The Real Carbon Footprint of a Web Page

July 26, 2007
If a banner ad falls in the woods, does anybody see it? Seriously, does a banner ad have a carbon footprint? Over at, David Needle has a fascinating discussion about the whole banner ad Vs. print ad debate regarding carbon footprint. There is a discussion of the Green Grid and other socially and environmentally responsible ways to ensure your data center is as green as can be.
My take is the carbon footprint of a web ad requires an indirect calculation. Theoretically, I could run a website without a single banner ad and have millions of viewers. I would still be sucking up electricity and giving off tons of CO2. The banner ad (or any ad for that matter) is responsible for financing most websites so perhaps measuring the “carbon footprint” of such ad vehicles make sense.
On the web, each new page is crawled, indexed, resaved and backed up frequently. It would be an interesting exercise to see how much of a carbon footprint each internet page has. Google alone copies all web pages, indexes them, crawls them frequently and performs assorted other proprietary algorithms which generate carbon.
This doesn’t even take into account the carbon generated by viewers. A viral video on YouTube could be watched by millions and force service providers to install more equipment in their data canters.
Overall, I would bet a single web page on average generates up to 5,000 times the carbon required to post the page to begin with. Think about how many web pages for example are backed up each day! This ratio– is also an annual cost and it increases over time as new search engines start to crawl the web.
Here is a chart giving you an idea of just how much more electricity is needed (carbon generated) for a typical web page each year! Notice I assume each web page is only viewed 5 times per year. I also assume 25 search engines will save the page and subsequently back these pages up every other day. The results are staggeringly large to say the least.
Additional Carbon Emitted
Average Annual Multiple
52 (weekly)
Page Views
Spiders, bots
Duplicated Content
Duplicate Content backups
25*183 = 4,575
This is a fascinating concept and thanks to David for getting us thinking about the web and how it contributes to the green movement. One last point. Many magazines also post the same content from print, online meaning the comparison between print an online possible irrelevant.

Be sure to see me at the Green Technology World Conference in Los Angeles this September 2007 if you want to discuss this further.

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Comments to The Real Carbon Footprint of a Web Page

  1. Don Carli :

    Great post....

    Heightened awareness about climate change, rising energy costs and the increasing power requirements of IT are driving enterprises to pay closer attention to the energy usage and greenhouse gas emissions associated with their digital media and IT infrastructure.

    Print and digital communication media are both essential to business, government and everyday life, but they also both require the use of massive quantities of energy, petrochemicals, materials and transportation that result in the emission of millions of tons of greenhouse gasses each year.

    In fact it has been shown that the management of touchpoints employing multiple media is far more effective than the use of any one medium alone.

    Identifying the environmental footprints of both print and digital media supply chains is an important first step toward developing strategies for the sustainable use of communication media.

    Each year, almost 20 billion catalogs are mailed to American consumers and the energy used to produce just the paper required is enough to power 1.2 million homes for a year, and it results in 5.2 million tons of CO2 and other greenhouse gas emissions†equivalent to the output of two million cars. As you note in your post most catalog marketers also maintain e-commerce websites with content that paralleling their printed catalogs, and the amount of energy required to power the required data center servers, desktop computers and the networks that make those sites function are far from trivial.

    A typical coal-fired power plant emits approximately 2 pounds of CO2 per kilowatt hour and the IT required to produce, maintain and access digital media consume billions of Kilowatt hours of electricity.

    According to recent EPA reports U.S. data centers used almost 60 billion Kilowatt hours of electricity in 2006, roughly 1.5% of all retail U.S. electricity sales, and US office and network equipment used almost 75 billion Kilowatt-hours of electricity, about two percent of the total electricity used in the U.S.

    When telephone switching equipment and manufacturing energy for semiconductors and computers is included, the total goes up to about three percent of all electricity use in the U.S. It is more than the electricity consumed by all of the color televisions in the U.S. and similar to the amount of electricity used by the entire U.S. transportation manufacturing industry, which includes the manufacture of automobiles, aircraft, trucks, and ships.

    Based on typical energy consumption factors it is reasonable to assume that the average desktop computer connected to a server interacting with a client application results in the emission of approximately 20 milligrams of CO2 per second of usage. Multiply the number of visitors to a site times the length of their visit and one can develop an estimate of the client and network related carbon footprint of a site or of a banner ad.

    The upshot of these trends is that publishers, marketers digital media and supply chain professionals will feel increasing pressure from investor and other stakeholders to analyze, offset and ultimately reduce the carbon footprints of the print AND digital media that are responsible for.

    To that end the nonprofit Institute for Sustainable Communication seeks support for its Sustainable Advertising Partnership (go to ) in order to foster the development of a rigorous set of standards and guidelines for the calculation of print and digital media footprints as a first step toward ultimately reducing them by at least 10 million tons of CO2 emissions per year.

    ...and we also invite advertising, marketing and communication and media supply chain professionals to join us in California on January 24th at CalPoly in San Luis Obispo for the Business of Green Media Conference as well as in Boston on October 1-2 for SustainCommWorld: The Green Media Conference and Exhibition ( go to where members of the communication value chain will come together to discuss best practices and develop constructive solutions that will ensure the sustainability and security of print and digital media supply chains.


    Don Carli

    Don Carli
    Senior Research Fellow
    The Institute for Sustainable Communication
    250 East 40th St. 26D
    New York, NY 10016
    Office: 212-922-9899

    Consider the environment before printing, storing, forwarding or responding to this post. Neither the molecules nor the electrons involved are free. They have effects on living things and the Planet†including you and those you may hold dear.

    ISC's websites and email servers are hosted by - solar powered web hosting.

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