Posted by Kristin Landry
on November 5th, 2010
When is the last time you ordered 25 items in one internet shopping spree? Did the work of 3.5 shopping trips in one online shopping experience? Drove 50 kilometers to get to the shopping mall? That’s the distance you’d have to travel to outweigh the carbon impact of a typical online shopping spree, seeing as they now have to ship all purchases to each customer individually, rather than shipping everybody’s purchases to the single store location. In other words, visiting your local shopping mall is more environmentally friendly than making your purchases online.
The Institute of Engineering and Technology (IET) at Newcastle has examined a phenomenon they call the “rebound effect,” in which well-intentioned green policies have side effects that diminish or completely overturn the initial carbon emission reductions. The implications of this particular study are still unclear, as it was performed in Britain, where shopping and transportation habits may differ from those of the typical American. The differences in mass transit systems, bicycle culture, and convenience of a car would influence the carbon emissions reductions possible.
This rebound effect can also be seen in telecommuting, or working from home. This practice increased energy use by 30%. It also allows people to live further from the workplace, which in turn would put them further from other things, increasing what is known as “urban sprawl.” Nobody says it better than the chair of the IET Transport Policy Panel Phil Blythe. Put simply, “policy makers must do their homework to ensure that rebound effects do not negate the positive benefits of their policy initiatives and simply move carbon emissions from one sector to another.”
Posted by James Wilson, PhD
on May 13th, 2009
A news story broke a few weeks ago (courtesy of a study by McAfee, the virus protection software company) pertaining to the global energy costs of email spam. The study outlined a very thorough breakdown of the life-cycle of spam, from creation and dissemination to filtering and viewing. The energy usage per year for each step was analyzed for each major country and also generalized over the global scale. The conclusion: over 33 billion kilowatt-hours (KWh) of electricity are used globally each year as a result of spam. According to McAfee’s numbers, this is equivalent to the electricity usage of 2.4 million homes in the U.S., and equals the GHG emissions of 3.1 million passenger cars. Not a small amount.
This story reflects a burgeoning trend by companies to spin their products in a way that shines favorably on the environment. We probably never thought about the impact of spam on CO2 emissions, but thanks to McAfee, we can now feel good about buying their product. This is all well and good, and simply reflects the very positive cultural and societal movement towards cleaner and more efficient energy production and usage in order to reduce our environmental imprint. However, as with all science, it is necessary to analyze studies like this in detail, and to be cognizant of any conflicts of interest that may exist. In the case of corporate advertising, the vested interest of the company in producing data which leads to more sales is glaring.
The most interesting part of the McAfee study is that about 80% of the energy associated with spam comes from the user end: viewing and deleting spam, manually filtering, and searching for false positives (scanning the spam folder for valuable emails accidentally filtered from the inbox). The energy associated with each of these categories is defined as “user hours,” calculated by multiplying the time spent for these acts by the average power required by the computer.
It is in the application of these “user hours” that McAfee confuses and distorts the issue, and inflates the environmentally deleterious impact of spam presumably for its own economic benefit. The energy associated with user hours is only a factor if, in lieu of viewing and filtering spam, the computer would have been off. It is the difference in energy between normal non-spam behavior and behavior with spam, the opportunity cost (to use a business term), that should be used in the analysis. The only scenario where the McAfee analysis is correct would be where the computer is on an extra amount of time due to the user time spent dealing with spam. If you spend 15 minutes a day dealing with spam, do you stay an extra 15 minutes at work, or at home on the computer, AND do you turn your computer on and off each time you use it? It is safe to say that most people’s computing behavior does not follow this pattern. (Read more…)