Energy Efficient Computers

This desktop is Energy Star qualified and rated EPEAT Silver
This desktop is Energy Star qualified and rated EPEAT Silver

Computers are ubiquitous in modern life, with 72% of all employed adults using a computer at work, and Californians having an average of 0.9 desktops and 0.5 laptops per household. That adds up to over 29 million computers statewide. The average corporate desktop and laptop require about 700 and 87 kilowatt-hours to operate each year, respectively, and the average home desktop and laptop require about 284 and 48 kilowatt-hours to operate each year. Adding that up, total computer (including monitor) energy consumption is about 7 Terawatt-hours each year, equal to the annual energy output of 2 coal plants.

Fortunately, there are many ways to increase computer energy efficiency. Here are some of the biggest opportunities:

  • Implement power management systems to automatically turn off computers and monitors when they are not in use
  • Reduce "idle" power consumption - the power used when the computer is turned on, but is not actively processing new information
  • Increase power supply energy efficiency
  • Reduce component power consumption - efficient case fans, hybrid or flash hard drives, using one larger memory chip instead of multiple smaller ones, and other minor upgrades can improve efficiency yet have neutral or even positive impact on performance
  • Purchase laptops or laptop-style compact desktops - laptops are optimized for long battery life, which means they are also more energy efficient than desktops
  • Purchase a more efficient monitor - LCD monitors use much less energy than CRTs, and Energy Star qualified monitors can use 25-60% less energy than standard models.

There still remains an enormous potential to reduce computer energy consumption. If new software and upgraded computers are able to reduce computer energy use by 75% - a very achievable goal - Californians will save 5.2 Terawatt-hours of electricity per year, enough to power over 880,000 homes.

Photo Credit:  Courtesy of Sony Electronics; Sony JS Series

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This ultimate efficiency computer can save nearly 70% relative to the Energy Sta
This ultimate efficiency computer can save nearly 70% relative to the Energy Star standard
Ultra-Efficient Computing

In 2007, Ecos Consulting, the Electric Power Research Institute, and the California Energy Commission decided to test the limits of energy efficient desktop computers. Focusing on reducing power consumption during idle and active modes, their goal was to create both market-ready and ultimate-efficiency computers that would still have good performance.

The team started by selecting the most efficient available motherboard and chips - one of the most important steps in creating an efficient computer. They used processors that can dynamically scale performance to match program requirements, saving energy when processing demands are low, and selected components with low electrical losses.

Next, the team reduced idle power consumption by an additional 25-36% by selecting efficient components. 80 Plus certified power supplies and efficient case fans saved about 7 Watts. Using a single, larger memory chip instead of two smaller ones saved another 1 or 2 Watts, without impacting performance. The team also specified a hybrid hard drive, which supplements the traditional spinning disk with a flash buffer, saving 5 or 6 Watts. New, flash-only hard drives, which have emerged since this research was completed, can save even more energy by eliminating the spinning disk altogether. Plus, these hard drives are faster than traditional hard drives, improving performance.

Putting everything together, the team found that nearly all of their prototypes had sufficient performance to run typical office software under the Microsoft Vista operating system, while consuming 40 to 70% less energy than Energy Star qualified computers.

This translates into a huge savings potential: if all U.S. enterprises adopted the ultimate efficiency computer, corporations could eliminate 11.2 million tons of CO2 emissions, save 16.7 billion kilowatt-hours, and save $1.67 billion in electricity costs.


EEC chart

Computers spend most of their time in idle mode, and efficiency improvements in this mode do not impact processing performance, so idle mode savings are an easy way to make a big impact.


Photo and Chart Credit:  Courtesy of the California Energy Commission and Ecos Consulting

This notebook is rated EPEAT Gold, the highest possible sustainability ranking
This notebook is rated EPEAT Gold, the highest possible sustainability ranking
Sustainable Procurement


At the heart of Silicon Valley, the businesses and residents of San Jose are at the forefront of computing. And as one of the ten largest cities in the United States, the City of San Jose is itself a major user of computers. So it's not surprising that as part of its sustainability initiatives, the City of San Jose decided to push the envelope in sustainable computing, becoming the first city to require purchase of EPEAT qualified computers.

San Jose was drafting an RFP for computer purchases in early 2006, just as the EPEAT standards were finalized. Even though no products were yet officially certified, they knew that about 60 models would qualify, so they decided to insert the requirement into the RFP. The requirement was a great success, and has been standard practice in the city ever since.

The city likes the EPEAT system because there are many qualified models available, there are measurable benefits, the standard covers all aspects of sustainability, and the requirement is easy to specify & implement. Plus, the city has found no difference in performance between EPEAT-certified and non-certified computers. In fact, the program has been such a success that by March 2008, the city had purchased 1,776 computers and 1,770 monitors. Thanks to their EPEAT program, by March 2008 the city had saved:

• 1.5 Gigawatt-hours of electricity
• 1 million pounds of materials
• 52,000 pounds of carbon equivalents
• 2.7 million pounds of air emissions
• 6,000 pounds of water emissions
• 60 pounds in toxic materials usage
• 2,100 pounds in hazardous waste
• $126,000



Photo Credit:  Courtesy of Sony Electronics:  SONY VAIO TT Series

Energy Star qualified computers like this one come with automatic power manageme
Energy Star qualified computers like this one come with automatic power management
Power Management


Verizon is one of the largest telecommunications corporations in the world, serving about 100 million customers in the United States and generating revenues of over $97 billion each year. Verizon's workforce numbers nearly 224,000 employees, and most of them require computers to do their jobs. As a result, Verizon's IT department has to manage over 185,000 desktop and laptop computers in locations across the country.

With so many computers, Verizon's computer-associated electricity bills add up to millions of dollars every year. So in 2003, Verizon worked with the Energy Star program to activate monitor sleep settings, using a free program called EZ GPO. By setting monitors to go into standby mode after 15 minutes of inactivity, Verizon was able to cut monitor power consumption from 60 to 1 or 2 Watts per monitor during periods of inactivity, resulting in company-wide savings of over $5 million annually. The monitors automatically "wake up" when a user moves the mouse or uses the keyboard, so there is no negative impact on the user experience.

Building off of this success, in 2008 Verizon successfully piloted full computer power management on 11,000 computers in 14 locations. The software Verizon adopted, called PC Powerdown, enables Verizon to remotely turn computers & monitors on and off, so they can be turned off at the end of the day and briefly "woken up" during the night to receive software updates. The progam also enables Verizon's IT managers to monitor computer on time, so they can quantify how much Verizon is saving with the new power management features. They found that while the average computer was on for over 23 hours on weekdays, with the new settings computers were on for only 16 hours per weekday. Including weekends, these pilot computers spent an average of 16 to 17 hours per day in standby mode.

With the average desktop using about 65 Watts (excluding the monitor) and the average laptop using about 30 Watts, spending an additional 7 hours every day in standby mode helps Verizon to realize significant energy savings. Based on the pilot results, Verizon plans to roll out complete monitor and computer power management on all 185,000 feasible computers, with expected savings of about $7 million.


Photo Credit:  Courtesy of Panasonic; Panasonic Toughbook F8