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EARTH: 
Investigating the whole "Earth Covered House" concept

Since my whole journey down the Energy Smart road started when I realized that my basement office was the most pleasant environment in my house, I decided I should research the whole concept of houses built in/under the ground.  Being a native of Australia, I knew of the underground houses that he been built in abandoned Opal mines in places like Cooper Pedy, and many years back I spent a couple of days living in a friend-of-a friend's underground house in West Virginia (USA).  But all things considered I was pretty green (excuse the pun).

My initial search of the Web provided a few token references, but the most helpful Web Resource was the book-title search at Amazon.com.  One of the most interesting and informative "underground" books in this area was by Malcolm Wells, a self proclaimed "Underground Architect".  This book of architectural sketches (titled "The Earth-Sheltered House : An Architect's Sketchbook ") is like an annotated history of Wells's own journeys through the world of earth sheltered houses. Although Wells only seems to have constructed several such homes, he has produced designs for a large variety of structures (both residential and commercial).

I learned several key things during my research:

  • Unlike my own personal experience, earth covered houses did NOT have to be dark and damp.  The correct utilization of the land's topology can facilitate many designs with more usable natural light than a conventional home. 
  • The correct (East-West) orientation of the home's major axis can provide optimal winter heating and summer heat rejection.
  • An slab floor over an earthen or rock base can be used as a thermal mass to store daytime solar energy to be released at night in the winter months
  • A system of air ducts built into the thermal slab (above) can be used to passively regulate the temperature of indoor air during both the summer and winter months.  The use of supplemental air blowers can increase the efficiency of this system.
  • Waterproofing of the roof system is very important, and special consideration must be given to earth expansion caused by freezing.
  • It is not intended to link the internal temperature of the home to the temperature of the surrounding earth.  Instead, the floor, walls and ceiling are insulated from the surrounding soil.  This surprised me initially, but I've since come to realize that the benefit of being below grade comes from the relatively small thermal differential between the desired inside air temperature (Approx 75 Deg. F) and the relatively constant soil temperature (50-60 deg. F). 
  • The cost and hassle of actually having a roof of earth (verses an in-ground house with a conventional insulated roof) cannot be justified merely by the insulating properties of the soil.  One must also consider the intangibles of the additional green-space provided by an earthen roof, and the positive effect on wildlife and the environment.
One particular design of Wells' caught my imagination.  It's fairly simplistic in it's basic premise, but it truly satisfied my desire for a comfortable but practical design.  A conceptual interior view is shown to the right.

One wall is almost completely glass with a south facing view (suited for the Northern Hemisphere).  A raised portion of the roof, penetrates the earthen cover to provide a skylight effect down the length of the house.  The potential openness of the design appealed to me very much, and this concept became the building block for many of my own tentative designs.

A cross section of the design is also showed to the right.  In my initial version of this design, the house spanned 32 feet from front to back (as seen in profile), and was approximately 64 feet long.  Notice that this design requires a sloped lot with a grade of about one in three to satisfy my own target dimensions.

A more developed concept is shown in my preliminary design where the rectangular design is replaced by a more interesting "pizza slice" shape that cuts back into the hillside.  The "As Built" design is featured on my final design page.



Purchase the book for many more designs.

Design Concepts
Earth - Sun - Water - Hybrid
© 2000-2012, Phil and Lisa's relaxed lifestyle home.
An exercise in Energy Smart, Not So Big living.
www.OurCoolHouse.com - Ideas@OurCoolHouse.com

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This site is all about building a cool, energy efficient house, that makes maximum use of earth sheltered design, passive solar heating and cooling, geothermal exchange energy management, and right sizing of the house for it's designated use. The home's placement is on a south-facing hillside in Deep Creek Lake, Maryland. This site describes the design process, the technologies used and the expected results. We also have a comprehensive Links Page for anyone who is also interested in designing a similar project.