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Archive for the ‘Insulation’ Category

Withyfield Cottage by Ben Law

Withyfield Cottage by Ben Law


Withyfield Cottage interior by Ben Law

Withyfield Cottage interior by Ben Law


More work by Ben Law. His ideas are spreading throughout the region. The video below shows his finished home before he built the addition.

“Beautiful, sustainable, luxury holiday accommodation. Located on a working dairy farm on the edge of the South Downs National Park, this unique roundwood timber, straw bale and cedar shingle holiday cottage is the perfect spot to escape and unwind.
Inspired and built by Ben Law and his team (as seen on Channel 4’s Grand Designs) the cottage is a testament to contemporary green building practice. Supremely comfortable, beautifully furnished and well equipped yet made by local craftsmen using local materials.”

Source: Withyfield Cottage

The Woodsman’s Cottage

“This video from Grand Designs on British TV was voted the most popular show ever by viewers, and apparently Kevin McCloud’s favorite also. Ben Law’s house has been described as possibly the most sustainable house anywhere. It’s built almost entirely with reject wood culled from the local forest: bowed or leaning trees for the crucks, wavy slab wood siding from milling lumber, and coppicing. All this left over ‘waste wood’ from standard log milling operations is typically burned or left to rot. Ben stacked straw bales around the outside of the timber frame for superinsulation.”

Ben Law Woodsman
Woodland House book
Previous blog post: Ben Law’s Woodland Home
Cruck Frame Houses

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Kelly and Owen,
I’d like to thank you for all of the wonderful information you have offered for free to the world! I’ve been following along for about a year now and it just keeps getting better and better.

I have a question about insulation and thermal mass. I live in Austin Texas and our summer nights are a lot of times only 20 degrees cooler than the day time high. Which that day time high can get to over 110F. If I build with only earth/adobe filled bags, I don’t think that the house would be very comfortable during the summer months. I’m planning on rebuilding a small dilapidated shed in about a year using the hyperadobe method. The shed will have plumbing and electrical. Basically I’m going to build it just like I would build a house for our family to live in full time. This is going to be a proof of concept to show my lovely wife that it’s not a bad idea and that a house built in this fashion can look professional.

So my question is, how would you go about insulating a building built with the hyperadobe method, or would you build using a different method?

Thank you for any information!
Mike

Hi Michael,
I just looked up what the year-round underground temperature is in Austin, TX, and noticed that it is 71 degrees F. You couldn’t ask for a nicer temperature to live in! A substantially bermed or underground home in that locality could easily become a zero energy home, as far as heating and cooling goes.

You are right that a solid adobe-walled home there would be too hot in the summer for sure. Yes, it can be insulated, either with exterior insulation, or by filling the bags with an insulating material, and this would help keep the interior more comfortable…but you are still going to need air conditioning most likely.

If it were me, I’d go underground!
Kelly

[Owen: This can include building above grade with earth berming/earth sheltering to reduce the risk of flooding.]

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Straw/Clay Mixer

Straw/Clay Mixer


“Rather than laboriously tossing clay slip with straw by hand to make light clay straw for finishing the stuffing of the bale walls, we used this mixer to speed up the process. We could mix large batches of light clay straw in a short amount of time as well as maintain a consistent amount of clay and moisture on the straw.
Two people load the mixer at one end with straw and clay slip. The clay slip gets mixed beforehand in buckets. It is a combination of water and either bagged clay or soil with a certain clay content.
The long barrel of the mixer is sloped downwards away from the end that gets loaded, and the straw and clay slip are tossed together as they move down the length of the mixer.”

