Tell us about the design of your Adanado rammed earth home. 

Our Adanado home's interior is 1,160 square feet. It is a simple layout—living room on one side, master bedroom on the other, and the kitchen bridges the two primary spaces. Between the bedroom and living room, there is a large covered terrace. It has a spectacular view of Mt. Blanca, the Great Sand Dunes National Monument, and several other 14ers (14,000-foot-high peaks). There is also a small study adjacent to the living room that can be used as a second bedroom.

What are some of the primary sustainability features? 

The house was built literally from the earth on site. That means very few materials were trucked into the site, and for those, we used as many locally sourced materials as we could find. The forms for the walls were plywood that, when removed from the walls, we used as our roof sheathing. We are completely off-grid. A well was dug before the beginning of construction, and a solar panel was installed to operate it. All of our power is solar energy; we are not grid-tied. We have a battery bank for electricity storage, and our heating comes from the sun. We installed an evacuated tube system for both domestic hot water and floor heating. The sun heats the liquid, which then flows into our storage tank and circulates through the home. We made our own clay wall finishes for the interior surfaces.

What proportion of cement was used to stabilize the walls? 

Approximately nine percent. We started at seven percent. But we found that due to the high sand content and lower clay content of our native soil, we needed to increase the amount of Portland to ensure stabilization slightly.

I saw that you excavated all of the soil for the walls on-site. Does this contribute to reducing the embodied energy of the home? Can most house sites do this? 

It significantly reduces the carbon footprint. Before using site soils, get them tested. Salt content is a significant factor, as too much can cause the walls to deteriorate. You need the right blend of sand and clay, and the topsoil needs to be removed past the root zone of any plant material. The testing process is simple. You can send samples to companies for sodium analysis; a clay/sand analysis is as simple as putting your soil in a jar with water and seeing how it settles out. Many times soil can be supplemented if what you have on-site isn't ideal. Road base is a material that is frequently used for rammed earth walls and is relatively inexpensive and sourced locally.

What can you tell us about how rammed earth homes help with temperature control and indoor air quality? 

The walls moderate temperature due to their thermal mass. Once heated, they remain warm and radiate heat back into the space. This minimizes the heating load during the winter. In the summer, we open the windows in the evening to let in the cool desert air. Once the walls are cool, they stay cool all day, which means we don't need air conditioning. Earthen walls and clay finished walls have no off-gassing. As natural substances, they breathe and help regulate indoor humidity.