Hello, I'm building my first greenhouse and need some advice. First I live in Iowa in climate zone 5 and this will be a four season greenhouse. The structure will be 20' X 12' and will sit on a heavily insulated 44" kneewall that will be below grade on three sides. The greenhouse will have lowE double pane glass on the sides and will have 5 wall polycarbonate on the roof. The greenhouse is being built in Canada and will arrive one month from now. The question I have is should I put insulation below the concrete slab or should I use the ground under the slab as a heat sink? I'm just curious what the experts here would recommend. I've got a 45K BTU furnace so it should keep it warm with or without floor insulation.
Thanks in advance,
Keith
