Managing Office Plug Loads

ENERGY MANAGERS’ QUARTERLYNewsletter || Second Quarter || June 2008

E SOURCECustomer DirectNewsletter licensed for distribution to the customers of E SOURCE members

Managing Office Plug LoadsSpencer Sator

A plug load is the energy consumed by any electronic device that’s plugged into a socket. In offices, this includes computers, copiers, coffeemakers, task lamps, vending machines, refrigerators, and projectors—many of which consume some electricity even in standby mode or when switched off. Because office plug loads account for about one-fifth of an office energy bill—roughly as much as heating, lighting, or air conditioning—there are significant opportunities for energy managers to cut energy consumption, boost the bottom line, and trim corporate greenhouse gas emissions through wise equipment procurement and effective practices.

Contents

IT Plug Loads: The Elephant in the Room 4

Often-Neglected Office Energy Hogs 7

An Array of Smaller Plug Loads 8

The Changing Picture 9

Notes 11

2 CEMC-EMQ-Q2-2008 || E source Energy Managers’ Quarterly© 2008 E Source Companies LLC. Distribution outside subscribing organization prohibited.

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Managing Office Plug LoadsSpencer Sator

Of all nonpayroll operating expenses in office buildings, the largest share—almost 30 percent—goes to utility bills. And while building managers have traditionally targeted lighting and HVAC systems as the best way to trim energy consumption, reducing office plug loads has the potential to yield significant savings as well.

A plug load is the energy consumed by any electronic device that’s plugged into a socket. In offices, this includes computers, copiers, coffeemakers, task lamps, vending machines, refrigerators, and projectors—many of which consume some electricity even in standby mode or when switched off. Because office plug loads account for about one-fifth of an office energy bill—roughly as much as heating, lighting, or air conditioning—there are significant opportunities for energy managers to cut energy consumption, boost the bottom line, and trim corporate greenhouse gas emissions through wise equipment procurement and effective practices.

Due to the decentralized nature of plug loads, making incremental improvements is often easier and cheaper than making large-scale efficiency upgrades to HVAC and lighting systems—and it often produces a faster payback period. This is especially the case in buildings that are rented or shared, where large-scale infrastructural improvements might not be feasible.

In today’s office, virtually all employees use computers. With active-mode power consumption that can top 100 watts, computer-related plug loads are among the largest electric draws in an office. Additional information technology (IT) loads come from servers, printers, scanners, speakers, and other peripherals.

Although IT equipment is often the most obvious energy consumer in an office, there are many more energy hogs that people often forget. A personal space heater, for instance, uses 5 times more energy per year than a single laptop computer; a break room refrigerator draws 10 times more, and a single soft drink vending machine can consume more than 40 times the energy of that laptop. So while energy managers often focus on the most obvious consumers, it’s sometimes more effective to target a few large items or those that are never turned off—such as routers or large coffeemakers (Table 1, page 3).1

In addition to the immediate savings gleaned from controlling office plug loads, there are secondary benefits. For instance, researchers at the Florida Solar Energy Center found that for every 100-watt reduction in computer energy consumption in an office building, there’s a corresponding 28-watt drop in cooling loads.2 And because large offices are commonly charged higher rates during peak cooling hours, these midday HVAC savings can be especially lucrative. Meanwhile, benefits from using low-power liquid crystal display (LCD) flat screen monitors include longer equipment life and quantifiable increases in employee productivity thanks to reduced eye strain.3

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CEMC-EMQ-Q2-2008 || E source Energy Managers’ Quarterly 3© 2008 E Source Companies LLC. Distribution outside subscribing organization prohibited.

In the lighting realm, using more low-wattage light-emitting diode (LED) desk lamps not only saves energy compared to incandescent bulbs, but if properly deployed, LED lamps may allow managers to delamp overhead fixtures for even greater savings. So while institutions, corporations, and small businesses have the potential to save billions of dollars per year by reducing plug loads, they can potentially save billions more from the associated reductions in HVAC and lighting demands—all while increasing employee productivity.

