In planning my design for the buildings I intended to utilize as many solar features as possible. In the first place, being at almost 8500 feet altitude I knew that comfort in living areas and working in large shops meant summer air conditioning would not be a problem; but winter was another story. In New Mexico there are so many sunny days in both summer and winter that it is insane not to take advantage of southern exposure. In summer the sun is so high that south facing glazing will not overheat with just a little shading. And in winter the sun drops down low enough in the south to clear such shading. The required overhang can be calculted using simple charts.
In winter strong SW direction winds can suck heat out of any building exposed on a hilltop as is this location . This means that the traditional plaza design is ideal to shelter living sections of a house with other less used buildings, as well as providing a protected outdoor space and reflective south walls for a sun trap: a great comfort to more delicate plant species. Thus all these conditions converged into a plan which practically designed itself. After briefly consulting an architect, I relied heavily upon the Rodale publication The Passive Solar Energy Book by Edward Mazria. It recommends north side insulation,glass heat traps around entryways, and materials for use in construction, and provides specifications for sizing,etc. As I planned to continue using adobe I encountered some interesting problems. Popular notions hold that adobe is good insulation, being earth and subject to such stability. But in fact it takes massive thickness for adobe to achieve normal R values for insulation (I recall some figure like 23 feet.) Indeed the Federal Government in its infinite wisdom, refused to support continued construction in the Indian pueblos using adobe. Adobe buildings like Taos pueblo which have provided shelter for 900 years were deemed inappropriate and Federal regulations now required frame housing. (I wonder when the bureaucrats will get around to making them tear it down!)
While it's true that the thick walls act similar to a cave in maintaining a constant natural 50 degrees, there is a simple solution to the problem: insulate the outside of the wall and use it for a heat sink (storage). With a moderate but steady supply of inside heating, adobe is a very even and comfortable material to live in; which is probably from where the common notion regarding its insulation value arises. Thus my plan emerged as an integral part of the construction itself as well as add on features subsequent to completion.
A lot of clerestory design was used in south facing buildings. Sun comes in the upper part of walls which provides a warm flow of light during the daytime, and can be closed off with insulating shades at night. (Above) a shop clerestory roof is built and then covered with a sloar plastic.
The heavy emphasis on insulation required some experimentation. Here the north wall of a shop is being insulated by filling a space between two courses of adobes with (free) sawdust. I also nailed rigid insulation to the outside of adobe walls and then plasted over it.
A useful feature suggested by an architect involved preheating firewood. A lot of heating value is lost bringing firewood up from cold outside temperature to burn temperature. Warm wood is also easier to light. Thus when I had an unused corner of the plaza on a south facing side, I added a small
glassed in wood room to dry and preheat firewood.(left)
A bigger commitment involves greenhouses. I have two. But with a short growing season they are invaluable for both house heat and fresh tomatoes. If I could only figure out how to raise corn inside....
The greenhouse also provides a location for a low-tech hot water system. This unit consists of plain copper pipes snapped into a "big fin" aluminum plate which preheats water before passing into an electric tank. Unfortunately at this altitude it has to be drained in winter to avoid freezing the pipes.
A better (but more expensive) system in the guest house operates on freon. The freon heats in the plate, turns to hot gas which rises up tubes to surround the tank on the roof where it then cools and condenses, flowing down the tubes in a liquid, to begin the cycle again. This system makes hotter water and has no winter freezing problem. Unfortunately the company selling it is now out of business and so no repairs are possible when problems occur. Not an uncommon situation when dealing with solar, especially after the tax credits were eliminated and companies went out of business.
Another disappointment has been my plan for heat storage. The crawl space under the livingroom and library comprises and area about 20 feet by 80 feet and ranges in depth from 1 foot to 3 feet. Into this space were poured tons of river rock which surround pipes with holes. The plan was to pump hot air from the green house under the floor for nighttime release from the rock heat storage. After plumbing all this I found the rocks absorbed everything I could put to them and hung onto all of it without releasing enough to matter. I was heating the earth below. So I ripped out the duct work from the greenhouse and simply put two opening windows in the clerestory to circulated the warm air of daytime into the house. This works fine and keeps us better in touch with the outdoors.
A final experience involves roof collectors. During the heyday of fly by night solar companies I arranged to try a commercial hot air collector for space heat in the guest house. I also built my own according to plans from the San Luis Valley Solar Association of Colorado. Their plan involved painting my tin roof black, glazing it, and then framing in the rafters behind the roof to blow air across the inside suface and down into the room. Depending on the glazing, the cost can be minimal. The commercial heater operates at maybe one third the efficiency of the homemade version!