Building Materials:
What Makes a Product Green?
from BuildingGreen.com

Quite a bit of attention has been focused on the issue of sustainable or green building materials. What makes a given product "green"? How do you evaluate the relative greenness of different products? How do you find green products? More important, perhaps, manufacturers are asking, "How can we make our products greener?"

This article is an attempt to lay out for public examination and discussion our standards for what makes a building product green. We expect these standards and thresholds to evolve over time.

The Challenges in Defining What is Green
The Holy Grail of the green building movement would be a database in which the life-cycle environmental impacts of different materials were fully quantified and the impacts weighted so that a designer could easily see which material was better from an environmental standpoint. Though efforts are afoot along these lines, we are not even close to realizing that goal. Very often, we are comparing apples to oranges. We are trying to weigh, for example, the resource-extraction impacts of one product with the manufacturing impacts of another, and the indoor-air-quality impacts of a third.

In building a house or office building, a great many materials and products will be used. Even in the greenest of projects it is likely that many products will be used that are not themselves green - but they are used in a manner that helps reduce the overall environmental impacts of the building. A particular window may not be green, but the way it is used maximizes collection of low winter sunlight and blocks the summer sun. So even a relatively conventional window can help make a house green. Creating a green building means matching the products and materials to the specific design and site to minimize the overall environmental impact.

This article examines products in isolation - not how to use a product to make a building green, but rather what makes a certain product green. Green products could be used in dumb ways that result in buildings that are far from environmentally responsible. In a well-thought-out building design, however, substituting green products for conventional products can make the difference between a good building and a great one.

Defining Standards When Feasible
Our tactic is to identify quantifiable, easily verifiable, standards where those could be defined, then base other decisions about what should be included on the collective wisdom of our editorial staff. In a few product categories, such as energy-consuming appliances and VOC-emitting paints, specific thresholds can be established relatively easily. But for many criteria, the lines are much fuzzier and judgment calls are required.

It is important also to note that multiple criteria may apply - in other words, a product may be considered green for more than one reason. Take recycled plastic lumber, for example; it is made from recycled waste, and it's an alternative to preservative-treated wood. Straw particleboard products are made from agricultural waste materials, and they are free from formaldehyde offgassing. A product with multiple benefits could qualify for inclusion on the basis of its overall environmental performance, even if it doesn't meet a threshold in any one category alone. Conversely, a product with green attributes might not qualify if it also carries significant environmental burdens.

This article reviews the criteria - not listed in any order of priority - used to designate building products as green, and therefore suitable for inclusion in our GreenSpec directory.

1. Products Made with Salvaged, Recycled, or Agricultural Waste Content

The materials used to produce a building product - and where those materials came from - is a key determinant of green.

1a. Salvaged products -- Whenever we can reuse a product instead of producing a new one from raw materials - even if those raw materials are recycled - we save on resource use and energy. Many salvaged materials used in buildings (bricks, millwork, framing lumber, plumbing fixtures, and period hardware) are sold on a local or regional basis by salvage yards. Fewer salvaged materials are marketed widely, and it is generally only these that are profiled in a national directory such as GreenSpec. Local and regional green product directories can really shine when it comes to finding salvaged materials.

1b. Products with post-consumer recycled content -- Recycled content is an important feature of many green products. From an environmental standpoint, post-consumer is preferable to post-industrial recycled content, because post-consumer recycled materials are more likely to be diverted from landfills. In some cases, products with recycled content are included with caveats regarding where they should be used. Rubber flooring made from recycled automobile tires is a good example - the caveat is that these products should not be used in most fully enclosed indoor spaces due to offgassing concerns.

In certain situations, from a life-cycle perspective, recycling has downsides. For example, energy consumption or pollution may be a concern with some collection programs or recycling processes. Also, closed-loop recycling is generally preferable to downcycling, in which a lower-grade material is produced. As more complete life-cycle information on recycled materials - and the process of recycling - becomes available, we intend to scrutinize recycled products more carefully.

