Customer Comments: "Foundation -- Dug to 3 inches below grade and then filled with ½ inch pea gravel. Construction of greenhouse per instructions provided by manufacturer. This stage went amazingly smoothly. Construction of interior benches using 5-quarter x 6 inch cedar. Uprights sit on concrete pads below the gravel. Mechanical -- My house is heated with a water-sourced heat pump. I diverted the exhaust water from the house heat pump to the greenhouse and through a radiator. The bottom left image shows the in- and outflow plumbing. When the heat pump in the house runs the water flows through the radiator and a fan distributes air at the same temperature as the water, generally about 50 degrees. I installed an inline flow switch that turns the fan on only when water flows. This will heat the greenhouse in the winter and cool it in summer. Best of all, it’s essentially free to run because I have to pump the water anyway. Additionally, I installed a thermostatically controlled 220 resistance garage heater as a failsafe. I have it set at 40 degrees which will prevent the greenhouse from ever experiencing freezing temperatures."