Even during the toughest of times, you'll need to stay connected to the Cloud and stay warm. Insulated and built from junk materials, and half buried. It will stay warm because of a floor of large paving stones that absorbs heat during the day. It all fits on one sheet of 4x8 plywood sitting in a strata of volanic ash.
A tight fit but when there's zombies outside everybody doesn't mind staying together for warmth. Inside is the solar powered charger and 20 gallons of drinking water