Source: TRC Timberworks & Natural Homes

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Weaver-Hovemann timberframe and straw/clay home by EcoNest

Weaver-Hovemann timberframe and straw/clay home by EcoNest


Timberframe and straw/clay house in Crestone, Colorado (click to enlarge)

Timberframe and straw/clay house in Crestone, Colorado (click to enlarge)


Mixing straw/clay for filling gaps between straw bales

Mixing straw/clay for filling gaps between straw bales


Straw/clay has been in use for thousands of years with great success. The focus of our blog is obviously earthbag building, but we’ve decided to include coverage of other natural building methods to broaden our horizons and reach a wider audience. It’s good to know a whole range of building ideas so you can obtain the best possible house. For instance, maybe you want to use earthbags on exterior walls and straw/clay on interior walls. This is a very good option that requires no formwork. You could stuff straw/clay inside pallet walls for soundproofing between rooms. Most often straw/clay is combined with a timberframe that carries the loads.

“One of the best low-cost insulating materials is clay-coated straw (or other lightweight plant materials). A light coating of clay acts as both a binder and preservative. Clay-coated straw has been shown to last over 700 years as a non-deteriorating insulation! As the clay dries, it binds the straw together in a surprisingly rigid mass. It’s a “natural styrofoam”.

Materials
Any stiff agricultural waste similar to straw will work. Hay is too flimsy and has seeds, so it doesn’t work very well. Barley straw, wheat straw, and other grain straws work well. Clay can be gotten from the earth. Many subsoils are primarily clay. River bottoms and river banks are usually clay. Clay is also used by brick and tile manufacturers and can be bought from them cheaply. (in our area, about $16 per ton)
Even soil which has a moderate amount of clay such as commonly used for adobe, about 35-50% clay, will work. The slurry is not as sticky, compared with pure clay, but even ordinary mud works well enough. This is not rocket science. Use a dry wall stirring paddle and electric drill to mix the clay or mix in any kind of mixer. Mud mixed in a box with a hoe works.

Method
1. Break the clay into small particles so that it will mix with water easily.
2. Make up a slurry of clay and water. Any soil that is mostly clay will also work. The consistency should be like cream or a thin milk shake.
3. Spread the straw out on the ground. Dampen the straw with a spray nozzle if available.
4. Pour (drizzle) the slurry over the straw, then toss and mix the straw so that it becomes lightly coated. Ordinary garden rakes work well. The clay should only very lightly coat the straw. This is NOT adobe. Maybe 5-10% clay, 90-95% straw. When dried in the wall, you can hardly see the clay, but it binds the straw together very well.

Uses
In addition to being an insulator, it can be used as a wall forming material. In the middle ages, even up to the present time, the method works like this:

1. A post and beam structure is first built.
2. Two boards are temporarily nailed to the posts, one on each side.
3. The resulting cavity is filled with straw-clay.
4. The material is tamped down (a 2×4, 4×4, or small post will do). The idea is not to compact it into a solid mass, you couldn’t do it easily anyway because the straw will remain springy until it dries.
5. The two side boards are moved up immediately and stuffed again and again until the wall is as high as desired. No need to wait for the straw-clay to dry before moving the boards up. (A moveable, sliding form could also be used to make walls.)
6. A saw is used to cut out windows, or window frames are placed first.
7. The wall is allowed to dry and is hand plastered inside and out. The soft undulating plastering adds a charm that cannot be found in modern buildings.”

Source: Planetary Renewal.org
Image source: EcoNest
Image source: Windy Ridge Woodworks
Image source: Our House of Straw

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Passive Annual Heat Storage (PAHS) diagram

Passive Annual Heat Storage (PAHS) diagram


A simple underground house design uses a novel insulating/water-shedding blanket that covers the structure and surrounding soil. The umbrella creates a huge subterranean thermal reservoir that soaks up the sun’s energy during summertime and stores it for winter heating. In many cases, the clever design makes a heating system unnecessary.
By John Hait

My first earth-sheltered house, an underground geodesic dome was partially complete when the truckload of insulation my colleagues and I had ordered arrived. Right away, we knew we had a problem: How do you put flat, rigid polystyrene insulation on a round house?

We called housing experts all over the country, but no one had any ideas. Finally, Ray Sterling at the University of Minnesota’s Underground Space Center suggested that we place a flat, insulating “umbrella” in the earth above the building. This, he said, would keep the domelike house warm by insulating the soil around it.

