Passive Solar Greenhouse Construction - Comments and Suggestions

1. As a foundation, concrete piers (10" diameter x 18" deep) were poured every 6' apart and foundation beams were laid over them. The beams were secured from shifting by 1/2" bolts which were imbedded in the concrete and bolted through the beam.
2. A 2' wide x 4" thick concrete pad should be poured inside the greenhouse against the back (north) wall to provide a solid base for the water barrels and keep them from falling over. Reinforcing rod should be imbedded in the concrete to keep it from cracking.
3. Black 55 gallon plastic barrels are filled with water and stacked two high on the pad and if desired, the top barrels may be secured to the wall with rope and metal eye bolts to help prevent them from falling over.
4. The front roof is composed of two 6 mil plastic sheets lying together with an inflation fan blowing air between them to create a dead air space. This increases the insulation value as compared to one plastic layer and reduces heat loss in cold weather. The inflator fan is mounted externally on a side wall and blows air though a jumper hose that extends through the wall and into the bottom layer of plastic. Aluminum rail systems may be purchased that secures the plastic to the greenhouse frame and also simplifies replacing future plastic.
5. The front wall is plastic also (the front roof plastic just hangs down over the front wall) to allow additional surface area for sunlight to enter the greenhouse. The front plastic may be permanently secured to the stud wall, or if desired, may be secured to a PVC pipe and rolled up in warm weather for increased ventilation. If the roll up option is used, the plastic must be completely sealed to the stud wall in cold weather to eliminate drafts and heat loss. Aluminum rail systems may be purchased to secure the plastic.
6. The walk through door and ventilation fan/or motorized shutter may be placed on either end of the greenhouse as desired, although the fan and shutter must be placed opposite each other.
7. The plastic strips joining the 4'x 8' sheets of bathroom paneling should be sealed with silicone calk to prevent moisture from seeping into the wall and causing deterioration.
8. The center support post inside the greenhouse should be located in the middle (12' from each wall) and directly under the roof ridge. It should be set on a concrete pier or set in concrete to prevent settling. The 2-state thermostat that controls the ventilation fan and shutter should be mounted on this post about 4'-5' off the ground.
9. Bat insulation (6") is installed between the studs in the rear wall, rear roof and both side walls to prevent heat loss in cold weather.
10. A fuse box and electrical breakers should be installed to protect the electrical components of the greenhouse.
11. It is critical that the greenhouse interior be white in color to reflect heat and the water barrels be black in color to absorb heat for the system to store and dissipate heat correctly in cold weather.