I am a member of a small group of natural building enthusiasts from around the world who are meeting online once a month to share ideas. This has been very productive and useful for all of us. Our last meeting was dedicated to a discussion about earth-sheltering that I led. Below is an outline of the main points that we considered.
What are the pros and cons of digging into the ground or earth berming, including green roofs?
- Thermal buffering
- Energy efficiency
- Protection from the elements (both for the building and the inhabitants)
- Fire resistance
- Wind resistance
- Potential for passive annual heat storage (PAHS)
- Aesthetically blends with the environment
- Opens roof space back to nature
- Blocks electrical magnetic frequencies
- ionic charging
- Limited views
- Limited appropriate materials for building
- Often requires concrete and steel
- Flooding could be an issue
- Burrowing varmints
- Danger of collapse in an earthquake
What materials can be used?
Low embodied energy
- stabilized earth blocks
- wooden beams
Moderate embodied energy
- synthetic composites
- steel (if recycled)
- poured earth
High embodied energy
- reinforced concrete
- insulated concrete forms
What physical or social constraints are there for living underground?
- Robust design
- Heavy roof
- Need for water proofing
- Pressure from the surrounding soil
- Actual footprint may be quite large because of the surrounding soil
- Customs favor above ground building
- perception of being “dark and dank”
- Perception of being high cost
- Not as appropriate for urban density
Concerns that earth-sheltering alleviates:
- Reduces the use of energy and CO2
- Wind protection
- Fire protection
Loss of habitat
- Returns vegetative space to nature
Underground sites from around the world:
- Cappadocia in Turkey
- Southwest US cliff dwelling
- Loess region of China
9 thoughts on “Earth-Sheltered Architecture Discussion”
Hi Kelly, I could have used this group about 5 years ago when I was researching all these issues and finding solutions for the bermed earthbag dwelling I’ve been working on for the last 4 years. Regardless, the building is watertight and held a 43⁰f advantage (no heat yet) against the recent winter storms and zero temps.
It’s interesting that you mention burrowing animals as a disadvantage, as I considered this as well even though I couldn’t find anyone else discussing that aspect. I used 3″ of crushed limestone gravel to protect my waterproof membrane. Then about 3″ of soil on that. The gravel has an extra benefit of allowing rain to flow off the building without digging valleys and taking the soil with it.
Before I started construction I actually got Owen’s stamp of approval since it’s fairly unique.
I wrote more about it here in a recent reddit post, including a few pictures and sketches lower in the comment section.
I’d be interested in sharing what I’ve learned and learning more from the group.
That’s all very interesting; thanks for sharing. Our group is still in its beginning stages and trying to formulate a framework that is good for everybody. Would you mind if I do a blog post here about what you are doing? I can share it with the rest of the group.
I definitely wouldn’t mind if you blog about it. Let me know if you’d like any more details. I’m currently working on the floor and plastering walls. Likely a year left to go, but I gave up serious estimations a long time ago. I can say that all of the trees for the posts/beams/rafters came from my place, mostly from a few hundred foot radius. Also, I plan to finish around 20k$, as I’ve done most of the work myself and reclaimed what I could, including all the free windows.
Great. I’ll let you know when I do this. Thanks.
I did a blog post about this at https://naturalbuildingblog.siterubix.com/a-heroic-earthbag-project/
Wow, I feel famous, thanks Kelly!
Earth-sheltered home is less susceptible to the impact of extreme outdoor air temperatures than a conventional house.
I am in my 11th month of building against a cliff face on a mountain. I have found no one else who has done precisely what I am doing but I have used “The Hand-Sculpted House” by Ianto, Michael and Linda as my reference and improvised from there.
I originally planned to build a single house against a 20′ cliff face but wisely decided to do a couple of structures prior to gain experience.
I am now on my third one, a real tiny house with earthen and rock floor and a living roof.
It will have a loft and a floor cooler.
I have many pictures but see no way to attach them yet.
I am doing all the work by hand, no power tools, using local materials.
I have moved half ton boulders 100′ feet using gravity and physics, including a hand ratchet, often an inch at a time.
I have thought of doing this for twelve years and drew up 30 sets of floor plans.
I decided when I turned 72 that I had better get started.
We moved to the SoCal High Desert ten years ago and live just ten minutes from CalEarth, which we visited a year after arriving.
That was my introduction to earth building and while I did not choose to go with earth bags I respect all that Ian has done with that group since the passing of its founder.
Many of the buildings in this area were built of adobe, which is cob formed into bricks.
All the locals get what I am doing and support me in every way.
I do not use straw yet.
I will when I use the straw bales for the southern walls but I was given 750 lbs. of horse manure eight months ago and have not used a third of it yet.
I also took a tip from the local pioneers who used tumbleweeds in place of straw.
Cob is remarkable and infinitely flexible when you use what you have around you.
I have at least four types of soil on my site, which puzzles me since it is all from a monzonite granite mountain (Google Strawberry Peak, Lucerne Valley, CA to see my site). I vary the manure and clay portions according to what I am doing.
I have lots of rocks.
For cob houses you need a stone or concrete (which I will NOT use) foundation at least 18″W X 18″H.
In some places my foundation is 5’X 5′!
Hey, I gotta put that rock somewhere!
I would like to join your group.
Bruce, we are just beginning to form policies around membership with the group… I’ll let you know what is possible as it becomes clear.