Material considerations are integral to make designs environmental. They are used temporarily for construction and form every part of the hotel structure and designed landscape. Selection of material is important with respect to type of material, recyclability, recycled content, embodied energy, hazardous constituents, and life cycle analysis.

ENVIROMENTAL DESIGN ISSUE
Introduction

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ENVIROMENTAL DESIGN ELEMENT
Overview

A variety of issues need attention when selecting materials for a building. Each issue stands on its own merit and does not override any other issue. The design team should consider all issues in conjunction with environmental goals set out for the project.


Reduce material use, reuse, and recycle – in that order of priority.

Use new materials thoughtfully; consume the minimum for the purpose; avoid waste. Design building to utilize common dimensions of materials.

Perform and environmental-impact and cost analysis of all materials based on life-cycle principles.

ENVIROMENTAL DESIGN ISSUE
Introduction

issue content

ENVIROMENTAL DESIGN ELEMENT
Overview

A variety of issues need attention when selecting materials for a building. Each issue stands on its own merit and does not override any other issue. The design team should consider all issues in conjunction with environmental goals set out for the project.


Reduce material use, reuse, and recycle – in that order of priority.

Use new materials thoughtfully; consume the minimum for the purpose; avoid waste. Design building to utilize common dimensions of materials.

Perform and environmental-impact and cost analysis of all materials based on life-cycle principles.

ENVIROMENTAL DESIGN ELEMENT
Needed at all?

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ENVIROMENTAL DESIGN ISSUE
Decision Criteria

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ENVIROMENTAL DESIGN ELEMENT
Building Reuse

When an existing structure is available, attempt to design the building to utilise the existing structure and materials. This will reduce the overall embodied energy of the development.


Utilize existing building structures whenever possible.

ENVIROMENTAL DESIGN ELEMENT
Resource Reuse

Select salvaged or recycled materials and components. This will reduce costs and lower overall embodied energy. Many large dimensional wood products are now only available through salvage businesses.


Salvage materials and components whenever possible. Specify reclaimed and salvaged materials whenever possible

ENVIROMENTAL DESIGN ELEMENT
Material Efficient

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Recycled Content

Materials and components with recycled content reduce environmental impacts. Give preference to post-consumer recycled content over post-industrial content.


Specify minimum recycled content for materials and components.

ENVIROMENTAL DESIGN ELEMENT
Natural vs Synthetic

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Toxic?

Minimize or elimnate the use of treated lumber. Instead choose materials that are better suited to resist deterioration. If wood preservative is required seek out the least toxic or non-toxic alternatives.

ENVIROMENTAL DESIGN ELEMENT
Local or Regional

Products that originate and/or are made from/with local materials and are manufactured locally generally have less environmental impacts. These products do not include the high environmental costs of transportation. Purchasing locally supports local workers and enhances the sustainability of the locality.


Specify local or regional materials that originated or were manufactured within 800 km of the construction site or building.

ENVIROMENTAL DESIGN ELEMENT
Recyclable

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ENVIROMENTAL DESIGN ELEMENT
Biodegradable

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Impact Displacing

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Rapidly Renewable

Selecting components and finishes that contain rapidly renewable materials favours sustainable industries and avoids the use of products from endangered ecosystems such as old growth forests.


Specify products from rapidly renewable sources.

ENVIROMENTAL DESIGN ELEMENT
Certified Sustainable or Organic

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ENVIROMENTAL DESIGN ELEMENT
Packaging

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Maintenance Required

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ENVIROMENTAL DESIGN ELEMENT
Health and IAQ Issues

Selecting materials is one of the most important steps to avoid indoor air quality problems.


Review emission levels from building products at the following stages: installation, occupancy, and maintenance and removal.

Consider these additional materials issues and effects: the sink effect (i.e. absorption of chemicals by materials), moisture and temperature, natural materials.

ENVIROMENTAL DESIGN ELEMENT
Life-cycle Cost

An accurate comparison of the land, water, air, and climactic impacts of various electricity generation options requires "life cycle" analyses, which examine the effects of producing and transporting fuel, building and subsequently decommissioning facilities, generating power, and treating and disposing of waste. For ease of comparison, some studies translate these diverse impacts into dollars, in keeping with past regulatory practices of attempting to identify the leastcost resource strategy. Such comparisons are controversial and, to some readers, unsatisfying, since many human health and environmental effects have no clear dollar cost.

