One unusual feature of many passive solar homes is that they are partially buried. Given the natural human dislike of living underground, this often strikes people as a "caveman" approach to efficient living but, in reality, it is an efficient means of conserving potentially enormous amounts of energy. And no, living in a home that uses earth berming or earth sheltering is not like living in a cave!

• Earth berming is the practice of building a wall of earth around the outside of the home. The berm is about three or four feet tall and covers all but the south side. It is particularly useful for protecting homes built on flat terrain.
• Earth sheltering is a more extreme version of earth berming, where the north side (and perhaps the east and west sides) of the house is buried more extensively, often right up to the roof.

Surprisingly, with proper design and forethought, earth-sheltered homes are just as light as traditional houses built entirely above ground. They can offer beautiful views out of the south-facing side while protecting the north from cold winds and buttressing the building's heat retention ability with earth.

A good way to think of earth sheltering is of sitting on a beach, facing south, with a cool wind at your back. You will eventually get cold with the constant breeze, but if you wrap a towel around your shoulders – as earth sheltering wraps the planet's "towel" around your home – you can enjoy the sun and the view while staying warm.

Earth sheltering has multiple benefits:

• The barrier protects the northern face of the building (and potentially the east and west) from cold winds, reducing heat loss in cold months.
• The surrounding earth offers geothermal heating for the home. Below the frost line, earth remains at a fairly constant temperature of around 50°F (10°C), so an earth-sheltered home is much easier to heat in winter.
• In summer, the earth provides heat protection and an enormous amount of external thermal mass to wick away excess heat inside the home. Earth-sheltered houses are a lot easier to cool.
• The noise reduction provided by an earthen buttress is impressive, especially compared to stick-built homes entirely above ground.
• Fire protection is also greatly improved by having tons of earth piled up on three sides of your home!

The important part of earth sheltering (or earth berming) is that you employ a professional who knows how to do it properly. Badly-implemented earth berms or shelters can cause immeasurable damage to your home, including collapsing the roof, accumulating water that rots the sides and foundations of the house, and even sinking ground which drags your walls and pipes with it. Make sure your designer knows what they're doing!

If you can't practically earth-shelter or -berm in your location (or the thought of living partially underground gives you the creeps, despite the fact that there's plenty of light), you can still protect your house with a grove of trees or some other form of windbreak.