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Green Building Methods and Procedures PDF Print E-mail

Introduction

GREEN HOMES ARE SAFE TO LIVE IN, AFFORDABLE TO OPERATE, and less damaging to the local, regional, and global environments.

Interest in green building has been growing by leaps and bounds in recent years for a number of reasons. Home-owners are alarmed by news about mold and asthma and about the alphabet soup of toxic chemicals that enters our homes through building products, furnishings, and consumer goods. We want the place where we live to be safe. We spend 90% of our time indoors and a significant chunk of that in our homes; these spaces should not make us sick. A green home is a healthy home.

Some people are worried that rising energy prices could make their homes too expensive to live in. In recent years, we have seen dramatic increases in the price of gasoline, natural gas, electricity, and heating oil. Evidence that worldwide oil production may be nearing a peak even as demand continues to grow leads to the concern that even higher prices may be just around the corner. (The process of natural gas and electricity tend to rise and fall with the price of oil.) With more and more people nearing retirement age and facing the prospect of living on a fixed income, many are wisely concerned about the rising costs of operating their homes. This includes energy costs but also the costs of maintaining the home. A green home is affordable to operate its energy use is low, and it is made with durable, low-maintenance materials.

Finally, more and more homeowners are beginning to recognize that their actions can make a difference. There is growing awareness about our impacts on the environment, and an increasing willingness to do something about it. Surveys show that efforts to make their homes more environmentally friendly are high priorities for homeowners and potential home buyers even if those measures increase costs.

Doing the right thing by creating a green home makes sense all around. It's good for your family's health, it saves money, and it's good for the environment.

Why choose Green Building Products?

There are really three stakeholders to benefit from the use of green building products: the people who work with the materials (not only on the job site but also in the factories where the products are made); the homeowners who live with those materials; and the local, regional, and global environment that is protected through the production and use of these materials.

The direct benefits of green building products to workers and homeowners are the easiest to justify. Manufacturing facilities and construction companies can save money if employees don't have to use special protective gear and if they stay healthier, losing less time to sick leave. And the importance of a safe, healthy home goes almost with out saying. Since we spend so much of our time indoors, it's imperative that our indoor environments don't make us sick. Asthma now affects one in eight children, and medical experts are increasingly pointing to homes and the products we put in them as the culprits that cause respiratory illnesses. Further, there are a slew of chemicals we introduce to our homes whose health effects we know almost nothing about, such as the plasticizes that make vinyl shower curtains and wall coverings flexible, brominated flame retardants in foam cushions, and fluoropolymers such as Teflon used to insulate some wiring and component in some finishes. Some of these chemicals are now showing up in the blood of humans worldwide and are being linked to behavioral and developmental problems.

Homeowners benefit directly from many products in the operation of their homes: heating, cooling, water use, maintenance, and repairs. Some green building products are more energy-efficient or more water-efficient than conventional products; others are more durable or require less maintenance. These direct benefits will save people money or time over the life of their homes and can easily be justified on those grounds.

Selecting green products solely because they protect the environment can be more difficult to justify but is no less important. While most homeowners will be sympathetic to concerns about rainforest's destruction, ozone depletion, or toxic chemical releases from manufacturing plants, those impacts are far away, and most of them don't affect us directly. However, growing awareness about global warming is helping people understand the fact that actions in one place can have environmental impacts elsewhere. If, as most scientists believe, global warming is going to become a lot more apparent over the coming years and decades, it may become easier to dram the connection between our purchasing decisions and a wide range of impacts. If that happens, the environment could become a much bigger factor in the way we think, act, and make purchasing decisions.

When it comes to choosing green building products, both direct and indirect benefits are important. The relative priorities of these benefits, though, will vary significantly from person to person.

What Makes a Product Green?

This is a very complicated question. Many different factors come into play in determining the "greenness" of products and materials; very often the distinctions are not black-and-white. Much of the complexity in examining the environmental and health impacts of materials results from the fact that the impacts can occur at different points in the life cycle of a product, and those impacts can vary tremendously from product to product.

The science of examining the environmental and health impacts of products is referred to as life-cycle assessment, or LCA. This process examines a product from "cradle to grave," some prefer to think of this cycle as "cradle to cradle," recognizing the idea of taking a product at the end of its useful life and turning it into the raw material for something else's recycling.

A green product is one whose life-cycle impacts are low. A floor tile made from recycled glass is considered green because it is made from a waste materials something that would otherwise end up in a landfill. Mineral silicate paint is green because it is highly durable and won't require frequent recoating or other treatment throughout its life. Metal cabinets can be green if they don't emit VOCs (volatile organic compounds) or other pollutants. A compact fluorescent light bulb is green because it reduces energy consumption in the home. Sometimes, more than one environmental attribute apply to a products for example, recycled plastic decking that is made from a waste product, is more durable that standard wooden decking, and doesn't release copper or other chemicals that can harm the environment (as can conventional pressure-treated wood).

A challenge in choosing green products is balancing all of these different and often unrelated considerations. A product might be made of recycled material but release harmful levels of VOCs; another might be durable but manufactured with chemicals that are significantly hazardous to the environment or to humans. We are often comparing apples to oranges when trying to decide which environmental impacts should carry greater weight. Fortunately, there are some efforts under way to quantify the environmental impacts of building materials using standardized measures.

Building for Environmental and Economic Sustainability (BEES) is a life-cycle assessment software tool that was developed by the National Institute of Standards and Technology (NIST). This tool helps architects, engineers, and environmental building consultants understand environmental and health impacts over a product's life cycle. While relatively few products have been assessed through BEES to date, it offers great promise for life cycle assessment of building materials as the underlying database grows.

The nonprofit Athena Sustainable Materials Institute is amassing a comprehensive, public database of life-cycle inventory information about generic (as opposed to brand-specific) building materials. These inventories include detailed information on the environmental burdens that result from producing building materials.

Other organizations, including Green Seal, Scientific Certification Systems, NFS International, the Institute for Market Transformation to Sustainability, and others are developing sustainable product standards for various product categories, such as carpet and textiles.

As more rigorous and specific standards for green building products are developed, the selection criteria for product directories such as this one will become more quantitative. Until that time, the selection process for a product directory has to be based on the expertise of those creating it. Specifics of how products are selected for this directory are described below.

What is GreenSpec?

GreenSpec is the leading national directory of green building products. Included here are those GreenSpec products that are most relevant to home building. Our intent with GreenSpec is to highlight the greenest building products; we don't include some products with green attributes because there are similar products considered even greener. While we do our best to be comprehensive, there are doubtless many building products that would qualify for GreenSpec but are not yet included. If you have recommendations for products that should be considered, e-mail This e-mail address is being protected from spambots. You need JavaScript enabled to view it .

Manufacturers do not pay to be included in GreenSpec. Decisions about which products to include are based totally on criteria developed by the GreenSpec and Environmental Building News editorial team. This policy allows us to be unbiased in selecting products and in writing the descriptions of those products. Because manufacturers don't pay to be listed in GreenSpec, they can't control what is said about the products. In other words, what you read about products in this book is based on the research our staff has done; it is not written by marketing staffs of manufacturing companies.

Product Selection Is Only One Part of Green Building

While this book focuses on the selection of products for building and remodeling to make a home more environmentally friendly, it is important to point out that green building is about much more than products. Green building is also about such issues as:

  • Energy-efficient design and construction where windows are located, how much insulation is installed, and how effectively air leakage is controlled;
  • House size not building a larger home that is needed;
  • Where the house is built so that use of automobiles can be minimized and important natural areas can be protected;
  • Design and construction detailing to avoid moisture problems the leading cause of indoor air quality problems in houses.

While the products and materials used in a home are often the most visible aspects of "green," these other issues are at least as important and often significantly more important. Indeed, it is possible to build a compact, energy-efficient home close to alternative transportation that would be considered "green". Conversely, a house could be built from 100% green products yet not be very green at all because it isn't energy efficient, because it's much bigger than necessary, or because building it damaged and ecologically sensitive area.

Selecting green building products is a very important aspect of green design, but it's not the whole story. Be sure to pay attention to the broader issues. For more information on green building, visit www.BuildingGreen.com

Product Selection Criteria Used in This Directory

Building Green has been researching green building products and publishing information on them since 1992. Through writing hundreds of product reviews in the monthly newsletter Environmental Building News, and listing nearly 2,000 products in the comprehensive GreenSpec database of green building products, Building Green has developed specific criteria for what makes a product green. These criteria include:

PRODUCTS MADE WITH SALVAGED, RECYCLED, OR AGRICULTURAL WASTE CONTENT

The materials used to produce a building product, and where those materials come from, are important green criteria and probably the best known. When many people think of green building products, they think of products made from recycled materials.

