Trombe was the name of a French engineer who developed the Trombe wall, which forms a large solar thermal collector. A typical Trombe wall is 8 to 16 inches thick masonry faced with a double layer of glass which is placed a few inches from the wall to create a small airspace. The wall absorbs heat from sunlight passing through the glass. The heat is stored in the wall and conducted slowly inward through the masonry. In the northern hemisphere of course we want oiur wall to face south for access to direct sunlight. A dark surface on the side facing the sun facilitates heat absorption.
Solar energy facts show that the wall can be made of concrete, brick, rammed earth, or adobe. This is a technique that can be used for a new building or a solar retrofit. If it is designed right, this method of passive solar can cut down significantly on heating and cooling energy demands. The sun begins to heat the wall about midmorning, and continues to heat it all day. When the sun goes down the wall radiates its heat to the room inside. Rooms heated by a Trombe wall feel more comfortable because of the gentle infrared heat given off by the wall's surface.
Builders can use Trombe walls along with windows, eaves, and other design features, to achieve a balance of solar heating and cooling for a building's interior. Shading and vents to the outside can prevent the wall from gaining heat during the warmer months. A Trombe wall's performance is inhibited if the interior of the wall is not open to the room inside. For example, if shelves or cabinets are placed against the surface. Sometimes designers place projections on the inside wall to prevent bookshelves being placed against the wall. One of the things to remember when a Trombe wall is installed using adobe, rammed earth, concrete or other masonry, is that it may take a full heating season for the wall to dry out completely. The second season should show the true results.
Our solar energy facts lead us to the conclusion that a design including a Trombe wall is well worth consideration. This technique when combined with baseboard heating or even a small wood or gas stove is an excellent choice for new construction. A solar greenhouse including a Trombe wall is a viable option for a solar retrofit. Any good design will incorporate correct use of insulation. When I am ready to put up a new building, I will definitely include a Trombe wall as a part of the whole.
Showing posts with label solar energy facts. Show all posts
Showing posts with label solar energy facts. Show all posts
Wednesday, August 26, 2009
Solar Energy Facts-Straw Bale Construction
People have been using straw one way and another for building purposes for thousands of years, but it wasn't until the late 1800's that they began making bales out of hay and straw. In the treeless sandhills of Nebraska around this time, some enterprising person decided that straw bales might make a good house. There was probably a lot of trial and error involved in the first few houses that went up, but eventually they got so good at building houses out of straw bales that some of these houses are still standing-over a hundred years later!
Straw is an agricultural byproduct, much of which is burned to get rid of it. In the United States alone over one hundred million tons is burned annually, which contributes drastically to air pollution. Our solar energy facts show us that using straw in a well thought out design is a low impact resource that benefits not only the homeowner but the environment as well.
There are basically two methods of straw bale construction; post and beam, where the straw is used for infill and the roof is supported by the post and beam structure, which can be made of wood, steel, or concrete. The other method of construction is load-bearing, where the roof is actually supported by the bale walls themselves. A top plate is laid on the bale walls and secured with strapping or metal rods that go all the way to the foundation. The roof is then fastened to the top plate.
Straw bale construction can be used almost anywhere in the U. S, as long as care is taken in wet climates to assure that the bale walls be kept dry. In areas where moisture is a problem special precautions such as: roof overhangs, good foundations, and starting the bale stacks up off the ground, are good ideas. Solar energy facts tell us there are a number of advantages to building with straw, some of which are: superior insulation, soundproofing, and a certain comfort from the combination of straw and plaster. The straw itself is cheap and plentiful in agricultural areas, and the bales are easy to build with, as they are stacked like bricks and then pinned together using rebar, wood, or bamboo stakes. For added strength chicken wire or welded lath is sewn to the bales and then the walls are earth plastered or stuccoed inside and out.
