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.
Earthship Strombeek, Belgium
One of the first contacts I could make was with Josephine (owner of the small demo model in Strombeek, Belgium). Turned out that after Reynolds left it took a while before the windows where placed. The earthship was never really used for anything else than a cats shed.
Strombeek 2000 - Photo: David Verstappen, Earthship Belgium
Josepine could not provide us with any data on inside temperature versus outside, but she did claim that it would stay warmer inside on a cold day. How much of a difference was unknown to her. So, I requested her if she could do some measurements and send us the data, but I never received any.
10 years later - Photo - David Verstappen, Earthship Belgium
What did strike me was that the earthship, that looked so nice on the pictures taken in 2000, now looked like a bunker on the outside because of the excessive use of cement. That, for me, made it loose a great deal of it's appeal and started my quest to a cement free earthship. After all, cement is responsible for 9-10% of of the carbon emmision world wide and often contains toxic waste from other industrial processes. Not really a environmental friendly material in my opinion.
Performance wise seen I didn't get any usable information by this visit.
Earthship Fife, Scotland
My mailing with the people of Sustainable Communities Initiatives (SCI) resulted in me buying 'The Earthship Toolkit. Your Guide to Building a Zero Waste Zero Energy Future', as this book should describe the whole process of experiences gained.
And it did bring some valuable information on the whole building process and climatic adaptations. And it is definitely word reading if you plan on building an earthship yourself. But on the part of performance there was nothing, as no studies where done on this matter.
Earthship Fife - work in progress
A problem that occurred in Earthship Fife, Scotland was using very wet soil to pound the tires with. This may help get them better compacted but you also trap a lot of moist on the inside once the building is closed. So what happened is that the wet soil, trapped by the burial, led to evaporation of moisture into the roof cavity and this led to problems with the wood used in the roof.
Earthship Valencia, Spain
I didn't manage to get an answer to my questions from Oscar and Lisa. But through my later contacts with Mischa Hewitt from Brighton, I learned that performance of an earthship in Spain was not a problem. He gained this information on a meeting held in earthship Brighton evaluating 10 years of earthships build in Europe.
Back when the earthship wasn't finished yet - Photo: Earthship Valencia, Spain
Later I did learn from their web site they had some issues with the earthship overheating in summer due to the south faced windows. So winter time seems to be doing well, but summer time did give some problems, that were solved by simply placing awnings at the south side and summer shades over the enormous skylights to stop the heat from coming through. This reduced inside temperature from over 30oC to 22oC.
I also learned to know that they had some grey water problems, because of poor design in the grey water system. They had to adapt the system, to not take in any water from the kitchen sink anymore. This seemed to cause a nasty smell, that disappeared after the grey water system was adapted.
Earthship Brighton, England
From the book 'Earthships. Building a zero carbon future for homes' I learned that the University of Brighton had placed temperature sensors in the walls of earthship Brighton way back in 2006, when the building wasn't completly finished.
This got my hopes up that by now (that was in summer 2010) they should have a lot of data and a really good picture on the matter of performance. The book only provided data for a short period and while construction work was ongoing inside and doors where open quite often.
While I was doing my little research, Mischa Hewitt was conducting a same kind of research. He was looking to get more details on the performance of the earthship in Zwolle and me into getting more details on earthship Brighton.
So we had several tele-conference meetings to discuss the matter. Turned out that the measurement done in Brighton was only for a short period, so that was a bummer.
After monitoring the University of Brighton concluded that1 :
- Initial results indicated the thermal 'battery' – the rammed earth tyre wall – was moderating the external severe temperatures but satisfactory thermal comfort conditions will require additional heating in winter and some means to relief the summer overheating
- The earthship is still settling to its thermal equilibrium with the surrounding and long term monitoring will be needed to establish better understanding of its behaviour.
- Studies are under way including computer simulations to evaluate alternative design options to improve the thermal performance
1. Source: Thermal behaviour of an earth sheltered autonomous building – the Brighton Earthship, Dr. Kenneth Ip and Prof. Andrew Miller, Centre for Sustainability of the Built Environment - University of Brighton - United Kingdom
Study done on the Brighton Earthship - Screenshot: W. Raets, Earthship Belgium
Mischa made clear that the fact that there is no floor insulation makes a cold draft come up from underneath so, even when heated, it still feels uncomfortable. One thing we both concluded was that tapping into the earth temperature makes no sense for Brighton since the temperatures will be too far off the comfort zone temperatures, so insulating the floor makes a lot of sense. The high humidety of the UK was also a concern in the ventilation process. The concept definantly needs adapatations to make it work in a UK climate (and most of Europe for that matter).