Salvaged products

Whenever we can reuse a product instead of producing a new one from raw materials even if those raw materials are from recycled sources we save resources and energy. Many salvaged materials used in buildings (including bricks, mill-work, framing lumber, plumbing fixtures, and period hardware) are mostly 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. Certain salvaged products are not recommended, including toilets, faucets, and windows because the water-and energy-savings of today's high-performance products offer far greater benefit than any there might be in using the old ones. With salvaged wood products, be aware that lead may be present. Test painted wood for lead paint or residue left from lead paint (easy-to-use test kits are available). If found, avoid the product or have the wood stripped and sealed.

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 pre-consumer recycled content because post-consumer recycled materials are more likely to be diverted from landfills. For many product categories, there is currently no set standard for the percentage of recycled content required to qualify for inclusion in GreenSpec; such standards will increasingly be developed in the future as more products begin using higher percentages of recycled materials.

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 higher-emitting products should not be used in most fully enclosed indoor spaces due to potential off gassing of harmful chemicals.

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. As more complete life-cycle information on recycled materials and the process of recycling becomes available, we will scrutinize recycled products more carefully.

Products with pre-consumer recycled content

Pre-consumer (also called "post-industrial") recycling refers to the use of industrial by products as distinguished from materials that has been in consumer use. Examples of pre-consumer recycled materials used in building products include iron-ore blast furnace slag used in making mineral wool insulation; fly ash from the smoke stacks of coal-burning power plants used in making concrete; and PVC scrap from pipe manufacturing used in making roofing shingles. 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 better than pre-consumer recycled content, the latter can still qualify a product for inclusion in GreenSpec in many product categories especially those were there are no products available with post-consumer recycled content.

PRODUCTS THAT CONSERVE NATURAL RESOURCES

Aside from salvaged recycled content, there are a number of other ways that products can contribute to the conservation of natural resources. Examples of these include products that use less material than the standard solution for a particular function; products that are especially durable or low-maintenance; wood products that carry third-party certification demonstrating well-managed forestry; and products made from rapidly renewable resources.

Products that reduce material use

Products meeting this criterion may not be distinctly green on their own but are included in GreenSpec because of the resource efficiency benefits that they make possible. For example, drywall clips allow the elimination of corner studs in wood house framing; 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.

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.

Certified wood products

Third-party 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-wood 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 non-salvaged solid wood product must be FSC certified to be included in GreenSpec. Engineered wood products in GreenSpec do not qualify by virtue of their resource efficiency benefits alone. A few manufactured wood products, including engineered lumber and particleboard or medium-density fiberboard (MDF), can be included if they have other environmental attributes such as the absence of formaldehyde binders.

Rapidly renewable products

Rapidly renewable materials are distinguished from wood by having a shorter harvest rotation typically 10 years or less. They are biodegradable, often low in VOC emissions, and usually 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 should also be considered. Examples include natural linoleum; bamboo flooring; form-release agents made from plant oils; natural paints; geotextile fabrics from coir and jute; products made with bamboo or cork; and such textiles as organic cotton, wool, and sisal. Note that not all rapidly renewable materials are included in Green Spec non-organic cotton, for example, is highly pesticide-intensive. In some cases, even though a product qualifies for Green Spec 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.

PRODUCTS THAT AVOID TOXIC OR OTHER EMMISIONS

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 criterion, a few product components were singled out for avoidance in most cases; substances that deplete stratospheric ozone, those associated with ecological damage or health risks, including mercury and halogenated compounds. In a few cases, these substances may be included in a "green" product, but that product has to have other significant environmental benefits (for example, low energy or water use).

Substitutes for conventional 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 still contain HCFCs. We have created several subcategories here for green products:

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 woo products, agricultural or nonagricultural plant products, and mineral products such as natural stone and slate shingles. Being minimally processed is not, in itself, enough to qualify a wood product for GreenSpec, however.

Alternatives to ozone-depleting substances

Included here are categories in which the majority of products still contain or use HCFCs (hydro chlorofluorocarbons), such as certain types of foam insulation and most compression-cycle heating and air-conditioning equipment. As ozone-depleting substances are phased out, the relative importance of this criterion drops (for example, polyisocyanurate insulation is no longer made with HCFC-141b as the blowing agent, so the environmental benefit of expanded polystyrene, EPS, over polyiso has disappeared).

Alternatives to hazardous products

Some materials provide a better alternative in an application dominated by products for which there are concerns about toxic constituents, intermediaries, or by-products. Fluorescent lamps with low mercury levels are included here, along with form release agents that won't contaminate water soils with toxicants. Also included here are alternatives to products made with chlorinated hydrocarbons such as polyvinyl chloride (PVC) and brominated fire retardants.

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 can eliminate the need for broad-based pesticide applications.

Products that reduce storm-water pollution

Porous paving products and green (vegetated) roofing systems result in less storm-water runoff and thereby reduce surface water pollution. Storm-water treatment systems reduce pollutant levels in any water that is released.

Products that reduce impacts from construction or demolition activities

Included here are various erosion-control products, foundation products that eliminate the need for excavation, and exterior stains that result in lower VOC emissions into the atmosphere. Fluorescent lamp and ballast recyclers and low-mercury fluorescent lamps reduce environmental impacts during demolition (as well as renovation).

Products that reduce pollution or waste from operations

Alternative waste-water disposal systems reduce groundwater pollution by decomposing organic wastes more effectively. Porous paving products and green (vegetated or "living") roofing systems result in less storm-water runoff and thereby reduce surface water pollution and sewage treatment plant loads. Masonry fireplaces and pellet stoves burn 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.

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 its construction. Many products are included in GreenSpec for these benefits. There are several quite distinct subcategories:

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. As these energy-saving products gain market acceptance, our threshold for inclusion in GreenSpec 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.

With windows, energy performance requirements for GreenSpec listing are based on the National Fenestration Rating council (NFRC) unit U-factors; with U-factors, the lower the number, the better it insulates. The base standard for windows is a unit U-factor of 0.25 or lower for at least one product in a listed product line. If the windows are made from an environmentally attractive material (e.g., high recycled content or superb durability, such as fiberglass), the energy standard is less stringent: a U-factor of 0.30 or lower. If the frame material is non green, such as PVC (vinyl), the energy standard is more stringent: a U-factor of 0.20 or lower is required. There are a few exceptions to these standards, such as high-recycled-content windows made for unheated buildings.

Equipment that conserves energy

With energy consuming equipment such as water heaters, clothes washers, and refrigerators, the criteria for GreenSpec listing are based on energy performance ratings that rely on U.S. Department of Energy test standards. In most appliance categories, GreenSpec has a higher energy performance threshold than ENERGY STAR for example, exceeding those standards by 10%-20%. With certain product categories, such as compact fluorescent lamp (CFLs), all products qualify from an energy standpoint, but some are eliminated due to performance problems.

Renewable energy and fuel cell equipment

Equipment and products that enable us to use renewable energy instead of fossil fuels and conventionally generated electricity are highly beneficial from an environmental standpoint. Examples include solar water heaters, photovoltaic (PV) 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.

Fixtures and equipment that conserve water

All toilets and most shower-heads today meet federal water efficiency standards but not all of these products perform satisfactorily. With toilets, GreenSpec considers both water use and flush performance based on a standardized test procedure. To be listed in GreenSpecs toilets must use at least 20% less water than the federally mandated 1.6 gallons per flush (gpf), a designation referred to as a high-efficiency toilet. Most toilets must also meet the minimum performance standards of the Uniform North American Requirements (UNAR) for toilets. With faucets, special controls that help conserve water are the usual basis for inclusion. Some other water-saving products, such as rainwater catchments systems, are also found here.

PRODUCTS THAT CONTRIBUTE TO A SAFE, HEALTHY INDOOR ENVIRONMENT

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

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 manufactured wood products made without formaldehyde binders. 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 criteria should be based not on simple VOC content, but on resultant VOC concentrations in the space after a given period of time the EPA has worked on such an approach for paints (including a way to factor in higher impacts for more toxic VOCs), but results from such research are not yet available.

Products that block the introduction, production, or spread of indoor contaminants

Certain materials and products are green because they prevent the introduction (or Development) of pollutants especially biological contaminants into the home. Duct mastic, for example, can block the entry of mold-laden air or insulation fibers into a duct system. "track-off" system for entryways help to remove pollutants from the shoes of people entering. Coated duct board compared with standard rigid fiberglass duct board prevents fiber shedding and helps control mold growth. And true linoleum naturally controls microbial contamination through the ongoing process of linoleic acid oxidation. (Note that vinyl flooring which is PVC flooring is often mistakenly referred to as linoleum. PVC is not considered a green product.)

