(Northern Climate Earthship)
Earthship Modifications For A Northern Climate
From buildings made of cans used as bricks in the seventies to the current Global Model we know and love, the Earthships evolution has been incredible and continues today. The Global Model may be the most recognized Earthship but for every climate theres an Earthship to match. The simple Hut Earthship designed for the tropics, the Windship designed to survive tsunamis and hurricanes, E.V.E. or Earthship Village Ecologies which addresses the cost of housing and of course the Global Model which will be our focus as it is the best Earthship design for our climate.
Creator Michael Renyolds along with an incredible team have been developing the Earthship in Taos New Mexico for over 35 years. While the words "New Mexico" may invoke thoughts of a much warmer climate Taos is very similar to much of Canada. At an elevation over 6000' above sea level Taos experiences very similar conditions including snow and well below freezing temperatures. While the climate in Taos is comparable there are differences that we are beginning to address so the Earthship can better suit our Northern Climate (NC).
Talking Trees is based out of North Frontenac (NF) Ontario Canada which has more extreme sustained versions of the conditions in Taos. Taos does experience freezing temperatures but there is a large swing from day to night and winter overall isn't as intense. In North Frontenac the sub zero temperatures of winter can last 4 months with -20c sometimes lasting for weeks. Taos also receives 283 sun days a year on average while NF receives 150. To address these variations in climate Talking Trees has made the first round, of what we're sure will be many modifications to come in the continuing evolution of the Earthship.
Northern Climate Earthship Modifications
For our Northern Climate Earthship we will be addressing the challenges of our climate in relation to Taos.
-Roof and Beams
-Front Glass Size
Roof and Beams
The roof of the Global Model has 2 main features in its structure, the main roof and a smaller front roof. The smaller roof attaches the main roof to the front greenhouse wall which supports the solar panels and the glycol system for solar hot water. In the NC Model the roof structure has been modified to have continuous beams from the back berm to the front greenhouse wall. This has many effects on the performance, design and simplicity of the roof. The complex framing of the smaller roof that houses the solar panels is removed with this modification allowing for the front greenhouse wall to connect directly to the underside of the roof beams. In doing this we have removed what I will call "break points" from the exterior of the Earthship. These break points are joints where one component connects to another allowing water the opportunity to penetrate. Removing these points reduces the chance of water penetration and also avoids water getting trapped in the joints where a freeze-thaw cycle can slowly pull the joints apart. When it comes to the construction of this roof modification it is incredibly simple to install and also allows for the metal roofing to be continuous from front to back with only plumbing vents as break points.
The new roof design also changes the pitch or slope of the roof from a 2/12 pitch to a 3/12 pitch. (3/12 pitch means that for every 12" the roof is long it goes up 3") This helps incorporate the larger front glass and venting system and also lowers the back tire wall by 1 row of. This steeper pitch will also help with water flow on the roof and shedding snow in the winter.
The roof beam modification effects the location of the vent boxes as we are now trying to avoid break points and keeping the vent boxes in the roof creates multiple break points for water penetration. In the NC Model the vents have been moved to the front greenhouse wall above the windows but below the front roof overhang. This location is the warmest in the house as it is at the highest southern point which should maintain the natural convection of the Earthships cooling system. To maintain the current flow rate of natural convection the square footage of these vents are the same square footage as the roof vents in New Mexico.
Front Glass Size
The modifications to the roof structure, including the change in pitch and how the front wall now attaches to the roof allows for larger windows in the NC Model. The standard glass size on the Global Model in Taos is 84" or 7' while the NC Model has 96" or 8' windows. This should allow more of the low winter sun to enter the Earthship further charging the thermal mass of the floor and tire wall. While the glass is the largest area for heat loss we are incorporating insulated blinds to the interior of the front greenhouse wall windows which can be closed at night greatly reducing heat loss.
Anyone living in a climate like Ontario knows the challenges winter brings. We've talked about the modifications of the larger greenhouse glass providing more winter sun as well as the insulated blinds but winters here can be serious and we've made other modifications to help address this. The Earthship already employs a solar hot water glycol system for domestic water use as well as melting ice and snow from the roof, scuppers and ease-trough. This system will be expanded in the NC Model to incorporate a radiant floor system that will also have a propane hot water on demand backup. The NC Models will incorporate the thermal mass of the tires and floor, expanded window size and radiant floor system to keep the NC Model warm and cozy no matter the temperature outside. Most NC Models will also have a wood stove or rocket mass heater which can be used in place of, or in conjunction with the other heating systems.
The power systems in the NC Model aren't really different than in Taos but simply applied to every NC Model. Where in Taos they receive 283 sun days on average we here in Ontario receive about 150. To ensure the electricity needs of the NC Model are always, met having a combined solar/wind system seems to be a good choice. While we can upgrade the solar system to meet all the electrical needs I think most of us would agree that if its not sunny its probably windy. It will be up to each homeowner to decide what they prefer but for me a solar system combined with a small vertical axis windmill is the best option for this climate.
The Earthship is the most Holistic Home design in the world.