It doesn't need to be a dome per see but some sort of roof...a stepped dome would probably be the most efficient.... The main reasons are: To provide an atmospherically contained/controlled environment. To minimize/avoid fatalities due to frequent peak heat conditions. To dehumidify the air to avoid wet bulb extremes. (WB35degC has happened already twice apparently) To use as both roof, energy, garden and water collector. To protect against micro storms and violent cyclonic weather systems.