Sustainable Building Materials Notes

Core Concepts of Sustainable Building Materials

• Sustainable building materials require access to information about the environmental and health impacts of the materials used in construction.
• When selecting a material, designers ask:
  • Does its manufacture depend on the extraction of nonrenewable resources, or is it made from recycling or rapidly renewing materials?
  • Is additional energy required to ship this material from a distant location, or can it be obtained from a local source?
  • Does a material contain toxic ingredients or generate unhealthy emissions, or is it free of such health concerns?
• Information about building materials and products can come from different sources and take various forms: it may be self-reported by the product manufacturer, or it may come from an independent trusted third party.
• Information formats can include:
  • neutrally expressed transparent disclosure of material attributes, or
  • a rating that gauges the merits or demerits of such attributes.
• Information may address a limited scope of concerns, or describe the full range of impacts of a material throughout its life cycle from raw material extraction to end of life disposal or repurposing.
• Product Data Sheet (PDS)
  • Industry standard product data sheet is a simple example of manufacturer’s self-reported information.
  • The PDS (PDF) provides a description of a product, its material makeup, and physical properties, and guidance for use.
  • It may also include information relevant to sustainability concerns.
  • The scope of information in a PDS is not independently verified and is left entirely to the manufacturer.
• Environmental labels (eco labels)
  • Third-party environmental ratings.
  • Example: Green Seal standard GS-11 for paints and coatings.
  • Green Seal is an independent organization that develops sustainability standards and certifications.
  • For a paint product to be certified to its standard, the product must meet minimum performance criteria, be free of toxic ingredients, and not exceed content limits on volatile organic compounds (VOCs).
• By relying on certification, designers can confidently make environmentally responsible choices without performing in-depth investigations of individual products.
• Product disclosures are another form of reporting that provide transparent information about material ingredients and manufacturer practices.
  • Example: International Living Future Institute Declare label describes a product’s origins, its material ingredients, and end-of-life disposal or recycling options.
  • Providing this information in a standard format helps designers more easily compare relative attributes of alternative materials or products.
  • Like a product datasheet, manufacturers may support independent auditing to improve accuracy, unlike eco labels.
• Environmental Product Declarations (EPD)
  • EPDs describe the full life cycle environmental impacts of building materials and products.
  • Example: Western Red Cedar Lumber Association’s typical red cedar decking product declaration.
  • This 10-page document describes the product’s material characteristics and details environmental impacts across its life cycle.
  • Example data reported per 1 m² of decking:
  • Nonrenewable energy consumed: $73 ext{ mg} ext{ or } 70{,}000 ext{ BTU}$
  • Global warming potential: $6.8 ext{ kg CO}<em>2 ext{e} ext{ (approximately } 15 ext{ lb CO}</em>2 ext{e)}$
  • Freshwater consumed: $86 ext{ L} ext{ or } 23 ext{ gal}$
• Additional metrics in the report include material consumption, smog production, ozone depletion, acidification, eutrophication, waste materials generated, and more.
• The report includes information about the standard to which the information is prepared and independent verification of results.
• While an EPD does not provide an environmental rating, it can be used to compare environmental consequences of different materials (e.g., cedar vs. recycled plastic decking).
• Environmental Building Declarations (EBDs) reflect the idea that as life cycle data become available for most materials and products, the same life cycle analysis can be applied to whole buildings to meaningfully compare environmental impacts of alternative building designs.
• Much of the environmental reporting provided by product manufacturers follows an international standards series designated ISO 14040 (and related family standards), which established guidelines for the deployment and use of environmental labels and declarations.
• Relying on information produced to common accepted standards gives designers and builders greater confidence in the consistency and relevance of information about the material life cycle and embodied impacts.
• Preparation of environmental product and building declarations depends on accounting for environmental impacts of materials and products throughout their life cycles. This begins with raw material extraction, continues with manufacture, construction, and use, and finishes at end of life where the material is disposed of or put into new use (e.g., cradle-to-grave analysis).
  • Life cycle analysis (LCA) is one of the most comprehensible methods to quantify the environmental impacts associated with materials and building.
  • Though each life cycle stage is tallied, questions include: How much fossil fuel, electricity, water, and other materials are consumed? How much solid waste, greenhouse gases, and other air and water pollutants are generated?
• The total of these impacts describes the environmental footprint of the material.
• Embodied energy (a concept derived from LCA)
  • Embodied energy is the sum total of energy consumed during a material’s life cycle.
  • Energy consumption frequently correlates with the consumption of nonrenewable resources and the generation of greenhouse gases.
  • It is often assumed that materials with lower embodied energies are better for the environment, but comparisons must be functionally equivalent.
  • Example: A material with embodied energy of $10{,}000 ext{ BTU per pound}$ is not necessarily environmentally preferable to one with $15{,}000 ext{ BTU per pound}$ if two pounds of the first material are required to accomplish the same purpose as one pound of the second. Different energy types (fossil, nuclear, or renewable) should be considered when comparing.
  • In many cases, the difference in embodied energy between cradle-to-grave and cradle-to-grate analyses is small because most energy use occurs before the material is installed or after disposal.
  • The concept of embodied energy can be extended to other measured inputs or outputs from a life cycle analysis (e.g., embodied water).
• Embodied water
  • Embodied water refers to the freshwater consumed as a consequence of building with a particular material.
• Limitations and caveats of LCA
  • While LCA represents the most comprehensive material assessment method currently available, it does not address all impacts arising from the use of a material or product.
  • For example, LCA of wood products may not capture biodiversity loss, decreased water quality, or soil erosion caused by poor forestry practices.
  • These concerns are better addressed by forestry certification programs or other global warming potential metrics within the material environmental product declaration.
  • The ultimate consequences for ecosystems, wildlife populations, and human health are not fully described by LCA/EPD alone.
• Connecting to practice and ethics
  • Use of standardized data supports better, more consistent decisions.
  • Consider forestry practices and certifications when evaluating wood products.
  • Recognize that life cycle data are one tool among many; real-world decisions also involve ecological, social, and health considerations.