by John Motley, Assistant National Director
It always amazes me the way something can come from nothing. This has never been more true than with my first experience constructing a Compressed Earth Block building. Two months ago there was a bare plot of land with a few stakes delineating the crude outline of what was to become a foundation, now there is a completed building with four walls, four windows, a door and a roof. But beyond the basic structure we have incorporated various renewable and sustainable technologies that will help the building maintain a regular temperature despite outside conditions.
The compressed earth block home that we will complete this summer is made from compressed earth blocks using a machine generously donated by the company EARTHinBLOCKS. The blocks are made onsite from locally sourced materials. Approximately 90 percent of the mix for the blocks is from the refuse of the local gravel company on the Pine Ridge Indian Reservation. We re-purpose waste material by combining it with a small amount of Portland cement and water to create blocks that are then compressed to 2,000 psi. This pressure causes cement to bind with the earthen material and then cures for up to a week. The blocks are four inches high by eight inches thick and then the length of the block can vary based on the amount of material put in to the compressor. The blocks are very dense and as such have high thermal mass. This means that the blocks are slow to change temperature, so in the summer months they stay at the average daily temperature and do not fluctuate, this means a cool building during the heat of the day and a warm structure during the chilly nights.
We have also incorporated a radiant heat floor that is warmed by solar hot water panels requiring no electrical input. This will help the office stay warm during the cold Dakota winters. We have also built a double wall out of the earth blocks that will absorb heat from our wood burning stove and radiate that heat throughout the night.
These blocks require no mortar due to their tongue and grove design. This allows for a group of six to put up four walls with windows and doors in four days. We purchased prefabricated roof trusses that also were able to be installed without any skilled labor in one single afternoon. In seven days we went from a blank slate to a beautiful building that will serve as a demonstration home for anyone interested in learning more about Compressed Earth Block.
Trees Water & People is working to promote this type of construction to Tribes across the Great Plains who are struggling to find ways to build affordable and sustainable homes for their members. This construction has an upfront cost of less than $20,000 but the energy savings alone will offset the cost of the building within 15 years. Stay tuned as we continue this important work: sustainable building + renewable energy for a greener future on tribal lands.
We owe a special thank you to EARTHinBLOCK’s founders Elsie Walker and Susan England for their support and their time in completing this project.