Green building with plastics
The Industry View
Water Cube; The National Aquatic Centre in Beijing China is the largest building to use EIFE roofing material. In this application the thin film is made into translucent pillows that modulate light and provide a degree of thermal insulation [Photo: Yang Lei, Consulate-General of the People’s Republic of China]
by Marion Axmith
At first sight, plastics may appear to be a poor fit in the context of green building. Many in the design and construction industry consider plastics “unnatural” and nowhere near as “green” as more traditional materials like wood. However, more considered analysis reveals that plastic building materials bring a lot of advantages to the table, including energy efficiencies and lower greenhouse gas emissions. The materials are durable and effective so, whether a project is being built according to the latest LEED, Green Globes or other recognized industry tool, plastics can make a significant contribution.
The Whole Solution
Today, there is a wide variety of plastics being used in building and construction applications. Vinyl represents the lion’s share of the market at around 50%, followed by polyethylene at 12%, and polypropylene at 7%. Both polyurethane and nylon each account for around 9% of the plastics used in building and construction applications. ABS represents 3% and polystyrene and polyethylene terepthalate each account for another 2%. The remaining 2% is comprised of “other” plastics. [see pie chart next page.]
Common building and construction applications include roofing, siding, fencing, walls, decking/railings, insulation, electrical products/wire and cable, sealants, concrete forms, pipe and fittings, entry doors, wall coverings, flooring, windows/frames, and house wrap/vapour barriers.
Many of the plastics being used in building and construction are recyclable. For example, vinyl manufacturers recycle almost 100% of their in-plant vinyl production scrap. In Europe, some 83,000 tonnes of vinyl from the building and construction industry was recycled in 2006. This was more than double the amount recycled in 2005, and included applications like pipe, window profiles and coated fabrics.
Here in Canada, the Vinyl Council of Canada [VCC] and the Environment and Plastics Industry Council [EPIC] have jointly worked on several Canadian pilot plastic recycling projects for demolition and new construction applications.
A Best Practices Guide was developed as a result of this work to demonstrate to industry how to implement recycling projects at their own construction sites. The pilots showed that little effort was needed on the part of the construction workers to facilitate the recovery, reuse and recycling of vinyl siding [and other vinyl products such as window frames], and that such programs are economically feasible.
The VCC has also implemented a new pilot recycling program for plastic pipe manufacturers in the province of Ontario. The program was launched in 2007 and includes vinyl, polyethylene and ABS waste construction pipe.
Although vinyl has been used for more than half a century and is one of the most analyzed and tested materials in use today, some misconceptions about it still exist. The topic of dioxins is one. In relative terms, vinyl is an extremely small source of dioxin, less than 0.5% of emissions. This is so small that levels in the environment would be unchanged even if vinyl were not being manufactured and used every day in important products.
Other dioxin sources include forest fires, volcanoes, wood-burning fireplaces, vehicle emissions and manufacture of other building materials. According to the U.S. Environmental Protection Agency [EPA], dioxin levels in the environment have been declining for decades while production and use of vinyl have more than tripled.
Vinyl additives have also been studied closely by independent scientists, the
federal government, and industry. Vinyl products have been found to perform favourably in terms of energy efficiency, thermal-insulating value, low contribution to greenhouse gases, low maintenance and product durability. Recent lifecycle studies show the health and environmental impacts of vinyl building products are comparable to or less than the impacts of most alternatives.
In February, 2007, the final report of the U.S. Green Building Council panel on PVC [vinyl] reaffirmed the conclusions of its 2004 draft report that PVC should not be the subject of a negative credit in the Council’s LEED rating system. The panel also found that data gaps frustrated its efforts to reach general conclusions about materials. While a great many studies have been conducted on PVC, and its health and environmental profile is well established, the report recognized that there are major data gaps with respect to many competing materials.
A Lighter footprint
Plastics materials, including vinyl, are increasingly being used in green building projects to help lessen the environmental impact of a building in several key areas, such as energy, materials, water and indoor environment.
For example, it takes only 35 litres of fuel to make enough plastic housewrap for one 180m2 home. But that housewrap can help to save 1,250 litres of heating fuel per year, which reduces greenhouse gas [GHG] emissions by 1,793 kilograms of carbon dioxide a year. Similarly, the use of plastic exterior foam insulation in Canada alone reduces GHG emissions by three million tonnes per year – equivalent to the annual emissions of 700,000 vehicles.
