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Green computing

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Environmental technology
Environmental science

Green computing is the study and practice of using computing resources efficiently. Typically, technological systems or computing products that incorporate green computing principles take into account the so-called triple bottom line of economic viability, social responsibility, and environmental impact. This differs somewhat from traditional or standard business practices that focus mainly on the economic viability of a computing solution. These focuses are similar to those of green chemistry; reduction of the use of hazardous materials such as lead at the manufacturing stage, maximized energy efficiency during the product's term of use, and recyclability or biodegradability of both a defunct product and of any factory waste.

A typical green computing solution attempts to address some or all of these factors by implementing environmentally friendly products in an efficient system. For example, an IT manager might purchase Electronic Products Environmental Assessment Tool (EPEAT)-approved hardware combined with a thin client solution. As compared to a traditional desktop PC configuration, such a configuration would probably reduce IT maintenance-related activities, extend the useful life of the hardware, and allow for responsible recycling of the equipment past its useful life.



In 1992, the U.S. Environmental Protection Agency launched Energy Star, a voluntary labeling program, designed to promote and recognize energy-efficiency in monitors, climate control equipment, and other technologies. This resulted in, among other things, the widespread adoption of sleep mode among consumer electronics. The term "green computing" was probably coined shortly after the Energy Star program began, and generally referred to power consumption-related issues. There are several USENET posts dating back to 1992 which use the term in this manner.[1] Also in 1992, the Swedish organization TCO Development launched the TCO Certification program to promote low magnetic and electrical emissions from CRT-based computer displays. The program was later expanded to include criteria on energy consumption, ergonomics, and the use of hazardous materials in construction.

Fueled by recent trends towards sustainability, the modern use of the term refers to systematic approaches to using computing technology efficiently. These include items such as addressing electronic waste, regulatory compliance, telecommuting policies, virtualization of server resources, cost accounting of energy use, thin client solutions, and many others.


There are different philosophies related the implementation of green computing solutions. Virtually all proponents believe that businesses need to reevaluate some of their technological solutions and/or policies.

  • Tactical incrementalists tend to preserve existing IT infrastructure and policies but will incorporate some environmental and social factors into future decisions. An example of this is to encourage power management policies for computing equipment. Changes of this type are generally easy to implement, are not part of a unified plan, and require little political effort. Similarly to a standard business model, fiscal viability remains the primary concern, with little or no value being attributed to the environmental or social factors.
  • Strategic leaders recognize that environmental and social factors are contributing to a trend in disruptive technology. As such, there is considerable value to altering the existing infrastructure and policies. While the primary rationale is still cost efficiency, other factors such as branding, marketing, or hiring may be referenced as well. A baseline study will probably be conducted, and more complex, pronounced initiatives will be implemented. For example, the IT department may be held accountable for the cost of all electricity from computer related equipment, or desktop computing will be replaced with thin client computing.
  • Deep green technologists believe that computing has reached a point of diminishing returns and needs to be substantially reevaluated. Many are of the opinion that the dawn of the 21st century resulted in a rush to technology, which has resulted in an ongoing hubris for computing initiatives that are fiscally unfounded and environmentally destructive. This hysteria shows itself in many forms; ROI, for example, is rarely calculated for IT projects across the industry, and the growing stocks of electronic waste throughout the world is reaching crisis levels. Unlike the other categories, social and environmental factors are construed as being on equal footing with fiscal responsibility. For example, a deep green technologist might implement a carbon offset policy to neutralize the cost of electricity for computing, or use solar powered web hosting services.

