Selecting Carpet and Resilient Flooring
Interior materials and finishes are a component of buildings where life-cycle impacts may be significantly greater than the impact associated with the initial manufacture and installation of the material. Floor coverings in particular, which are subject to mechanical wear, may be replaced several times during the life of a building.
By Jim Taggart with Shelley Penner
CSA Standard S478-95 Guideline on Durability in Buildings predicts a service life of about 10 years for carpet and resilient flooring in commercial applications. Since the standard was issued, however, manufacturers in all sectors have been striving to improve the longevity of their products. Nonetheless, replacement for aesthetic reasons prior to functional obsolescence is still common.
Selecting green building materials is rarely straight forward, and usually involves trade-offs between a number of criteria such as:
- • Health and IEQ implications of materials and installation methods
- • Durability and in-service maintenance requirements
- • Environmental impact of extraction and manufacturing processes
- • Recycled content and recyclability
In addition, with the manufacture of many flooring materials still highly centralized [e.g. synthetic carpet in the southeast US and California, linoleum in Europe], the impact of materials transportation over the life cycle of a building can be significant, and regionally manufactured materials are to be preferred.
Similarly, despite the considerable progress that has been made in the recycling of synthetic materials, products made from natural materials are generally to be preferred because of their [typically] lower environmental impact. Of course, as with all finish materials, aesthetics and initial cost continue to be significant factors in product selection.
CARPET : Carpet has traditionally been chosen for its aesthetic, acoustic and thermal properties.
The most common types of carpets are:
- • Tufted broadloom, manufactured using synthetic fibre, wool or a mixture of both
- • Fusion bonded modular tile and roll products, manufactured using synthetic fibre
- • Woven carpets, manufactured using wool fibre
Green Label and Green Label Plus Programs
The Carpet and Rug Institute [CRI] launched its Green Label program in 1992 to test carpet, cushions and adhesives to help specifiers identify products with very low emissions of VOCs. CRI has recently launched its next series of improvements called Green Label Plus setting an even higher standard for carpet and adhesives. www.carpet-rug.org
The manufacture of carpet and all of its components, including fibres, dyes, backing, binders and treatments, involves the processing of petrochemicals, and produces significant environmental impacts. These include air and water pollution, as well as solid and hazardous waste.
Tufted carpet is by far the most common. Multiple rows of pile yarn tufts are simultaneously stitched through a primary backing to form a fabric. Most primary backings are woven or non-woven polypropylene. Manufacture is completed with the addition of a secondary backing that may be a solid lamination or liquid coating.
Synthetic latex is the most frequently used back coating and laminating compound. Most carpet latex consists of styrene-butadiene rubber blended with inert powdered fillers, such as calcium carbonate.
Fusion bonding uses heat to implant the fabric onto an adhesive-coated backing before die-cutting the carpet into modular tile and roll products. Common secondary backings for fusion-bonded carpet are polyvinyl chloride or polypropylene [olefin]. Competition amongst carpet manufacturers [such as Shaw, Interface, Beaulieu and Tandus] has improved manufacturing processes, reducing or eliminating the use of raw materials containing high levels of VOCs. Similarly, products have been re-engineered to require fewer resources and less energy during manufacture.
High quality carpet is produced with sheared wool. Wool is scoured using detergents or solvents to remove most of the natural oil [lanolin], and then carbonized with sulfuric acid to remove tough dirt. The wool receives final washing and drying, and is carded and combed for spinning. Cleaning and treating the wool for spinning generates wastewater. Wool is naturally flame-resistant.
In January 2011, leading manufacturer Nature’s Carpet launched it’s new ‘dark green’ Everest line, made from 100% undyed British wool, with an all-natural jute and rubber backing and adhesive system.
Most carpet dyes, whether for synthetic or natural fibre carpets, are organic compounds derived from petrochemicals. Some dyes may contain heavy metals. Carpet is dyed using either pre- or post-dying methods. Pre-dying methods – such as solution and stock dying – tend to be more costly than post-dying but produce significantly less waste water.
Most manufacturers of synthetic carpets now offer product lines with significant post-industrial and post-consumer recycled content in both the face fabric and backing. At this point, the industry leader is probably Interface, whose Convert™ line of carpet tiles contains a minimum of 65% recycled content, of which half is postconsumer nylon 6,6 fibre reclaimed through the company’s ReEntry 2.0® program.
Both Shaw and Desso have carpet products that are Cradle to Cradle® certified. Shaw’s Anso® Nylon 6 fibre has been similarly certified as the only 100% closed loop fibre currently on the market.
