A passive approach to solar heating, incorporating the Trombe (thermal storage) wall conceptand direct solar gain (1), offers several advantages over active systems. Such a system issimple and has thermal and architectural advantages in that the Trombe wall not only forms allor part of the south wall of the house, but also serves as collector, storage, and built-inradiant heating panel. However, unless all rooms in the house communicate directly with theTrombe wall, control of heating is difficult and separated rooms tend to be cold and must beheated by different means.

This suggests the combination of the passive and active features of solar heating to gainthe advantages of both. Such an approach was implemented by the author and his family in theconstruction of their three-bedroom, 181.7 m² (1955 ft²) house in Los Alamos, New Mexico,which was completed in December 1976. A second design consideration was to construct an architecturallypleasing home with standard building materials. The house is located at an elevationof 1950 m (6400 ft), where the winters are cold (35000 C°days = 63000 F°days), butsunshine is plentiful.

This paper describes the design, cost, and just over the first year's operation of the system.Owner/occupant observations are also reported. Although operatior in the active mode hasnot yet been fully successful, data are reported for both the passive and active modes.Finally, measured energy consumption for the year is presented, and a calculation of the actualsolar contribution to space heating is discussed.