TABLE 1: Average annual plug loads of common office items

Energy managers often focus on computers as the most important plug load in an office. This is certainly a smart approach because of the large number of computers in a typical office. However, other items such as beverage vending machines, break room appliances, and space heaters also account for significant power draws.

Source: Lawrence Berkeley National Laboratory

ItemAnnual energy

consumption (kWh) Operating cost ($/year)a Cost-saving strategies

Cold beverage vending machine Use VendingMiser or other occupancy sensor; replace old, inefficient units

Coffee maker, large commercial Attach to timer so it is not heating water overnight; consider a smaller household model

Water cooler Choose an Energy Star model

Refrigerator Replace older, inefficient models

Router Attach to timer to turn off overnight

Personal space heater Reduce need by maximizing HVAC system comfort and efficiency

Computer, desktop Use aggressive power-management settings; use power strips; consider power-management software

Projector Choose an efficient model

Monitor, cathode ray tube Replace with flat panel monitors

Monitor, flat panel Purchase Energy Star models; purchase the smallest screen possible for a given application

Incandescent lamp, 75 watt Replace bulbs with compact fluorescent lamps

Computer, laptop Use aggressive power-management settings; use power strips; consider power-management software

Personal fan, 8- to 16-inch Reduce need by maximizing HVAC system comfort and efficiency

Task lamp, 24-inch fluorescent bulb Turn off when not in use

Computer speakers Turn off when not in use; attach to power strip with other computer equipment

Clock radio/small stereo Turn off when not in use; attach to power strip with other computer equipment

Ethernet hub

3,318

1,349

799

701

350

329

236

204

186

97

88

72

62

33

21

20

11

298.62

121.41

71.91

63.09

31.5

29.61

21.24

18.36

16.74

8.73

7.92

6.48

5.58

2.97

1.89

1.80

0.99 Attach to timer to turn off overnight

Notes: kWh = kilowatt-hour; a = based on $0.09/kWh.


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IT PLUG LOAdS: ThE ELEPhANT IN ThE ROOMIn most offices, computers account for more energy consumption than any other end use. The annual energy consumption of computers varies widely, from under 30 kilowatt-hours (kWh) for a rarely used laptop to more than 1,000 kWh for a large desktop that uses several peripheral technologies and is often left on overnight (Table 2). Although the computer itself usually accounts for the largest share of energy use, the monitor, speakers, printer, modem, router, scanner, and other equipment can all consume significant amounts of electricity. By choosing efficient products and powering down after use, businesses can significantly reduce their energy costs.

Computers. The average desktop computer consumes 75 watts in active mode, 4 watts in sleep mode, and 2 watts while turned off. A computer that’s turned off nights and weekends uses about 170 kWh per year on average, costing about $15 per year at $0.09/kWh. However, a desktop computer left on continuously will consume more than 650 kWh annually at a cost of almost $60. A high-performance system with a powerful graphics card and multiple drives can cost significantly more. Even a midsize corporation might spend $100,000 on computer energy each year.

Monitors. In addition to the computer, a monitor requires a significant amount of energy—even though LCD technology has produced some savings. Today’s flat panel LCDs draw substantially less power than cathode ray tube (CRT) monitors, which now account for less than 10 percent of new monitor sales. On average, a 15-inch LCD monitor consumes 20 watts while turned on, a 17-inch uses 31 watts, and a 19-inch model draws 35 watts. By comparison, a 17-inch CRT consumes 61 watts. Monitors of all types draw roughly 1 watt while in standby mode or when turned off. Over the course of a year, a 17-inch LCD monitor will cost about $9 to operate, compared with $15 to $20 for a similarly sized CRT. Although this difference might seem negligible, it can certainly add up quickly in companies with hundreds or thousands of employees.

TABLE 2: Annual energy consumption of different computer types

The annual energy consumption of computers can vary widely—from nearly 2,000 kilowatt-hours (kWh) for a high-powered machine that’s left on continuously (168 hours per week) to less than 100 kWh for a laptop that’s only on during business hours. These differences in energy consumption translate to operating costs that range from about $5 for the laptop to $150 or more for the high-powered work station at average electricity costs.

