Pineapples, earthships and northern boreal forest

Rather than getting into philosophical debates about whether earthships work or not, how about I share with you our own personal experience.  Then you can make up your own mind on whether you want to build an earthship or not.

We started our project in 2007, building not one but two earthships.  Our earthship is the second one we built and it was started in 2008.  We moved into it in the fall of 2009 despite the building not being completed.  Before I go any further, I need to explain what thermal mass is and how it works as there are many misconceptions about the concept.

Thermal mass is the capacity of a dense object to store heat.  If you threw a stone into a fire and left it there long enough, the stone would store so much heat that it would start to glow red hot.  That stone could then be moved to another location and the heat would then radiate out from the stone to warm the environment.  This principle has been used by the indigenous peoples for thousands of years in their sweat lodges and wigwams.  

The whole purpose of thermal mass is to move heat in, store it and then move it back out.  In a traditional home, heat is valuable.  As a result, insulation is put into the walls and ceiling to hold onto that heat as much as possible.  Insulation significantly slows down the movement of heat in order to keep the space inside the home warm during the winter.  Thermal mass buildings have very little insulation as we want the heat to move in and out of the thermal mass.  The only insulation I have is R70 in the roof to hold the heat down and R12 about 6 feet behind the tires in the earth berm to keep the frost out of the walls.  The building stores heat generated in the summer time and then releases that heat in the winter.  Natural, passive air conditioning and heating. We used clay and sand rather than stones to build the earthship, but the principle is still the same.  Water is, in fact, the best medium for capturing, storing and releasing heat.  

So, after 8+ years of living in the earthship, what did we find?

The ambient temperature of the thermal mass at the surface usually ranges between 17C (winter) and 21C (summer).  It takes about two years of heating the home to significantly charge the thermal mass so that an equilibrium can be found.  So it was chilly for the first few years.  On a clear sunny day in the winter, the earthship can hit 27C when it is -40C out side.  The evenings cool off and it will dip to about 15C at night with no fire burning.  We burn wood just to make up the difference and bring the room temperature back up to 21C during the day.  We do not burn anything at night.  We rely on the thermal mass to keep the building warm through the night.  In the summer time, temps can also reach 27C but the thermal mass always cools off the house at night and we sleep under covers as the night time temps reach about 17-19C. 

But the power of thermal mass is actually best demonstrated by our observations of the earthship before we even moved in.  Imagine the building having a roof and walls but no windows or insulation (pictured above).  We had two sheets of plastic hanging on the wall where the windows would be and a single sheet of plastic on the ceiling, tin on the roof.  I monitored the temperature of the building all winter and when it was -45C out side, the lowest temperature we recorded was -4C.  During the day it would hit +10C.  That is with no insulation, no windows, no other heat source other than the sun and the thermal mass.  I highly recommend that we build these buildings for the homeless and poor.  No doubt in my mind!

Our earthship, now that it is sealed up, would NEVER freeze during a cold northern boreal forest winter.  We could leave for the Bahamas all winter and not ever worry about the building freezing.  The coldest it would reach is +10C.  People cannot tell me that thermal mass does not work in northern climates.  As further proof, how about we show some of the plants that we steward.  

This is our pineapple plant that Carey started from the top of a pineapple we purchased in the grocery store.  It took two years of growing then this showed up.  A flower!  This flower grew and grew inside our earthship!

To our surprise it kept growing.  It liked it so much in the earthship that it kept on growing despite the harsh environment mere inches away!

It was not the largest fruit we have seen from a pineapple.  However, it was the most juicy, luscious, greatest tasting pineapple we have ever had!  It was home grown in a plant hardiness zone 2b, 2 hours north of Edmonton.  We also have a lime tree and we got three limes from it last year and Carey also has avocados on the go as well.  

                          Our flowering lime tree, picture taken this morning

      Avocado trees.  One is about 5 years old, the smaller ones are 3 years old.

I know it is hard to see from this picture, but under that skinny lid is our cisterns.  Two - 2000 gallon tanks buried in the earth berm of the earthship.  However, if you look closely, the tops of the tanks are showing as I don't have a proper seal between the insulated lid and the insulated walls.  As a result, I do get several inches of ice on the tops of the tanks.  But despite the exposure to -40C temperatures and long cold winters, the water has never frozen our pipes or pump as the thermal mass of the earthship keeps the bottom from freezing.  We have neighbours who bury their tanks 6 feet down and still have pipes freeze.  They get quit frustrated with us when they see our tanks.  

If you are expecting a constant 21C temperature in an earthship or any off grid building for that matter, then go else where.  I firmly believe that experiencing fluctuating temperatures helps us with our health and vitality and that the artificial, constant room temperature in most buildings is not healthy at all.  But I am completely confident that even if we completely ran out of fire wood, we would never freeze in our earthship, even in the coldest days of January or February.  It is the most reliable building one could ever build in a northern climate.  

This past winter, the power went out and several counties had to declare a state of emergency as peoples furnaces were not running as they depend on electricity.  Pipes froze and people had to be rescued from their own homes due to extreme cold.  That would not happen if people were living in earthships.  I am absolutely convinced that thermal mass buildings is the way to go in the norther climates!  

I even use it to build greenhouses and keep the goat water from freezing ... another topic for another day.