Products that remove indoor pollutants

Products that qualify for GreenSpec based on this criterion include certain ventilation products, filters, radon mitigation equipment, and other equipment that helps to remove pollutants or introduce fresh air. Because ventilation equipment is now fairly standard, only products that are particularly efficient or quiet, or that offer other environmental benefits, are included.

Products that warn occupants of health hazards in the building

Included here are carbon monoxide (CO) detectors, lead paint test kits, and other indoor air quality (IAQ) test kits. Because CO detectors are so common, other features are needed to qualify these products for GreenSpec, such as evidence of superb performance.

Products that improve light quality

A growing body of evidence suggests that natural daylight is beneficial to our health and productivity. Products that enable us to bring daylight into a building, such as tubular skylights, are included in GreenSpec.

Products that help control noise

Noise, from both indoor and outside sources, adds to stress and discomfort. A wide range of products are available to help absorb noise, prevent it from spreading, mask it, and even reduce it with sound-cancellation technologies.

Products that enhance community well-being

Beyond the walls of a building, many products can contribute to safer neighborhoods, increasing walk ability and making high-density communities appealing.

Sitework & Landscaping

Sitework and landscaping are typically the first and last tasks, respectively, on a building site. Steps can be taken at the beginning of sitework that can increase the value and reduce the cost of landscaping after construction. Siting of the building itself usually has already occurred, but there is still often an opportunity to influence such issues as solar access and minimizing site disturbance.

A site survey should precede any site-work to identify sensitive areas and features to be protected, such as wetlands, trees, and other vegetation. It's well worth the effort to save trees if they are healthy and not too close to the structure. Mature trees on a lot can add more than 15% to the value of a house, and appropriately placed trees can reduce a buildings conditioning needs by more than 40%.

A tree's root system extends quite a distance from the trunk typically at least to the drip line of the farthest branches. Even just compacting the soil can harm the roots, so a large area around each protected tree needs to be fenced off. To ensure cooperation of subcontractors in this effort, one strategy is to specifically list in their contract the value of each mature tree and hold them responsible for that value if the tree is damaged.

Invasive plants introduced from other parts of the world can wreak havoc on the ecological balance of a region, so nonnative species should generally be avoided in landscaping (though noninvasive exotic species those that don't spread and outcompete native plants are less of a concern). Plants that are native to your area are also adapted to your climate, so they tend to need less care and maintenance, and require less watering saving time and money. Most lawns are planted with nonnative turf grasses, such as Kentucky Bluegrass, which require watering in most U.S. climates. Hardy, native species such as buffalo grass and certain fescues should be used instead, or lawn areas should be replaced with other landscapes that require less water, fertilizer, herbicides, and maintenance.

Handling storm-water runoff can be a major design issue. Conventional solutions include concrete or PVC drainage pipes and, on larger projects, detention ponds; these are expensive and tend to increase the contamination of the water from surfaces to allow rainwater infiltration directly into the ground; these are far better environmentally and usually less expensive. Use of swales for rainwater instead of curbs and storm-water drains is also preferred.

Resource-efficient products and building materials for site-work and landscaping include porous paving systems suitable for driveways, walkways, courtyards, and parking areas; and landscaping timbers made from recycled plastics, which are more durable in ground contact than preservative-treated wood. Retaining walls and hard-scape surfaces can often be made from salvaged materials, such as broken up concrete paving (which some green builders refer to as "urbanite").

Outdoor Structures

Outdoor structures include freestanding built items such as fences, tables, benches, planters, playground equipment, and other items that are installed or used out-of-doors, such as exterior sun-shade systems. Green criteria for products in this category include durability, low maintenance, and recycled content.

Prefabricated site furniture, landscaping timbers, fencing, and other outdoor products made with recycled plastic and wood-plastic composite lumber are available from many sources; they are more durable than wood, require less maintenance, and make use of materials that might otherwise end up in landfills. Products made with durable, rot-resistant, FSC-certified hardwoods such as Ipe can also be a good choice. (Certification from the Forest Stewardship Council means that the wood has been sustain ably harvested from well-managed resources.)

Architectural trellises can contribute to reduced solar gain and improved light quality in buildings, increased comfort for outdoor spaces, and are visually appealing. Combined with quick-growing seasonal vines, solar benefit in winter and solar shading in summer are both achieved.

For aquatic applications such as docks and pilings, avoid treated wood in favor of recycled plastic, which is impervious to marine borers and will not leach toxic chemicals. Though generally somewhat more expensive than treated wood, they will last longer an important consideration in light of the expense of the more frequent replacement needs of wooden components.

Decking

Until 2004, most preservative-treated wood was pressure treated with CCA (chromated copper arsenate). Concerns about arsenic and chromium leaching from decks and fences led to the removal of CCA-treated lumber from the market. Disposal of the existing billions of board feet of CCA-treated wood already in use will be an ongoing problem as it reaches the end of its useful life. Degradation of CCA-treated wood leaves residual toxins; burning it results in airborne toxins or, if burned in controlled incinerators, highly toxic ash.

Direct substitutes for CCA-treated wood include less toxic products such as ACQ (ammoniacal copper quaternary) and CBA (copper boron azole). ACQ is corrosive to standard steel over time so stainless steel screws and nails and double-coated, hot-dipped galvanized hangers and hardware are typically recommended. CBA is less corrosive to steel. Aluminum hardware shouldn't be used with either. Both ACQ and CBA rely on copper as the active ingredients, and copper is highly toxic to many aquatic organisms; for this reason neither should be used on boardwalks, docks, or decks overhanging ponds, marshes, or other aquatic locations. Neither are approved for saltwater applications. For wood that isn't exposed to weather, borate-based preservatives (without copper) are effective against insects while being much less toxic than other chemicals. Treatments using sodium silicate followed by heat offers a very attractive alternative to conventional copper-base treatments.

There are also problems associated with using naturally rot-resistant wood species, such as redwood and cedar. Clear-heart redwood is generally cut from old-growth forests. Redwood trees take a long time to mature, and there are very few remaining stands of privately owned redwood. Small but increasing amounts of redwood and cedar are available from certified, well-managed forests. The quick-growing rings, is less resistant to rot and insects than old-growth wood. Sustain ably harvested, long-lasting exotic hardwoods such as Ipe, imported from Brazil and Bolivia, are increasingly available; look for third-party FSC certification. Forest Stewardship Council (FSC) certification involves third-party evaluation and monitoring of sustainable forestry practices and chain-of-custody verification that wood products were derived from certified forests.

In some settings, a patio made from local stone makes an attractive alternative to a wood deck.

For exposed applications, recycled plastic lumber is an excellent alternative that will handily outlast most wooden decking materials: 50-year warranties aren't uncommon. Products combining recycled plastic with wood fiver offer a more wood-like feel and less thermal expansion in the sun. Prefabricated picnic tables, benches, and garbage can enclosures made with these materials are available.

Foundations, Footers, & Slabs

Conventional foundations, footers, and slabs use a lot of c oncrete, which is energy-intensive and polluting to produce up to a ton of CO2 is released in producing a ton of cement. Admixture components such as calcium chloride (an accelerator), gypsum (a retarder), and sulfonated melamine formaldehyde (SMF, a plasticizer) also affect the environmental impact of the concrete. Depending on the chemical, the impact may be on-site or at the plant. Also, concrete foundations and slabs do not provide much by way of thermal insulation, though they can provide thermal storage. Foundations, footers, and slabs should always be detailed to reduce thermal bridging as much as possible.

Forming can account for a significant portion of the total cost of poured concrete. Essentially, things get built twice: once in forms and again in concrete. Plywood has been the mainstay of concrete-forming companies for many years, though some companies have invested in reusable, durable forms a more resource-efficient solution that is still relatively labor-intensive. Reusable forms also require form-release agents, most of which are petrochemical-based and offgas larger amounts of volatile organic compounds (VOCs). Vegetable-based form-release oils are available.

For large buildings and some sites with poor soil conditions, foundations are engineered to specific structural requirements, and fairly extensive use of concrete may well be necessary. For certain applications, replacing up to 50% of the cement in a concrete mixtures with fly ash from coal-burning power plants will reduce the environmental impact of producing the material, and this substitution can actually strengthen the concrete. Fine-ground blast-furnace slag from metal foundries can have similar properties to those of fly ash.

