Insulated floor
We built our RAL home on suspended floor, because a house with such a floor provides minimal possible footprint on the environment (no bulldozing).
However, suspended floor can waste a lot of precious energy in winter, especially on windy days. For this reason we insulated the floor with aluminum foil based fiberglass wool bats, stapled to joists to create closed air spaces. Mesh protects the insulation from damage.