Plastics’ versatility and flexibility, not to mention environmental benefits, make the material a good choice for many different applications – everything from roofing insulation to floor tiles and wall paper.
• For example, studies have shown that foam insulation sheathing materials, housewrap materials and air barrier systems made of plastic can help reduce a building’s operating energy costs by anywhere from 10 to 50%. These same building systems can also reduce the penetration of dust, pollen and other air-borne pollutants, can reduce moisture infiltration, and can greatly contribute to the overall acoustics of the exterior envelope. According to the National Research Council of Canada, faulty air barriers can lead to uncomfortable indoor environments, high heating and air conditioning costs, and accelerated decay of building materials.
• Plastic spray foam sealants are used in many of today’s buildings to expand and fill gaps around windows, pipes and electrical outlets. Similarly, insulated concrete forms are being increasingly used to provide added stability over traditional stud-wall buildings and to act as air barriers.
• Vinyl’s flexibility and resistance to breakdown under high electrical voltage make it the leading material for wire and cable insulation.
• Vinyl siding provides a maintenance free and highly durable exterior that will not dent or rot. It is significantly lighter in weight than some alternative materials, which saves on energy and fuel during transportation. Plastic window frames also offer a maintenance-free commodity with high thermal efficiency and weather resistance. High-strength polycarbonate windows have lower thermal conductivity than glass, reducing heating and cooling energy needs. Plus, vinyl siding and plastic windows can be re-used or recycled, thereby diverting waste from landfill.
• Inside the building, plastic tubing and pipe prevents corrosion and provides superior flow capacity. Plastic pipe manufacturing is resource efficient, consuming less energy than alternative materials. And plastic electrical products have proven themselves capable of withstanding the rugged demands of underground, roof, behind walls and under-the-floor conditions.
• Plastic fences and decking are also becoming increasingly popular, thanks to their durability and longevity. In addition, many of today’s products also incorporate recycled plastic.
Plastics in green Building Rating Systems
Today, the opportunity to use plastic materials in construction projects is as diverse as the buildings themselves. But if you’re building according to a recognized standard, it’s important to understand the contribution plastics can make.
In Canada, the two rating systems that currently dominate the market are Green Globes and LEED. Both systems give consideration to the environmental impact, energy efficiency, cost, performance and availability of a product. Green Globes also uses a life-cycle analysis approach in their evaluation of a product, and establish sustainable building/product criteria based on the best available scientific data. All of these factors contribute to a sound, objective method of evaluation capable of withstanding the test of time.
The tables left summarize how plastics can contribute to the acquisition of credits under both systems.
Notable Applications of Plastics in Recent Building Projects
material, which is a fluorocarbon-based polymer ethylene tetrafluoroethylene. The material was chosen over more traditional materials like glass or fiberglass as a critical design component.
The plastic can be manufactured into a thin film, and then stored in rolls before being applied in sheets or as inflated pillow-like units of varying size, shape and colour – like the Watercube. The ETFE roofing material is approximately 1% of the weight of glass and can reduce building costs from 10 to 60%.
Another interesting application for recycled plastic can be found at the Vancouver Convention Centre or parts of the Toronto Boardwalk. Composite decking is becoming increasingly popular for both commercial and residential applications. These types of products generally use recycled or virgin polyethylene or a combination of the two and then mix it with natural fibres, such as wood, to create a composite lumber product that offers greater benefits over traditional wood.
The product won’t rot, crack, warp or splinter. It is denser than wood and virtually maintenance free. It is also insect-resistant and more durable. The plastic composite market is growing by leaps and bounds at 14 % per year. Estimates suggest that it reached US$1.4 billion in 2007.
These projects, and others like them, demonstrate that the plastics industry continues to evolve, with new products and product formulations being developed to meet the ever-changing needs of green designers and builders.
Marion Axmith is Director General, CPIA, and may be reached at firstname.lastname@example.org or at 905-678-7405, ext. 227.
More information about the sustainability of plastics in building and construction can be found at http://www.plastics.ca/greenbuildingPrint this article | Send by e-mail