How does the greenhouse heating system work?
During the day, hot air from the top of the greenhouse is sucked by a fan down a pipe and into a hole in the ground. The hole should be filled with something that absorbs heat – rocks and stones are most common. There must be enough gaps to let the air through easily. At night, when the temperature in the greenhouse drops, cool air is sucked down the pipe and blown on to the warm rocks. These warm the air, which then passes back into the greenhouse to heat it. This simple system has also been used to heat conservatories. The fan can be powered by solar panel, and a battery so the fan continues to work at night.
