We have broken ground on the 8th Living Building Challenge project in BC. The ground was easy and sandy. Ground water was found about 8’ below the surface. This was expected due to the spring rains and high water tables of the nearby creek. Our rain water tanks and earth tubes will be kept 1’ above ground water. Our foundation and footings are well above this level (2’ required by local code).
Integral Design Group used their expertise and experience in the designing of this unique system. The HVAC is designed to take fresh air and return air through a number of 4” diameter pipes called earth tubes. In the process the air takes on the temperature of the ground. According to studies the earth tubes an have change the temperature by up to 13 degree Celsius. In the building world there is lots of discussion about this use of this passive technology. The long and short if it is, it works.
“We love the earth tube system installed in our home” Chris and Cathy Jennens, Kelowna, BC
In this house we will be running all of the air supply to the house fan through these tubes. Manually adjusted dampers will mix the approbate amounts of fresh air into the system. These dampers will be adjusted in the spring and fall.
Many materials for the earth tubes were considered. (More detailed discussion can be found here ) Concrete, steel, HDPE, PVC, and polyethylene, . Concrete works well for larger projects but is expensive and laborious to install without the use of heavy machinery. Steel when coated offered an attractive alternative, however it’s proximity to water table and cost of install put questions in our mind about longevity and ruled it out of this project. HDPE is available in many sizes including the 18” diameter we required, but the costs of the piping and heat welding required to connect the joints was expensive. PVC is toxic and not permitted on LBC projects. That left us with polyethylene or “big O” as it’s referred to. This piping is inexpensive, flexible, but only comes in 4” diameters. Our challenge now is to bury the 18 4” pipes, each 100’ long, into the space beside the Ethel Lane House.
Integral Design Group has been excellent in helping with the design of Ethel Lane House. Their scope of work includes:
Here is a wonderful explanation of the systems of Ethel Lane House prepared by Integral Group.