A friend of mine, Rich Rosen of the Tellus Institute in Boston, has been involved in a very interesting exchange on Andrew Revkin’s New York Times blog. I strongly recommend checking it out, but the gist of it (for those in a real hurry) is that although research is good, we understand the basic physics of energy technology well enough to know that we are not going to find renewable technologies that will be cheaper than coal. We have to make the transition to more sustainable energy sources, but we should start now, with the technologies at hand, laying out actual money, and not expect solar energy, fusion power, or the hydrogen economy to come rolling in and rescue us with painless, or even relatively painless, sustainable sources of energy.

Rich and Andrew Revkin are discussing large scale power sources, but the same physics and economics constrain the future of buildings. After we have picked up the “free” 20-30% savings that come from correcting today’s really bad practices, we get to energy savings measures that have 20 year payback periods or more. But we have to lower energy consumption much more than 20-30% – we must get carbon emissions down by 80-90% by 2050. We already know how to make buildings that use very little energy, and to some extent how to convert existing buildings: lots of insulation, not much glazing, carefully controlled ventilation, and smart controls. Research may give us more options – aerogel windows could make glazing much less lossy – but these improvements will arrive incrementally and they will cost money.

As a society, we will just have to start spending more on energy use reduction and on sustainable sources – if they were cheaper we would be using them already. Not pleasant news, but the alternative isn’t a silver bullet, it’s a nuclear weapon scale problem: the rapid or gradual collapse of the ecosystems that sustain our civilization.

Check out Andrew Revkin’s blog.