I attended a workshop on Wednesday, July 29 which featured a concept called "the passive house". While this concept contains much of what those of us educated during the original energy crisis would call passive design, it goes much further in some respects. The first is that the building is super-insulated, with double or triple the typical R values required by building codes. This allows the mechanical unit and ductwork to be much smaller than in a typical house. Also the mechanical system is typically what is called an ERV, or energy recovery ventilator. An ERV supplies fresh outside air but keeps most of the heat inside the house. I will have more to say about ERV's later.
The person leading the workshop was John Semmelhack of Charlottesville, VA. The interesting thing about John is that he has built his own house according to this concept, and has had to deal with the real economics of it. His house was built for approximately $200.00/SF, which seems quite reasonable for a custom house.
For more information see: www.passivehouse.us