© E SOURCENotes: LCD = liquid crystal display; CRT = cathode ray tube.

40 hours/week 50 hours/week 70 hours/week 168 hours/week

High power with large LCD monitor

200 416 520 728 1747

Standard with CRT monitor 136 283 354 495 1188

Standard with LCD monitor 106 220 276 386 926

Laptop with docking station with LCD monitor

56 116 146 204 489

Laptop only 30 62 78 109 262

Computer systemAverage active-mode

power (watts)

Annual energy consumption (kWh)

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Laptops. Portable laptop computers use considerably less energy than desktop models. The average laptop draws only about 25 watts while turned on and 2 watts in standby and while turned off. And because laptops often have more aggressive power-management settings built in, they will often cost less than $10 per year in electricity to operate. From an energy use standpoint, it makes more sense for companies to provide employees with energy-efficient laptops instead of larger, more consumptive desktops.

Peripherals. Peripheral equipment can also be responsible for significant power draw. A printer or scanner can consume more than 30 watts while in use and about 6 watts in standby. Bookshelf speakers require several watts and often remain turned on 24 hours a day. But modems and wireless routers usually consume more electricity than any other peripheral—together, these draw up to 50 watts and often remain on continuously. This translates to more than 350 kWh per year, or about 6 times more than a laptop uses over the same period.

Strategies for Reducing Computer-Related Energy CostsA typical company can easily spend $100 per employee each year on computer-related energy expenses and associated HVAC costs, although these expenditures can be slashed through several low- or no-cost approaches. The cheapest approach to saving energy is to simply set aggressive power-management settings on all computer equipment. To do this, IT staff, energy managers, and/or executive management should hold a meeting to explain the plan, then follow up with an e-mail or two explaining to employees how to enable power-management features on their machines—and exhorting them to do so. Finally, to sustain participation most effectively, you should follow up with new employees and with those who missed the message the first time. Although this method is essentially free and may result in greater awareness and less energy waste, there’s no way to ensure that employees will comply with the power-management policy—nor is there a simple means of determining energy savings. However, this may prove to be the most effective approach in many offices.

If power-management settings on individual computers turns out to be ineffective, there are low-cost or free network-based power-management software options available. This software differs from individual computer power settings because it’s centrally controlled—this helps IT personnel ensure maximum energy savings and users are less likely to disable it. A 2004 study by the Lawrence Berkeley National Laboratory demonstrated the potential impact of network-based power management when it revealed that 60 percent of office computers remain on overnight and during weekends, and only 6 percent use aggressive power-management settings.4 Other reports suggest employees don’t turn off computers or disable power settings—either because it’s policy to leave equipment on overnight, they don’t care about saving energy, or they believe the computer will go into sleep mode by itself (although most monitors automatically go into standby, few computers do).5 Clearly, building managers and network administrators can significantly reduce operating costs if these idle machines are switched off (Table 2, page 4 and Table 3, page 6). For more information, see the E source purchasing advisor on Office Equipment: Computer Power-Management Software.

http://www.esource.com/BEA/demo/BEA_esource/PA_52.html


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Another low-cost approach to trimming energy consumption is supplying power strips to employees. Although limited in the amount of potential savings, power strips are an easy way for employees to switch off all their often-forgotten energy users—like computer speakers and radios—quickly and easily at the end of the day. Power strips can yield additional savings if used with a computer because they eliminate off-mode power draw.

And when replacing old office electronics, always look for Energy Star–qualified equipment. In addition to certifying the most efficient models, the Energy Star program provides companies and consumers with regularly updated product lists for all types of computers and peripherals, savings calculators, and other resources.

Servers: The Other IT Plug LoadServers are among the fastest growing plug loads in the business sector. Although many companies have a dedicated server room or data center, few actively manage the energy consumption of these machines and the associated air-conditioning loads. One of the most effective ways to cut energy use is through virtualization, which allows you to consolidate multiple server functions into a single machine.

