The great thing about active solar air heaters is that they’re easy to build, requiring only a good grasp of carpentry and a modest amount of electrical knowledge. In addition, they’re inexpensive to build and maintain, and the energy saved is high (exactly how high depends on what kind of system one would be supplementing).
Earlier this year, authors Stephen  and Rebekah Hren  (The Carbon-Free Home: 36 Remodeling Projects to Help Kick the Fossil Fuel Habit) visited the North Carolina School of Science and Math and gave a presentation on solar air heaters. Later, the students decided to build one themselves, with Dr. Marion Brisk. They filmed the project and put it up on YouTube in the hope it could be replicated.
Stephen helped out for the first couple of hours.
Watch Part 1:
Watch Part 2:
Watch Part 3: