by kevin, on October 30th, 2009
Caba Barkskin - Rethink Technology
part 3 of 5
In the last two posts (resource preservation – context and resource preservation – criterion) I outlined a basis for considering building material selection criterion that contribute to resource preservation. With this post I’ll drill down on the six material categories previously mentioned. Here they are in detail:
Reused
According to Architecture 2030, 1.75 billion square feet of buildings are torn down and five billion square feet is renovated each year in the United States. Another five billion square feet of new construction is added annually. With so much building stock getting demolished there should be ample supply of salvageable components. Structural steel, bricks, concrete block, stone, windows, doors, wall framing elements, some MPE components, and others are good candidates for reuse. Especially since many are composed of non-renewable natural resources.
A definition of this category as building components that can be reused directly. Some may require refurbishment or alteration to enable a second or third life, but these are materials that keep their form and function in going from an existing building to a new building.
One hurdle to clear is a lack of infrastructure. There are far more options for recycling raw materials than there are for salvaging services or operators of significant size or reach. There are many local or regional operators, but we’re unaware of any large national building material salvage exchange. For building component reuse to increase, improved infrastructure and easily accessible material markets will have to be built up. But building components are not the only candidates to consider. Many other industries can be explored for prospects. Other forms of construction can also lead to unexpected raw materials. In some regions, state surplus warehouses can be mined for components not previously considered in the built environment.
Recycled Content
There are three types of recycled content. Material salvaged at the the point of extraction – mine, well, forest, etc. – are called secondary materials; products made with waste collected at factories as part of manufacturing processes are called post-industrial; and products made with waste collected from products already in the market which have served a useful purpose are called post-consumer. The most important of the three are products composed of post-consumer waste since it lessens the amount of material typically headed to landfill or incineration. Post-industrial is also favorable, especially when a manufacturer creates new products from what would have previously been waste or discarded material.
In the built environment, there are construction materials which already employ a high percentage of recycled content. Today, very little steel is consigned to the landfill. It and similar metals are relatively easy to remove from demolition. As much as ninety percent can typically be salvaged and returned to production plants, melted down, and mixed with virgin material. New technologies, such as color and shape recognition, have been developed to help automate material separation processes and retrieve more value from disassembled buildings.
The construction industry is second only to packaging in its use of plastic. Most of us are familiar with the triangle symbol formed by three arrows enclosing the polymer type number. The symbol suggests all are recyclable, yet in reality most polymers end up in landfills as there are not recycling programs for all types of plastics. Even more difficult for anyone involved with building design or construction is the fact that most plastic used in buildings does not carry the symbol. Since few of us are polymer experts, far too much of the plastic in the built environment does not get recycled. For example, polyvinyl chloride (PVC) products technically can be recycled, but there are currently no recycling programs in place to do so. High impact polystyrene (HIPS) is a similar product, can be recycled, and there are a few companies currently offering product with a modest (fifteen percent) recycled content. The seven polymer code numbers are: 1 – polyethylene terephthalate (PET); 2 – high density polyethylene (HDPE); 3 – polyvinyl chloride (PVC); 4 – low density polyethylene (LDPE); 5 – polypropylene (PP); 6 – polystyrene (PS); and 7 – other, or a blend that cannot be separated or recycled. Of these, PET and the various polyethylene types are the easiest to be recycled. Many window and door systems are encased in PVC (code number 3), the best wall and roof insulation is expanded polystyrene (code number 6), polyester carpet is PET (code number 1), Tyvek vapor barrier is HDPE (code number 2), and vinyl flooring, wall coverings, and exterior sidings are all PVC (code number 3). In addition, buildings are full of code 7 products consisting of acrylics (paint), polymers (solid surfacing), and hydrocarbon derivatives. Knowing what type of plastic a product is, even if it doesn’t carry a polymer recycling symbol, helps you make design decisions. Especially when product manufacturers claim recyclability alone as an environmental attribute. Plastics are ubiquitous, but can be managed.
New products are introduced regularly with higher percentages of post-industrial and post-consumer content. And manufacturers are getting more aggressive in their efforts to explore what can be done to modify existing product formulations to include more recycled material. One potential barrier is the complexity of some manufactured building materials. Many are hybrid composites made of both renewable and non-renewable resources, are too difficult or too expensive to disassemble compared to recovery value, and may have components that are too hazardous to retrieve.
Reclaimed and Repurposed
In a previous post, Aleida offered our definition for reclaimed wood, but with this post I’ll expand on that to include all reclaimed materials. Where reused components come from existing buildings and are reused essentially unchanged in new construction, reclaimed materials can come from any other industry. They are typically modified to fit the needs of the built environment and change form and/or function in order to be repurposed.
The most common reclaimed material is wood. Some formerly abundant US timber species have fallen victim to disease, insect infestation, blight, and other maladies which have either extinguished supply or drastically reduced it. The only way to get access to some of this wood is through reclaim sources. It can come from the deconstruction of other buildings (barns, sheds, factories, etc.), from building related sources (stadium bleachers, furniture, storage tanks, etc.), or totally unrelated fields (boat sails, automotive parts, fabricated machine parts, industrial components, aviation parts, etc.)
A great secondary benefit these materials offer is amazing stories associated with the source. We often seek out supplies of unusual material that links directly to our clients, or our client’s customers. And with a growing list of suppliers throughout the country it’s getting easier to localize the source so that the material is regional and transport is minimized.
Rapidly Renewable
Two days ago we posted a blog (defining rapidly renewable) that attempts to clarify what constitutes a rapidly renewable resource. It seems these terms are bandied about too easily without consensus on meaning. We believe the definition should include a direct relationship between the biological maturity of the resource and human generational demand. In short we think there are hyper renewable resources, rapidly renewable resources, and just renewable resources based on how fast they are renewed and how quickly they are used.
One concern with some materials in this classification is source origin. Resources such as palm and bamboo are not grown domestically. There has been some concern that unscrupulous suppliers source from plantations that employ child labor, don’t pay a living wage, or harvest the plants in unsustainable aggressive ways. Most of those issues have been rectified by larger suppliers, but designers still need to be mindful that negative practices may still be occurring with smaller firms.
Reduced Virgin Depletion
Aggressive extraction, as well as natural events mentioned above, can push renewable resources beyond their elastic limits. We need to be careful when specifying building materials to research harvesting, mining, growing, and quarry methods. For the most part, resources extracted in the US follow either industry or government mandated guidelines that help ensure minimal impact. But the brewing controversy over mountain top removal mining for coal is a good example of how health concerns and public opinion can change quickly and disrupt supply. Designers hold similar power to public protest when selecting materials for building designs. We can vote with our dollars and move manufacturers toward processes that preserve resources and reduce the amount of virgin material consumed.
Salvaged wood, which falls in this category, was covered in a previous post so I won’t repeat the information here. But one of the best methods to lessen the consumption of virgin wood is to augment supply with material previously harvested but never brought to market. Sinker logs, bog trees, selective harvesting of dead timber, and other sources can go a long way to reduce demand on virgin supply. Similar substitution strategies are available for other materials and specific products.
Rethought Technology
Spectacular new technologies over the past fifty years have led to amazing advancements. But some have had unfortunate harmful environmental consequences. When it was first created more than one hundred years ago there were no known commercial applications for vinyl. Of the thirty billion pounds annually produced, sixty percent is used in building construction. It has provided measurable benefit, yet it is toxic to produce, toxic if on fire, and toxic at the end of it’s life. Most vinyl ends up in landfills or is incinerated. Vinyl does not biologically decompose. UV rays degrade the material is it breaks into smaller and smaller pieces over long periods of time – some estimate as much as ten or twenty thousand years. Those smaller particles can eventually leach out and contaminate the water cycle. Vinyl that’s incinerated may be more deadly as dioxin, one of the most carcinogenic compounds known, is released into the atmosphere.
But new companies are forming to leverage new thinking and new technology in ways that drastically improve the environmental impact of existing products and create totally new products previously unimaginable. New processes are fashioning new veneers, finishes, alloys, insulation, wall panels, translucent films, and much more. Still, other companies are turning to biomimicry and learning how nature works to develop new paints, solvents, adhesives, dies, stains, and more. Replacement products are also being developed. The environmental hazard posed by vinyl has created incentive to find substitutes. One leading commercial flooring manufacturer is adding renewable and/or recycled filler material in some of it’s products as they move toward reducing their total vinyl use.
All six categories have surprisingly deep lists of manufacturers and suppliers already embracing resource preservation. Other cutting edge thinking is breaking exciting new ground with many more products to come as the viability of sustainable material markets are proven. Let me know if you think I’ve forgotten any potential category, or if you have any ideas or suggestions for new products. My next post will include a list specific manufacturers and suppliers for each category and cover design strategies that maximize these six groupings. Please come back to check it out.
This is part three of five about resource preservation. Part one is entitled resource preservation – context, part two is entitled resource preservation – criterion, part four is entitled resource preservation – sources, and part five is entitled resource preservation – design.
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[...] resource preservation – strategy [...]
[...] resource preservation – strategy [...]
[...] context, part two is entitled resource preservation – criterion, part three is entitled resource preservation – strategy, and part four is entitled resource preservation – [...]