You can build that plaster out as thickly as you want if you feel you need still more thermal mass, but I don't see the point of making a whole redundant cob wall system, either inside or outside the bales. In a well designed home that employs passive heating and cooling concepts, the thermal mass is most useful on the inside where it can store and regulate the interior temperature. Change ), You are commenting using your Google account. I don’t really have the space to spread out and mold a few thousand bricks. One could insulate exterior walls with a pourous, light weight paper-adobe or papercrete shell which would transpirate moisture- breatheable buildings are healthier buildings. Summers can be around 95 for a high but it doesn't cool off much at night. I plan to retire in Mexico (an hour north of Puebla) in a couple of years and I will build a home there, hopefully out of adobe or padobe or fidobe or papercrete. My solution is to have a one and a half to two feet thick wall on the inside and a thinner wall on the outside with a six inch void between to be filled with expanded perlite. When you will need the auxiliary heat is primarily when the sun isn't out - at night and during cloudy weather. The two feet of cob might give you another R-10 or so. Large roof overhangs can address this, as can increasing the lime content because lime doesn’t trap water the same way cements o. Depending on the design of the building, there might be a way to attach a layer of hempcrete to the exterior of a cob wall with minimal additional framing. Anyone know what kind of insulation we could have if we built a thick (18 to 24 inch) wall? A more efficient approach would be to make most of the exterior walls out of a more insulating material such as straw bale. 7) Insulate the walls, and replace single-pane windows with thermal windows. Even in cold climates, so long as you dig below the frost line, the temperature of the dirt or rock is a fairly constant 55 degrees everywhere in the world. Change ), Papercrete / Paper-adobe: Insulation and Thermal Mass, Why I’m constructing alternative buildings…, Coating Earthbags with Paper-Adobe-Lime stucco, Papercrete / Paper-adobe: Insulation and Thermal Mass, Views about the influence of climate change, https://groups.yahoo.com/neo/groups/papercreters/info. There are many ways this could work, and some experimentation would be necessary to find the best techniques. It’s late January, and if we have a major cold spell, I’ll have to fire up the wood stove. Q: My husband and I are very excited about building a cob home for our family. My main concern would be that the foam would compromise the breathability of the wall. Wouldn't the amount of straw determine the R value as earth has so little? I like the idea of using it because of the insulation qualities. Putting it inside the wall and then having a brick wall outside of that is pitting thermal dynamics and the laws of nature against your wallet when it comes time to pay the heating and cooling bills. A house composed of insulative blocks can only be energy efficient without thermal mass in temperate climates. You may very well also have to extend the roof overhang to protect the earthen exterior from rain. Insulation only evens out temperature swings, or perhaps more to the point- a good jacket keeps you warm in winter so long as your body is producing heat. Building a cavity wall as you mentioned could be one way to achieve that. An important one is substantial roof overhangs/porches to keep the sun off the walls as much as possible. I have heard this or similar ideas proposed many times and I’m not aware of anyone who’s actually done it successfully with cob, although I have seen it done with adobe block. Stop producing heat and gues what, pretty soon you get cold even if you have a whole lot of insulation. Hot humid climates like yours are by far the most challenging for passive cooling. A: Adobe blocks have very nearly the same thermal properties as cob. I believe this approach would be simpler, less work, and more environmentally friendly than a cob cavity wall filled with foam. He teaches practical workshops and provides consultation to owner-builders on a wide variety of natural building techniques, site selection, and design. and when hit with a sledge hammer only dents isntead of shattering like a brick or concrete block of the same dimensions. That would reduce the amount of cob you have to mix. I’m going to soon start an adobe project in northern Wisconsin and was going to use the same technique; double-wall adobe, but my preference is to construct using the cob techniques you described in your book instead of first putting the labor into molding bricks. Wouldn’t putting insulation on the outside of the structure bring an end to that source of heating and cooling? In your area, I suspect the most straightforward approach would be to start with existing codes for adobe, and ask your local officials to adapt them as necessary. This is why the brick gets cooled down during the day. “For example, in the atmosphere, when a molecule of water evaporates from the surface of any body of water, energy is transported by the water molecule into a lower temperature air parcel that contains less water vapor than its surroundings. (adsbygoogle = window.adsbygoogle || []).push({}); Michael G. Smith has a background in environmental engineering, ecology, and sustainable resource management. You can get good thermal results by using them in appropriate ways in a suitable climate, but you need to understand how they work. Where could I find more information on a hybrid system like this? If you continue to use this site we will assume that you accept our policy, DIY Uses For Olive Oil – Help From Nature, Four ways to repurpose an old sewing machine, Kitchen Tips That Make Cooking And Cleaning Easier. Published March 7, 2016, Your email address will not be published. On completely overcast days when its freezing outside the greenhouse still heats up to 60 pretty reliably. How would you reach under windowsills and so on? The cavity wall you’re describing is possible, but I think it would be a lot of work - essentially building 2 separate cob walls and insulating between them. Fill in your details below or click an icon to log in: You are commenting using your WordPress.com account. The idea behind thermal mass is to collect heat or coolness and store it, and having good insulation on the outside of thermal mass insulates that thermal mass. (Boric acid would also help with this.) Would cob be a suitable material to use and should I use plywood shuttering to support it while it is drying or is there a better material you can recommend? You need thermal mass unless you’re fine with the traditional wooden-framed house concept of building an insulative box into which you pump heat and cooling. Particularly in this part of the world, the southwest U.S? Cob has great thermal mass but poor insulation value. I am interested in building a cob house, but from what I am reading, they do not have great insulation. I could be wrong, but I’m going to assume that something without paper in it would make a better thermal mass building component, because the paper is going to act to some degree as an insulator. This could be a major improvement for cob buildings in cold climates. Q: I was recently looking into hempcrete and it looks like an incredibly sustainable building method and I also found that it has excellent insulation properties and I was wondering whether at all hempcrete could be used in combination with cob as some have combined cob and straw bale building for increased home insulation. Required fields are marked *, Clever Ideas for Organization & Storage in Small Spaces, Stylish Ways to Decorate your Children’s Bedroom, Exterior Wrought Iron Stair Railings – Personalized Shapes, Building a Garden Pond Step By Step – Extra Aesthetics and Value, French Style House Plans – Pastoral Elegance, Attic Balcony Design Ideas – 11 Open Solutions, PPR Pipes vs Copper Pipes – Pros And Cons, The house of clicks, the visual experiment of Swedish architects. The solution you suggest will probably work, and I don't know of a better one.