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In most construction projects, building materials are evaluated and selected based on performance, aesthetics, and cost. With "green" or environmentally preferable products, these traditional selection parameters are expanded to include both health and environmental impacts. Environmentally-preferable products (EPPs), as defined by the federal government in Executive Order 13101, are those that have "a lesser or reduced effect on human health and the environment when compared to competing products that serve the same purpose."
The growing popularity of green buildings and green building programs (particularly the U.S. Green Building Council's LEED® rating system) is expanding both the demand for, and availability of, green products. For designers and specifiers, these changes are providing greater opportunities to improve the environmental performance of many building products. At the same time, assessing the health and environmental impacts of materials is a complex process, which can be further confused by varying (and sometimes contradicting) claims from product manufacturers. Fortunately, an expanding set of green product resources and tools exists to assist project teams in making appropriate, informed evaluations and selections.
The majority of available green products have one or more of the following health and/or environmental attributes:
- They promote good indoor air quality (typically through reduced emissions of VOCs and/or formaldehyde);
- They are durable, and have low maintenance requirements;
- They incorporate recycled content (post-consumer and/or post-industrial);
- They have been salvaged from existing or demolished buildings for reuse;
- They are made using natural and/or renewable resources;
- They have low "embodied energy" (the energy required to produce and transport materials);
- They do not contain CFCs, HCFCs or other ozone depleting substances;
- They do not contain highly toxic compounds, and their production does not result in highly toxic by-products;
- They are obtained from local resources and manufacturers;
- For wood or bio-based products, they employ "Sustainable Harvesting" practices;
- They can be easily reused (either whole or through disassembly);
- They can be readily recycled (preferably in a closed-loop recycling system);
- They are biodegradable.
The characteristics of green products can vary significantly depending on the material type. The green attributes of a concrete mix, for instance, might include the use of fly-ash (a post-industrial recycled content material), while the green attributes of an interior paint might focus on low VOC content. Because of this high degree of variability, the evaluation of green products requires a working knowledge of:
Relevant health and environmental impact issues associated with different material types;
Government, industry, and third-party standards for green products, where they exist; and
Available green products in the marketplace, including their specific green attributes, performance characteristics, appearance, and costs.
The "Tools and Resources" section below reviews a number of sources for this information.
As suggested from the above description, a wide range of terminology has developed in the field of green products. The following definitions represent a sampling of terms that are integral to the discussion on environmentally preferable materials.
Closed-Loop Recycling—A recycling process in which a manufactured product is recycled back into the same (or similar) product without significant deterioration of the quality of the product. Materials that can be recycled in this fashion include steel and other metals, as well as glass and some types of plastics (e.g., nylon carpet fiber).
Embodied Energy—The total energy required to produce a finished product, including the energy used to grow, extract, manufacture, and transport it to the point of use.
Indoor Environmental Quality (IEQ)—According to the U.S. EPA and the National Institute for Occupational Safety and Health, the definition of good indoor air quality includes: (1) the introduction and distribution of adequate ventilation air; (2) the control of airborne contaminants; and (3) the maintenance of acceptable temperature and relative humidity.
According to ASHRAE Standard 62.1, acceptable indoor air quality is defined as "air in which there are no known contaminants at harmful concentrations as determined by cognizant authorities and with which a substantial majority (80 percent or more) of the people exposed do not express dissatisfaction."
Material Safety Data Sheet (MSDS)—OSHA-required documents supplied by manufacturers of products containing hazardous chemicals. MSDSs contain information regarding potentially significant levels of airborne contaminants, storage and handling precautions, health effects, odor description, volatility, expected products of combustion, reactivity, and procedures for spill cleanup.
Post-Consumer Recycled Material—A reclaimed waste product that has already served a purpose to a consumer, and has been diverted or separated from waste management collection systems for recycling. Example: used newspaper that is made into cellulose building insulation.
Pre-Consumer Recycled Material—A material that is removed from production processes (including scrap, breakage, or by-products) and reused in an alternative process before consumer distribution. Example: mineral (slag) wool, a by-product of the steel blast furnace process, used for mineral fiber acoustical ceiling panels.
