A Solar Home

5. A Solar Home

5.1 Solarizing Your Present Home

The first step in solarizing your present home is to do an energy “audit”—to determine where the major heat losses occur and where the greatest energy efficiency gains can be made.

Every situation will vary, but one generally good strategy is to add a sunroom or a greenhouse onto the south side of the house. If this isn’t possible, at least more windows can be added on the south side. If you do have a porch on the south side, or one that at least has a south wall, consider converting it into a greenhouse or sunroom. A south-facing window can be converted into a solar window box greenhouse. We must always make the most out of what sun we get.

There are a number of other basic steps that can be taken to conserve energy, thus working with passive solar principles to improve what you already have. Some of these are:

1. Lower thermostat or turn down heater.
2. Turn water heater thermostat down to 120 degrees, and insulate it.
3. Weatherstrip doors and windows.
4. Caulk and seal openings.
5. Add storm windows.
6. Add awnings.
7. Add attic insulation; insulate walls.
8. Convert from gas or electric to wood heat; replace inefficient heaters with more efficient ones.
9. Add fans, vents, and ceiling fans.
10. Insulate pipes and ducts.
11. Add a solar water heater.
12. Add thermal heat storage or thermal mass (one example is a hot tub).
13. Add wood solar hot water heater.
14. Add entry room to act as an air buffer so that massive energy isn’t exchanged each time a door is opened (small adjoining room).
15. Add backup active solar systems for air and hot water heating.
16. Add insulated shutters and drapes.

Emphasis should be made again about the importance of providing adequate ventilation. We have already discussed the harmful fumes and byproducts of combustion that are present in rooms heated by most conventional methods and fumes that result from unhealthful building materials. Insulation must not become a threat to health. Ideally we could all use clean solar heat, but even then, we would want to remember that fresh air is essential to quality of life. In any case, it’s better to add a blanket and sleep with windows cracked—I remember visiting in Switzerland in the mountains a few years ago, and at night we just climbed under the thick down covers—the bedrooms upstairs weren’t even heated at all.

We should be conscious of the air quality in our living spaces at all times, waking and sleeping.

5.2 Building a Solar Home

The art of solar building design perhaps began when the cave men carved their dwellings into the south face of a hill in order to benefit most from the warm rays of the sun.

The use of south-facing windows to increase heat gain into a building became popular in the 30s and 40s in this country. In the summer, when the sun is higher in the sky than in winter, carefully designed overhangs shade the south windows and keep the building from overheating. Double-glazed windows or those insulated at night reduce the heat loss more.

The use of a greenhouse as a heat trap is an extension of the solar window design. On dark, cloudy days and at night, the greenhouse can be sealed off from the rest of the house to prevent heat loss. The greenhouse serves as a thermal mass to reradiate stored solar heat at night.

Water provides an excellent thermal mass, and has the highest heat capacity per pound of ordinary material. The storage tank is usually insulated to reduce conductive heat losses.

The seasonal angle of the sun changes in a regular, predictable cycle. When designing overhangs and collector angles, you need to know your latitude and the maximum high and low angles of the sun. The sun changes about 46 degrees from the summer to the winter solstice, higher in summer and lower in the sky in winter.

The insolation (or incident solar radiation) is the amount of energy that reaches the surface at a given location. Insolation tables are available for various latitudes.

Another factor to be considered in choosing a solar site is the amount of shading available. This can be in the form of overhangs or natural vegetation. A combination of shading, cooling, and ventilation elements must be considered as well as the solar factors. Evergreen trees planted to the north of a building help block the cold winter north winds, rain, and snow. Deciduous trees (those that lose their leaves in winter), such as fruit trees, are suitable for planting on the south, east, and west sides. In the fall and winter when the trees are bare, the sun’s rays penetrate to the building and in the spring and summer, the hot sun is blocked because the trees are full of leaves, flowers, and fruit. A simple idea thus becomes delicious and rewarding. Vines and climbers can also be planted to shade east, west, and south facades, as well as lattices or trellises covered with growth.

Walls should be as well insulated as possible on the outside and include thermal mass on the inside for heat retention. Thermal mass can consist of 55-gallon drums (water-filled) painted black for maximum absorption, or large rocks. Rocks can be used in the foundation and walls. (If using painted barrels, the nonsolar-collecting sides can be painted any colors.)

Inside walls that receive sunlight can be faced with brick or stone. There should be an insulator like gravel under the floor. Clay tile floors store heat well. They come in a rainbow of colors and designs, making some beautiful mosaics possible, that are both functional and aesthetic.

We receive our life nourishment from the sun, so it is only natural that we harness its energy and put it to good use.

5.3 The Solar Greenhouse

The primary reason for building a greenhouse is, of course, food production. Growing your own food saves money, and it is always ready to be picked—fresh, ripe, and organic, grown without the need for any farm machinery.

As mentioned, the greenhouse may be built on the south side of the building where it will receive full sun. It can be constructed quite simply with concrete blocks for the foundation, and other massive building materials such as ceramic brick, stone, adobe, poured concrete, or cinder blocks can be used for thermal mass. These massive walls are insulated on the outside surface.

For the glazing or clear film that is attached to the frame there arc many choices of material: glass, roll plastic, sheet plastic, corrugated clear plastic, etc. Doors and vents must be tight-fitting and weatherstripped, and all surfaces should fit tightly together.

At night, the windows should be blocked with movable insulating forms or covered with shutters or curtains. This will keep the heat level constant at night.

Heated air in the greenhouse rises and flows into a high opening to the home, and a low opening in the shared wall lets cool air from the house enter the greenhouse for heating. The plants in the greenhouse convert carbon dioxide into oxygen-rich air for the house occupants.

When you build a greenhouse, you will be creating a special space, a microcosm, a living place that will grow and truly add life to your home.