1c. Products with post-industrial recycled content -- Post-industrial recycling refers to the use of industrial by-products, as distinguished from material that has been in consumer use. Iron-ore slag used to make mineral wool insulation, fly ash used to make concrete, and PVC scrap from pipe manufacture used to make shingles are examples of post-industrial recycled materials. Usually excluded from this category is the use of scrap within the manufacturing plant where it was generated - material that would typically have gone back into the manufacturing process anyway. While post-consumer recycled content is a lot better than post-industrial recycled content, the latter can still qualify a product for inclusion in GreenSpec in many product categories - especially those where there are no products available with post-consumer recycled content.

1d. Products made from agricultural waste material -- A number of products are included in GreenSpec because they are derived from agricultural waste products. Most of these are made from straw - the stems left after harvesting cereal grains - though one product is made from rice hulls. Citrus oil, a waste product from orange and lemon juice extraction, is also used in some green products, but such products usually include other agricultural oils as well and are lumped under

2d. Rapidly renewable products.

2. Products That Conserve Natural Resources

Aside from salvaged or recycled content, there are a number of other ways that products can contribute to the conservation of natural resources. These include products that serve a function using less material than the standard solution, products that are especially durable products and therefore won't need replacement as often, FSC-certified wood, and products made from rapidly renewable resources.

2a. Products that reduce material use -- Products meeting this criteria may not be distinctly green on their own, but are included in GreenSpec because of resource efficiency benefits that they make possible. For example, drywall clips allow the elimination of corner studs, engineered stair stringers reduce lumber waste, pier foundation systems minimize concrete use, and concrete pigments can turn concrete slabs into attractive finished floors, eliminating the need for conventional finish flooring.

2b. Products with exceptional durability or low maintenance requirements -- These products are environmentally attractive because they need to be replaced less frequently, or their maintenance has very low impact. This criterion is highly variable by product type. Sometimes, durability is a contributing factor to the green designation, but not enough to distinguish the product as green on its own. Included in this category are such products as fiber-cement siding, fiberglass windows, slate shingles, and vitrified clay waste pipe.

2c. Certified wood products -- Third-party forest certification, based on standards developed by the Forest Stewardship Council (FSC), is the best way to ensure that wood products come from well-managed forests. Wood products must go through a chain-of-custody certification process to carry an FSC stamp. Manufactured wood products can meet the FSC certification requirements with less than 100% certified wood content through percentage-based claims (30% certified content is required if only virgin wood fiber is used; certified-wood content as low as 17.5% is allowable if the rest of the fiber content is from recycled sources). With a few special-case exceptions, any nonsalvaged solid-wood product and most other wood products must be FSC-certified to be included in GreenSpec. A few manufactured wood products, including engineered lumber and particleboard or MDF, can be included if they have other environmental advantages - such as absence of formaldehyde binders. Engineered wood products in GreenSpec do not qualify by virtue of their resource efficiency benefits alone.

2d. Rapidly renewable products -- Rapidly renewable materials are distinguished from wood by the shorter harvest rotation - typically 10 years or less. They are biodegradable, often (but not always) low in VOC emissions, and generally produced from agricultural crops. Because sunlight is generally the primary energy input (via photosynthesis), these products may be less energy-intensive to produce - though transportation and processing energy use must be considered. Examples include linoleum, form-release agents made from plant oils, natural paints, geotextile fabrics from coir and jute, cork, and such textiles as organic cotton, wool, and sisal. In some cases, even though a product qualifies for GreenSpec by virtue of its natural raw materials, it may have negatives that render it inappropriate for certain uses - such as high VOC levels that cause problems for people with chemical sensitivities.

3. Products That Avoid Toxic or Other Emissions

Some building products are considered green because they have low manufacturing impacts, are alternatives to conventional products made from chemicals considered problematic, or because they facilitate a reduction in polluting emissions from building maintenance. In the GreenSpec criteria, a few product components were singled out for avoidance in most cases: substances that deplete stratospheric ozone, CCA wood preservative, and polyvinyl chloride (PVC). In a few cases, these substances may be included in a "green" product, but that product has to have significant environmental benefits (for example, high post-consumer recycled content).

