Archive for December, 2007
The Paradox of Green Building
admin on Dec 18th 2007
By green we mean sustainable. By sustainable we mean the building must;
1. Last a long time. What ever renewable materials you use should far outlast the length of time it takes to renew them.
2. The materials we use should not poison you or your local ecology including the ecology of the earth and thus all life.
3. It should be comfortable and easy to maintain so its inhabitants will want to keep it up.
4. It should be energy efficient so its inhabitants can afford to stay in it.
5. Materials should be affordable and local.
Paradox 1. Our ancestors built green and we don’t.
I like to remind folks that all farming was organic before WWII. And likewise our building practices before the industrial revolution. On every continent but Antarctica people have built sustainable homes with long lasting and renewable resources. They built homes of stone, earth and straw and many of them have lasted for more than a millennium and are still inhabited. The oldest continually inhabited building on this continent is only 900 years old, the Taos pueblo.
Paradox 2: much of what we call green building isn’t.
So here is another paradox of Green Building. We build these green homes using mostly industrial materials such as concrete and block for the foundations, dimensional lumber for the frames, and a variety of normal roofing options. We use straw produced on industrial farms with carbon spewing machines that produce the straw bales, and we integrate them into a frame built with common construction practices. What makes it green?
1. Straw is an annually renewable resource.
2. Straw bale wells are have a high insulation value
3. By sequestering the carbon that was to be burned as insulation we can also save further carbon emissions by lowering utility bills and the plaster we use is lime based so it will continue to take carbon out of the air as it slowly turns back into limestone.
4. Currently most of the straw in country is wasted by being burned off the fields, mostly out west, because there isn’t a market for that much of it. But, it is enough to build a million energy saving straw bale houses every year.
5. And its easy enough to do that anyone can do it.
Building green is a much need improvement in the standards from current practices. However some so-called Green building materials may not be too green either in that they require materials costly to the environment or are toxic like polystyrene used in SIPS building panels which is vinyl and benzene, both carcinogens, or they may polyurethane which is carcinogenic also. And they require big factories with massive energy inputs, spewing carbon and then shipping materials long distances to the building site, much energy and the environment wasted. The centralized economic and monetary system that allows that practice for the profit of a few at the expense of many needs to change too if we want to count the ecology we live in as part of the many. So, standards need to continue to rise steadily until we get to sustainable.
Sometimes I see our work as a metaphor for our lives, we build integrating big shaggy building blocks into an industrial frame to transform our mode of building while we are shaggy hippies integrating ourselves into industrial society in order to transform it.
What do we do?
The people of Ghana have a practice called “sankofa” which means returning to the past in order to move forward. Taking cues from our pre-industrial past we are relearning how to build with what nature has provided locally to the site. We can create healthy wealthy sustainable communities. We need government and business to help in a cause greater than themselves which is getting us on a sustainable course so that there will be a viable planet for our children’s children’s children.
article source: ecoville architechs
So Many houses
We are not advocating to tear down all homes and build new. On the contrary, after decades of experience with remodels we see a massive need to improve the homes we have which is usually a 'greener' choice. However, new homes are still being built with little forsight for the everychanging world. New homes are being built under the same standards for the last 4 or 5 centuries, the energy crisis will likely continue as it is only a matter of time before the paridigm shifts. There are many that are still building homes with little concern or consciousness about the future challenges and we see multi million dollar homes that leak energy and are a resource sink and waste generator. According to US Energy, 76% of all power plant production goes to our buildings. At our current rate we need 5 earths to support our ecological footprint.
We can change this! We can improve the buildings we have and when we build new we can design buildings that are resource generators and waste sinks. It's much more enjoyable to be part of the solution and no more difficult!
Loose straw, burns easily, just like wood shavings. Baled straw tends to simply smoulder, like trying to burn a phone book. The key factor is how easily a fire can obtain oxygen; tight baling of the straw severely limits a free flow of oxygen. Most importantly, strawbale houses are traditionally covered with stucco. Tests have shown time and again that stuccoed strawbale houses have a much greater resistance to fire than do conventional wood structures. Strawbale structure fire tests have shown that stuccoed strawbale construction is able to withstand temperatures of 1800 degrees Farenheit for over one hour with no structural damage, which is sufficiently fire resistant for stuccoed strawbale to qualify as a commercial building material. The growing list of county building departments which have approved strawbale construction is indicative that strawbale construction is not only safe, but is in fact safer than conventional wood construction.
Being comprised of the stems of plants, Straw contains no food value. Bugs see straw as being a lot more like the Sahara Desert than a leftover pizza. Termites, the bane of wood homes, don't have the right digestive processes to consume straw and can accurately be described as disinterested. The existence of sound, longstanding strawbale houses has proven that this is true. There are additional non toxic measures that can be taken if concerned.
