passive solar has been with us since 1600, perhaps even earlier. this link takes you to an excellent primer on this intelligent approach to heating a home. it offers the following definition:
Passive solar heating is the use of solar energy to heat a building without mechanical or electrical energy. The architecture and construction capture, store, and distribute the sun's energy. Every building with windows exposed to the sun is passively heated, but heat losses may exceed the solar gains. Accordingly, if the passive heat gain is to reduce heating costs, the system heat losses must be minimized. Ideally, the concept includes mass to store daytime solar heat for nights, increasing the usability of the gains.
the reference traces the history of passive solar, it's key concepts as well as techniques for application. a must read for those thinking about building a new home or adapting their existing dwelling for more sustainable living.