More supply shopping

Tuesday found us on the way into Kamloops with a list of supplies we needed to complete the perimeter drain for the building, the thermal wrap and the rest of the materials to do the tire walls. We are now on our third row of tires. Sean and Anna left last Saturday on errands in the lower mainland. We sure miss their help! Things go slower without them!

As our tire walls increase in height, we need to start backfilling so that we have a same-level surface to work on. That meant putting in the perimeter drain and starting the thermal wrap. On Monday evening we sat down and made an extensive list of supplies that we needed for Wednesday, which is when we asked Alvin to return and do some trench digging. On our way into Kamloops Tuesday morning Chris hit the cell phone and started to get some prices.

Our biggest learning curve was on what kind of rigid insulation to buy for the thermal wrap. The thermal wrap is the layer of rigid insulation that is buried around the house (to the height of the roof) that contains the heat around the house and prevents any thermal heat we acquire in the house from seeping slowly out into the ground. For a better explanation of this go to Earthship Biotecture at: http://www.earthship.net/index.php?option=com_content&view=article&id=27:thermal-wrap-turbo-charge-your-earthship&catid=49:comfort&Itemid=30

Rigid insulation differs in kind and price. The blue kind is the one more generally accepted for burial. However, we found a white brand that was half the price. Most sales people told us that it was not acceptable for burial. However, we saw a little bit of text on the promotional material that indicated otherwise. Sharon Donchi (who used to arrange log home shows and now works at Home Depot) called the technical rep for this company and it turns out that it can indeed be buried. We however, wanted to achieve an R12 value, which is generally accepted by Code for a traditional basement wall. This less expensive brand was only R8. By the time we ran the numbers the blue brand was still more expensive but probably by only 10-20 per cent. Using the white brand may have been less expensive, but it did have a lower compression value AND it is not generally viewed by traditional building authorities as a product that can be buried. When all was said and done we decided on the blue brand.

Generally perimeter drains are constructed using a product called Big O. This is a black, perforated, flexible pipe that is laid in a slightly sloped drainage ditch around the building. The pipe is accompanied by filter cloth and drainage rock and then buried. The idea is that if water accumulates around and in the ground surrounding the house, it will drain into the pipe and be passed around and beyond the house. However, our family and friends had had issues with Big O collapsing over time so we decided to use perforated 4" PVC. We also decided to install three vertical cleanouts should we ever get a plug up. For us, digging through 10 feet of bermed earth is a bigger issue than with a traditional home! More pictures of the finished drain in a few days!

The PVC pipe was a lesson in going to the specialists. We priced this product at all the big box hardware stores and there was up to a $5 difference in a 10' piece (ranging from $20 locally to $15 at Rona Hardware). As we were driving past Andrew Sheret, I pulled in and Chris came back with a quote of $11.10 per piece. With savings in hand, we started loading up.

Today another volunteer earthship builder arrived. James is from Newfoundland but is moving to Victoria and decided that before he got a job there, he wanted to do a few things, inlcuding help us for a few days. We are glad to have his help and look forward to Friday when Sean and Anna return with their "mate" Josh.

The photos are fairly straight forward but I'm having trouble manipulating them and being able to put captions on them. The trailer shot is of 30 of our 140 pieces of rigid insulation. There are several shots of the drainage ditch and because I'm always behind the camera, Katie took some pictures of me, doing what I do best, apparently: sitting and supervising!

Floor Insulation ... what's the decision?

Now that I have sorted the toilets out I have gone back to thinking about the pros and cons of laying insulation under the floor of the building.

The Fundamental Conflict

I have been struggling with this issue since starting my house design. In a standard house floor insulation would be a no-brainer. Insulation is placed under the floor to prevent the warmth built up in the interior of the house from being leached away into the somewhat colder surrounding earth during the winter months.

Earthship purists argue that floor insulation cuts your building off from the massive thermal battery also known as the Earth. Consequently, although your bermed building has substantial thermal advantages over a typical stick framed house, it is not taking advantage of the earth's constant temperature and is consequently missing the boat (or ship so to speak).

My Take

To me this insulation issue has two practical realities; physical comfort, and the energy consumption required to maintain the house's environment at a livable level.

Typical house construction achieves physical comfort by using energy (fossil fuel, electric, wood) to maintain the inside of the building at a comfortable temperature. Take away the energy and the building quickly matches the surrounding temperature (frozen in the winter, and really hot in the middle of summer).

Our current house (two 1970's era 10'x30' office trailers placed side by side) adequately demonstrates using lots of energy to maintain a comfortable inside temperature in the winter. The walls and roof are very poorly insulated. Last year when it started warming up in the spring our ceiling developed 'leaks', despite having been re-roofed recently. In spots the roof insulation and vapour barrier is so thin or non-existent that the warm moist air rising through the ceiling condenses and forms ice between the ceiling and the roof. Presumably when the ice gets thick enough the formation of ice drops off because it is now insulating the ceiling! In the spring this ice melts and leaks back into our living space. We heat with electricity and due to our poor insulation we spend a lot to maintain a comfortable temperature in our 600 sqft.

A typical house built today has better insulation but the problem is the same. If the energy is shut off the house rapidly becomes a really well insulated (by current standards) ice box. So, we achieve a comfortable living space at a high energy cost.

The approach taken in earthship design is to passively heat the house with solar power stored in thermal mass. The idea is to achieve a comfortable living space at no or minimal cost. The issue becomes one of defining comfort. By today's standards comfort means a constant inside temperature in the neighborhood of 20 degrees celcius.

I think comfort may need to be redefined when high energy cost heating is limited. The reality is that the inside temperature will fluctuate somewhat (say in a range from 15 degrees celsius to 22 degrees celsius). This implies a willingness to use sweaters as required or supplementing the passive heat actively when the solar gain is not enough due to cloudy periods or cold snaps.

In many parts of the world a home that guaranteed a livable space with minimal energy might be considered a slice of heaven on earth. As little as 60 to 70 years ago many people in North America would have whole heartidly agreed. We have been spoiled by cheap energy to the point that acceptable comfort is quite rigidly defined!

This comfort versus energy usage trade off is highlighted in cold climates by the issue of floor insulation. Without floor insulation the building taps directly into the constant heat sink provided by the Earth, thus making the building easy to heat. In fact, you could probably lock the door on your building for the entire winter without taking any precautions with regard to frozen pipes or frost/water damage. The constant earth temperature and passive solar gain will guarantee that the living space maintains an above freezing temperature. The trade off for this low maintainance living is an inside space with fluctuating temperatures and a cold floor.

What Other Thoughts Exist on this ?

Still not feeling comfortable with this insulation issue, I read fairly extensively over the last couple of weeks to get a better handle on it.

Turns out a bermed earth house builder named Rob Roy has built earth bermed housing both with and without floor insulation and lived in both buildings. His buildings are both close to the Canadian border in New England so the winter temperatures he is dealing with are similar to ours. He documented his experiences in two of his books that I listed in the references. His first building had no floor insulation and his second one did.

His take on insulating a bermed building is very pragmatic and dependent on your climate (he differentiates between the northern and southern states). In a warm southern climate your primary goal is to maintain a cool inside climate during hot weather. Using no insulation under the floor of the building makes sense as the earth's temperature acts as a passive air conditioner.

In northern climates your goal is geared more towards maintaining a warm inside climate during cold weather. Quoting from Earth Sheltered Houses, "Without insulation ... the fabric of the building becomes one and the same with the earth's mass ... In order to control the mass fabric of the home itself, we must place the insulation between the home's mass and the earth." He is re-stating basic thermodynamics and his argument makes a lot of sense.

I suspect the earthship design has been successful without floor insulation because most earthships are being built in New Mexico and are more concerned with summer cooling than winter heating.

My Conclusions

We will provide alternate heating in our home with the two wood stoves shown in our plans. These stoves are more aesthetic for us than practical. We have had wood heat in the past, enjoyed it, and miss it now that we rely on electric baseboard haters. We hope to construct these stoves ourselves as detailed in the Earthship Volumes as opposed to purchasing.

We are also debating putting radiant heat in the floors to provide an active means of heating the thermal mass of our home. We have some concerns about our solar gain in December and January. We live in a fairly narrow river valley and get minimal sunlight due to clouds and fog during these months. We have access to significant quantities of waste wood due to our location so a radiant heat system fueled with wood seems practical to us. The decision to install radiant heat will be governed ultimately by cost.

In a typically Canadian manner I have chosen to straddle the fence on the issue of floor insulation. My intention is to insulate under the footings with 1" of rigid EPS (R5). I also plan to insulate under the floor spaces (again R5). I will NOT insulate under the planters or cistern. I also am thinking of leaving a percentage of the central floor space uninsulated.This practice of leaving some of the floor uninsulated is used sometimes in conjunction with radiant heat floors to guarantee that if the building is left unheated for periods of time over the winter the facilities sensitive to freezing will not be damaged because the building is coupled to the Earth's constant temperature. I think this decision will have minimal impact on my ability to control the temperature of the mass fabric of the home, and keep it hooked up to the Earth's thermal battery.

Floor Insulation; to insulate or not ... that is the question!

This is a hot topic ... people have been weighing in both for and against floor insulation by email and on the blog. In fact you might even say the discussion has been heated ... alright I'm going to drop the puns from this point forward!

As near as I can make out the basic earthship design has evolved somewhat since the publication of Michael Reynold's third earthship book, and some of the newer design details do not seem to be readily available (unless I have missed them in my reading).

In his newer work Mike Reynolds refers to a thermal wrap around the earthship and it took a fair bit of digging (I can't help it) to find out what this thermal wrap is. It turns out the thermal wrap is a layer of rigid insulation placed around the bermed walls of the earthship after an initial backfill of the walls has been done.

I am assuming the point of this thermal wrap is to increase the amount of insulated mass attached to the earthship, and consequently to increase the efficiency of the 'thermal battery' that is the basis of the earthship design.

I have upgraded my initial drawing and include a cross section view of this whole idea at the top of this article. I believe that this thermal wrap is supposed to address issues that the earthship design has had in colder climates, specifically that it did not retain enough heat during the winter, and thus was not successful in regulating its temperature. Also, I have read complaints that despite a given earthship staying warm enough during the winter months, the floor temperature was simply too cold.

So, on the one side of this argument is the original earthship concept. The basic premise of this argument is that the minimum temperature of the earthship should not dip lower than about 55 degrees F (stable earth temperature), and the warming action of the sun during the day should in fact keep that temperature in an acceptable range of 65-75 degrees F.

On the other side of the argument are the reported failures of the earthship design in cold weather climates. Reading between the lines I think the failure of the design stems from the ground under and to the north of the earthship still being affected by seasonal temperatures. In other words, the ground under the earthship settles out somewhere between stable earth temperature and a value above freezing. I suspect this failure is also tied to quality of winter sun in various regions. We live in a valley and I have some concerns about the amount of sun we get in December.

So where do I weigh in on this entire argument ...

I have now been in an earthship in Ontario on December 20th (2nd shortest day of the year) and it was -20 degrees C outside. The inside temperature was about 65 degrees F and the only additional heat was provided by a wood cook stove when food was being cooked. The basic premise that the earthship should maintain a reasonable and consistent temperature was being met. The floor in this earthship was not insulated, and the builder agrees with Micheal Reynolds that the floor should NOT be insulated.

I have to admit, although not intolerable, I did find the floor cooler than I would have liked. I tend to agree with the basic statement that an uninsulated floor is going to be cooler than your desirable room temperature of say 20 degrees C simply because stable earth temperature is below this temperature. It seems to follow that in a colder winter climate the floor will be that much colder than desired room temperature.

I intend on having a backup heating system in my house. I am actually in favour of radiant heat as opposed to direct wood heat, and I would prefer a warm floor. It would be possible to run the radiant heat in the tire walls and/or the floor. I do not see any need to insulate or heat the floor under the planters and a few other locations. Beyond this I have not come to any conclusions.