ENVIROMENTAL DESIGN ELEMENT
Embodied Energy

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ENVIROMENTAL DESIGN ISSUE
Common Building Materials

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ENVIROMENTAL DESIGN ELEMENT
Common Building Materials

The following discussion identifies problems and solutions for each of the CSI building material categories.

ENVIROMENTAL DESIGN ELEMENT
Concrete Issues (DIV3)

Resource efficient options:
-use fly-ash mixed with concrete up to 30% (may include ground blast-furnace slap from metal smelting operations);
-consider using palm tree husks;
-recycle crushed concrete, brick, and other masonry waste as a source of aggregates;
-utilize anti-corrosion agents such as epoxy coatings to reduce cracking and maintenance;
-use low-waste form work, recycle it, or incorporate form work into foundation design to serve as both structure and insulation value;
-when not in contact with earth or soil – consider eliminating air entrainment agents, plasticizers, water-reducing agents, sulphate resistant chemicals, curing agents (use water instead), calcium chloride; which will reduce costs.

ENVIROMENTAL DESIGN ELEMENT
Concrete Alternatives and Solutions

ENVIROMENTAL DESIGN ELEMENT
Masonry Issues (DIV4)

Resource efficient options:

-consider lightweight concrete blocks with expanded aggregates (i.e. pumice) that reduce weight and increase insulation value;

-select brick and block products with recycled content (i.e. sewage sludge and ash from incinerators and coal-burning plants);

-select glass blocks with recycled glass content.

ENVIROMENTAL DESIGN ELEMENT
Masonry Alternatives and Solutions

ENVIROMENTAL DESIGN ELEMENT
Metal Issues (DIV5)

Buildings utilize a variety of metals in construction.

Steel is a combination of metals that may include: manganese, silicon, carbon, sulphur, phosphorous, aluminum.

The raw materials for steel originate from sub-surface mines. Typically ores contain about 5 percent metal. Thus, significant rock waste or tailings are produced when exhuming these metals. The most significant environmental impact of this type of mining is acid generation from the oxidation of sulphide materials found frequently in metal mines. When present acid generation is an indefinite process that requires continual remediation.

Steel provides a high strength-to-weight ratio. Thus it forms the structure of many buildings. Although steel is essentially 100% recyclable indefinitely, the amount of recycled content in steel available in today’s market can vary and rarely reaches the 100% level (NOTE: Statistics below based on US Market).

2 Methods of steel making

BOF or Basic Oxygen Furnace

– steel that requires drawability (appliances, sheets, pails, soup cans, etc.)

– uses 31.7% recycled steel (31.7% avg => 20.4% p.c. + 9.6% p.i.)

EAF or Electric Arc Furnace

- steel that requires strength (structural beams, rebar)

- uses 95.5% recycled steel (95.5% => 58.9% p.c. + 31.2% p.i.)

Source: Steel Recycling Institute 2001.

Thus, structural steel components have a high proportion of recycled content, whereas sheet metal has significantly less recycled content.

ENVIROMENTAL DESIGN ELEMENT
Metal Alternatives and Solutions

ENVIROMENTAL DESIGN ELEMENT
Wood Issues (DIV6)

Resource efficient options:

ENVIROMENTAL DESIGN ELEMENT
Wood Alternatives and Solutions

Health and pollution issues:

ENVIROMENTAL DESIGN ELEMENT
Plastic Issues and Alternatives

Figure: Plastic in the waste stream USA, 1999.



Source: http://www.ohiodnr.com/recycling/awareness/facts/plastics/plasticrecycling.htm

Plastics (resins) are typically divided into 7 categories: Poly-Ethylene Terephthalate (PET), High Density Polyethylene (HDPE), Polyvinyl Chloride (PVC), Low Density Polyethylene (LDPE), Polypropylene (PP), Polystyrene (PS), and other less common or composite plastics. At present, most municipalities only recycle plastics in the first and second categories as the other types are more costly to recycle.

