Editing Earth shelter (section)

===Modern times===
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Since the late 1980s, earth-sheltered homes have become increasingly popular.<ref name="gray2019" /> The technique is more common in Russia, China and Japan.<ref name="gray2019" /> It is possible that Northern China has more earth shelters than any other region.<ref name="boyer1987" /> As of 1987, approximately 10 million people live in underground homes in the region.<ref name="boyer1987" />

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Some claim that thousands of people live underground in Europe and America.<ref name="gray2019" /> Notable European examples are the "Earth Houses" of Swiss architect [[Peter Vetsch]]. There are about 50 such earth shelters in Switzerland, including a residential estate of nine earth shelters (Lättenstrasse in [[Dietikon]]). In other parts of Europe, such as the UK, earth sheltering is more uncommon.<ref name="gray2019" /> Possibly the most well known examples of modern earth sheltering in the English-speaking world are [[Earthship]]s, the brand of passive solar earth shelters sold by Earthship Biotecture. Earthships are concentrated in New Mexico, US.

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Overall earth shelter construction is often viewed by architects, engineers, and the public as an unconventional method of building. Techniques of earth sheltering have not become common knowledge, and much of society is unaware of this type of building construction. Generally speaking, the cost of excavation, increased need for damp-proofing and the requirement for the structure to withstand greater weight relative to above grade houses means that earth sheltering remains relatively rare. In this respect, the [[Passive House]] (PassivHaus) energy performance standard applied to above grade airtight, [[superinsulation|superinsulated]] low carbon or [[zero carbon building]]s has had much wider uptake in modern times. Over 20,000 buildings certified to PassivHaus standards have been constructed across Northern Europe.<ref name="thorpe2018" /> Some postulate that over time the reducing availability of building space, and the increasing need and interest for environmentally friendly housing will make earth shelters more common.<ref name="gray2019" />

There are an estimated 30-40 million Chinese living in such earth homes today still, mostly along the Yellow River in Northern China. There are mainly two kinds of earth homes in the area. The first type is pit cave dwellings.<ref name="Long"/> Usually, people dig a sunken courtyard, which is a rectangular underground pit about 10 meters deep, then arrange rooms dug off the main courtyard. The second type is dwelling space carved out of earth cliffs which are often south-facing, and the facades are sometimes faced with bricks or stone. They usually come with larger courtyards since it doesn't bother to excavate.