Two of the large buildings Benchmark constructed for the Desert Living Center were built of rammed earth, a process taking quarter-inch particles of rock from a gravel pit, and mixing it with a small amount of dry cement and enough water to where it will hold together when it's packed. Green said he has also added beach sand to the mix on a project on the coast.
The mixture is then dumped into wooden construction frames, similar to concrete forms only stronger, and pounded into short layers. Benchmark developed special equipment for the process.
Green said he can do a lot with rammed earth because of the colors of various materials. The final effect is that it looks like concrete, only it's slightly rougher and contains wavy, multicolored patterns after it has dried.
One of the challenges Green faced was transplanting all his equipment and crews to Las Vegas, along with the truckloads of straw bales. Working with large pieces of equipment and with more than 100 subcontractors in the area at once also meant he had to spend a lot of time scheduling and planning ahead.
Building with straw bales or rammed earth is more expensive, Green said. Rammed earth takes roughly four times as much labor to build with as concrete does, he added. Straw bale buildings are also more time consuming and expensive to build with than a normal stick-frame house because the framework also has to be built. More materials and time are also used to cover the straw bales with plaster or stucco, inside and outside.
Straw bales have an advantage in that they are self insulating. Green said most bales are rated at R-54, though it performs considerably beyond that. It also cools so well that at the Desert Living Center, air conditioners aren't needed, he said.
He also said it's fire safe once its built, especially after it has been covered with stucco or plaster on each side. He compares it to trying to burn a phone book all at once. It isn't easy to ignite because the bales are so compacted, and fire can't get much oxygen. A typical bale is 75 pounds of tightly compacted straw.
To illustrate how tough it is to burn a straw bale structure, he told of a police building in Visalia he built that someone attempted to burn down by pouring gasoline on it. Green said they tried three times, and either the fire went out or it didn't burn enough to cause much damage.
He said the only time he has heard of a straw bale structure burning was a home in an area that was caught in a fire storm. The fire in that case was so hot, houses exploded from the inside, out.
full article
Monday, 20 August 2007
Structural Insulated Panels
A newer material Peak has already used in several homes is called SIPs or Structural Insulated Panels made by a company in Charleston. The panels are engineered “sandwiches” made from two pieces of Oriented Strand Board (OSB) -- a plywood-like substance -- and foam core in the middle.
“One of the things that turned us on to it is because it’s so much more energy efficient,” Burkes said.
The large panels are also extremely strong, which means they can be used to erect a building’s shell without having to use the conventional method of stick framing using lumber. SIPs shells can be put up quickly, saving labor costs, and they are stronger than stick frame walls.
Homes built with SIPs are better insulated and much more airtight than in regular construction. SIPs homes conserve energy by keeping air conditioning and heating costs down while creating better indoor air quality.
“Oakridge National Labs certified that with a 4-inch stick frame wall and a 4-inch SIPs frame wall, the SIPs were 50 percent more energy efficient,” Burkes said. “We love it because it’s easy to build with.”
The product is about 10 percent more than costs for stick framing a house, but Burkes said the extra cost will quickly be recouped through energy savings.
“We were shocked with how well it holds temperature,” Burkes said of the first time he used SIPs in a building.
There are other options available for people thinking about going green, or at least a little greener, in their homes.
An instantaneous water heater or a tankless hot water system is a good energy saver, Burkes said.
Normally water heaters heat and store water in tanks to be ready for use, but with an instantaneous system, no tank is necessary, and the system doesn’t use a lot of energy trying to keep the tank hot all the time.
Another method for creating hot water more efficiently is a solar hot water system, Burkes said. With these systems, cold water is piped up to solar panels on the roof where it is heated and then pumped into a storage tank.
“It’s using the sun’s energy basically for free hot water,” he said.
While solar panels are expensive, Burkes said he’s seen a homeowner get paid back in energy savings within three years.
Energy savings can be found right under the feet, too.
Installing radiant heat floors in a home under construction or in an existing home is proven to cut heating costs, Burkes said.
It works by putting water lines in the home’s concrete floors or under existing floors and running hot water through them. Radiant heat helps to keep the whole house at a more constant temperature, so heaters don’t have to do as much to keep things warm and toasty during the winter.
It might take a little effort, but being more environmentally friendly doesn’t have to involve major renovations.
Burkes said many people waste a lot of energy by not sealing cracks, doors and windows. Checking to make sure a home’s insulation is in good shape and replacing it if it’s not is another good way to stop energy waste.
Switching to energy efficient fluorescent light bulbs and replacing old heating and air conditioning units with a more efficient system can help to make a home a little greener, too.
“We can always be more energy conscious,” Burkes said. “It’s going to take a homeowner who’s willing to push to have a green house. (It takes) somebody who is going to look long-term.”
full article
“One of the things that turned us on to it is because it’s so much more energy efficient,” Burkes said.