Poly-Ethylene Terephthalate (PET) is perhaps the most environmental form of fossil fuel derived plastic as it can be recycled indefinitely. Soda bottles are made of this material and can be remanufactured into products such as fleece sweaters.

High Density Polyethylene (HDPE) is a plastic used to make milk containers and grocery bags. It can be down-cycled (i.e. cannot be recycled into the same product) to make products such as parking stops.

Polyvinyl Chloride (PVC) is a common plastic used in 70% of all building materials including piping, window frames, and vinyl siding. It is difficult to recycle and contains harmful constituents that can be released during use or when disposed in landfills. It is considered the plastic with the greatest potential health and environmental impacts. The PVC lifecycle (its production, use and disposal) results in the release of toxic, chlorine based chemicals. These toxins are building up in water, air and the food chain. The use of PVC compares unfavorably with other building materials in: air quality, embodied energy, recyclable and lifecycle toxicity impacts.

Low Density Polyethylene (LDPE) is used in food freezer bags, paint can lids, shrink wrap packaging and electrical wire casings. This plastic can be recycled similar to PETE plastics.

Polypropylene (PP) is used extensively in flooring products such as carpets. This type of plastic can be recycled although many products such as carpet include other materials that make it difficult to recycle.

Polystyrene (PS) is a common plastic used to make insulation products or packaging. It tends to disintegrate into smaller components and thus is extremely difficult to recycle or dispose of.

This category of plastics is the most difficult to recycle as it includes less common types of plastic and composite products like televisions and electronics that are difficult to separate.

ENVIROMENTAL DESIGN ELEMENT
Thermal Insulation and Moisture Protection (DIV7) - Issues

Resource efficient options:
-mineral-fibre is made primarily from basalt rock and steel mill slag, loose-fill, batts, and rigid board;
-glass-fibre is now available with 30%+ post consumer recycled glass content, loose-fill, batts, and rigid board;
-cellulose thermal insulation and acoustic sprayed coatings contain at least 70% post consumer recycled paper, does not settle after installation, may contain mineral fibre for fire retardancy and acoustic mediation;
-foamed polystyrene insulation is available with post consumer recycled content (See Table 3.3.1 above), expanded types are made with non-CFC gas, extruded types were made with CFCs – now with HCFCs, consider new varieties made without HCFCs;
-urethane foams, made with HCFCs, rigid board, and sprayed-in-place;
-vermiculite and perlite are naturally occurring materials, used in plaster mixtures, and loose-fill;
-spray-in-place foamed silicate mixture insulation is made from sodium silicate and magnesium oxychloride, used for fire retardancy, spray fill;
-strawbales…
-reflective film-radiant insulation, made from aluminium foil and metallized plastics, used to reduce radiant component of energy transfer, requires air space.

ENVIROMENTAL DESIGN ELEMENT
Thermal Insulation and Moisture Protection Alternatives and Solutions

-Health and pollution issues: precautions should be taken to avoid inhalation of insulation particles (especially glass-fibre), fumes from burning plastic insulation are particularly toxic and may be banned in some cases, consider using natural products w

ENVIROMENTAL DESIGN ELEMENT
Cladding and Roofing - Issues

Resource efficient options:
-metal panels, made of galvanized steel and enamelled or anodized aluminium, durable and recyclable, little material to cover area, generally for pitched roofs and cladding;
-composite shingles, tiles, and panels, made of fibre-reinforced cement products (some coated with plastics, enamels, or thin metals), consider colour and resulting impacts on design HVAC;
-stucco, …;
-higher-quality asphalt shingles and fibreglass shingles, available with recycled content, consider colour and resulting impacts on design HVAC;
-torch-on roofing for flat or low pitch roofs, easy to repair, easy to install topsoil and sod on top (adding insulation), no recycling system available, easy to remove;

ENVIROMENTAL DESIGN ELEMENT
Cladding and Roofing Alternatives and Solutions

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ENVIROMENTAL DESIGN ELEMENT
Sealants - Issues

Resource efficient options:
-selection of products with best durability and life span is optimum choice due to costs of replacing and damage resulting from sealant failure.