Straw or Hay?
Straw is an agricultural by product, the dry stalk of a cereal plant, after the nutrient grain or seed has been removed. Straw makes up about half of the yeild of a cereal crop such as barley, oats, rice, rye, or wheat. Intimes gone by, it was regarded as a useful by product of the harvest, but with the advent of the combine harvster, straw has become more of a burden, almost a nuisance to farmers.
Hay is grass or legumes that has been cut, dried, stored and used for animal feed. Hay is fed when there is not enough pasture or rangeland on which to graze an animal.
Moisture and Rotting
Both wood and straw can rot if wall moisture content rises above about 70% for extended periods of time. New information from Canada and the U.S. strongly suggests that all superinsulated homes (of which strawbale homes are only one type) must be designed to avoid moisture buildup or rotting can occur. Some data on the degradation of wood even suggest that our past and current understanding of the dynamics of moisture and vapor barriers is incomplete, and that many newer homes with standard insulation levels which employ moisture barriers are at risk due to inappropriate installation of the barriers. Strawbale enthusiasts are, if anything, more knowledgeable about both the dangers of moisture and are more familiar the technques of moisture control than most builders of conventional homes. The final word regarding moisture is that it is a design problem that is shared by both wood and straw, and that buildings utilizing strawbale walls are no more prone to moisture degradation than houses built of wood.
R-value is a measure of apparent thermal conductivity, and thus describes the rate that heat energy is transferred through a material or assembly. Materials are given a number, the higher the number the greater the insulation quality. In the mountains of Colorado the R-value code requirement of a wall is 21.
A straw bale wall is difficult to give an exact measurement, based on tightness of each individual bale, how the bales are oriented and so on. However the R-values range from 30 to 50 depending on orientation and other factors.
Everything under the sun
Everything we use in our lives has been effected by the sun. Our homes are solar whether we are conscious of it or not. The wood or straw that builds the house, the textiles in the house and the oil, gas or wood that we heat the house with is all stored solar energy. There are ways to maximze the use of the sun, Such as passive solar orientation of a structure. Passive solar design orients the home to take advantage of the suns heat throughout the day during the cooler months of the year and shades the living space during the warmer months. To take advantage of the suns free daily heat a house needs orientation, approriate glazing (windows), mass to store the heat, and insulation to keep the heat gained. Straw bale construction is the perfect marriage with passive solar. with the use of a slab foundation such as concrete or better yet adobe, the plaster skin on the inside of the wall as mass and the straw as insulation.
There are some great understandings and research to humans living with natural materials. See the links below for Biophillic design. Straw bale houses are commonly very tight building envolopes with the use of plasters. Using a plaster for wall coveringsHas many advantages and is another perfect marraige with strawbale construction. First, a plaster is for protection from the elements, fire, rain,sun, impact,etc...
The plaster also adds to the structural integrity by adding compressive and lateral strength. Plaster also controls water vapor, air infiltration, sound and acts as a thermal storage. There are many different materials used for plaster such as earth, lime, gypsum, and cement. Each material has it's advantages and disadvantages. Living in harsher climates may lead folks to a lime or cement stucco on the exterior and earthen(clay) ,lime, or gypsum on the interior.
Life cycles, and the view along the way
There is now a movement to better understand the lifecycle of materials that we use. One source says that 1% of what americans buy is still in use after 6 months. Cradle to cradle is the idea of re-using or recycling materials. As we have gone along through these industrial years we have been developing products that are high in function for there life and when there life is over they are difficult and/or costly to re-use and recycle. Furthermore, many materials have been using up precious limited resources. Causing adverse effects to the surrounding environment, regardless whether you belive in global warmiing, high production materials leave higher traces of compounds that were not present pre production. Lastly, they are showing adverse effects in human health, see sick building links below.
Natural materials tend to be more cradle to cradle in their lifecycle. At the end of there life they simply return to the earth from where they came, just like our human structure.
Visualize the difference between a vacent mobile home in 100 years and a unkept stone wall.
For the next 20 or so years we will see the baby boom begin to retire. During the same time we will see energy prices increase, healthcare stress and new solutions develop along the way. Super energy efficent, natural homes are part of the solution on all fronts. During one's retirement the concern for monthly spending needs to be addressed and a super energy efficent home addresses part of this burden by reducing energy bills. Health and quality of life is another area that needs to be addressed. The more natural the home the better for dealing with increased sensitivety to chemicals, Stronger immune response and psychological well being. Strawbale homes can be easily made ADA complient, single story and be designed to fit the needs of generations to come. The maintance on these homes can be similar to any other home, but it is possible with the appropriate choices to reduce these costs form the onset.