When we say underground building, our common understanding is literally an architecture under the ground or soil like meters deep. However, designer Malcolm Wells see it in a different way. He have designed an underground building that is passively heated. According to his illustrations, the building was built on the ground then it was being insulated and covered with a thick layer of soil like four feet thick. After covering, various plants are planted allowing the structure incorporates with nature. In this way, the building will be warm enough during cold season and will also be cold enough when the summer time comes.