ENVIROMENTAL DESIGN ELEMENT
Sealants Alternatives and Solutions

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ENVIROMENTAL DESIGN ELEMENT
Gypsum Products Issues

ENVIROMENTAL DESIGN ELEMENT
Gypsum Products Alternatives and Solutions

ENVIROMENTAL DESIGN ELEMENT
Engineered or Composite Wood or Plastic Panels Issues

Resource efficient options:
-hardboards, made from wood fibre that is pressed and heated, typically no adhesive is required as natural lignin in wood bonds to form panels, resource efficient, durable, can be easily recycled;
-particleboard and medium-density fibreboard (MDF) panels, made from sawdust, wood chips which are pressed with glue, resource-efficient, potential source of off-gassing if not sealed;
-low-density fibreboards, made from paper and wood fibre, most panels don’t contain glue, resource efficient, recyclable;
-veneered wood panels (i.e. oriented strand board with hard wood facing), resource efficient, recyclable, may contain adhesives that can off-gas;
-recycled plastic panels, made from consumer product waste, resource efficient, potentially recyclable, may contain ingredients that can off-gas;
-vegetable-oil based plastics, made with coloured minerals, metal shavings, wood fibre, or plastic waste, reusable, resource efficient;
-fibre-reinforced cement boards, made from recycled fibre, resource efficient, reusable.

ENVIROMENTAL DESIGN ELEMENT
Engineered or Composite Wood or Plastic Panels Alternatives and Solutions

ENVIROMENTAL DESIGN ELEMENT
High Pressure Laminates Issues

Resource efficient options:
-made from laminating paper and colourants together with melamine (i.e. phenolic) resin, durable, products with recycled content not available as of yet.

ENVIROMENTAL DESIGN ELEMENT
High Pressure Laminates Alternatives and Solutions

ENVIROMENTAL DESIGN ELEMENT
Ceramics and Terrazzo Issues

Resource efficient options:
-local or regional ceramic products reduce impact of transportation;
-some ceramic products are available with recycled content (70% or more);
-terrazzo, made from cement and crushed stone, resource efficient.

ENVIROMENTAL DESIGN ELEMENT
Ceramics and Terrazzo Alternatives and Solutions

ENVIROMENTAL DESIGN ELEMENT
Wood Flooring Issues

Resource efficient options:
-salvaged solid-wood flooring, resource efficient, less expensive but increase cost of installation, requires sanding and refinishing;
-new wood flooring, made with veneers or laminates, resource efficient, may contain glues that can off-gas;
-domestic hardwoods (i.e. oak, maple, birch, ash, Australian eucalyptus, Scandinavian beech), most likely to come from sustainable sources, sustainable tropical hardwoods are also available;
-steel-track system using wedges to hold flooring down provides greatest reusability, nailing offers reusable potential, glue offers least reusability.

ENVIROMENTAL DESIGN ELEMENT
Wood Flooring Alternatives and Solutions

ENVIROMENTAL DESIGN ELEMENT
Resilient Flooring Issues

Resource efficient options:
-true linoleum products, made from linseed oil, cork, wood dust, or jute, highly durable, renewable materials;
-recycled rubber flooring, made from recycled tires and waste, resource efficient, good for high traffic areas.

ENVIROMENTAL DESIGN ELEMENT
Resilient Flooring Alternatives and Solutions

ENVIROMENTAL DESIGN ELEMENT
Carpets and Underpads Issues

Resource efficient options:
-polyester and nylon blended carpets, made with recycled content from PET soft-drink containers, varied performance and durability characteristics;
-high density, low-pile wool carpet, renewable material, inherent fire resistance, adequate durability;
-carpet tile and releasable roll carpet systems, longer life span potential, reusable or recyclable;
-nylon 6, high level of recyclability;
-carpet pad, made from sponge plastics and rubber, available with recycled content;
-carpet pad, made from natural jute or other products…

ENVIROMENTAL DESIGN ELEMENT
Carpets and Underpads Alternatives and Solutions

ENVIROMENTAL DESIGN ELEMENT
Finished Concrete Flooring Issues

Resource efficient options:
-See Paints below, proper sealing and waxing can prolong life.