By reducing the number of physical machines required, server virtualization provides several benefits. The primary savings come from reduced energy demand because you’re operating fewer machines. The amount of these savings depends on many factors, including the age and specifications of the servers used before and after the virtualization. Virtual servers tend to use more energy because they’re typically newer, more powerful, and designed to perform more functions—but this incremental increase in energy consumption is usually more than offset by reducing the number of machines. Additional related savings include paying for fewer connections, reduced HVAC operating costs, and reduced capital cost from having to purchase fewer servers.

Virtualization also provides significant advantages for business continuity and disaster recovery. For example, virtualization can make disaster recovery much more manageable and economical because it’s quicker and often cheaper to duplicate data virtually on remote

TABLE 3: Potential savings from computer power management

Reducing computer and monitor “on” time from 24 hours a day, 7 days a week to 45 hours per week can yield significant savings.

© E SOURCENotes: kWh = kilowatt-hour. Assumes each system consumes 106 watts while on; electricity costs $0.09/kWh; 1.2 pounds CO2 emitted per kWh; savings based on reducing operating time by 123 hours per week.

Computer systems (standard desktop with

flat panel monitor) Energy reduction (kWh/year) Annual savings ($) Annual CO2 emission reduction (tons)

1

100

10,000

680

68,000

6,800,000

61

6,120

612,000

0.4

40.8

4,080.0

http://www.energystar.gov

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servers rather than physically copying to storage tapes. Because of all these advantages, virtualization is quietly gaining traction in the business sector, although adoption is still somewhat low.

OfTEN-NEGLECTEd OffICE ENERGY hOGSAlthough computers are often the first target of any companywide efficiency plan, there are a number of other plug loads that can yield similar or even greater energy savings.

Vending machines. Refrigerated vending machines typically operate 24 hours per day, seven days a week. In addition to consuming 2,500 to 4,400 kWh per year, they add to cooling loads in the spaces they occupy. At $0.09/kWh, annual operating costs typically range from $200 to $400. However, timers or occupancy sensors can yield significant savings because these technologies allow the machines to turn on only when a customer is present or when the compressor must run to maintain the product at the desired temperature. At least one device now on the market uses a passive infrared occupancy sensor to turn off the compressor and fluorescent lights in the vending machine when no one is around; a temperature sensor will power up the machine only as needed to keep products cool. Savings for vending machines equipped with these devices range from 24 to 76 percent, depending on usage patterns, occupancy in the area, and ambient conditions. When choosing new machines, select an Energy Star–qualified model to ensure that it uses efficient compressors, fan motors, and lighting systems; Energy Star–qualified vending machines are up to 50 percent more efficient than standard models.

Refrigerators. Over the past several decades, refrigerators have become increasingly efficient. Any employee break room or laboratory that uses older models will almost certainly see significant energy savings by purchasing a new model (Figure 1). You can achieve even greater savings over “average” models by choosing an Energy Star–qualified

fIGURE 1: Estimated annual energy consumption of refrigerators

Any company with old refrigerators should consider replacing them with new, high-efficiency models to save money.

© E SOURCENote: kWh = kilowatt-hour.Assumes electricity costs $0.09/kWh.

0

20

40

60

80

100

120

140

160

1972 1976 1980 1984 1988 1992 1996 2000 2004 2007Model year

Annu

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nerg

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0

200

400

600

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1,000

1,200

1,400

1,600

1,800

Annu

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unit. Sometimes high-efficiency models cost more, but a number of utilities offer rebates to customers who purchase high-efficiency models. When selecting any model, keep in mind that bigger isn’t always better. Refrigerator size correlates closely with energy consumption—so if you replace a small, old refrigerator with a large, new model, you might not see any savings. Also be careful when disposing old units: Older refrigerants can harm the ozone layer and are powerful greenhouse gasses. Ask your appliance dealer or utility about refrigerator recycling programs in your area.