These substitutes for products made with environmentally hazardous components may not, in themselves, be particularly green (i.e., they may be petrochemical-based or relatively high in VOCs), but relative to the products being replaced they can be considered green. Most of the products satisfying this criterion are in categories that are dominated by the more harmful products - such as foam insulation categories in which most products contain HCFCs, or commercial wallcovering, where vinyl (PVC) products account for the vast majority of the market. We have created several subcategories here for green products:

3a. Natural or minimally processed products -- Products that are natural or minimally processed can be green because of low energy use and low risk of chemical releases during manufacture. These can include wood products, agricultural or nonagricultural plant products, and mineral products such as natural stone and slate shingles.

3b. Alternatives to conventional preservative-treated wood -- CCA-treated wood poses significant environmental risk during disposal. Pentachlorophenol (penta) and creosote are considered carcinogens.

3c. Alternatives to ozone-depleting substances -- Included here are categories where the vast majority of products still contain or use HCFCs: rigid foam insulation and compression-cycle HVAC equipment.

3d. Alternatives to products made from PVC -- Most PVC products are over 40% chlorine by weight, and hazardous chlorinated hydrocarbons, such as dioxins, can be produced during incineration or as by-products.

3e. Alternatives to other components considered hazardous -- Fluorescent lamps with low mercury levels are included here, along with a selective absorber surface for solar collectors made without chromium.

3f. Products that reduce or eliminate pesticide treatments -- Periodic pesticide treatment around buildings can be a significant health and environmental hazard. The use of certain products can obviate the need for pesticide treatments, and such products are therefore considered green. Examples include physical termite barriers, borate-treated building products, and bait systems that eliminate the need for broad-based pesticide application.

3g. Products that reduce pollution or waste from operations -- Alternative wastewater disposal systems reduce groundwater pollution by decomposing organic wastes more effectively. Porous paving products and green (vegetated) roofing systems result in less stormwater runoff and thereby reduce surface water pollution and sewage treatment plant loads. Masonry fireplaces burn fuel-wood more completely with fewer emissions than conventional fireplaces and wood stoves. Recycling bins and compost systems enable occupants to reduce their solid waste generation.

4. Products That Reduce Environmental Impacts During Construction, Demolition, or Renovation

Some building products produce their environmental benefits by avoiding pollution or other environmental impacts during construction, renovation, or demolition. While a fairly small category in terms of the number of products satisfying the criterion, it is nonetheless important. The subcategories here refer to the construction stage where the benefit is typically realized:

4a. Products that reduce the impacts of new construction -- Included here are various erosion-control products, foundation products that eliminate the need for excavation, and exterior stains that result inlower VOC emissions into the atmosphere.

4b. Products that reduce the impacts of demolition -- Fluorescent lamp and ballast recyclers and low-mercury fluorescent lamps reduce environmental impacts during demolition (as well as renovation).

4c. Products that reduce the impacts of renovation -- Access flooring components and leased carpeting minimize environmental impacts during reconfiguration of work spaces.

5. Products That Save Energy or Water

The ongoing environmental impacts that result from energy and water used in operating a building often far outweigh the impacts associated with building it. Many products are included in GreenSpec for these benefits. There are several quite distinct subcategories:

5a. Building components that reduce heating and cooling loads -- Examples include structural insulated panels (SIPs), insulated concrete forms (ICFs), autoclaved aerated concrete (AAC) blocks, and high-performance windows and glazings. As these energy-saving products gain market acceptance, our threshold for inclusion in GreenSpec may become more stringent. For example, we may begin including only SIPs and ICFs with steady-state R-values above a certain threshold or with other environmental features, such as recycled-content foam insulation. Some products, such as insulation, clearly offer environmental benefits, but are so common that they need other environmental features to qualify for GreenSpec.

In the case of windows, the base standard for energy performance of windows is an NFRC-rated unit U-factor of 0.25 or lower for at least one product in a listed product name. If the windows are made from an environmentally attractive material (e.g., high recycled content or superb durability), the energy standard is less stringent: U-factor of 0.30 or lower. If the frame material is nongreen, such as PVC (vinyl), the energy standard is more stringent: U-factor of 0.20 or lower. There are a few exceptions to these standards, such as high-recycled-content windows made for unheated buildings.

