Deconstruction of a building, i.e. carefully taking it apart so that the pieces can be reused or recycled, provides benefits in four categories according to the Deconstruction Institute. We have already, using its Deconstruction Calculator, outlined the savings in land and economics for a 1,800 sq. ft house. The remaining categories are energy savings and reduction of green house gasses.
Energy
Significant amounts of energy are required at every step of constructing a home or other building. Energy is needed to harvest and transport raw materials, to turn them into building products, to transport those to the construction site and by the equipment used to put the building together.
The "embodied energy" required to construct our 1,800 square foot home amounts to 803.70 million Btus, the equivalent of 7,043 gallons of gasoline. As the laws of physics tell us, energy can neither be created nor destroyed. In this case the energy is embodied in the materials that were harvested, transported, manufactured and assembled and is recovered when the materials are reused or recycled because many of the processes outlined above do not have to be repeated. In our house, recycling of all of the steel and plastic used in its construction will preserve 52.74 Btus of embodied energy and reusing the lumber will save another 21.06 million Btus.
Green House Gas
All of this conservation of embodied energy means a large reduction in the amount of green house gases released into the energy. Much of that energy involved in harvesting, transporting, etc., etc., involves petroleum based fuels. Capturing and using embodied energy, especially when materials are reused, involves very little in the way of fuel. Recycling materials does require energy expenditure, but on a reduced level from using virgin materials. For example, every ton of wood that is reused means we are not creating 60 lbs of gases from harvesting and milling operations.
There are also gases released from decomposition in a landfill. Degrading of lumber releases methane gas and the Institute says that the 33 million tons of wood and other construction debris buried in landfills each year will release 5 million tons of gases. Eliminating this would be equivalent to removing 3,736,000 passenger cars from the road. Even our little 1,800 square foot house would reduce landfill gases by an amount comparable to putting about 3 passenger cars up on blocks and planting geraniums in them.
For more information on how a house is deconstructed and the materials reused, check out the project details of This Old House's New Orleans and Weston Projects at http://www.thisoldhouse.com/ or visit the website of The Deconstruction Institute (http://www.deconstructioninstitute.com/) and try out its calculator. If you want to locate a contractor in your area - this is a new but growing field - you might start with the nearest Habitat for Humanity Restore (these sell surplus and used building materials.) Some of the larger stores do deconstruction but the majority that do not might have a line on other local sources.