ENVIROMENTAL DESIGN ELEMENT
Finished Concrete Flooring Alternatives and Solutions

ENVIROMENTAL DESIGN ELEMENT
Paint Issues

Indoor Air Quality
Conventional paints are the most significant producer of indoor air quality problems. This is a result of the fact that paint begins as a liquid but must dry. The drying process involves the evaporation of liquid chemicals in the paint that enter the air as vapours. These chemicals often referred to as VOC's or volatile organic compounds are particularly harmful in the indoor environment.

ENVIROMENTAL DESIGN ELEMENT
Paint Alternatives and Solutions

Resource efficient options include:
-recycled paints, resource efficient
-solvent based paints
-low or no VOC paints
-low or no Biocide paints
-natural paint, made from all natural ingredients (i.e. citrus base), renewable, recyclable, compostable

ENVIROMENTAL DESIGN ELEMENT
Ceiling Tiles Issues

Resource efficient options:
-Ceiling tile, made from mineral fibre with added clay or gypsum fibres for fire retardency, reusable, recyclable.

ENVIROMENTAL DESIGN ELEMENT
Ceiling Tiles Alternatives and Solutions

ENVIROMENTAL DESIGN ELEMENT
Finishes - Specialties

Resource efficient options:
-demountable systems or office partitions, made with recycled content, significantly reduces waste due to change in floor plans;
-decking and patio products
-siding…

ENVIROMENTAL DESIGN ELEMENT
Furniture Issues

ENVIROMENTAL DESIGN ELEMENT
Furniture Alternatives and Solutions

Resource efficient options:
-used, refinished or reclaimed furniture, resource efficient;
-reconditioned furniture, resource efficient;
-furniture, made from steel, glass, and/or solid wood, reusable, recyclable;
-furniture, made from tropical hardwoods, durable, reusable, recyclable;
-upholstery and foams, previously made using CFCs, now available using HCFCs or other less harmful processes.

ENVIROMENTAL DESIGN ISSUE
Emerging Building Materials

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ENVIROMENTAL DESIGN ELEMENT
Straw Bale

History of Straw Bale
Agricultural materials have been used in construction for millennia. The earliest straw bale structure in North America was likely built in Bayard Nebraska in 1896. It was a ‘Nebraska-style’ load-bearing schoolhouse with a sod roof. These straw bale buildings were meant to be temporary shelter but once people lived in them they realized that the straw bale design afforded superior insulation and protection from the elements.

The first post and beam strawbale home was built in Alabama in 1936. Straw bale popularity waned however after World War II due mainly to the availability of other building materials such as timber and manufactured synthetic insulation products. The energy crisis of the 1970’s revived interest in straw bale and led to Roger Welsch’s 1974 seminal article, ‘Baled Hay’ in the journal Shelter.

The first permitted (bank-financed and insured as well) straw bale structure in the United States was built in 1991 in Tesuque, New Mexico by Virginia Carabelli. ‘The Last Straw’ newsletter began circulation this year as well by pioneer straw builders Matts Myhrman and Judy Knox. A permitted load-bearing straw bale structure followed in 1993. This was the same year of the first straw bale conference, ‘Roots of Revival’ in Arthur, Nebraska. The event attracted more than 50 design and construction enthusiasts.

Strawbale structures appeared in Canada as well, with significant work by Francois Tanguay in Quebec during the early 1980’s. He along with Michel Bergeron and the Canada Mortgage and Housing Corporation conducted strength and heat conduction research that allowed for further funding and wider adoption by the building industry. They also experimented with straw fibres in place of steel rebar in concrete. Their work led to the formation of ArchiBio (Architecture Bioclimatique). They later taught workshops in France and were involved in a number of straw bale buildings in Europe. However they weren’t the first as France’s first straw bale building was commissioned in 1979. In the early 1990’s a Fin designed and built a straw bale home without the knowledge that straw bale buildings existed.

In western Canada, a straw bale church built in the 1950’s remains as a testament to the early Alberta pioneers of this building archetype. Jorg and Helen Ostrowski have led the straw bale initiative in Alberta with the design of a number of straw bale buildings including what maybe the first straw bale commercial building in North America (2000).

Straw bales have been used to make buildings in the Steppes of Russia since at least 1994, in Mexico since the early 1990’s and in Guatemala in 1994. The technology has been spreading in Latin America with the aid of a variety of organizations including the ‘Farmer to Farmer’ program of the University of Arizona.