For homes and smaller buildings, alternative foundation systems are available that can reduce concrete use and increase energy efficiency. Many such products consist of stay-in-place insulating concrete forms (ICFs) made of polystyrene foam or a cementitious matrix of recycled foam or recycled wood fivers. Expanded polystyrene (EPS) foam should be preferred until extruded polysterene (XPS) foam insulation becomes available without ozone depleting HCFCs. Some EPS foam products have an integral borate treatment, which helps keep damaging insects out of the foam. The brominated flame retardants used in most EPS foam have health and environmental risks that are generating significant concern.

Precast concrete foundation walls are available in some areas. They use less concrete than site-cast foundations and are designed to accommodate interior insulation.

The depth of a foundation wall (and thus the amount of material required) can be reduced by raising the frost line, generally by placing foam insulation horizontally (usually extending about 4') around the foundation. These "frost-protected shallow foundations" can save money and materials where crawl-space or slab-on grade foundations are used in cold climates. "Rubble trench" foundations are another option one thatwas favored by Frank Llyod Wright. Pier foundations, which can reduce excavation requirements and concrete use significantly, may also be an appropriate choice.

Non-asphalt-based damp proofing reduces the risk of introducing chemicals into local aquifers and VOCs into the building, and they can be longer lasting.

In some parts of the country, rigid mineral wool panels are available that help insulate foundation walls while also providing effective drainage. Mineral wool typically includes iron-ore slag a pre-consumer waste product. And recycled aggregate or crushed glass can be used as aggregate in the concrete or as backfill for foundation drains.

Foundations can also be designed with termite shields or be backfilled with special termite-proof sand, so that toxic soil treatments are not required. Pesticides commonly used around foundations introduce hazardous chemicals to the environment and must be periodically reapplied.

Structural Systems & Components

The structure of a building should be designed for durability and soundness unless it's a temporary structure, in which case it should accommodate disassembly and reuse of the materials. Some structural materials may compromise the building's energy efficiency by creating thermal bridges from interior to exterior that allow heat to bypass the insulation; these should be addressed during building design.

For houses and small commercial buildings, wood is by far the most common framing material. Even with wood from certified, well-managed forests, measures should be taken to minimize the use of wood framing and maximize the amount of insulation in the building envelope. "Advanced framing" measures include framing at 24" on-center instead of 16", using single top plates (and lining up roof framing over the wall studs), using two- or three-stud corners, and insulating headers above openings.

Lager framing members, such as 2x10 and 2x12s, are made from mature trees that often come from scarce old-growth forests; engineered lumber products, such as trusses and I-joists, should be preferred. Finger-jointed lumber, which uses short pieces of wood that might otherwise become waste, makes straighter boards that are less prone to warp.

There are alternatives to wood. Light-gauge steel framing is used as a piece-for-piece substitute for wood framing. While it does contain some recycled content, the sheet steel used for light-gauge framing generally contains less recycled material than heavier types of steel. Steel is also quite energy-intensive to produce (high in embodied energy). Most important, however, is that steel conducts heat 400 times fore readily than wood: steel framing can easily compromise a building's thermal performance unless insulation is specially designed to block thermal bridging.

Masonry construction is common in many areas. Hollow-core concrete masonry units (CMUs) are hard to insulate effectively. A special type of masonry block called autoclaved aerated concrete (AAC) insulates much better than standard concrete block. Other types of block should generally be insulated on the exterior, or between the concrete block and the exterior skin.

Concrete wall systems that are more typically used for foundations including insulated concrete forms (ICFs) can also be used to form above-grade walls. Making concrete is energy-intensive and polluting: the production of a ton of cement releases up to a ton of carbon dioxide. Admixture components also affect the environmental impact of concrete. Though concrete walls can provide thermal storage, they don't provide much thermal insulation; concrete walls for conditioned spaces should always be insulated.

Structural insulated panels (SIPs sometimes called stress-skin or foam-core panels), usually made with foam-core panels), usually made with foam insulation sandwiched between oriented-strand board (OSB) skins, are a viable alternative for houses and other small buildings. They insulate well, are usually quite airtight, and go up quickly. Some panels are available with mineral-wool insulation or compressed straw as the core instead of plastic foam.

Foam-core panels are often used to enclose post-and-beam or timber-frame structures. These heavy timber structures use a great deal of wood, but they're likely to be very durable the finish materials and exterior skins can be replaced multiple times n the life of a solid timber frame. If the wood is local or from well-managed forests, this construction system can be a good choice. Some timber framers use salvaged timbers from buildings that are being demolished.

Other alternative structural systems include adobe, rammed earth, straw-bale construction, and cob construction (a hand-formed mixture of sand, clay, and straw). Log homes use a great deal of wood and don't insulate very well. Like their mainstream cousins, some proponents of alternative materials or methods claim mass-enhanced "effective R-values," which are relevant only under certain conditions.

Sheathing

Sheathing generally serves as a secondary weather barrier behind the exterior finish. It can also be the primary substrate for attaching the finish layer, and often provides diagonal bracing for the structure.

The most common sheathing materials for residential and light commercial construction are plywood and oriented-strand board (OSB). Plywood requires trees of diameter large enough for veneers to be peeled off as the cylindrical core is turned on a lathe. OSB can be manufactured from fast-growing trees of relatively low commercial value, and uses a higher percentage of the tree. OSB sheathing and wood I-joist framing, used together, can reduce wood requirements dramatically while providing superior structural integrity. Most OSB and ply wood uses phenol-formaldehyde (PF) adhesive that offgasses less formaldehyde than the urea-formaldehyde (UF) commonly used in interior particleboard and paneling. Some OSB uses primarily polyurethane-type (MDI) resin for its adhesive; it emits no formaldehyde but is more toxic in its uncured state, placing factory workers at risk.

Recycled-content sheathing is available in various types. A sandwich material with aluminum foil facings over recycled paperboard is available that meets most wind load requirements and costs less than OSB. Exterior gypsum sheathing, typically made with recycled paper facings, is often used on commercial buildings and is particularly good under stucco for houses. Some exterior gypsum sheathing products use fiberglass facings or integral fibers that do not support mold growth.

Exterior finish & Trim

The exterior finish is a building's first defense against the weather, and its most visible aspect.

Building systems that rely on the exterior finish as the sole weather barrier are susceptible to failure especially in climates with wind-driven rain or with out good drying conditions. The driving forces of wind and other air-pressure factors will force moisture through even the smallest openings. Because of this, siding or curtain wall systems designed around the rain-screen principle are much more effective and durable. This strategy uses a vented exterior finish and a tightly sealed secondary carrier that work together to equalize the pressure on both sides of the exterior finish, taking away the forces that would otherwise drive moisture inwards.

Recycled-wood-fiber composite siding and trim are more stable than materials made from natural wood, hold paint better, and generally cost less. Some hardboard products have had durability problems when improperly installed or when installed without adequate drying provisions in wet climates.

Fiber-cement siding is very durable, looks like wood when it's painted, and provides a fire-resistant surface. The wood fibers provide strength, elasticity, and good paint-holding ability.

Locally produced brick and stone are long-lasting, low maintenance finishes that reduce transportation costs and environmental impacts. Molded cementitious stone replaces the environmental impacts of quarrying and dressing natural stone with the impacts of producing cement.

Roofing

Roofs provide one of the most fundamental functions of building: shelter from the elements. They must endure drastic temperature swings, long-term exposure to ultra violet light, high winds, rain, hail and, depending on the climate, snow. In conflict with these performance and durability requirements, much of the roofing industry is driven by highly competitive economics and thin profit margins. Since shingles are rarely recycled, the 15 or 20 year typical life span of asphalt composite roofing products makes them highly resource-intensive. The National Roofing Contractors Association estimates that 75% of the dollars spent on roofing in the U.S. are for replacing or repairing existing roofs.

Durability is critical in roofing because a failure can mean serious damage not just to the roof itself but also to the building and its contents. Such damage multiplies the economic and environmental cost of less reliable roofing materials. Most roofing failures take place at joints and penetrations, so it's not just the roofing material that must be durable but the entire system, including flashings and edge treatments. Proper installation is vital.

Roofing can also have a significant impact on cooling loads within the building and even in the surrounding community. Use of lighter colored, low-solar absorptance roofing surfaces is one of the key measures advocated in the "Cooling Our Communities" program of the U.S. EPA. Reflective roofing can significantly assist appropriate insulation in dramatically reducing summertime solar gain into the building and thereby lowering the cooling load; Roofs with high solar reflectance also help to minimize the "urban heat island" effect, which raises the ambient temperature in urbanized areas.