“What a marvelous idea!” I thought when I heard his advice. After two weeks of rigorous examination, I realized that the concept was even more promising than I’d supposed. By then I was convinced that the dry earth under an insulating/water-shedding umbrella could store enough free solar heat from the summertime to warm the house through the entire winter (see diagrams above). This meant that a house could actually be constructed with an unchanging built-in temperature, which would make heating and cooling equipment unnecessary. Now, five years later, I still think it’s a marvelous idea. The Geodome, the house we built in the cold and cloudy climate of western Montana, remains at 66 to 68 degrees F, even through the coldest winters.

The success of the Geodome led to the establishment of the Rocky Mountain Research Center, a nonprofit organization dedicated to the development of what is now called the passive annual heat storage (PAHS) approach to free year-round passive-solar heating. Four basic points make PAHS different from techniques used in conventional solar-heated earth-sheltered houses:

– The house’s window shades are opened to collect solar heat in summer.
– The umbrella’s laminated sandwich of polystyrene insulation and polyethylene sheeting (about R-20) insulates a huge mass of surrounding dirt instead of just the house.
– The umbrella sheds water to keep the soil around the house dry.
– The natural-convection-driven ventilation tubes (see below) provide very high heat retention efficiency by acting as counter-flow heat exchangers.

Read the full article that was published in Popular Science magazine at the source: Earth Shelters.com (more good diagrams and details)

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This small structure is the ECHO Asia Seed Bank’s earthbag house that is nearing completion.  ECHO promotes community-based seed sharing and saving. It is also part of their mission to recommend appropriate ways for communities and organizations in the developing world to better store seeds.

James (ECHO Asia intern) and Lue (Assistant Seed Bank Director) were trained in earthbag house construction by Engineering Ministries International (eMi).  To prevent the invasion of surrounding warmer air (the seed bank is located in a tropical/sub-tropical region), a small door with a foam interior and a thick but light ceiling composed of sacks filled with burnt rice husks were installed.  And to keep costs low, almost the entire structure was made from local, cheap materials, including a roof of fan palm thatch.

Data loggers will be installed to record the interior temperature and relative humidity.  These will be compared with outside readings over a period of one year. So we look forward to reporting on the long term results of the modification of temperature by the earthbag house and the potential of such structures for community-based seed storage in the tropics.

See sustainabilityquest.blogspot.com to read the entire article.

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Rice hull house wall section (click to enlarge)

Rice hull house wall section (click to enlarge)


Post caps secure the beam to tops of posts

Post caps secure the beam to tops of posts


Yesterday’s blog post on Production Earthbag Building using Rice Hulls introduced one method for building walls with rice hulls. As you can see from the drawing above, the construction process is very straightforward. This method uses a standard post and beam frame with posts set in concrete footers and beams attached to the posts with post caps. The post and beam frame is carefully laid out, plumbed, leveled and squared to achieve good results. The roof is built after the concrete footers have set up. While you’re waiting for the concrete to dry, you can fill the gravel bags or tubes that help protect the rice hulls from moisture damage. Use double bags or tubes for added strength. You can fill the tubes with scoria or pumice in cold climates to create an insulated foundation.

With the roof and gravel bag foundation complete, now you’re ready to fill the rice hull tubes that wrap around the post and beam frame. Tie each tube to each post with baling twine. Fasten tubes out of sight on the backside of the posts to maintain the beauty of the wood frame. 6-penny common nails would work well for this purpose. Drape pre-cut lengths of baling twine every 2 feet or so for later attachment of plaster mesh. You can also use baling twine to tie the tubes together for added rigidity if necessary. Work carefully to keep everything in alignment so there are no bulges in the wall. If you do get some bulges, they can be dealt with by tying opposing dowels, bamboo or saplings together through the wall with twine. (See external pinning.) The tubes will create a solid, superinsulated wall after the plaster is complete.

Image source: Home Hardware
(shop for low cost alternative brands of hardware)

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