The greenhouse has a heat store under the floor. I am pumping the hot air on hot days from the top of the greenhouse through a pile of rocks under the floor using a 12volt extractor fan. The heat is allowed to seep back in the evenings. On hot days the rocks gain 10 degrees C by the end of the day and the night time temperature of the green house goes up by as much as 5 degrees. We are also using a rocket stove to keep the temperature in the early spring above ten degrees at night see rocket stove