Low-slope roofs, more common on commercial buildings, are typically single-ply membranes or built-up asphalt with polyisocyanurate insulation underneath. When these roofs are replaced, the insulation usually has to be replaced as well, taking up landfill space and creating new resource demands for the replacement materials. Systems that separate the insulation from the membrane, And that use a polystyrene insulation which can get wet and dry out without deteriorating, are often preferable because the insulation can be reused. In "protected membrane" applications the rigid insulation (usually extruded polystyrene, XPS) is actually installed on top of the roofing membrane, with concrete pavers on top of the insulation.

Most intriguing environmentally are green roofs (living roofs) in which soil and plantings are used over the water-proof membrane and specialized green roof components. These living layers help replace the ecological functions that are lost when a building footprint covers open land. By using drought-tolerant, low-growing sedums, the planting media requirements with a green roof are fairly minimal. A green roof does not eliminate the need for roof insulation.

Asphalt shingles with fiberglass or organic-fiber mats are still the most common choice for sloped roofing applications. Due to the durability concerns described above, only the heaviest-duty asphalt shingles (with a minimum 30 year warranty) should be considered. Alternatives are available in steel, plastic, rubber, and fiber-cement that use recycled-content materials and come in shake or shingle styles. Clay and concrete tiles are also an option, especially where hail isn't a serious threat. Weight is an issue with some of these products. Sheet steel is also increasingly popular on sloped roofs. Steel roofing should have a thick, galvanized or galvalume coating or be factory-coated with highly durable finish, such as polyvinylidene fluoride (Kynar 500), for maximum life.

The movement to integrate solar electricity generation into buildings called Building-Integrated Photovoltaics (BIPV) has reached the roofing industry with the introduction of photovoltaic (PV) shingles and larger integrated roofing panels. These are still quite pricey, and an electrician may have to work with the roofers during installation. Once installed, however, they produce electricity that can help power the building, and any excess can be sold to the utility company in most states.

Doors

Exterior doors are usually solid wood or foam wrapped in metal, or some other weather-resistant material. Most foam insulation in doors (polyisocyanurate) used to contain ozone-depleting HCFCs, but that is no longer the case.

Most insulated doors are relatively similar in energy efficiency since the market is so competitive; they're distinguished largely by the quality of their weather stripping and threshold. Insulating values of R-5 to R-7 are common.

Interior doors are usually wood, molded hardboard, or hollow core. Since Lauan plywood comes from nonsustainably harvested rainforest wood, it should be avoided. Molded hardboard is often made with some recycled content and pressed into shape; some hardboard is made with ureaformaldehyde and should be avoided. While solid wood is beautiful and a natural, minimally processed product, clear stock is becoming harder to get and may come from old-growth forests.

An increasing number of manufacturers are offering doors using wood from certified sources. Certification to Forest Stewardship Council FSC standards involves third-party evaluation and monitoring of sustainable forestry practices.

Windows

Windows are one of the most high-tech products in residential construction. Since the early 1980s, the energy performance of typical windows has increased by over 50%, the result of both improvements in glazing and in frame construction. The National Fenestration Rating Council (NFRC) publishes the energy performance of certified window products; in some states, manufacturers are required to label their windows with the NFRC"s rating. These ratings are like the EPA mileage rating for cars they may not provide actual energy consumption in a particular application, but are useful for comparison.

The emergence of energy-efficient windows is a key part of breakthrough in the overall design of houses and light-commercial buildings. Glazed surfaces no longer have to lose a lot of heat or feel cold in winter, so heating systems can be much smaller and less expensive. For example, heating elements are no longer required beneath windows to compensate for the drafts and cold surfaces that windows used to generate. In a well-designed, highly energy-efficient house, central heating may no longer be necessary at all though air distribution systems are still important to ensure good indoor air quality.

Low-e glass coatings, which increase the R-value of standard double-glazing from 2 to about 3, are gaining in market share each year. The premium of 10-20% for low-e easily pays for itself in a few years in most applications. The added benefit is a warmer window surface that's more comfortable to be near both in cold weather and in very hot weather. Double low-e and HeatMirror coatings on suspended films are available in premium windows, and can increase the center-of-glass insulating value up to R-9

By careful selection of low-e coatings, windows can be ‘tuned' to optimize the performance of a structure balancing heat loss, solar gain, and visible light transmission through the glass should generally be preferred. In cold climates, where solar gain can be beneficial in winter, glazing that transmits more solar energy is preferable on the south side of a building. On the east and west, less solar gain is preferable even in cold climates, because solar gain is greatest on these orientations during the summer, when air conditioning is likely to be used.

Use of an inert, low-conductivity gas in the space between layers of glazing is another way to improve thermal performance. Most low-e windows have argon gas fill; some super-energy-efficient windows have krypton or a mix of argon and krypton between the glazing layers.

Although standard for many years, aluminum windows are disappearing from most cold-climate markets. If aluminum frames are used, they should be constructed with a thermal break between the inner and outer surfaces to improve energy performance. Aluminum windows are rapidly being replaced by vinyl frames.

Vinyl frames are much better than aluminum in terms of thermal performance, but there are some environmental concerns associated with the production and eventual disposal of PVC. Vinyl windows vary greatly in quality; many have weather-sealing problems over the life of the window due to the expansion and contraction of the plastic. They're better suited to sliders and double hung windows than casements, because those styles are prone to warping and sagging. There are also concerns about the PVC resin itself and various compounds that are added to it to provide UV stability, flexibility, and flame resistance.

Wood windows are still the standard for energy efficiency. Vinyl or aluminum cladding adds value in its low maintenance qualities. Wood window manufacturers are facing increasing difficulty in finding affordable, knot-free material from which to manufacture their product; some are using finger-jointed material with an interior coating and exterior cladding.

Other energy-efficient materials, durability of the edge seals and spacers that separate the layers of glass is extremely important, as failure of this seal will cause condensation inside the window (fogging), and the loss of any low conductivity gas fill.

Insulation

Insulation is one of the most important components of any environmentally responsible building because it reduces energy consumption and the pollution that usually results. In this sense, any insulation material is a "green product. Good design and appropriate levels of central heating and cooling in many buildings.

Insulation is a key part of the building envelope and an important element in the entire building as an integrated system. Choosing an insulation material should include considering how it works with the rest of the wall, roof, and floor system and what additional functions, such as air-sealing, the material might serve.

Different types of insulation are also have varying impacts in terms of their raw materials and manufacture. These life-cycle impacts should be considered alone with factors such as R-value, air-sealing ability, and cost.

The quality of installation also makes a big difference in how well insulation performs. If insulation is not installed properly, it will not achieve the energy savings its rated R-value would suggest; a California study concluded that a 4% void in fiberglass batts resulted in a 50% decrease in insulation effectiveness.

The type of structural framing also affects the performance of insulation. Steel studs conduct heat much more readily than wood studs, so they create thermal Bridging that can bypass insulation installed in the cavities. Steal-framed exterior walls should have insulative sheathing installed over the framing members to reduce this problem in fact; the U.S. Department of Energy recommends that insulative sheathing should be used with steel framing in all U.S. climates.

Fiberglass insulation is the standard in the industry today. High-density fiberglass makes the small wall cavity 15-20% more effective in reducing heat loss. Most fiberglass manufacturers now incorporate at least 30% recycled material; some products are third-party certified for their recycled-glass content. The potential for health problems due to fiver shedding is controversial; loose fill is a greater risk than batts in this regard. While concern has been expressed that air borne fivers might be carcinogenic, those concerns have been allayed to some extent in recent years. Most fiberglass batts are manufactured with phenol formaldehyde as a binder, though some products use alternative binders or no binders at all.

Cellulose insulation is primarily made out of recycled newspaper, though not always from post-consumer sources. When it is damp-sprayed into open cavities, or blown into closed cavities at relatively high density, it forms a good infiltration barrier that adds to the airtightness of the house and it's less contractor-dependent for quality control in filling voids than fiberglass batts.

Rigid foam insulation applied to framing yields added infiltration resistance, reduced frame conduction losses, and higher overall wall R-value. Extruded polystyrene (XPS0 and polyisocyanurate (polyiso) rigid foam insulation used to be made with ozone-depleting CFC blowing agents, but when ozone-depleting CFC blowing agents, but when but when ozone depletion was identified as a major environmental problem, the CFCs were replaced with HCFCs through international agreement. HCFCs were eliminated from polyiso insulation as of 2003, but they are not scheduled to be totally eliminated from XPS until 2020. Polyiso is currently produced with hydrocarbon blowing agents. Expanded polystyrene (EPS) rigid foam has long been made with non-ozone-depleting pentane rather than HCFCs.

