intensity Discharge (HID) refers to lighting provided by mercury vapor, metal halide, and high-pressure sodium lamps. Although originally designed for outdoor and industrial uses, HIDs are also used in offices and other indoor application. The principal advantage of mercury vapor HID lamps is their long life, although they are only slightly more efficient than incandescent lamps.
• Reflectors – Highly polished retrofit reflectors are being marketed for use with existing luminaries (light fixtures) and can achieve a 50% reduction per fixture. Installing reflectors in most luminaries can improve its efficiency because light leaving the lamp is more likely to reflect off interior walls and exit the luminaire. Although the luminaire efficiency is improved, the overall light output from each is likely to be reduced, which will result in reduced light levels. To ensure acceptable performance from reflectors, measure “before” and “after” light levels at various locations in the room to determine adequacy.
• Lighting Controls – Maximum energy efficiency cannot be achieved without effective controls. Modern lighting controls provide benefits ranging from energy savings and electrical demand, to better support of the functions from which the lighting is needed. Manual controls should be used in spaces that accommodate different tasks or that have access to daylight. Occupants should be encouraged to shut lights off when they are not needed. Automatic controls such as occupancy sensors are available for turning off lights in unoccupied areas, while auto-dimming controls adjust light levels to existing daylight. Scheduling controls activate, extinguish, or adjust according to a predetermined schedule.
• LED Lighting - Light Emitting Diodes (LEDs) is one of today’s fastest evolving lighting technologies. LED light sources are more efficient than incandescent and most halogen light sources.
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White LEDS today can deliver more than 20 lumens per Watt, and are predicted to achieve greater than 50 lumens per Watt by 2005. Other inherent features of LEDs include very low power consumption and virtually no heating effect, making it ideal for a wide range of new and existing applications. Due to the decrease in energy used for the lighting of a building, air handling costs drop, generating both additional initial and ongoing investment savings. Another advantage of LEDs over conventional lighting is that light emitted from an LED is directional. Incandescent, halogen, or fluorescent lights are omni directional, emitting light in all directions. Lighting must be redirected using secondary optics or reflectors. Each time a light beam is reflected it looses some of its intensity, resulting in fixture losses typically from 40 to 60%. The directed nature of LEDs can result in fixture efficiencies of 80 to 90%, requiring less total lumens to provide the same level of illuminance.
11.4.5. Office Equipment and Plug Load
Office equipment or plug load consists of the computers, monitors, printers, photocopiers, facsimile machines, televisions, refrigerators, vending machines -- virtually any equipment that gets "plugged in" to electrical receptacles in the space. Energy efficient office equipment provides equivalent or better performance than standard equipment to users but using significantly less energy. Energy use in the office has increased significantly in recent years due to rapid growth of microcomputer use. This has led to a corresponding increase in energy required to operate this equipment and associated loads on heating, ventilation, and air conditioning systems. Federal guidelines have been established to promote energy efficiency in the acquisition, management, and use of microcomputers and associated equipment.
Plug load power density in watts per square foot may exceed the lighting UPD in some areas of the facility. It is essential to make sure that plug load energy is not ignored. The Energy Manager should inventory major equipment, noting wattage where available. If wattage is estimated from nameplate voltage and current, multiply by 0.3 for an estimate of actual average operating power. Primarily look for ways to reduce operating hours of existing equipment and to influence customer selection of properly sized energy-efficient equipment in the future.
The ENERGY STAR® program, established by EPA in 1992 for energy efficient computers, provides on its web page, a list of products meeting its strict criteria for energy efficiency and other environmental benefits. Also consider the following in attempting to manage office equipment and plug load:
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• Are computers, monitors, printers, copiers, and other electronic equipment left on at night?
• Is EPA ENERGY STAR® equipment specified for new purchases?
• Does existing ENERGY STAR® equipment have its capability enabled at system startup?
Everyone can save energy and money by enabling power management on their computer monitors. With over 55 million office computers in the U.S., EPA estimates that over 11 billion kWh could be saved through monitor power management.
Free software provided by the EPA automatically puts monitors to rest when not in use - saving a significant amount of energy and money. What`s more, monitor power management will not affect computer or network performance.
NOTE: See section 11.4.20 ENERGY STAR® products.
11.4.6. Domestic Hot Water (DHW) System
Domestic hot water systems are used to heat water for hand-washing, bathing, cooking, cleaning, and other potable hot water uses. Systems may be simple, self-contained water heaters or complex, site-built systems with extensive recirculation distribution systems.
