Designing Energy Efficient Buildings
Amory Lovins (from the Rocky Mountain Institute) is a visiting professor for energy and the environment at Stanford University. He gave a series of talks about using clever design to improve energy efficiency in a variety of industries. I found the talks about improving the efficiency in buildings to be particularly interesting. It's amazing what one can do if one uses a few simple (or not so simple) technologies and designs in buildings.
Dr. Lovins gives examples of buildings in almost all the world's climates that can be built without costly energy wasting air conditioning or central heating systems. Using modern building materials can make a house very comfortable at a fraction of the cost. Better insulation turns out to be cheaper than the alternative of investing in artificial climate control. Better airflow design can make a house more healthy and comfortable.
Anyone that is living or working in a house that is too hot/cold in the summer/winter should listen to these lectures. Anyone that is building a new house should also definitely listen to these fascinating lectures.