Flooring & Floorcoverings

Flooring and floorcoverings are subject to physical abuse from feet and heavy objects; and since they're the lowest spot in a room, they tend to collect dirt, moisture, and other contaminants. A good flooring material should be very durable to reduce the frequency of replacement and it should be easy to clean. At the same time, softer surfaces may be preferred for reasons of comfort, noise absorption, and style, setting up a potential conflict in choices. Raw material and manufacturing impacts must also be considered with many types of carpeting and other floorcoverings.

Carpet systems, including carpet pads and adhesives, have been identified by the EPA as a potential source of indoor air pollution. Testing and monitoring are ongoing; the Green Label and more stringent Green Label Plus programs of the carpet and Rug Institute help prevent the most severe instances of toxic off gassing from new carpet. High-end commercial carpets tend to be more chemically stable than inexpensive residential-quality carpets; some manufacturers are willing to provide detailed air-quality testing data on their products. Carpets may also contribute to air quality problems by trapping pollutants and moisture, and damp carpeting can provide a medium for growth of mold, mildew, and dust mites. Flexible-foam carpet padding frequently contains brominated flame retardants (BFRs); these compounds, chemically similar to PCBs, are raising health concerns because they are being found in human blood and breast milk worldwide, and there is evidence of health effects. BFRs from carpet padding can be released into the living space, especially as the carpet padding ages. In residences, hard flooring surfaces with area rugs, which can be thoroughly cleaned, are often preferable to wall-to-wall carpeting.

Modular carpet tiles can be replaced selectively, reducing the cost and environmental impact of recarpeting an entire room when one are becomes worn or damaged. Some carpet tiles also contain a high percentage of recycled content, and others can be resurfaced and reused. Carpet tiles with random patterns allow easy replacement of individual tiles. Some companies now have extensive recycling programs; when installing new carpeting, it may be possible to have the old carpeting hauled away for recycling at a price no higher than the cost of disposal.

A wide variety of high quality carpet is made from recycled soda bottles (PET) and offers the feel and performance of conventional carpet in residential or other low-traffic settings. Natural-fiber carpet with jute backing can be a good alternative to synthetic fibers, particularly if the carpeting is made domestically. Imported wool carpet is typically treated with pesticides before it can enter the country. Some sources suggest that the lifecycle cost of wood carpet, which includes the agricultural degradation of grazing and other factors, may be quite high.

The underlayment used between a subfloor and floor covering is often made from Luan, a tropical hardwood that comes from unsustainable logging operations in South-east Asia. Other underlayment products are available and should be chosen in consultation with your floorcovering supplier. For example, recycled-content, formaldehyde-free, gypsum-based underlayment is recommended by major tile manufacturers as a substrate. Under Carpet, a recycled-newsprint-and-paraffin product is a good alternative. Wool underlayment is also available.

Vinyl flooring, whose primary component is polyvinyl chloride (PVC0, may be a source of VOC offgassing, both from the flooring itself and from the adhesive. There's also concern about toxic byproducts, such as dioxin, which may be produced in accidental fires or if the material is incinerated at the end of its useful life. Natural linoleum, made primarily from cork and linseed oil, is a possible substitute, though it's currently manufactured only in Europe. VOCs are also released from linoleum but these are from minimally processed linseed oil and are not generally considered as harmful as those from petrochemical sources. Nevertheless, some chemically sensitive people may find them problematic. Adhesives used for linoleum must also be screened carefully for toxic offgassing.

Ceramic and porcelain tile have a high embodied energy, but their durability makes them environmentally sound in the long run. Some high-quality ceramic tile incorporates recycled glass. Regionally produced stone flooring is a good natural finish when sealed with low-toxic sealers.

Terrazzo is a long-lasting, nontoxic floorcovering option that uses crushed stone, and sometimes post-consumer recycled glass, in a cementitious matrix. The embodied energy of Portland cement is a consideration. Epoxy-based "synthetic terrazzo" may also utilize recycled glass; while the 100%-solids product is considered safe for installers and is benign when cured, bispehonal-A (BPA) is used in the manufacture of epoxy. BPA is a bioaccumulating chemical considered by some experts to be an endocrine disrupter even at minute quantities. Like brominated flame retardants, BPA has been showing up in nature in increasing amounts.

Hardwood Flooring from certified well-managed forests may be an excellent environmental choice. Other hardwoods come from forestry operations that may not be environmentally responsible. Tropical hardwoods, in particular, should be avoided unless FSC-certified due to the sensitivity of those ecosystems. Certification to Forest Stewardship Council FSC standards involves third party evaluation and monitoring ofsustainable forestry practices. Reclaimed and recycled wood flooring milled from the large timbers of old structures, trestle bridges, or "sinker logs" is another option.

Fast-growing bamboo is manufactured into hardwood-type strip flooring by a number of Southeast Asian companies, offering an intriguing alternative to standard hardwood. Very-low-formaldehyde products are now entering the marketplace, and at least one manufacturer claims to be formaldehyde-free.

Interior Finish & Trim

Particleboard and medium-density fiberboard (MDF) are almost always made with a urea formaldehyde (UF) binder. This is one of the largest in-home sources of formaldehyde gas a known human carcinogen. These products can offgas for 5 years or more into the living space. UF-based particleboard and MDF are typically used for cabinet boxes, substrates for countertops, shelving, and stair threads. If possible, these materials should be avoided. Any UF-based materials used in a building should be sealed with a low-toxic, low-permeability coating.

A few formaldehyde-free particleboard and MDF products are available, including some made with straw instead of wood fiber. These are made with a urethane-type (MDI) resin. Be aware that MDI is highly toxic before it cures, so its use increases the health risk to factory workers if a manufacture doesn't have good safety standards. Once cured, MDI-based wood panel products are very stable, with out measurable offgassing.

Conventional drywall is quite attractive from an environmental standpoint. It is typically made from 100% recycled paper backing and natural gypsum, which is plentiful and can be low-impact to extract. More and more drywall today contains pre-consumer waste in the form of synthetic gypsum created by sulfur removal systems in the smokestacks of coal-burining power plants. This material is sometimes referred to as flue-gas desulphurization gypsum.

The joint compound used to finish drywall contains synthetic additives that may affect some chemically sensitive people; specialty alternatives are available. Dry-mix, setting-type joint compounds, which are sold in powder form and mixed on site, contain fewer additives.

Cabinets made from nontoxic materials and finishes or solid wood are available. People with chemical sensitivities often find enameled-metal cabinets to be the least problematic.

Clear wood trim materials are increasingly difficult to find (or more expensive), and they place a high demand on virgin timber. On the other hand, this is an application where high-quality would can be fully seen and celebrated. Finger-jointed trim for stain applications, are good substitutes.

Whenever possible, woods used in interior finish and trim should be from certified well-managed forests; third party certification to standards developed by the Forest Stewardship Council (FSC) provides a way that users car verify environmental claims. Currently there are two U.S.-based organizations that certify forest operations (and wood products): Scientific Certifications Systems, and the rainforest's alliance (SmartWood).

Tropical hardwoods should be avoided unless they come from FSC-certified sustainable sources, as their harvest can cause irreparable damage to tropical rainforests. Only a few of the many species of tropical woods have much commercial value often large areas of forest are damaged in pursuit of a few trees. The roads left behind by loggers provide access for slash-and burn- farmers and other settlers, so penetration by logging operations is frequently the beginning of a chain of activities that totally destroy the forest. Fortunately, well-managed tropical forests are increasingly becoming certified.

Caulks & Adhesives

Caulks and adhesives are applied wet, and then dry or cure in place. During that process a carrier evaporates, leaving the active agents in place. During that process a carrier evaporates, leaving the active agents in place. For most products this carrier was traditionally a volatile organic solvent that turned into an airborne volatile organic compound (VOC) as it evaporated. Air quality regulations and health concerns have driven a shift toward waterborne products. Evaporating water isn't a health concern, though other components of the coating or adhesive still generally release some VOCs.

Caulks and adhesives have their greatest effect on indoor air quality during and immediately after installation. The health hazard is particularly acute for installers. Most conventional products offgass VOCs formaldehyde and other chemicals that are added to enhance the performance or extend shelf-life of the product. Little scientific date is available on the health effects off many of these chemicals and even less on the effects of exposure to a combination of such chemicals that may occur in buildings. Quality substitutions, which are lower in toxicity or non toxic, are available for all of these products.