The creation of domestic hot water (DHW) represents approximately 4% of the annual energy consumption in typical non-residential buildings. Where sleeping or food preparation occurs, this may increase to 30% of total energy consumption.
A typical faucet provides a flow of 4 to 6 gallons per minute (gpm). Substantial savings can be realized by reducing water flow. Purchasing reduced-flow faucets or adding a faucet aerator is a cost-effective way to save water. Self-closing and metered faucets shut off automatically after a specified time, or when the user moves away, resulting in significant water savings. Faucet aerators replace the faucet head screen, lowering the flow by adding air to the spray.
High-efficiency aerators can reduce the flow from 2-4 gpm to less than 1 gpm at a fraction of the cost of replacing faucets.
It has been shown that reductions in DHW temperature can also save energy. Since most users accept water at the available temperature regardless of what it is, water temperature can be reduced from the prevailing standard of 140 degrees Fahrenheit (F) to a 105 degrees F utilization temperature, saving up to one half of the energy used to heat the water.
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An often overlooked energy conservation opportunity associated with DHW is the use of solar energy for water heating. Unlike space-heating, DHW needs are relatively constant year round and peaks during hours of sunshine in non-residential buildings. Year round use amortizes the cost of initial equipment faster than other active-solar options. Also consider:
• Could a lower cost energy source be used for heating water? • If use is high year round and conventional energy sources are
relatively expensive, solar water heating may be practical.
• Is hot water delivered at the lowest possible temperature to meet the load and maintain health requirements?
• Are tanks and distribution lines properly insulated?
• Is water use minimized by use of low-flow showerheads and faucet aerators?
• Could self-closing faucets be used?
• For recirculation systems, is the circulation pump shut off or the system temperatures reduced during low-use periods?
11.4.7. Process Systems
The process system will vary greatly based on the type of facility. In food service facilities, the process system will consist of food preparation, storage, cooking, and associated cleanup equipment. In manufacturing facilities, the process system is that used to manufacture the product. In industrial facilities, the process system typically represents the largest component of energy use. While studies have shown that the potential for process re-engineering to reduce energy use is tremendous, process re-design is outside the scope of most energy audits.
Talk to facility maintenance personnel to get their input into how to reduce energy use in the process. Inventory major equipment and note operating schedules. Look for ways to reduce the price of energy by rescheduling equipment.
• Could big electrical loads such as fork lift battery chargers and arc welders be rescheduled for off-peak times?
• Major savings in process energy are frequently found in secondary utilities generation and in reducing leaks in distribution systems throughout the plant.
• Large thermal loads coincident with high electrical demand year round for two and three shift plants may indicate potential for cogeneration of thermal and electric energy. Look also for ways to reduce the load or need for energy and to increase the operating efficiency.
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• Could heat be recovered from one process or component and used to reduce use of another?
• Could heat-generating systems be removed from the air-conditioned environment?
• Should insulation be added, repaired, or replaced?
• Could process temperatures or pressures be modified?
• Could the efficiency of electric motors or drive systems be increased?
11.4.8. Steam Systems
Energy savings can often be realized through the installation of more efficient steam equipment and processes. Upstream inefficiencies will affect process heating and cost of producing steam; while downstream inefficiencies (leaks, bad traps, poor load control) can also affect process heating and have severe effects on the boiler and cost of producing steam. Opportunities for energy reduction can be found in implementing some of the following actions:
• Generating steam through boiler controls, water treatment, and cogeneration.
• Checking steam leaks and bad insulation. • Replacement of faulty steam traps.
• Optimizing excess air in the boiler for more efficient steam generation.
• Ensuring an effective water treatment system is in place.
Steam traps are an important element of steam and condensate systems and may represent a major energy conservation opportunity. Steam traps are automatic valves that allow condensate formed in the heating process to be drained from the equipment. They also remove non-condensable gases from a steam space. Inefficient removal of condensate and non-condensable gases almost always increases the amount of energy required by the process because these act as insulators and thereby reduce system efficiency.
Although monitoring equipment does not save energy directly, it does identify the status of failed steam traps. The rate of energy loss is related to the size of the orifice and system steam pressure. The maximum rate loss occurs when traps fail with valves stuck in the open position. The orifice could be any fraction of the fully open position.
Water losses will be proportional to energy losses when condensate is not returned to the boiler. Even when condensate is returned to the boiler, if steam bypasses the trap and is not condensed prior to arriving at the deaerator, it may be vented out of the system along with non-condensable gases. This translates to a reduction in heating
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