The cost of straw bale construction is comparable to stick and wood, depending on the amount of labor the builder can provide. A great deal of labor is involved in the plastering of the bales. The plastering on straw bale construction is very important. The breatheability of the walls is dependent on the proper mix and application of stucco or plaster. Some people choose not to use a netting on the outside of the straw, but to plaster directly to the straw itself. When using this option, the first coat applied is a thin clay slurry which is absorbed into the surface of the straw. Three more coats follow this to achieve a final thickness of from one to three inches. There are many different recipes one can use for the plaster, which include materials such as: earth, loam, sand, lime, and cement. Many of these recipes use mostly the earth found directly on the building site, combined with lime or cement.
Renting a stucco spraying rig would undoubtedly save a great deal of labor. Some people doing this work invite a bunch of friends and relatives and have a plastering party! It's important to have someone with experience or at least knowledge of the process. Workshops are offered in many parts of the country and would be a very valuable investment in time and money for any prospective builder.
Our solar energy facts show us that straw bale construction is an extremely important resource in many areas of the country. Habitat For Humanity has built straw bale houses. Mother Earth News has had several articles on building with straw. Here are some books on the process: Serious Straw Bale: A Home Construction Guide for All Climates(Real Goods Solar Living Book) by Paul Lacinski and Michel Bergeron, Building a Straw Bale House: The Red Feather Construction Handbook by Nathaniel Corum and Jane Goodall, More Straw Bale Building: A Complete Guide to Designing and Building with Straw(Mother Earth News Wiser Living Series).
Straw is an agricultural byproduct, much of which is burned to get rid of it. In the United States alone over one hundred million tons is burned annually, which contributes drastically to air pollution. Our solar energy facts show us that using straw in a well thought out design is a low impact resource that benefits not only the homeowner but the environment as well.
There are basically two methods of straw bale construction; post and beam, where the straw is used for infill and the roof is supported by the post and beam structure, which can be made of wood, steel, or concrete. The other method of construction is load-bearing, where the roof is actually supported by the bale walls themselves. A top plate is laid on the bale walls and secured with strapping or metal rods that go all the way to the foundation. The roof is then fastened to the top plate.
Straw bale construction can be used almost anywhere in the U. S, as long as care is taken in wet climates to assure that the bale walls be kept dry. In areas where moisture is a problem special precautions such as: roof overhangs, good foundations, and starting the bale stacks up off the ground, are good ideas. Solar energy facts tell us there are a number of advantages to building with straw, some of which are: superior insulation, soundproofing, and a certain comfort from the combination of straw and plaster. The straw itself is cheap and plentiful in agricultural areas, and the bales are easy to build with, as they are stacked like bricks and then pinned together using rebar, wood, or bamboo stakes. For added strength chicken wire or welded lath is sewn to the bales and then the walls are earth plastered or stuccoed inside and out.
The cost of straw bale construction is comparable to stick and wood, depending on the amount of labor the builder can provide. A great deal of labor is involved in the plastering of the bales. The plastering on straw bale construction is very important. The breatheability of the walls is dependent on the proper mix and application of stucco or plaster. Some people choose not to use a netting on the outside of the straw, but to plaster directly to the straw itself. When using this option, the first coat applied is a thin clay slurry which is absorbed into the surface of the straw. Three more coats follow this to achieve a final thickness of from one to three inches. There are many different recipes one can use for the plaster, which include materials such as: earth, loam, sand, lime, and cement. Many of these recipes use mostly the earth found directly on the building site, combined with lime or cement.
Renting a stucco spraying rig would undoubtedly save a great deal of labor. Some people doing this work invite a bunch of friends and relatives and have a plastering party! It's important to have someone with experience or at least knowledge of the process. Workshops are offered in many parts of the country and would be a very valuable investment in time and money for any prospective builder.
Our solar energy facts show us that straw bale construction is an extremely important resource in many areas of the country. Habitat For Humanity has built straw bale houses. Mother Earth News has had several articles on building with straw. Here are some books on the process: Serious Straw Bale: A Home Construction Guide for All Climates(Real Goods Solar Living Book) by Paul Lacinski and Michel Bergeron, Building a Straw Bale House: The Red Feather Construction Handbook by Nathaniel Corum and Jane Goodall, More Straw Bale Building: A Complete Guide to Designing and Building with Straw(Mother Earth News Wiser Living Series).
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