Mischa also made clear that the only earthship where the thermal mass works as promised is the one in Valencia and he thinks that for the Southern regions of Europe the Reynolds way of thermal mass implementation could work, but for the rest of Europe it needs further improvement to make it work properly. Insulation needs to be properly implemented as the Reynolds way leaves room for thermal bridging, which has a negative effect on the thermal mass performance and can cause condensation and mould on the walls.
Earthship Ger, France
The performance of earthship Ger is still a mystery to me since Kevan Trott didn't feel like contributing to what is going on in Ger. This actually didn't come as a surpirise, since Kevan does payed consultancy and project management for earthships and uses Ger as a rental. In both cases talk about negative performance would probably cost him money.
But from what Mischa told me, concluded on a meeting with European earthship owners in Brighton in 2010, only Valencia is performing as promised. And since Kevin was participating in the Brighton meeting, I could presume that performance in Ger isn't as told by Reynolds. But I have no details on this.
Earthship Ger while still being built - Photo: David Verstappen, Earthship Belgium
What I do know from my correspondence with Kevan is that there are issues to be dealt with, but he didn't get into detail on what those issues where. What I also know is that in a recent project I saw Kevan implementing insulation underneath the tyres. So my hunch is that there are some problems in Ger that have to do with the thermal mass performance that needs improvement like in Brighton.
But then again, Ger is a mystery to me and nothing is based on real facts, I hope to get there some day and find out more.
A first problem Reynolds encoutered at Zwolle was the fact that the underground wasn't stable enough and ground water levels do not permit digging in. So they started with making a huge concrete slab to built the earthship on.
Another thing that struck me in the design was the fact that the North side was opened for an entrance.
You can see the steps up indicating the earthship being higher than its surroundings - Photo: D. Verstappen
One of the co board members of Earthship Belgium passed me a mail from a woman who is deeply involved in earthship building in the Netherlands. She had visited earthship Zwolle and wrote this:
'Today I again looked at the earthship in Zwolle. This is because we wanted to know whether or not the building complied the winter warmth. It was cold and I was shown around by someone who has followed the project from the beginning to the end of the construction . Because of the cold it was closed to the public in winter.
He pointed me to the necessary errors in this building. Especially the high humidity in the Netherlands and the lack of sun in the winter has not been taken in account. The American model was not nearly enough to be applied to the Dutch climate.
Already within a short period, there is pretty much mould on the inside of the building. There are cracks in the cement around the tyres. There are some elements that, in the Netherlands, should not have been used in this way.This is actually the first winter and it does not comply . I'll let you know so that you may be able to take these factors into account. So that the building can be better.
To be honest, I think within one year it looks like a very decrepit building where no thought has been given to.'
In short the problems mentioned are:
- High humidity and lack of sun are not taken into account enough.
- Cold on the inside
- Mould on the inside of the building
- Cracks in the cement around the tyres
This is quite a list and it made me want to get in contact with someone from earthship Zwolle to have it all confirmed. After some mailing I finally got in contact with mr. Evertse from ROC Landstede: Life & Nature, Doepark Nooterhof Zwolle. The are the ones who run the teahouse in the earthship.
He confirmed me first hand and personally all that is menitioned above and I learned some more, like the water catchment not being used because of insufficient quality of water caused by falling leaves, the built in natural cooling room not complying to Dutch standards for a public building and the earthship being completly on grid!
His general idea was that, looking at ecological buildings, Europe has far more better solutions than building an earthship and that the building should have been adapted better to the Dutch climate by in cooperating local know how.
Earthships as implemented by Reynolds will only perform as promised in the most Southern parts of Europe. All other regions will need to be adapted to meet local climatic requirements.
Main focus needs to be on:
- Making the thermal mass perform better
- Mould and moist issues
- implement the local climate into the design
For Earthship Europe and her associated organisations this is the reason to take the concepts of an earthship as our guide rather than the Reynolds implementation of the concepts. With the concepts and local climate in mind you can design for a better earthship or earthship inspired building for your own specific situation.
And concerning the Global model (one model for everywhere) I can only say: 'Would you built an igloo in the desert?'