Tuesday, January 26, 2010

Embodied Energy

A woman I know proudly stuck a minature wind turbine on the top of her house to show the world that she was serious about saving energy. The little turbine actually generated electricity which she'd use (I'm not sure for what). Someone later pointed out that the turbine probably used more energy in its manufacture than it would create in its whole lifespan.

The JPGreenhouse folks are serious about energy efficiency as a way to work against climate change. They are retrofitting their house so it uses very little day to day energy. (I wrote about this in my last post.) But beyond that, they were careful to use building materials that didn't use a lot of energy in their manufacture--cellulose insulation made from recycled newspaper for example. Their walls would be a lot thinner and save as much energy from heat loss if they used a high-tech building material like Polyisocyanurate panels--but there is a lot of energy used in the manufacture of these panels which are made, like most plastic and foam materials, from oil.

The concept of embodied energy is a way to look at how much energy is used in the manufacture of a product (any product) as well as how much energy it's using while we have it. The website 'WattzOn' has an 'Embodied Energy Database' which lists the average number of watts that were used in the manufacture of a given product. It's worth thinking about as you purchase new stuff. (And, of course, if you buy or get something used, that cuts down the embodied energy by quite a bit because you are extending the life of the product and stopping the waste of all that energy.)

An article that talks about embodied energy, and is more directly related to building projects like the JPGreenhouse, is "Reducing the Embodied Energy of Buildings" from the magazine Home Energy. One of the more interesting findings in the article concerns the cost of recycling. (Yes, recycling uses energy, too--sometimes more than you'd think. See my post of 11/24/09.) There's a table in the article that talks about the energy savings from using recycled materials vs 'virgin' materials. At the top of the table is aluminum, which uses an enormous amount of energy in its manufacture. The energy saved by using recycled materials is 95%. (Please, recycle those aluminum cans and all the aluminum foil you can!) At the bottom of the table is the amount of energy saved by using recycled glass--it's 5%. So, all things being equal, you'd still save a bit of energy by using recycled glass, but if the recycled glass was shipped from farther than you could get newly manufactured glass (and don't forget that shipping/trucking/transport uses energy as well) it probably wouldn't be worth it.

Another interesting thing from the Home Energy article was that 'energy-efficient' buildings often used more embodied energy in their creation. A Canadian article cited claimed that "...the more operating-energy efficient the house is, the larger percentage embodied energy will be of the structure's total energy." I'm not sure this would be true, however, if you used recycled newspaper for insulation and reused triple paned windows (the JPGreenhouse did both).

The moral is: Don't assume that your snazzy new 'energy efficient' toy is actually going to help the environment by saving lots of energy. That's corporate capitalist greenwash: "Saving the planet by buying more stuff!" It's not true and, in fact, there is more than embodied energy involved in making these products--there is also the toxic wastes produced in the manufacture. (See The Story of Stuff for more on this.) If you really want to make a difference, as I put in my post of 11/24/09, 'Reduce and Reuse'.

Quote of the Day: "That is why an electronic gadget can be sold for five bucks, even if its production contaminates drinking water supplies, makes workers sick and creates piles of toxic waste along the way. The price tag doesn't include the true cost of making the item." - Annie Leonard

1 comment:

Jerry said...

Excellent points. There is so much to consider that it can be overwhelming to even think about starting!