5b. Equipment that conserves energy -- With energy-consuming equipment, such as water heaters and refrigerators, we have good data on energy consumption and can set clear standards accordingly. In some product categories - clothes washers, for example - ENERGY STAR standards were adopted because those standards provide a high enough threshold to represent just the very top segment of the product market (less than 10%). In other product categories - e.g., refrigerators and dishwashers - we set a higher threshold than ENERGY STAR: for example, exceeding those standards by 10% or 20%. With lighting and lighting control equipment, certain generic products qualify, such as compact fluorescent lamps and occupancy/daylighting controls, while in other categories only a subset of products qualify. In some cases, products that meet the energy efficiency requirements are excluded, because of evidence of poor performance or durability. Microturbines are included here because of the potential for cogeneration (combined heat and power) that they offer.

5c. Renewable energy and fuel cell equipment -- Equipment and products that enable us to use renewable energy instead of fossil fuels and conventional electricity are highly beneficial from an environmental standpoint. Examples include solar water heaters, photovoltaic systems, and wind turbines. Fuel cells are also included here, even though fuel cells today nearly always use natural gas or another fossil fuel as the hydrogen source - they are considered green because emissions are lower than combustion-based equipment and because the use of fuel cells will help us eventually move beyond fossil fuel dependence.

5d. Fixtures and equipment that conserve water -- All toilets and most showerheads today meet the federal water efficiency standards, but not all of these products perform satisfactorily. With toilets and showerheads we include products that meet the federal standards and show evidence of especially good performance based on surveys or testing. We hope that in the future more consistent performance ratings for such products will make this selection process easier. Some other products, such as rainwater catchment systems, are also included.

6. Products That Contribute to a Safe, Healthy Indoor Environment

Buildings should be healthy to live or work in, and product selection is a significant determinant of indoor environment quality. Green building products that help to ensure a healthy indoor environment can be separated into several categories:

6a. Products that don't release significant pollutants into the building -- Included here are zero- and low-VOC paints, caulks, and adhesives, as well as products with very low emissions, such as nonformaldehyde manufactured wood products. Just how low the VOC level needs to be for a given product to qualify for inclusion in GreenSpec depends on the product category. Ideally those standards should be based not on simple VOC content, but on resultant VOC concentrations in the space after a given period of time - EPA is working on such data for paints (including a way to factor in higher impacts for more toxic VOCs), but this information is not yet available.

6b. Products that block the introduction, development, or spread of indoor contaminants -- Certain materials and products are green because they prevent the generation or introduction of pollutants - especially biological contaminants - into occupied space. Duct mastic, for example, can block the entry of mold-laden air or insulation fibers into a duct system. "Track-off" systems for entryways help to remove pollutants from the shoes of people entering. Coated ductboard - compared with standard rigid fiberglass ductboard - prevents fiber shedding and helps control mold growth. And linoleum helps to control microbial growth because of the ongoing process of linoleic acid oxidation.

6c. Products that remove indoor pollutants -- Qualifying for inclusion here are certain ventilation products, filters, radon mitigation equipment, and other equipment and devices that help to remove pollutants or introduce fresh air. Because ventilation equipment is now fairly standard, only products that are particularly efficient or quiet, or that have other environmental benefits are included.

6d. Products that warn occupants of health hazards in the building - Included here are carbon monoxide (CO) detectors, lead paint test kits, and other IAQ test kits. Because CO detectors are so common, other features are needed to qualify such products for GreenSpec, such as evidence of superb performance.6e. Products that improve light quality -- There is a growing body of evidence that natural daylight is beneficial to our health and productivity. Products that enable us to bring daylight into a building, including tubular skylights, specialized commercial skylights, and fiber-optic daylighting systems, are included in GreenSpec. Some other products, such as full-spectrum lighting systems and highly reflective ceiling panels, could also be included in GreenSpec under this criterion.

Final Thoughts
The primary intent with any green building products directory is to simplify the product selection process. Such directories, including GreenSpec , are designed to save you time. For a directory to properly serve your needs, you must be able to trust it - you must have confidence that the process used to select products for inclusion is logical and based on good information and careful analysis.

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A comprehensive evaluation of what makes building materials "green", or sustainable, was put together by the people at BuildingGreen and the Environmental Building News. They established criteria of sustainability for selecting products for their GreenSpec directory.