Winter is finally here!  The last four days have been below zero with the last few days much colder (it is -11 celcius this morning).

The earthship  seems to be holding up well.  The inside temperature is hovering around 5 degrees celcius, and I expect this will improve when we insulate the south wall, deal with the sky lights, and move our current house out of the way of the sun next year!  We are getting a lot of condensation on the south windows (expected), and frustratingly the drain channels built into the windows have all frozen.  My assumption is that as we increase the inside temperature this issue will resolve itself.

We have turned our attention to interior details (wall pack out, insulation …) and   systems.  Sandra has been working on packing out the north wall of the utility room so that we can think about mounting electrical panels, and I have been thinking about electrical (more in a later post), gray water and heating.

We have always planned to have an alternative source of heat, our winter months are simply too overcast in this valley to rely on the sun all winter.  In our last house we heated exclusively with wood for years and we miss it!  Also, burning wood helps clean up all of the scrap wood that is accumulated on our business property. We have considered many different wood burning appliances for our house; traditional stove, outdoor wood furnace and wood gasification (later) to name a few.  What we keep coming back to for our initial wood heating system is a rocket mass heater.

I have been investigating these  heaters off and on for years, and then last year we were given a copy of Rocket Mass Heaters; Super-efficient Woodstoves You Can Build (by Ianto Evans and Leslie Jackson) by the people at Our Ecovillage on Vacouver Island after we gave a  short, impromptu talk about our building project.  It seemed like fate and I have been studying this stove in more detail over the last year … I guess it was the ‘You Can Build’ part of the title that tipped the scales in favour of this stove!

In a nutshell (and yes I wish we had one of these in our current house) a rocket mass heater relies on thermal mass to keep a building warm and is thus a very good fit with an earthship.  These stoves are very efficient (hence a clean burn), and in fact share characteristics with wood gasification.  It turns out there is an earthship in Quebec that has built one … we really like their design and hope to come up with something similar.

The following is my initial design for a rocket mass heater … anybody with feedback is welcome to comment!