Even so-called zero-VOV materials may still release small amounts of organic compounds. People with chemical sensitivities should always test these products before applying them on their projects, or having them applied by workers. Aside from solvents with well-known health effects (such as benzene, toluene, or xylene), the scientific community offers little guidance on the distinction between acceptable and problematic VOCs

In most categories, the GreenSpec criteria for "low-Voc" products are 50 grams per liter, which is well below even the most stringent Voc regulations in California.

Glue-down carpets and resilient flooring should be applied only with low- VOC adhesives. Alternative carpet fastening methods should also be considered these include:

  • tackless strips, commonly used in residential settings;
  • a hook-and-loop (Velcro-type) tape system that allows sections of carpet to be lifted and reattached as needed;
  • peel-and-stick adhesive systems, such as those used on modular carpet tiles the acrylic adhesives used on tiles are generally considered safer.

Paints & Coatings

Paints and coatings are applied as a fluid, and they dry or cure in place. During that process a carrier evaporates, leaving the active agents in place. For most products this carrier was traditionally a volatile organic solvent that turned into an airborne volatile organic compound (voc) as it evaporated. Air quality regulations and health concerns have driven a shift toward waterborne products. Evaporating water isn't a health concern, though other components of the coating or adhesive still generally release some VOCs.

Paints and coatings have their greatest effect on indoor air quality during and immediately after installation. The health hazard is particularly acute for installers. Most conventional products offgas VOCs, and other chemicals that are added to enhance the performance or extend shelf-life of the product. Little scientific data is available on the health effects of many of these chemicals and even less on the effects of exposure to a combination of such chemicals that may occur in buildings. Quality substitutions, which are lower in toxicity or nontoxic, are available for all these products.

Even so-called zero-VOC materials may still release small amounts of organic compounds. People with chemical sensitivities should always test these products before applying them on their projects, or having them applied by workers. Alternatives to conventional paints made from plant-based solvents may also release significant amounts of VOC's, but many people find these compounds less objectionable than those derived from petrochemicals. Aside from solvents with well-known health effects (such as benzene, toluene, or xylene), the scientific community offers little guidance on the distinction between acceptable and problematic VOCs

In certain categories, the GreenSpec criteria for "low-VOC' products is 50 grams per liter, which is well below even the most stringent VOC regulations in California.

While wet-applied products emit the most VOC/s immediately after curing, some continue to offgas such compounds for a long time. In addition, VOCs emitted during curing can become attached to other surfaces in the space, especially fabrics, and then be re-emitted over time. To reduce this problem, painting should be done with soft surfaces covered and direct ventilation provided until the coating is dry.

For wood-floor finishes, waterborne polyurethane is suggested. It contains no crosslinking agent a type of chemical that adds hardness but is toxic. Waterborne finishes have been tested for durability, and many wear comparably to solvent-based ones. Installers often prefer waterborne finishing products because they dry quickly, allowing several coats to be applied in one day.

Mechanical Systems/HVAC

Heating, ventilation, and air-conditioning (HVAC) are the "engine" that drives the comfort systems in most structures. They directly consume the largest portion of energy in buildings which makes them critically important from an environmental standpoint. Additionally, good indoor air quality, to a significant extent, depends on the ventilation they provide, while a problematic mechanical system can create and distribute indoor pollutants.

The first place to look to minimize the impact of a mechanical system isn't the equipment, however; it's the building's design and construction. Careful, integrated design and optimal levels of insulation can minimize the need for supplemental heating, ventilation, or air- conditioning. In situations where a central mechanical system is still necessary, an efficient building envelope can reduce the size of that system. A high-performance domestic water heater is fully capable of supplying heat to a very well-insulated house in most U.S. climates.

In a well-designed building, distribution requirements are also greatly reduced offering tremendous potential savings in both first cost and operating costs. Houses with very well-insulated walls and high-performance windows, for example, may no longer require heat distribution at the exterior walls to provide comfort. Short duct runs to the closest point in each room save a great deal of money and space, and reduce the potential for wasteful air leakage from the duct system (which should be sealed with duct mastic, not duct tape, at all joints).

After reducing the loads that a mechanical system must meet, it's important to size the system carefully to meet the remaining loads. An oversized system wastes money and materials initially and then operates wastefully, because heating and cooling equipment is at its most efficient when operating at full capacity.

Mechanical equipment should be as efficient as possible, durable, and installed for ease of regular maintenance. As is common practice with heating and cooling, fresh air should be provided to each occupied space and distributed to avoid pockets of trapped, stale air.

To avoid the risk of backdrafting toxic flue gases such as carbon monoxide into a home, only sealed-combustion equipment should be used in houses.

Many air-conditioning systems still rely on HCFC refrigerants, which destroy the ozone layer if allowed to escape. These are being phased out in favor of non-ozone- depleting alternatives. The system efficiency, potential for refrigerant leakage, and ozone-depletion potential of the refrigerant should all be considered when choosing an air-conditioning system.

Good controls are also important. They should have setback options to adjust temperature and fresh air set- points according to occupancy levels and time of day, and be easy to understand and use. "Smart" microprocessor- driven controllers with occupancy-detecting sensors can "learn" the activity of a household over time, activating mechanical equipment.

A mechanical system also requires careful commissioning to ensure optimal operation. During commissioning, mechanical equipment is checked for proper operation, distribution systems are balanced, and controls are all checked. All too often, careless mistakes in installation and set-up result in poor system performance. Without a commissioning process, these mistakes might not be caught for years. Commissioning is important in both commercial buildings and homes. Clear, thorough documentation is critical to ensure proper ongoing maintenance and operation of systems of any size.

Biomass for woodstoves, pellet stoves, wood-chip boilers, and other combustion devices is renewable as long as production of that biomass is sustainable that is, as long as harvesting doesn't outpace regeneration or stress the ecosystems. Some of these heating systems can generate significant amounts of air pollution; however, so appropriate pollution controls such as catalytic converters or secondary burn chambers should always be incorporated.

Plumbing

Access to fresh water is one of the world's major geopolitical issues, yet in most of the U.S. we still use drinking-quality water as if it were free and unlimited. A substantial portion of this usage happens in buildings where Leaky plumbing drips it away and fixtures designed decades ago use exorbitant quantities. In some areas of North America, water is drawn from ground and surface sources at unsustainable rates in other words, withdrawals from aquifers exceeding annual recharge rates. For much of the year, for example, the Colorado River no longer reaches the Gulf of California. In the U.S., we currently withdraw over 300 billion gallons of fresh water per day from streams, reservoirs, and wells. Even in places where the water supply has traditionally not been a concern, problems are appearing as populations grow or precipitation patterns change (perhaps due to global climate change).

Toilet flushing uses over 4 billion gallons of water per day in the U.S. alone. While older toilets use about 4 gallons per flush, modern toilets conform to the requirements of the Energy Policy Act of 1992 and use no more than 1.6 gallons per flush (gpf). Simply replacing those older toilets with the new ones has been found to reduce a household's overall water use between 10% and 30% Some toilets use less water or even none at all. GreenSpec includes toilets that provide exceptional flush performance as determined by the Maximum Performance (MaP) testing protocol. Other water-saving designs, devices, and systems are also included. The Energy Policy Act of 1992 also mandates that shower-heads and faucets can use no more than 2.5 gallons per minute (gpm); some models use substantially less. Retrofitting these devices in older buildings is usually a very easy and extremely cost-effective investment.

Consumption of potable water can also be reduced by recycling graywater for nonpotable uses, such as irrigation and toilet flushing; however, these systems may be prohibited by local health codes. In most of California it is legal to use graywater for landscape irrigation, provided the system is designed to meet certain conditions.

The drain on limited water supplies can also be reduced by harvesting rainwater. On some of the Virgin Islands, rainwater-storing cisterns provide the primary water supply to most homes. In parts of the U.S., it is not uncommon for collected rainwater to be used for landscape irrigation, toilet flushing, laundry, and other nonpotable uses. For use as potable water, collected rainwater should be filtered and disinfected.

The other end of the plumbing system is waste-water disposal. Many conventional waste-water treatment systems, including both large municipal systems and private on-site septic systems, are inefficient and/or expensive. Alternative technologies are available for systems of all sizes: from composting toilets and recirculating sand filters, to ecological waste-water treatment systems that rely on enhanced biological treatment processes.

Electrical

The plastic insulation and jacketing on electric and data wire and cable can contain lead, plasticizers, flame retardants, and chemicals that may be toxic. Polyvinyl chloride (PVC) and fluoropolymers (Teflon®) are commonly used on wire and cable. Toxic compounds may be released in the event of fire or as the wire jacketing deteriorates over time. Wires and cables are available with non halogenated insulation and jacketing and with no heavy metals.