Regulations and industry initiatives


Many governmental agencies and have implemented standards and regulations that encourage green computing. The U.S. Environmental Protection Agency's Energy Star program, which was launched in 1992, was revised in October 2006 to include stricter efficiency requirements for computer equipment, and a tiered ranking system for approved products.[2][3] In Europe, the Swedish Confederation of Professional Employees certifies personal computers, monitors, and other office equipment that meets the ergonomics, energy usage, emissions, and hazardous substances requirements of the TCO Certification program. The European Union's directives 2002/95/EC (RoHS), on the reduction of hazardous substances, and 2002/96/EC (WEEE) on waste electrical and electronic equipment required the substitution of heavy metals and flame retardants like PBBs and PBDEs in all electronic equipment put on the market starting on 2006-07-01. The directives placed responsibility on manufacturers for the gathering and recycling of old equipment.

In 2003, the California State Senate enacted the Electronic Waste Recycling Act, which establishes a state-wide recycling program for obsolete computer and consumer electronics equipment.[4] To pay for the program, the Act imposes a fee for each unit sold at retail, based on the size of the display.[5] The Act also establishes restrictions on hazardous substances, equal to the European Union's RoHS Directive.[6]


The Green Electronics Council offers the Electronic Products Environmental Assesment Tool (EPEAT) to assist in the purchase of "green" computing systems. The Council evaluates computing equipment on 28 criteria that measure a product's efficiency and sustainability attributes. On 2007-01-24, President George W. Bush issued Executive Order 13423, which requires all United States Federal agencies to use EPEAT when purchasing computer systems.[7][8]

In May 2007, IBM launched Project Big Green, a 1 billion-USD-per-year effort to design and promote energy efficiency in corporate data centers.[9]

On 2007-06-12, Google, Inc. and Intel Corporation officially launched the Climate Savers Computing Initiative, with the goal being to reduce the electric power consumption of PCs in active and inactive states.[10] The name stems from the World Wildlife Fund's Climate Savers program, which was launched in 1999.[11] The WWF is also a member of the Computing Initiative.[10] The CSCI provides a catalog of green products from it's member organizations, and information for reducing PC power consumption.

Approaches to green computing

Several methods are available for minimizing the environmental impact of a computing system.

Energy Portal

Power generation

See also: Green energy

All computers require electrical power to operate, regardless of the system's efficiency. One of the goals of green computing is to use power generated from sources that are more environmentally friendly than coal-fired power stations. Some companies provide power from low impact sources, like windmills and hydroelectric dams. Other sources include locally-installed photovoltaic panels, which generate electrical energy from the Sun, or power produced by nuclear power plants.

A laptop can be even powered by human power which brings additional exercise, like in the Twibright Exciter project.


Main article: x86 virtualization
See also: Comparison of virtual machines

Computer virtualization is the process of running two or more logical computer systems on one set of physical hardware. The concept originated with the mainframe operating systems of the 1960s, but was commercialized for x86-compatible computers only in the 1990s. With virtualization, a system administrator could combine several physical systems into virtual machines on one single, powerful system, thereby unplugging the original hardware and reducing power and cooling consumption. Several commercial companies and open-source projects now offer software packages to enable a transition to virtual computing. Intel Corporation and AMD have also built proprietary virtualization enhancements to the x86 instruction set into each of their CPU product lines, in order to facilitate virtualized computing.

Power management

Main article: Power management

An open industry standard called Advanced Configuration and Power Interface (ACPI) provides a standard programming interface that allows an operating system to directly control the power saving aspects of the hardware. This allows the system to automatically turn off components such as monitors and hard drives after set periods of inactivity. In addition, a system may hibernate, in which it turns off nearly all components, including the CPU and the system RAM, greatly reducing the system's electricity usage. To resume from this state, some components, such as the keyboard, network interface card, and USB ports may remain powered, to receive input from the user. ACPI itself is a successor to an earlier Intel-Microsoft standard called Advanced Power Management, which allows a computer's BIOS to control power management functions.

In the absence of ACPI or APM support, some external components, such as computer displays, printers, scanners, speakers, and hard drives may be turned off manually when not in use. In this state, though the external periphals may be off, the main system continues to consume electricity. To minimize the impact, the system could run file sharing software or volunteer computing software, donating its resources to a long-term project.

