It is a waste of time unless I grow food that can't be purchased. Sweet lemons, kumquats, figs, honeyberries, sour cherries, kale/collards, pears & peaches with flavor
It would be much cheaper and offer much more use to build your house with 12 inch insulated walls and 30 inches attic and have a separate greenhouse for plants.
Going down to 25F Monday night-Tuesday morning so I brought my Meiwa kumquat on Flying dragon inside Sunday even though it is only going down to 35F A close up of the graft.