Carbon Impact of Carpet
Carpet stands out as a high-impact material in interior projects, renovation projects and tenant improvements. In fact, new carpet can be one of the single largest contributors of embodied carbon among commonly used interior finishes1, though its embodied carbon impact varies substantially (as much as 8x) depending on the type and brand of carpet selected.
Whether in tiles (modular carpet) or rolls/sheets (broadloom carpet), the carbon impact of carpet is almost always driven by the extraction and processing of oil and gas into the different petrochemicals and plastics in the various component layers. The production of nylon fiber from crude oil is the largest source of embodied carbon emissions for most carpet. Natural fibers (such as wool) can also have significant embodied carbon impacts from industrial processing.
Final manufacturing of carpet uses substantial quantities of energy, especially thermal energy (typically from natural gas or other fossil fuel sources) to evaporate water and melt plastics into backing. For broadloom carpet manufactured using yarn-dyed (also referred to as “piece-dyed,” “skein dyed,” “continuous dyed,” “post-dyed,” “digital dye placement”) fibers, these final stages of manufacturing can be a significant percentage of total embodied carbon emissions. For carpet tile products made with solution-dyed (pre-dyed) yarn, emissions from the final manufacturing stage are relatively small compared to the impacts of raw materials extraction, petrochemical synthesis, and plastic component manufacturing upstream in the supply chain.
Specifying carbon neutral carpet tile products with solution-dyed yard is the most impactful way to reduce the embodied carbon emissions of carpet.
Carbon Smart Attributes
Specify carpet tile rather than broadloom or sheet carpet to reduce installation and maintenance waste
Broadloom carpet typically generates 10-20% installation waste and cannot be easily repaired if damaged in one section, whereas carpet tile results in 1-5% installation waste and the useful life of the floor can be extended with selective tile-by-tile replacement for damaged sections. Specify carpet tile to minimize waste and waste-associated emissions such as landfill emissions and emissions associated with the production of new or replacement material.
Specify carpet with high recycled plastic content, especially in nylon face fiber
Making nylon carpet yarn from crude oil is typically responsible for over 50% of the carbon footprint of nylon carpet. Use available high-recycled content nylon yarns to decrease this footprint by over 80%. The most common form of recycled content in carpet is pre-consumer recycled mineral filler in carpet tile backing, which does not significantly decrease the carbon footprint of carpet. Look for recycled and bio-based content that displaces virgin petrochemicals and plastics.
Specify carpet with solution-dyed nylon yarn
Dyeing white yarn during the manufacturing process requires additional energy, water and chemicals. Specify carpet with solution-dyed nylon yarn, in which the plastic is colored with pigments before extrusion into yarn (“solution-dyeing”). This also makes the carpet resistant to fading and discoloration.
Balance embodied carbon with durability
While carpet products made from commodity plastic fibers (PET/polyester, polypropylene, etc.) have a lower initial carbon footprint than recycled nylon (an engineering plastic), these products are often not durable enough for most commercial environments and can wear down quickly, requiring replacement. Understand the lifespan of the product and specify the product with the lowest embodied carbon over the life of the building.
Avoid plush, high-pile carpet with virgin nylon fiber
The amount of carpet fiber in a product drives its carbon footprint, so products with more yarn will always have a higher footprint unless they are made with recycled or bio-based plastic. Avoid plush, high-pile carpet with virgin nylon fiber to reduce the embodied carbon impact of the carpet.
Design & Construction Guidance
Specify products that are carbon neutral
Until carpet materials innovation allows for products with a negative carbon footprint (see Innovation section), ask for products to be carbon neutral for their entire life cycle (cradle-to-grave) with the use of high quality carbon offsets.
Glue-down only when necessary for safety or performance
Carpet that is not permanently affixed to the floor will also be easier to maintain, selectively replace, rearrange, reuse, and recycle, extending the useful life of the carpet. Use adhesive carpet tile connectors to create a floating, modular floor that can dramatically decrease the embodied carbon of installation when compared to standard installation with full-spread adhesive that affixes the carpet to the subfloor.
Consider eliminating floor finishes where appropriate
Using structural materials (i.e. exposed concrete slabs or CLT floor panels) as finish materials eliminates the embodied carbon emissions of additional architectural finishes. Look for options to reuse or refurbish flooring and consider carbon smart alternatives. If possible, eliminate floor finishes and leave structural members exposed. It’s important to balance overall embodied carbon emissions with tenant needs, as exposed flooring can create acoustic or underfoot ergonomic issues for building occupants, which could lead to increased tenant improvements and/or early renovation.
Acknowledged Challenges, Questions & Unknowns
Upcoming innovation
While the use of recycled plastics can dramatically reduce the carbon footprint of carpet (especially where efficient plastic recycling technology is available), manufacturing and materials innovation will soon make it possible to create carpet with a net positive impact on the climate. Mineral fillers and plastics made by capturing and converting atmospheric CO2 or industrial CO2 emissions are now commercially available and being incorporated into carpet tile backing. Not all biobased products are low carbon, but when done right, using biomaterials from abundant bio-based waste (plants, wood, algae, etc.) can result in products that remove more carbon from the atmosphere than they emit, a net positive carbon footprint. Durable carbon positive yarns have not yet been commercialized for carpet, but LCA modeling shows that using recycled plastic fiber for low faceweight (weight of the carpet pile per square yard) carpet tile on bio-based backing will be able to produce carbon positive carpet tile in the near future.
RESOURCES
1 | Carbon Leadership Forum on LCA for Average Tenant Improvement
Additional Resources
Hensler, Connie, 2014, Journal of Industrial Ecology, Shrinking Footprint: A Result of Design Influenced by Life Cycle Assessment https://onlinelibrary.wiley.com/doi/10.1111/jiec.12173
Nylon broadloom EPD (Mohawk): https://spot.ul.com/main-app/products/detail/5c11147255b0e84548fc10b5?page_type=Products%20Catalog
Piece-dyed Commercial Broadloom EPD (Bentley): https://www.scscertified.com/products/cert_pdfs/SCS-EPD-04246_Bentley-HighPerfPC-PieceDye_111816_web.pdf
Wool carpet tile EPD (Forbo, expired): https://forbo.blob.core.windows.net/forbodocuments/332/FORBO_117.1_EPD_Westbond_Wool.pdf
Other Carpet EPDs (Embodied Carbon in Construction Calculator (EC3)): www.buildingtransparency.org
https://www.buildinggreen.com/product-guide/resilient-flooring
SEE ALSO