Certified or Sustainably Harvested Wood—Wood products obtained from "well-managed forests," usually certified through third-party organizations. While there is currently no industry consensus on what constitutes sustainable forest management, several organizations have established criteria, most notably the Forest Stewardship Council (FSC). In general, well-managed forests conserve biological diversity, water resources, soils, and the overall ecosystem of the forest.
Third-Party Certification—The certification of a specific product or process that is performed by an organization independent from those who produce the product or process. Certification is often used to substantiate the environmental attributes of specific products (such as the percentage of recycled content) or processes (such as a sustainable harvesting operation for forests).
Volatile Organic Compound (VOC)—Chemicals that contain carbon molecules and have high enough vapor pressure to vaporize from material surfaces into indoor air at normal room temperatures (a process known as off-gassing). While most VOCs are relatively inert at typical indoor concentrations, they can react with oxidants such as ozone and possibly nitrogen oxide and nitrogen dioxide to form reactive species and possibly strong irritants, including various acids and aldehydes. VOCs may cause eye and upper respiratory irritation, nasal congestion, headache, and dizziness. Examples of building materials that contain VOCs include, but are not limited to, solvents, paints, adhesives, carpeting, and particleboard.
B. Tools and Resources
A wealth of information has been developed (and continues to be developed) pertaining to green building materials. To effectively evaluate and specify green products, designers and specifiers must familiarize themselves with a number of the available resources. The topics below represent a wide range of green product information, from broad concepts (guiding principles that define sustainability goals for materials), down to project specifics (product listings and specification guides).
Guiding Principles for Sustainable Materials
Several organizations and private companies have defined principles based on the concept of sustainability to be used as long-term guidelines in the development of new or reformulated products. These guidelines define goals such as closed-loop recycling and the elimination of products with bio-accumulative toxins. Although there are few products that currently meet these sustainability goals, the criteria are useful for assessing current materials in comparison to an ideal, rather than in comparison to other available products. Examples of guiding principles can be found at:
The Natural Step and GreenBlue.
Life-Cycle Assessment (LCA) Tools
Related to, but not to be confused with life-cycle economics, LCA is a methodology for evaluating the environmental impacts of a material through its entire "life cycle"—from its initial production through to its eventual reuse, recycling, or disposal. LCA attempts to identify and quantify all relevant environmental impacts for materials so that comprehensive comparisons can be made. Although LCA reports are often complex and technical in nature, tools such as Building for Environmental and Economic Sustainability (BEES) and Athena Impact Estimator for Buildings, attempt to summarize LCA information in a manageable format specifically targeted to design professionals.
The American Institute of Architects Environmental Resource Guide, while no longer under development, can also be a useful document for reviewing the environmental impacts of various construction products.
Users should understand some of the current limitations of LCA, which include the following:
There is no single standard for LCA methodology; a few different organizations have developed their own protocols (see "Additional Resources—Life-Cycle Assessment Tools" below for examples). The LCA methodologies are often complex, and may include weighting factors that can be adjusted by the user.
Complete and accurate life cycle data on materials is very difficult to obtain, and is often unavailable or incomplete for many material types. LCA data from different studies may use different methodologies, or may be based on significantly different data sets.
Some LCA models are based on broad material types (e.g., steel framing, brick, nylon carpets), which rely upon industry averages, while others attempt to compare specific products available from different manufacturers.
Most LCA models have been developed to compare the environmental impacts of different materials. The models do not typically include sustainability goals, or other suggested criteria to improve the environmental performance of a given material type.
LCA should not be confused with Life-Cycle Cost Analysis (LCCA), although LCCA can be an integral part of a full life-cycle assessment. Life-Cycle Cost Analysis, which can take into consideration environmental costs, is explained in detail in a separate Resource Page of the WBDG.
Green Building Rating Systems
Green Building Rating Systems establish overall environmental performance criteria for entire buildings. In the U.S., the one national green building-rating system is Leadership in Energy and Environmental Design (LEED®) developed by the U.S. Green Building Council (USGBC). The current LEED program is available online, with detailed support documents and training available from the USGBC. Among its 5 major topics (Sustainable Sites, Water Efficiency, Energy and Atmosphere, Materials and Resources, Indoor Environmental Quality), the LEED® program includes criteria for the following green building material types: reused materials, recycled-content materials, local/regional materials, rapidly renewable materials, certified wood, and low-emitting materials.
