On October 24, 2015, we visited the home of the owner of EcoFarm, an earth bermed home built on the design principles popularized by Mike Reynolds’ Earthships. This house heats and cools itself and produces zero energy costs!
Unlike the standard Earthship design of Mike Reynolds, this house’s roof is mostly subterranean. Except for the greenhouse front portion of the house, the house’s roof is concrete with earth over the concrete. The earth acts as a layer of thermal mass surrounding the house, which allows it to maintain a comfortable temperature year-round. Recall that the earth maintains a steady 14 degrees C (~57 degrees F) once you get below the frost layer. Here is how this particular roof was put together:
- Concrete forms the main roof structure.
- An epoxy layer is put over the concrete to form a moisture barrier.
- A few inches of sand, a half meter of scoria, and then more sand helps reduce the weight load on the concrete.
- A layer of geofabric prevents large particles from getting through.
- Soil is layered on top to provide thermal mass and insulation.
In the front of the house, the greenhouse section is covered by a metal roof and is where the solar panels rest.
This doesn’t really qualify as part of roof construction, but it’s worth mentioning here that a layer of geofabric and plastic extends down the earth bermed sides of the house to a point just below the drainage pipes that run from the back to the front of the house. This is critical for preventing water from getting into the house.
Beneath the concrete roof, Ed installed a suspended ceiling purely for aesthetic reasons. This literally hangs from the concrete and is then plastered over. It creates a beautiful organic look with a gently curving ceiling.
Sadly, I didn’t get a picture of the main area of the house, but it’s a beautiful open-layout kitchen with brick flooring, brick trim along doming archways, and plastered walls and ceilings. Everything is designed for maximum thermal mass. Both bricks and plaster absorb and hold heat when it’s warm and release it when it’s cold. Furthermore, plaster naturally regulates humidity by slowly absorbing and releasing moisture in the air as humidity goes up and down.
Along the front edge of the main area of the house, there are a series of glass sliding doors that they can open or close to help regulate temperature. On the other side of the sliding doors is the area that would typically be reserved for a greenhouse in the Mike Reynolds design (pictures further below). By using varying combinations of opening or closing the exterior windows and opening or closing the interior sliding doors, it is quite easy to regulate the temperature to whatever is desired. In this part of Australia, temperatures range from freezing to 45 degrees C (~110 degrees F). The owner says the house is always comfortably around 22 C (~71 F).
On the other side of the sliding doors rests the greenhouse section of the house. In Ed’s implementation of the Earthship design, it is less of a greenhouse and more of an indoor patio, but it’s function still remains the same. It serves as a heat regulator for the remainder of the house. Thermal energy radiating from the sun enters through the glass wall facing the equator, is absorbed into the thermal mass of the brick and plaster, and released into the remainder of the house throughout the day and night. Of course, it’s also incredibly beautiful and a great place to relax.
Finally, the main bedroom is situated along one front corner of the house and it feels like it’s practically outside with the amount of windows and natural light coming in. The bathroom is just off the bedroom, yet further inside the house. This means that not as much natural light comes in from the windows. However, Ed had installed light tubes that penetrate up to the surface. Even during the night, the light tube amplifies enough light from the moon and stars to create a low level of light in the bathroom and other back areas of the house. Below is a picture of the outside of the light tube. It’s designed in such a way to amplify light without allowing any water or fire embers in (during bush fires). It also does not magnify the light that would create fires within the building.
Roof penetrations were minimized by having as many utilities come through the same penetration as possible. Along with flues, hot water and electrical connections come through the same roof penetrations. Outside, they simply look like a little stone structure coming out of the ground. The house uses solar electricity and water from the grid, so it is not water independent. This is a departure from the Mike Reynolds design that uses rainwater catchment into cisterns that then pump the water throughout the house. Ed did not want to have to deal with pumps and water purification systems that would have been required by local building codes.
More Building Code Issues
Another departure from the Mike Reynolds Earthship design was that Ed does not reuse greywater for internal purposes nor for outside gardens. This, like with the rainwater harvesting, was due to restrictions placed on him by the local council and building codes.
Even more crazy is that Ed was forced to fill the space in between the suspended ceiling and his concrete roof with insulation even though there is over a meter of sand and dirt fully insulating the house. This is because soil “does not compute” in the algorithms used in the local building codes. Not worth the fight, he ended up spending money on a bunch of useless insulation.
This house cost Ed over $500k to construct. However, he admittedly has a lot of “nice” embellishments used purely for aesthetic purposes.
- Brick flooring – this could easily be replaced by polished or painted concrete and still achieve the desired effect with thermal mass.
- Suspended ceiling – this could be replaced by painting or plastering the underside of the concrete roof or by using a timber frame.
I don’t believe cost was an issue for Ed, since he obtained all the funds necessary to build the home from an insurance settlement after his original home was destroyed in a bush fire. If I were to do this myself, I would need to be a little more frugal in my design.
This is Totally Doable!
I’ve done so much reading on alternative home construction it is nice to see a finished real-world example functional and in use. Not only that, it’s incredibly beautiful.