Space heaters. During winter, personal space heaters can account for a significant plug load in many offices. Even a modestly sized space heater can consume 1,000 watts when running. Over the course of an 8-hour work day, that heater can use as much energy as a laptop does in a month. And if left on overnight, space heaters can pose a fire risk. To discourage employees from using space heaters, the best approach is to maintain the HVAC system so that it provides adequate and evenly distributed heat throughout the office. The costs to heat an area with a highly efficient, well maintained HVAC system are usually much lower than relying on personal space heaters.

Water coolers. The hub of the office gossip pool is also a major energy guzzler. According to the Lawrence Berkeley National Laboratory, the average office water cooler consumes a prodigious amount of energy to heat and cool water—some 800 kWh per year.6 Because much of this energy is from standby losses, a simple and cheap method of cutting energy waste is to attach a timer. If programmed to only operate for 10 hours a day, 5 days a week, office water cooler energy waste can be significantly reduced. Alternatively, when it’s time to replace old coolers, choosing an Energy Star–qualified model can yield significant savings over standard models because they have thicker insulation, more efficient cooling systems, and other efficiency-boosting features.

AN ARRAY Of SMALLER PLUG LOAdSIn addition to the relatively large energy consumption from IT equipment, vending machines, refrigerators, space heaters, and water coolers, there are scores of smaller plug loads in the office. Although many won’t consume as much power as a refrigerator, the high prevalence of some items—such as task lamps—still means offices can reap significant savings by pursuing sound energy practices and purchasing high-efficiency devices.

Task lighting. Auxiliary lighting at employee workstations is responsible for significant energy consumption, particularly because task lamps are used by so many people. The first cost-cutting approach any company can take is to replace incandescent bulbs with compact fluorescent lamps (CFLs) in task lighting. CFLs have a somewhat higher initial price tag, but the added expense pays for itself very quickly in energy savings. Also, training nighttime custodial staff to turn off task lights and attaching timers or occupancy sensors can help ensure that these items aren’t left on overnight. If employees are already using CFLs or linear fluorescent lamps for their task lighting, you can still save energy by switching to light-emitting diode (LED) task lamps—the best of which use roughly half the power of fluorescent task lamps. Although LED task lamps come with a high initial cost, studies have shown that companies that provide employees with several LED task lamps and aggressively delamp overhead fixtures can cut overall lighting energy costs by as much as 70 percent.7

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Copiers and fax machines. Though offices usually have relatively few fax machines and copiers, these items can still represent a significant plug load. This is because these machines can consume a lot of power in both active and standby modes. The best approach with any machine you have in your office is to choose aggressive power settings. But be careful not to make power settings too tight—employees may become frustrated if they constantly have to wait an extended period for machines to wake up from sleep mode. And, as with other products, choosing Energy Star models can save significant amounts of energy—up to 500 kWh per year per copier.8 These savings may be even greater for companies that are replacing old, inefficient models.

Clock radios and personal stereos. Much like linear fluorescent task lighting, individual radios and stereos don’t necessarily consume a lot of energy. But because so many employees have them in some companies, the power draw can be significant. Like task lighting, the best low-cost approaches for managing energy consumption of these appliances includes encouraging custodial staff to shut the units off or attaching radios to a timer if employees tend to leave them on overnight.

Personal fans. As with personal heaters, offices that have efficient, properly maintained HVAC systems can maximize comfort and keep auxiliary employee fan use to a minimum. The energy consumption of a building’s HVAC system is usually lower than running numerous small fans.

Kitchen equipment. Besides refrigerators, the employee kitchen has a number of energy consumers that includes microwave ovens, coffeemakers, dishwashers, hot water kettles, and ranges. In addition to choosing the most energy-efficient models when purchasing new equipment, you can also save energy and money through several additional strategies. With large, commercial-size coffeemakers, using a timer will save a tremendous amount of energy. After refrigerated vending machines, coffeemakers are often the single largest individual plug load in the office—with most of the energy going towards keeping the water hot 24 hours a day. By adding a simple timer, you can save close to $100 per year per machine. Note that these savings don’t apply to smaller, residential-style coffeemakers, which heat water as it flows out of a holding reservoir. Elsewhere in the employee kitchen or break room, remember to only run a full dishwasher, choose pots and pans that are at least as large as the burner you’re using, and switch off or unplug any appliance not in use.

