I was reading in Dwell about the Oxley Woods development in England and the distinctive "eco-hat" package of solar and other technological contrivances that allow for a large gain in energy efficiency at low monetary costs. The article doesn't seem to be online, but this website has a decent explanation of the project. The whole subject of green architecture is one I find pretty fascinating. In this and other cases, it turns out that a lot of the work is being done not by technology as such (thought obviously technology matters) but by design -- simply doing the architecture with an eye to the energy use implications of the plan.
That kind of thing makes green architectural schemes well worth public investment. Given the appropriate financial incentives, firms can come up with different kinds of ways to meet the projects goals. But once the work's been done, the underlying design principles simply add to the general stock of human knowledge and become something that other firms can borrow or improve upon.