Natural fibre carpets are not presently recycled. Blending synthetic and natural fibres is sometimes done to reduce costs, however this prevents future recyclability.
Until recently, undercushion was typically manufactured from petroleum by-products. Now, there is a sponge rubber under cushion that combines synthetic latex with 65% post-consumer recycled tire rubber. There is also an open cellular rubber reinforced with solid rubber particles bonded with latex. Some rubber undercushion contains a minimum 80% recycled tire rubber.
Felt underlay is composed of either synthetic and or natural fibres. Synthetic fibres are usually waste by-products from other manufacturing processes. Another felt underlay blends jute and horsehair. A porous, open weave permits better air circulation when vacuuming and aids in keeping the carpet clean. Felt underlay is more chemically stable and produces less air pollution than the foamed types.
Adhesives are either the more hazardous, solvent-based, or safer water-based latex. The emissions from carpet adhesives can continue for several days to weeks or months, depending on the adhesive and site conditions. Low VOC, pressure-sensitive adhesives used for carpet tile installations adhere to most surfaces with very slight pressure. Using broadlooms that can be stretch-fixed, or carpet tiles that can be secured with TacTiles, will avoid the potential IEQ problems of adhesives.
RESILIENT FLOORING: The environmental performance of resilient flooring is evaluated under the ‘FloorScore’ rating system, developed jointly by Scientific Certification Systems and the Resilient Floor Covering Institute [RFCI]. FloorScore is a third-party system that verifies product compliance with the CHPS 01350 indoor air quality standard through the independent review of VOC emission data and periodic inspections of manufacturing facilities. www.scscertified.com
Linoleum, unlike vinyl flooring, does not contain chlorine or plasticizers. All of the ingredients of linoleum with the exception of acrylic topcoat and a small amount of zinc-drying agent are biodegradable.
Linoleum is processed from natural, renewable ingredients primarily linseed oil, pine rosin, sawdust, cork dust, limestone and jute, which have been heat cured. Ground-up stone and wood are added for colour. Powdered limestone is used as filler, and titanium is the primary pigment.
VOCs are generated at several stages of the manufacturing process, but are captured and burned with high efficiency. Manufacturing recycles a significant amount of waste back into the product. The fibre backing on most linoleum is made from jute, or composed of fibreglass and polyester fibres. Linoleum can have a distinctive odour, but emits no dangerous VOCs.
Leading manufacturers such as Forbo and Armstrong, have general purpose and specialty lines, as well as products for use on walls, countertops and other surfaces.
Cork is a renewable resource that undergoes very little processing. The bark is peeled off cork oak trees on plantations [usually in Portugal and Spain] every 8 to ten years. Manufacture involves few toxins, and nearly all the waste is recycled back into the product. Tiles and planks are manufactured with a urethane binder.
Cork flooring is a durable material in dry well-maintained environments. It has good thermal and acoustic properties, is shock-resistant, non-conductive and dissipates static electricity. Cork can also be used as an underlayment for ceramic or wood flooring. Some cork flooring is fabricated using waste material from the bottle cork industry.
Natural rubber is a renewable raw material and does not contain any harmful chemicals. It is extracted from the sap of the tropical rubber plant, without harming the plant. Synthetic rubber is obtained through the polymerization of petroleum products, which is able to produce material with varying characteristics, but which also produces air and water pollution. Products on the market include natural rubber, synthetic rubber, shredded, post-consumer rubber, or combinations of these.
Natural rubber is combustible and produces continual minor off-gassing that, while objectionable, is not hazardous to most people. It is hard-wearing, permanently resilient and sound deadening, making it ideal for use in sports and recreation facilities. It is also widely used in commercial and institutional applications.
Some rubber flooring is anti-static and chemical resistant making it suitable for healthcare and other specialty uses. No waxes are required to maintain rubber floors. Some manufacturers now produce natural rubber flooring in a wide range of colours using environmentally compatible colour pigments; while Dinoflex produces rubber flooring for commercial and recreational applications using post-consumer recycled tire rubber.
Designers now have a range of green choices when it comes to floor coverings. While aesthetic considerations may influence the initial choice of material, other strategies can be used to further minimize the environmental impact of any product:
- • Using modular tiles where possible to minimize waste
- • Where roll or sheet material is used, sizing rooms to minimize waste
- • Using loose lay or mechanically fastened materials where possible
- • Using low-toxicity, water-based adhesives and sealers.
Shelley Penner, BID LEED® AP is Director of Practice with Penner & Associates Interior design in Vancouver. She is co-author [with Paul Kernan] of the Metro Vancouver Best Practices Guide: ‘Material Choices for Sustainable Design’ upon which this article is based.