Our Calculations
The Internet Service:
MoveNeutral currently offsets carbon emissions of websites based on the number of hits received to the website (However, MoveNeutral offsets the servers directly in an audit). For websites that are not audited, MoveNeutral offsets, on average, 500 milligrams of carbon dioxide emissions per page view. This specific amount is based on a series of calculations and assumptions (provided below). Where possible, MoveNeutral has attempted to use higher estimations than actual averages to ensure that, on average, MoveNeutral offsets at least the correct amount of carbon dioxide emissions. When more accurate figures or numbers for the calculations are received, MoveNeutral will update these calculations. You are invited to provide feedback and/or more accurate numbers for these calculations (however, please provide support for your information, preferably in the form of published papers).
The following calculations incorporate carbon offsetting for the energy consumption of the server(s) providing the webpage, the energy consumption for the interconnecting devices between the server(s) and the user's computer, and the energy consumption required for cooling the server(s). Each of these calculations are provided in sections below.
Servers generally consume 1500-2500 kilowatt-hours in a year and the pounds of carbon dioxide emitted per kilowatt-hour is, on average, 1.54 (based on National carbon dioxide emissions). Using the higher end of these numbers, a single server is responsible for two tons of carbon dioxide emissions per year. In general, websites and webpages are hosted on efficient servers. For example, blogs on blogging websites (e.g., blogger), social networking sites (e.g., facebook, myspace, etc.), or even private websites where the host uses virtual servers all use efficient methods. For these reasons, MoveNeutral has used data corresponding to efficient servers (in terms of page views per server). Efficient servers are capable of handling over 300,000 page views in a day. Using this and other similar data corresponding to efficient servers, one page view corresponds to 13.7 milligrams of carbon dioxide emissions. Cooling requires 7 kilowatt-hours per rack, and assuming a modest 7 servers per rack, one page view corresponds to 1.9 milligrams of carbon dioxide emissions for cooling.
On average, there are between 10 and 15 hops in a data path between the server(s) and the client computer. These interconnections correspond to routers, hubs, WAN switches, LAN switches, and other servers. Using national average data, and assuming that each page view corresponds to one second of time for each device, a route including 15 hops corresponds to 5.7 milligrams.
The corresponding total for these three calculations is 21.3 milligrams of carbon dioxide emissions per page view. However, MoveNeutral is aware that many small and medium companies (and even users hosting their own website using a home computer) do not use servers in the manner caluclated above. Because MoveNeutral is committed to ensuring the carbon neutrality of your website, MoveNeutral uses 500 milligrams per page view on average, a factor of over 25 of our calculations for efficient servers. MoveNeutral adjusts this number for individual users or companies upon determination of further data regarding your servers / hosts and average page view data.
The Facebook Product:
Based on our current information, we estimate that Facebook uses approximately 5,000 servers and has 10,000,000 active users. Accordingly, MoveNeutral offsets at least 17.5 grams of carbon dioxide per week (2.5 grams of carbon dioxide per day) each time the Facebook Product is activated on a given profile. Activiation occurs by clicking or otherwise activiating the Facebook Product on a Facebook Profile. This activation may be performed by any user viewing the Facebook Profile. MoveNeutral will offset at least this amount of carbon dioxide.
The Vehicle Product:
The average U.S. driver travels 12,000 miles on the road per year and each gallon of gas corresponds to 23.6 pounds of carbon dioxide emissions. MoveNeutral uses 35 miles per gallon for small, efficient cars, 25 miles per gallon for medium, efficient vehicles, and 15 miles per gallon for large or inefficient vehicles. Correspondingly, the resulting carbon emissions (rounded to the nearest ton) are 4 tons for small, 6 tons for medium, and 9 tons for large.
References of Interest:
http://www.eia.doe.gov/cneaf/electricity/page/co2_report/co2report.html#intro
http://www.dssw.co.uk/research/computer_energy_consumption.html
http://www.sigcomm.org/sigcomm2003/papers/p19-gupta.pdf
http://www.scaleoutadvantage.techweb.com/news/hom_iw20070901_cutenergy.jhtml
http://www.google.org/recharge/dashboard/calculator
http://cta.ornl.gov/data/index.shtml
http://www.dell.com/html/us/products/calc_energysmart/dell_ec.htm
http://www.news.com/PC-milestone--notebooks-outsell-desktops/2100-1047_3-5731417.html
http://michaelbluejay.com/electricity/computers.html