ThE ChANGING PICTURERecently companies have become increasingly aware of energy issues and are now adopting more sophisticated, dynamic approaches to curb consumption. Organizational energy initiatives have emerged for a variety of reasons. As climate issues have become more important, many companies have instituted green initiatives or have opted into carbon tracking programs in anticipation of national cap-and-trade legislation. The simple fact that energy prices have increased substantially over the past decade has also spurred many companies into action. Still others see benefits from a customer-relations standpoint or are seeking to capitalize on tax breaks or other financial incentives.

Whatever the motivation, curbing energy consumption boosts the bottom line of any business. And in an increasingly global marketplace, cutting-edge energy management is a


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critical strategy that can yield a competitive advantage. To that end, effectively controlling office plug loads is among the easiest and most inexpensive ways a company can reduce its carbon footprint, cut costs, and enhance its overall economic picture. Companies have increasingly adopted two strategies that have proven effective in reducing plug loads: widespread telecommuting and working toward becoming carbon neutral.

The rise of our modern communication and information infrastructure in the last two decades has made telecommuting a practical choice for millions of people in North America. When employees work from home, there is a potential to significantly shift the energy picture of an office building. A typical company that allows 1,000 employees to telecommute once a week will save more than $4,000 per year in IT energy costs alone. There is potential for thousands more in savings from reduced cooling loads caused by employee computers, reduced paper consumption, reduced lighting, and other measures. And if a company uses rotating work spaces or allows a share of its employees to work from home all the time, a smaller building becomes feasible—which usually means lower bills for rent, heating, cooling, and lighting.

Many companies are also looking to become carbon neutral. Increasingly, clients, partners, or customers are demanding that the companies with which they do business have the smallest carbon footprint possible. Additionally, federal legislation or taxes could penalize large emitters at some point in the future. As a result, many companies are looking to reduce or eliminate altogether their net carbon footprint.

The most popular avenue to mitigate carbon emissions is through renewable energy credits and/or a voluntary cap-and-trade scheme. But before any company initiates these programs, it’s usually best to maximize in-house energy efficiency as a far more cost-effective first step. Only after all feasible efficiency measures are fully explored, the next logical step will be to begin purchasing carbon offsets.

Controlling office plug loads is among the least expensive and most straightforward efficiency measures in any office. The decentralized nature and relative low replacement costs for many technologies means that companies can initiate programs at whatever pace they find comfortable and economically realistic. Before installing efficient lighting and HVAC upgrades—and long before purchasing carbon offsets—companies can enjoy the economic, social, and competitive advantages of simply turning off office appliances when not in use and shopping for the most efficient models when it comes time to replace old equipment.

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NotEs 1 Marla Sanchez, et al., “Space Heaters, Computers, Cell Phone Chargers: How Plugged In Are

Commercial Buildings?” Lawrence Berkeley National Laboratory, LBNL-62397 (February 2007).

2 Florida Solar Energy Center, “Measured Performance of Energy-Efficient Computer Systems” (1996), www.fsec.ucf.edu/en/publications/html/FSEC-PF-303-96.

3 Alan Hedge, “Ergonomics Considerations of LCD versus CRT Displays” (May 2003), ergo.human.cornell.edu/Pub/LCD_vs_CRT_AH.pdf.

4 Marla Sanchez, et al. [1].

5 1E Ltd., “PC Energy Report 2007: United States,” www.1e.com/energycampaign/downloads/1E%20Energy%20Report%20US.pdf.

6 Marla Sanchez, et al. [1].

7 California Energy Commission, “Integrated Office Lighting: Making It Personal,” (November 2007), www.esource.com/esource/getpub/public/pdf/cec/CEC-TB-33_IntegOfficeLtgSys.pdf.

8 U.S. Department of Energy, “Energy-Efficient Products: How to Buy an Energy-Efficient Copier,” www1.eere.energy.gov/femp/procurement/eep_copier.html (accessed April 2008).

Managing Office Plug Loads

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