Insulation

Insulation should be a considered factor – especially if it gets really cold! Domes of similar construction often are constructed by using a fan to blow-up an envelope, which is used for blowing-on concrete mix, doing re-bar reinforcement, etc., including blowing on a layer of chemical insulation. Chemical insulations typically melt in intense heat (some can burn) and give off extremely toxic fumes. For this reason, I did not recommend interior insulation.

Exterior insulation is better for two reasons. First, the thermal mass (all that heavy concrete and steel) is on the inside of the structure; thus allowing for greater temperature stability due to temperature fly-wheel effect. Second, exterior insulation can be added later, as indicated. Natural materials can be piled better over a low-profile dome without sliding off. Soil is a fair insulator. A layer of plastic sheeting can be applied, then a layer of natural insulator (preferably low-flammability), another layer of plastic sheeting, then soil. This dome can even be built in a shallow depression and be back-filled over.