Green Product Standards
To consistently assure the environmental performance of certain material types, several public agencies and private organizations have developed green product standards. These standards define the specific green criteria for various material types. In some cases, a trademarked "green" label can be used for complying products.
Green product standards can range from government regulations and guidelines (e.g., the EPA Comprehensive Procurement Guidelines for recycled content in products) to industry guidelines (The Carpet and Rug Institute's Green Label Plus program for Carpets), to third party certification standards (e.g., Green Seal standards for paints, FSC standards for wood products). Because of the detailed criteria spelled out in green product standards, many of them can also assist in the development of project specifications (see Specification Guidelines section below).
While green product standards outline important criteria for different material types, they typically do not review the performance and variations of individual products from specific manufacturers. Some green product standards, however, do include lists of sample products or manufacturers that meet their criteria.
Green Product Directories
This information is used to profile individual products from specific manufacturers. Green Material Directories provide listings of available products (typically organized by CSI Sections) with the environmental attributes claimed by the manufacturers.
Given the many tools and resources available for evaluating and identifying environmentally preferable materials, it is useful to develop an organized process for making product selections. While there is no definitive process for selecting green materials, several organizations have created methodologies to make the process manageable and logical. One example is Environmental Building News' 12 step method to help users focus on important environmental considerations, and to prioritize certain environmental factors. The process was initially proposed in the January 1997 issue of the publication.
Selecting environmentally preferable materials requires research, critical evaluation, and common sense. Issues such as code compliance, warranties, and the performance "track record" of green products, particularly newly introduced materials, must be carefully considered.
Specifiers are advised to collect the following information when preparing to evaluate environmentally preferable materials:
- Critical performance criteria required of the material to be selected.
- Appropriate environmental product information, as noted in the "Tools and Resources" section above.
- Material Safety Data Sheets (MSDS) for all products for which they are available. MSDSs can be useful in evaluating the potential hazards associated with the installation, use, and disposal of many products.
- Maintenance expectations for the material or system.
- Corporate environmental policy statements for the manufacturers under consideration.
Specifiers should expect that some green products may be subject to limited availability or long lead times, particularly when ordered in large quantities. Finally, users should be wary of environmental claims (both positive and negative) that have not been substantiated by independent sources.
Relevant Codes and Standards
Green Products Databases
- EcoStructure Magazine—A publication on environmentally preferable buildings, products, and systems
- EPA Comprehensive Procurement Guidelines—A key component of the government's "buy-recycled" program, the EPA's CPG provides information, specification criteria, and manufacturer's lists for a wide range of recycled content products
- EPA Environmentally Preferable Purchasing Program—helps federal agencies procure greener products and services and harness federal purchasing power to green markets.
- GSA Federal Acquisition Service
- Sustainable Sources—This site contains the entire contents of the Sourcebook produced by the city of Austin, Texas as part of their Green Builder Program. Provides concise, practical reviews of materials and pertinent life cycle issues (attributes and concerns). Also provides lists of product manufacturers and trade organizations. Numerous links to other related green building websites.
- Sustainable Facilities Tool – Green Procurement Compilation
Life-Cycle Assessment Tools
- Athena Impact Estimator for Buildings
- BEES (Building for Environmental and Economic Sustainability)
- ISO 14040 Environmental Management - Life-Cycle Assessment - Principles and Framework
- Society of Environmental Toxicology and Chemistry (SETAC)—A Technical Framework for Life-Cycle Assessment
- U.S. Life-Cycle Inventory Database
Product Certification Services
- Forest Stewardship Council United States (FSC)
- SCS Global Services
- Rainforest Alliance Certification
Building Rating Systems
- Building Research Establishment Environmental Assessment Method (BREEAM)
- Leadership in Energy and Environmental Design (LEED®)
- Green Building Pages—A web-based resource guide for green building materials and green building.
- GSA Sustainable Facilities Tool (SFTool)—SFTool's immersive virtual environment addresses all your sustainability planning, designing and procurement needs.
- Construction & Building Materials Directory by Sweets™—Provides manufacturer's product information on numerous construction products.