Electrical current flow creates electromagnetic fields (EMF5), which according to some experts may cause a range of adverse healthy effects. While many studies have been conducted, these health concerns have yet to be proven to the satisfaction of mainstream scientists. Due to the uncertainty surrounding this issue, it makes sense to take steps to minimize exposure to such fields, as long as these measures aren't expensive (a strategy referred to as "produce avoidance"). Such measures might include locating main electrical service lines away from occupied areas and specifying that wiring be installed in such a way as to minimize EMFs. Electronics may also be sensitive to EMFs, so rooms with computers and other such equipment should be designed with that in mind.

Lighting

Lighting is a major user of electricity. Besides using electricity, electric lighting also generates heat, contributing to cooling loads that are generally met by using more electricity for air-conditioning. Thus, improving the energy efficiency of lighting has benefits that go beyond the direct electricity savings by the lighting products.

Fluorescent lamps are three to four times more efficient than incandescent lamps. Quality fluorescent lamps today provide far better light quality than the older lamps that often produced a bluish cast. Electronically ballasted fluorescent lighting also doesn't generate the hum and flicker that many people find objectionable in older, magnetically ballasted fluorescent lighting. Both straight-tube fluorescent and compact-fluorescent lamps (CFLs) are widely available. In general, thinner-diameter fluorescent lamps offer higher efficacy (lumens per watt) than larger-diameter lamps. LED (light-emitting diode) light sources are also being introduced and are approaching the efficacy of fluorescent lamps. The highly focusable nature of LEDs enable significant energy savings in certain applications. Unlike fluorescent, metal halide, sodium, and other high-intensity discharge (HID) lamps, LEDs do not contain mercury.

Older magnetic ballasts for fluorescent lighting may contain highly toxic PCBs or the less toxic but also problematic DEHP; these should be handled carefully and disposed of properly when changing or servicing fixtures. Fluorescent lamps (as well as all HID lamps) also contain small amounts of the toxic metal mercury. These lamps should never be landfilled or incinerated but instead be recycled by a company that reclaims the mercury. Some new lamps are available with mercury levels far below the industry average, and these should be used whenever possible.

Daylighting strategies must be carefully designed if they're to result in net energy savings. In commercial buildings, savings often don't accrue unless there are automatic controls; but in homes, those controls may not be as necessary to achieve savings. Daylight also introduces heat that can increase cooling loads (though daylight's ratio of heat to light is less than that of all common artificial light sources). Daylight can also cause problems with glare. In spite of these potential pitfalls, daylighting is a valuable strategy for saving energy and improving the well-being of occupants.

Appliances

Appliances are significant ongoing users of energy and portable water. Federal standards for some appliances are helping to ensure that certain new appliances will be far more efficient than models they are replacing, but some manufacturers offer products that significantly exceed federal standards. Many of the most efficient appliances come from Europe, where energy is more expensive than in North America.

Horizontal-axis clothes washing machines have long been the standard among commercial-quality washers and in Europe. They use much Less water than the typical American top-Loader, are generally on the clothes, use Less detergent, wash more effectively, and because they spin faster  remove more of the moisture from a Load of Laundry, which reduces the amount of energy needed for drying. For years these models were almost impossible to find in the U.S., but now most major American manufacturers are producing them. Although more expensive than standard toploaders, the extra cost of a horizontal-axis washer will be covered by detergent savings alone even before the water savings, energy savings (by using Less hot water and reducing drying time), and wear-and-tear on clothing are factored in.

As with other appliances, seek out an efficient dishwasher that meets the convenience and feature requirements and don't use energy-guzzling features, such as heat drying, when it isn't necessary. Most models have a water-saving cycle that should be used for lightly soiled dishes or partial Loads (though it usually makes the most sense to wash only full Loads). Note that hand-washing dishes may use more water and energy than a dishwasher, depending on how one does the hand-washing.

Driven by national standards, the energy efficiency of refrigerators has improved greatly over the past few decades. Unfortunately, a common practice when buying a new refrigerator is to keep the older one for storing beer and soda; this practice should be avoided. In general, refrigerators in the 16- to 20-cubic-foot range tend to be most efficient (because these are the most popular sizes, this is where manufacturers invest the most R&D funding), as are those with freezers on top or bottom instead of side-by-side. Avoid extra convenience features like ice-makers unless they'll really get used.

For ranges and cooktops, electric elements should be preferred over gas simply to avoid the toxic byproducts of gas combustion in the house. If a gas appliance is used, an effective, exhausting vent-hood (rather than one that simply filters and reticulates the air) should be used whenever the burners are on. As quiet a range-hood fan as possible should be selected to increase the Likelihood that it will be used by occupants. Halogen electric elements provide the instant-on, instant-off performance that many cooks seek in a gas range.

Most gas ovens use a significant amount of electricity because they have a glow-bar that is on continuously in order to reignite the gas fame immediately if it is blown out somehow. In fact, a microwave oven can use less electricity to bake a potato than a gas oven! While microwaves are a more efficient way to cook, there are some concerns about the possible Leakage of microwaves if the door seals aren't perfect.

Furniture & Furnishings

The introduction of furnishings that offgas hazardous chemicals can undo all the care given to using "dean" building materials. Furniture and furnishings incorporate many separate products and all of the issues that go with them. As a result, they can be a significant source of IAQ problems coming from binders in wood composites such as particleboard, from finishes used on the products, from flame retardants used in foam cushions, and from adhesives used to assemble the products. Those items incorporating fabric, such as upholstered furniture and workstations, can a [so collect dirt and airborne contaminants, releasing them later.

Most of the plastic laminates used on inexpensive furniture are made from phenolic resins. These compounds are somewhat toxic to work with but relatively stable and they're easy to keep clean after manufacture.

Hardwoods especially tropical hardwoods used in furniture manufacture should be third-party certified according to Forest Stewardship Council (FSC) standards to ensure that they were harvested in an environmentally responsible manner. FSC certification involves third- party evaluation and monitoring of sustainable forestry practices.

Most fabrics used on commercial furniture and workstations are primarily polyester. Wool is a durable and attractive natural alternative, though it is sometimes treated with toxic mothproofing agents. The polyurethane foam padding used in furniture generally contains polybrominated diphenol ethers (PBDEs), which are bioaccumulating datives of PCBs. These flame retardants are released into the building as the foam padding ages.

Furniture should be as simple as possible, with a minimum of different materials, and it should be assembled with mechanical fasteners rather than adhesives to facilitate end-of-life recycling.

Some innovative designers have produced lines of furniture made from various recycled materials and with high recyclables.

Renewable Energy

Renewable energy sources offer environmentally attractive alternatives to fossil fuels and nuclear power. Although no energy system can claim to be 1000/0 pollution free, renewable are orders of magnitude better than our conventional energy systems. The U.S. Department of Energy estimates that the annual influx of accessible renewable resources in the U.S. is more than 200 times the total amount of energy used. Technologies for converting these energy sources into electricity or usable heat are improving in efficiency and dropping in price.

The simplest way to utilize renewable energy in buildings is with climate-responsive design passive solar heating in winter, summertime cooling with natural ventilation, and daylighting.

The field of building-integrated photovoltaic (BIPV) is expanding dramatically, with enormous arrays of PV panels on large, institutional buildings and smaller arrays integrated into individual homes. These typically come in the form of panels that can be wall- or roof-mounted, though PV panels that serve a dual rote as glazing and power production are now also available. Solar-domestic hot water systems have quick paybacks in climates where sophisticated freeze-control systems aren't needed.

In colder climates the paybacks are longer, but such systems can still be a very worthwhile investment.

While large-scale hydroelectric facilities are associated with some significant environmental problems (most notably the displacement of humans and other species, and the interruption of fish migration); carefully sited small-scale hydropower may be a good option.

The Union of Concerned Scientists estimates that wind power could supply one-fifth of U.S. electricity demand. Small, home-based wind machines range in output from 250 watts to 10 kilowatts (compared to utility-sized wind turbines can product more than 750 kilowatts of power).

One issue affecting many renewable energy sources is that their power production varies with the time of day and season. In some cases, the peak production actually matches peak demand for example, photovoltaic systems generate the most electricity on hot days, when cooling loads are highest. In other cases, different forms of energy storage are needed to match the energy demand with energy production.

Distributors & Retailers

Green building products are increasing[y available from mainstream distributors and building suppliers, but only a few U.S. cities are fortunate enough to have specialized green building suppliers that stock a significant range of products. In most places, green building products that aren't available through mainstream suppliers will need to be purchased directly from the manufacturer, by mail, order, or from regional distributors specializing in those products. Specialized distributors and retailers of green building products are addressed here.