Some software programs allow the user to manually adjust the voltages supplied to the CPU, essentially reducing the amount of electricity used by the CPU while it's on and powered. Since many CPUs have "safety-nets" on either side of the spectrum (+/- the voltage parameters of a given CPU), one is able to reduce the amount of volts the processor uses, hence reducing both the amount of heat produced and the amount of electricity consumed. Some CPUs from Intel Corporation and AMD, particularly those intended for use in laptops, have technology to automatically adjust the processor voltages depending on the workload. This technology is called "SpeedStep" with intel processors, "PowerNow!"/"Cool'n'Quiet" with AMD chips, LongHaul with VIA CPUs, and LongRun with Transmeta processors.

In 2007, Intel Corporation released a utility called PowerTOP, which measures and reports on a PC's power consumption. This utility is available only for PCs running a Linux operating system.

Newer hardware

As of 2007, at least four personal computer vendors (Everex, Linutop, Systemax, and Zonbu) ship dedicated low-power thin client PCs. These systems are designed primarily for the purpose of reducing power consumption, by providing minimal hardware peripherals and low-voltage components. These design decisions limit the computational performance of such machines, which makes them impractical for applications that require a lot of processing power, such as computer gaming and video production. Dedicated low-power PCs generally are physically much smaller than traditional desktop PCs, and as such can be mounted under desks or on walls, creating more usable desk space. The Geode processor from AMD (originally from National Semiconductor), is one example of a CPU that strives for minimal power consumption while maintaining full compatibility with the x86 instruction set.

Solid state drives store persistent data in either flash memory or DRAM, which do not need any mechanical parts, unlike traditional platter-based hard disk drives. The spindle motor and the data platters are primarily responsible for a hard disk drive's power consumption.[12]

LCD monitors typically use a cold-cathode fluorescent bulb to provide light for the display. Newer displays use an array of light-emitting diodes (LEDs) in place of the fluorescent bulb, which reduces the amount of electricity used by the display.[13] This also reduces the amount of hazardous substances in the system, as all fluorescent bulbs contain trace amounts of mercury.

Desktop computer power supplies (PSUs) are generally about 70–75% efficient;[14] to produce 75W of DC output they require 100W of AC input and dissipate the remaining 25W in heat. An industry initiative called 80 PLUS certifies PSUs that are at least 80% efficient. Typically these models are drop-in replacements for older, non-certified PSUs of the same form factor. As of 2007-07-20, all new Energy Star 4.0-certified desktop PSUs must be at least 80% efficient.[15]

Environment Portal

Materials recycling

Main article: Electronic waste

Obsolete, but still functional computer systems can be donated to various charities and non-profit organizations. Many charities have minimum system requirements for acceptable computer systems.[16] Broken systems, or those too old to be useful to charities, can be recycled through some retail outlets[17][18] and municipal or private recycling centers, often at a fixed cost per item.

Recycling old computers has the benefit of keeping defunct systems - and the harmful materials contained within, such as lead, mercury, hexavalent chromium, among others - out of the regular waste stream and thus, out of landfills. However, some observers note that some old computers, gathered through recycling drives, end up shipped to developing countries, where environmental standards are less strict than in North America and Europe. Columnist Sascha Segan wrote in PC Magazine that there is little accountability for where computers go after being collected for recycling from the consumer.[19] In her book Garbage Land, author Elizabeth Royte quoted the Silicon Valley Toxics Coaltion, which stated that 80% of the post-consumer e-waste collected for recycling is shipped to countries such as China, India, and Pakistan, where the electronic devices are manually broken apart and sifted to collect precious metals, such as copper and gold.[20]

