I've spent some time this morning being transfixed by a back and forth between Brad Delong and Chris Bertram (of Crooked Timber) who has been influenced by Tom Walker (about whom I know really nothing other than now I like his blog and I'm going to read his manuscript should I have the time). At issue is the application of the Lump of Labor fallacy to energy efficiency. The argument is that there is a rebound effect (or Jevons Paradox) relating to energy efficiency that would reduce or eliminate the environmental benefits of efficient construction or installation. The thought is that increased efficiency would lower energy costs and the result would be greater consumption.
Personally, I do not think we will have the opportunity to test this theory empirically for several years as domestic energy consumption will remain depressed due to economic factors. Further, I think that over the next decade there will be increases in societal pressures to reduce consumption as the anti-intellectual backlash against environmental concerns abate. This latter thought might be a bit pie-in-the-sky. Anyway, check out the links, as you will either find them fascinating or as an excellent replacement for Ambien; valuable either way.