The large panels are also extremely strong, which means they can be used to erect a building’s shell without having to use the conventional method of stick framing using lumber. SIPs shells can be put up quickly, saving labor costs, and they are stronger than stick frame walls.
Homes built with SIPs are better insulated and much more airtight than in regular construction. SIPs homes conserve energy by keeping air conditioning and heating costs down while creating better indoor air quality.
“Oakridge National Labs certified that with a 4-inch stick frame wall and a 4-inch SIPs frame wall, the SIPs were 50 percent more energy efficient,” Burkes said. “We love it because it’s easy to build with.”
The product is about 10 percent more than costs for stick framing a house, but Burkes said the extra cost will quickly be recouped through energy savings.
“We were shocked with how well it holds temperature,” Burkes said of the first time he used SIPs in a building.
There are other options available for people thinking about going green, or at least a little greener, in their homes.
An instantaneous water heater or a tankless hot water system is a good energy saver, Burkes said.
Normally water heaters heat and store water in tanks to be ready for use, but with an instantaneous system, no tank is necessary, and the system doesn’t use a lot of energy trying to keep the tank hot all the time.
Another method for creating hot water more efficiently is a solar hot water system, Burkes said. With these systems, cold water is piped up to solar panels on the roof where it is heated and then pumped into a storage tank.
“It’s using the sun’s energy basically for free hot water,” he said.
While solar panels are expensive, Burkes said he’s seen a homeowner get paid back in energy savings within three years.
Energy savings can be found right under the feet, too.
Installing radiant heat floors in a home under construction or in an existing home is proven to cut heating costs, Burkes said.
It works by putting water lines in the home’s concrete floors or under existing floors and running hot water through them. Radiant heat helps to keep the whole house at a more constant temperature, so heaters don’t have to do as much to keep things warm and toasty during the winter.
It might take a little effort, but being more environmentally friendly doesn’t have to involve major renovations.
Burkes said many people waste a lot of energy by not sealing cracks, doors and windows. Checking to make sure a home’s insulation is in good shape and replacing it if it’s not is another good way to stop energy waste.
Switching to energy efficient fluorescent light bulbs and replacing old heating and air conditioning units with a more efficient system can help to make a home a little greener, too.
“We can always be more energy conscious,” Burkes said. “It’s going to take a homeowner who’s willing to push to have a green house. (It takes) somebody who is going to look long-term.”
full article
Rammed Earth Bricks
New homes built of mud or straw, with a lawn on the roof, sheep fleeces for insulation and heat from the ground or a boiler fired with sawdust – this is one vision of the future for our green and pleasant land.
The Centre for Alternative Technology (CAT) in Machynlleth, the ancient Welsh capital, opened in 1975. The centre, in a former slate quarry, is blessed with mountain streams, which help fire up some of the energy projects.
Many of the techniques currently being explored are not new – indeed, much of the work at CAT revolves around materials and methods that have been used for centuries. It is often a case of "looking forward to the past".
There's nothing new about rammed earth walls, for example. Ancient cob cottages built by labourers trampling mud and straw have survived for hundreds of years, provided they had "a good hat and boots" (roof and footings).
Among the energy-saving building techniques being developed and used in public buildings are grass roofs and rammed earth bricks covered with hemp and lime render. These, unlike traditionally fired bricks and clay tiles, use hardly any energy in their manufacture.
Traditional bricks may become museum items and housebuilders will have to use other materials to give their properties what estate agents call "kerb appeal".
Indeed, the production of cement for building is known to account for more than five per cent of global carbon dioxide emissions. CAT recommends 'limecrete' be used instead of cement-based concrete.
full article
The Centre for Alternative Technology (CAT) in Machynlleth, the ancient Welsh capital, opened in 1975. The centre, in a former slate quarry, is blessed with mountain streams, which help fire up some of the energy projects.
Many of the techniques currently being explored are not new – indeed, much of the work at CAT revolves around materials and methods that have been used for centuries. It is often a case of "looking forward to the past".
There's nothing new about rammed earth walls, for example. Ancient cob cottages built by labourers trampling mud and straw have survived for hundreds of years, provided they had "a good hat and boots" (roof and footings).
Among the energy-saving building techniques being developed and used in public buildings are grass roofs and rammed earth bricks covered with hemp and lime render. These, unlike traditionally fired bricks and clay tiles, use hardly any energy in their manufacture.
Traditional bricks may become museum items and housebuilders will have to use other materials to give their properties what estate agents call "kerb appeal".
Indeed, the production of cement for building is known to account for more than five per cent of global carbon dioxide emissions. CAT recommends 'limecrete' be used instead of cement-based concrete.
full article
Saturday, 18 August 2007
Those in straw houses
Owners of Austin-area homes built with bales of straw and other natural materials like the idea that they are having less of an impact on the environment, and they're getting health and economic benefits as well.
