Although M. Reynolds talks a lot about the performance of his earthships and even uses it to promote them, he never presents any real research or figures on the actual performance in different climates.
That made me wonder if there was any research done on the matter and if all he claims is true. Do earthships perform in any European climate was a question that occupied my mind. And I did have my concerns about parts of the earthships and how they are applied by Reynolds.
First thing I had my doubts about is that he talks about tapping into the earths warmth. The way Reynolds explains it in 'Comfort in any climate' is that the temperature of the outer few feet of earth heat up and cool down in response to surface weather. However at about 4 feet (1.2 m) the temperature is more constant, around 58oF (14,4oC). That might be the case for New Mexico but it sure is not the case in most European situations.
Afther some research into the matter I learned that the top part (first 1 to 1,5 meter) flucuates most (like Reynolds claims). At a depth of about 1 to 1,5 meter the temperature is more stable (like Reynolds claims). But what is that temperature and is it the same all over the world?
I learned that on average you can take the years average temperature of your location and that is about the temperature of the earth at 1,5 m deep. The average temperature in Belgium is 9,8oC (49.6oF). So tapping into the earth will give you the uncomfortable feeling of 9,8oC, when you probably want at least 19,8oC. Quite a diffrence to make up for compared to starting from 14,4oC. For average temparatures of other countries visit www.climatetemp.info. Take into account that some countries might have quite big differences between for example south and north of the country. More local averages will give a much clearer picture.
I expect this tapping into the earth has a negative effect on performance in many European countries. To me it made more sense to insulate underneath the entire earthship (walls included) instead of just insulate the thermal wrap.
Second thing of concern are the huge thermal bridges in Reynolds earthship design. To most construction engineers in Western Europe it is well know that thermal bridges can cause moist and mould problems. The difference in temperature between the insulated and not insulated part causes moist to gather at that point. This is not prevented by completly sealing of water from the outside since the produced moist comes from the inside. In time, when not properly handled, it will turn into mould.
Third thing of concern is ventilation. Ventilating in summer when it is warm will not give a great deal of problems the Reynolds way. But winter time in cold and moisty climates do need another way of ventilatiing during these seasons.
A fourth thing of concern is the thermal mass. It is clearly made for a New Mexico situation. Longer days in winter, probably more clear sky days and less days with a grey sky no sun coming through. To me this is a matter that needs a lot of research. I can hardly imagine that the few ours of sunlight on a very short winter day in Sweden make the thermal mass work, provided the sky is clear blue and without any clouds. The amount of heat lost through the windows should be investigated, as should the amount of heat gained though them and those should be compared to get any idea on the matter.
Average insolation - Source: wikipedia
Fifth concern is the being self sustainable mainly on solar power and some wind power. Gazing at the map of average insolation (a measure of solar radiation energy received on a given surface area in a given time), most of Europe will have a hard time in getting through winter being self sustainable on solar power. Since the days are very short and the nights, when power is most needed, can be very long.
I would advise some extra alternative resources of energy supply that are self sustainable, like for example gaining methane from the black water system for production of energy on demand on short days.
Quite some concerns there and quite some research still to be done.
Winter 2009 I started with tryng to gather more information on the performance of earthships. And although I have been searching the internet since, only little ever came up.
So I decided I needed other ways of obtaining the information. So by spring 2010 I decided to get on contact with the earthships built in Europe in hope they could provide me with the much needed information. And this turned out to be just as hard as finding information on the internet.
Here is a overview of my quest for that information and what I learned about it. I'll take the earthships in the same order as they were build in and documented in the article Europe.
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