In other words, they live underground.
Why would anyone want to do that?
Well, if a house is underground, it is insulated from heat and cold by earth and plants, and it can often stay a comfortable temperature by passive or fuel-efficient ways, such as sunlight on a concrete-block wall. With trees and other vegetation planted over the house, more rainwater is conserved, more carbon dioxide is take out of the atmosphere, erosion is minimized, and of course a more natural, beautiful landscape is preserved.
A man named Malcolm Wells built a lot of underground houses and urged others to build some, as well. He didn't necessarily start by digging down in to the earth. Instead, he built a strong, waterproof building (apparently more concrete than wood), and then he covered it with earth and planted it with native plants.
- Here Wells makes some suggestions for celebrating Underground America Day. Hmm...I like the idea of making a meal from things that grow underground (potatoes and carrots and peanuts come to mind), riding a subway, and designing the perfect underground house or school or shopping mall!
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