The bales for the 18-inch walls have been covered with stucco on the home's exterior and smooth adobe plaster on the interior, helping to keep the home earthy, comfortable and quiet. His average monthly utility bill is about $55. And the large, deep window sills are perfect for his two kids to sit and read their favorite books.
In addition to straw bales, green builders also are using rammed earth, or dirt compressed into building blocks; cob, a mixture of adobe and straw; and aerated concrete blocks.
The building project started last fall, with carpenters erecting the post-and-beam structure that would support the weight of the roof. Then on a sunny November day, people came to the Rainey's bale-raising party from as far away as Houston and Oklahoma. News of straw-bale raising workshops is spread through word-of-mouth and Internet message boards.
For six hours, everyone worked to raise the walls, using more than 300 bales of straw. Some stacked the bales, some droves stakes through the bales to anchor them together. Others tied bamboo stakes together on both sides of the bale wall, giving it stability until plastering.
Rainey estimates it will take three more months for contractors to finish the electrical wiring and plumbing. Then the Raineys will hold another workshop, led by a local contractor, this time covering the topic of plastering interior walls. Before the walls are plastered, Rainey must trim the edges of the straw bales to ensure a smooth wall surface. Small recesses will be cut into the walls for niches, and wood studs will be added in preplanned areas in order to have wall support to hang pictures.
So far, the biggest surprise in the building project was related to insurance coverage. In short, his insurer told him it wouldn't cover a straw-bale structure. But Rainey said he talked with other people in town who know about sustainable building and found a carrier who covered such homes.
Obregon said that many people wrongly think that straw bales are highly flammable, and that this leads some insurers to refuse coverage. But Obregon said that structural engineers have tested straw for fire safety and discovered that when properly installed, these structures do not burn easily.
"The heat transfer is not an issue. It's great," Obregon said. In fact, densely packed bales limit oxygen flow.
"The biggest concern for our area can be the moisture level in straw bales," he said. It's important to keep the bales moisture-free, especially before the wall-raising, he said. It's also important to waterproof the exterior walls, to create wide roof overhangs and to seal the doors and windows tightly.
Vicki Howard of Austin chose an alternative to straw-bale construction. She decided that living in a house built of dirt would be a clean, although counterintuitive, solution to her health problems. So she lives in what's called a rammed-earth home.
full article
The bales for the 18-inch walls have been covered with stucco on the home's exterior and smooth adobe plaster on the interior, helping to keep the home earthy, comfortable and quiet. His average monthly utility bill is about $55. And the large, deep window sills are perfect for his two kids to sit and read their favorite books.
In addition to straw bales, green builders also are using rammed earth, or dirt compressed into building blocks; cob, a mixture of adobe and straw; and aerated concrete blocks.
The building project started last fall, with carpenters erecting the post-and-beam structure that would support the weight of the roof. Then on a sunny November day, people came to the Rainey's bale-raising party from as far away as Houston and Oklahoma. News of straw-bale raising workshops is spread through word-of-mouth and Internet message boards.
For six hours, everyone worked to raise the walls, using more than 300 bales of straw. Some stacked the bales, some droves stakes through the bales to anchor them together. Others tied bamboo stakes together on both sides of the bale wall, giving it stability until plastering.
Rainey estimates it will take three more months for contractors to finish the electrical wiring and plumbing. Then the Raineys will hold another workshop, led by a local contractor, this time covering the topic of plastering interior walls. Before the walls are plastered, Rainey must trim the edges of the straw bales to ensure a smooth wall surface. Small recesses will be cut into the walls for niches, and wood studs will be added in preplanned areas in order to have wall support to hang pictures.
So far, the biggest surprise in the building project was related to insurance coverage. In short, his insurer told him it wouldn't cover a straw-bale structure. But Rainey said he talked with other people in town who know about sustainable building and found a carrier who covered such homes.
Obregon said that many people wrongly think that straw bales are highly flammable, and that this leads some insurers to refuse coverage. But Obregon said that structural engineers have tested straw for fire safety and discovered that when properly installed, these structures do not burn easily.
"The heat transfer is not an issue. It's great," Obregon said. In fact, densely packed bales limit oxygen flow.
"The biggest concern for our area can be the moisture level in straw bales," he said. It's important to keep the bales moisture-free, especially before the wall-raising, he said. It's also important to waterproof the exterior walls, to create wide roof overhangs and to seal the doors and windows tightly.
Vicki Howard of Austin chose an alternative to straw-bale construction. She decided that living in a house built of dirt would be a clean, although counterintuitive, solution to her health problems. So she lives in what's called a rammed-earth home.
full article
Subscribe to:
Comments (Atom)