See also

  • CPU power dissipation


  1. ^ (1992-11-20). "leaving it on?". comp.misc. (Web link). Retrieved on 2007-11-11.
  2. ^ Jones, Ernesta (2006-10-23). EPA Announces New Computer Efficiency Requirements. U.S. EPA. Retrieved on 2007-09-18.
  3. ^ Gardiner, Bryan (2007-02-22). How Important Will New Energy Star Be for PC Makers?. PC Magazine. Retrieved on 2007-09-18.
  4. ^ California's Electronic Waste Recycling Act: California takes the battle against electronic waste to manufacturers, retailers and consumers. Los Angeles Business Journal (2004-08-02). Retrieved on 2007-11-12.
  5. ^ Electronic Waste Recycling Fee. California Integrated Waste Management Board (2007-10-24). Retrieved on 2007-11-12.
  6. ^ Restrictions on the use of Certain Hazardous Substances (RoHS) in Electronic Devices. State of California Department of Substances Control. Retrieved on 2007-11-12.
  7. ^ Green Electronics Council (2007-01-24). "President Bush Requires Federal Agencies to Buy EPEAT Registered Green Electronic Products" (PDF). Press release. Retrieved on 2007-09-20.
  8. ^ The White House: Office of the Press Secretary (2007-01-24). "Executive Order: Strengthening Federal Environmental, Energy, and Transportation Management". Press release. Retrieved on 2007-09-20.
  9. ^ IBM (2007-05-10). "IBM unveils plan to combat data center energy crisis; ...". Press release. Retrieved on 2007-09-20.
  10. ^ a b Business Wire (2007-06-12). "Intel and Google Join with Dell, EDS, EPA, HP, IBM, Lenovo, Microsoft, PG&E, World Wildlife Fund and Others to Launch Climate Savers Computing Initiative". Press release. Retrieved on 2007-12-11.
  11. ^ What exactly is the Climate Savers Computing Initiative?. Climate Savers Computing Initiative (2007). Retrieved on 2007-12-11.
  12. ^ Power Consumption. The PC Guide. Retrieved on 2007-09-17.
  13. ^ Cree LED Backlight Solution Lowers Power Consumption of LCD Displays (2005-05-23). Retrieved on 2007-09-17.
  14. ^ Schuhmann, Daniel (2005-02-28). Strong Showing: High-Performance Power Supply Units. Tom's Hardware. Retrieved on 2007-09-18.
  15. ^ Computer Key Product Criteria. Energy Star (2007-07-20). Retrieved on 2007-09-17.
  16. ^ Delaney, John (2007-09-04), " ", PC Magazine 26 (17),
  17. ^ Staples Launches Nationwide Computer and Office Technology Recycling Program. Staples, Inc. (2007-05-21). Retrieved on 2007-09-17.
  18. ^ Goodwill Teams with Electronic Recyclers to Recycle eWaste. Earth 911 (2007-08-15). Retrieved on 2007-09-17.
  19. ^ Segan, Sascha (2007-10-02). "Green Tech: Reduce, Reuse, That's It". PC Magazine 26 (19): 56. Retrieved on 2007-11-07.
  20. ^ Royte, Elizabeth (2006). Garbage Land: On the Secret Trail of Trash. Back Bay Books, 169-170. ISBN 0-316-73826-3. 

How-to articles

  • Build a Green Datacenter - Microsoft TechNet
  • Saving Power on idle PCs - CalTech
  • University of Buffalo's guide to Green computing
  • Using Linux to repurpose old PCs

News articles

  • Green IT adoption in North America lags good intentions - Tekrati, 2007-07-16


  • The Climate Savers Computing Initiative - committed to reducing the power consumption of computers by 50% by 2010
  • Electronic Products Environmental Assessment Tool (EPEAT)
  • The European RoHS-WEEE directive
  • GreenIT - Sustainable information technologies for public and private sector clients.
  • The Green Grid - Global consortium dedicated to developing and promoting energy efficiency for data centers.


  • SusiClimate - a Mac OS X application which calculates the PC's current CO2 emissions in realtime.
This article is licensed under the GNU Free Documentation License. It uses material from the Wikipedia article "Green_computing". A list of authors is available in Wikipedia.
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