Sustainable Building Technical Manual - Etn-presco.net

. ☛ SUGGESTED PRACTICES AND CHECKLISTIDesign Considerations❑ Specify energy-efficient office equipment.The U.S. Environmental Protection Agency (EPA) and the electronics industry are workingto cut the power consumption of desktop computers by 50 percent by the year2000 through the Energy Star program. The program encourages the use of special featuresto put personal computers, printers, and copy machines into a low-energy “sleep”mode when idle. In addition, energy-saving computer chips, originally developed forlaptop computer applications, will be used in desktop machines. Look for the EnergyStar label when making equipment purchases. The EPA also publishes a list of energyefficientretrofit kits for older computer equipment.❑ Specify energy-efficient appliances.Many energy-efficient and environmentally sound appliance alternatives now exist.New refrigerators consume less than one-half the energy of older models. In addition,some are CFC-free. Dishwashers that use less than one-half of the water and energyconsumed by older models are also available.❑ Consider higher system voltages.Less energy is lost in distribution systems with higher system voltages. This factor isoften ignored in an effort to minimize initial construction costs. The long-term impactof lower voltages typically is not quantified.❑ Improve power factor.Power factor is the ratio of active power to apparent power. The electrical load may shiftthe phased relationship between electric current and voltage, thereby altering the powerfactor. These shifts are often caused by large motors. Poor power factor results in increaseddistribution and motor losses that require additional energy. Use motor selection, propermotor sizing, and corrective equipment (such as capacitor banks) appropriately.❑ Use K-rated transformers.K-rated transformers better accommodate electric power irregularities or harmonics.They can be used when tenant equipment (such as personal computers) introduces harmonicson the power system. These devices accept the harmonics without a reductionin system rating or efficiency.❑ Size conductors correctly.Selecting conductors of the proper size can reduce voltage drop and power losses andshould be considered, particularly for more concentrated loads. Neutral leg currentflow, associated with equipment that has switched power supplies, should be addressedin design.Renovation and Retrofit Issues❑ Optimize energy use of current equipment and specify more efficient systems withfuture equipment procurement.❑ Retrofit computers with shut-off devices.Some users believe that turning off equipment can shorten its lifetime; however, equipmentmanufacturers have stated otherwise. Low-cost devices that sense periods of inactivitycan automatically turn off computer equipment after a set period of time. Theseindividual computer devices can be set to turn off a computer’s central processing unit(CPU) and monitor separately. These devices have been shown to be extremely costeffective,with payback periods of around one year.