| If you live in an area with a lot of sunny clear days, | | | | collected and pumped out. Once the sides of the |
| then a solar greenhouse is worth considering. This | | | | excavation are squared, build a concrete footing |
| kind of greenhouse relies on captured energy from | | | | around the circumference and lay a mortared and |
| the sun, which heats the inside space during the day | | | | filled concrete block wall on it, insulated on the |
| and releases it at night. A solar greenhouse usually | | | | outside with 1 inch rigid insulation and a layer of |
| requires some type of heat sink or thermal mass | | | | heavy plastic. Build the wall one block higher than the |
| that can store the heat for slow release over night. | | | | surrounding ground, keeping the block courses level |
| Often this sink consists of several black barrels filled | | | | and plumb. |
| with water, a back wall of concrete, or a rock or | | | | Before building the roof, level the floor and either lay |
| brick area. | | | | bricks on a bed of sand or make a floor with 4 |
| Another solar greenhouse option is the sun pit. A sun | | | | inches of pea gravel. At one end, plan your stairs for |
| pit greenhouse is a greenhouse that is sunk below | | | | entry. Siting them inside the space rather than |
| ground level, and takes advantage of the earth's | | | | outside will help keep out any water from heavy |
| natural insulation as well as solar energy. Although not | | | | rains. Frame the roof and end walls atop the last row |
| as common today as they once were, this type of | | | | of concrete blocks, with the ridge or center a good 8 |
| greenhouse may appeal to you if you have a sunny | | | | to 10 feet above the floor. |
| well-drained spot for it. | | | | The north side of the roof can be covered with |
| A sun-heated pit greenhouse has walls below ground | | | | plywood and roofing felt, and a weatherproof |
| level, with the roof sitting above ground. The roof | | | | covering while the south facing side can be either |
| can be arched, A-frame or rounded. The length of | | | | glass or fiberglass panels, fitted in place and sealed |
| the roof should face south to collect the most solar | | | | with weatherproofing. The end walls must have |
| energy. Paying attention to drainage is important, | | | | ventilation openings, and of course, one end will have |
| since you don't want to be working in a muddy or | | | | the entry door. In a larger structure you will need |
| water filled space. In all likelihood, you will need a | | | | extra venting in the roof. |
| backhoe to excavate the space, which should be 4 | | | | Sunk below the ground, a well built sun pit |
| feet deep and no smaller than 8X12. | | | | greenhouse takes advantage of the sun's energy and |
| Dig a sump in a spot on the pit floor, about 30 inches | | | | the natural insulation of the earth. Carefully managed, |
| deep and 18 inches wide, and line it with bricks. This | | | | it can be a successful alternative solar greenhouse. |
| will allow any irrigation water or seepage to be | | | | |