Benefits of Straw Bale Buildings
Straw bales are almost the ideal building material. Typically straw is treated as an agricultural waste product as it is slow to decay unlike nitrogen-rich hay. As a result, farmers often burn straw on the field as a means to remove it. This creates significant air pollution. Sacramento California suffers for a month each year as a million tons of straw are burnt in the valley releasing carbon monoxide and particulates that cause respiratory problems and cancer. This pollution is equal to the total amount produced annually by the state’s electrical generation facilities combined. It is estimated that enough straw is incinerated each year in the U.S. to build 5 million 2000 square foot homes.

As a resource instead of a waste product, straw bales can be sustainably grown (ideally as perennial crop; intercropped in China) in low quality soil and are a biodegradable all natural material. Bales are durable, breathable, and provide significant thermal mass and sound attenuation. The R-value of straw bales is 3/inch (2.4 with grain) as compared to wood 1/inch, brick 0.2/inch, and fibre glass batt insulation 3/inch. The embodied energy of straw bales is approximately 1/50th of concrete (1 ton straw = 112,500 BTUs, 1 ton concrete = 5,800,000 BTUs). A typical straw bale wall has 1/30th the embodied energy of a timber frame wall. Straw bale construction requires non-specialized labour (basic skills can be learned in a 2-day workshop), minimal tools, and is a catalyst for social interaction and community involvement.

Details of Straw Bale Construction
Straw bales can be made from rice, wheat, rye, flax, barley, and oats. Halophytes (plants that grow in salt water) and recycled paper fibre may also be used. Bales that are bound with string (jute or polypropylene) are easier to work with than wire.

Straw bale walls are effective as load-bearing members and typically sustain 10,000 lbs/sq.ft. when bales are laying flat. Bales that are arranged on edge (see Figure below) are less effective as load-bearing members but are better insulation and thus preferred for straw bale infill insulation. Straw bale design is effective at absorbing seismic loads. With 8 out of 10 buildings worldwide constructed of earth, adobe, and stone, straw bale could significantly reduce the damage caused by earthquakes around the world.

Straw bales have exceptional fire resistance due to the lack of air circulation that penetrates the bales. Rodents are less a concern than once thought. More space is available for rodents in other building methods, and the seed of the straw, which attracts rodents has been removed. Termites prefer wood and can be deterred by termite shields, sand barriers, vapour barriers, diatomaceous earth and borax (also a good fire retardent).

Load-bearing designs are more difficult to attain building code approval (where required) and thus a variety of infill designs are often used.

ENVIROMENTAL DESIGN ELEMENT
Cob

Earth is probably the world's most common building material. The word cob comes from an Old English root meaning a lump or rounded mass. Cob building uses hands and feet to form lumps of earth mixed with sand and straw, a sensory and aesthetic experience similar to sculpting with clay. Cob is easy to learn and inexpensive to build. Because there are no forms, ramming, cement or rectilinear bricks, cob lends itself to organic shapes, curved walls, arches and niches. Earth homes are cool in summer, warm in winter and suitable to rainy climates.

Cob has been used for millennia even in the harsh climates of coastal Britain. Thousands of comfortable and picturesque cob homes in England have been continuously occupied for many centuries and now command very high market values. With recent rises in the price of lumber and interest in natural and environmentally safe building practices, cob is enjoying a renaissance. This ancient technology doesn't contribute to deforestation, pollution or mining, nor depend on manufactured materials or power tools. Earth is non-toxic and completely recyclable. In this age of environmental degradation, dwindling natural resources, and chemical toxins hidden in our homes, doesn't it make sense to return to nature's most abundant, cheap and healthy building material?

ENVIROMENTAL DESIGN ELEMENT
Adobe

Adobe is one of man's first building materials. The mass of the adobe walls will absorb heat and radiate it back out into the house at night. In the summer the converse is true. Thus the swing in temperature inside the house is very mild. For thousands of years adobe houses have represented the practical wisdom of people who learned how to use the materials at hand to build homes that fitted the climate and landscape in which they lived. Adobe making runs back to the time of Pharaoh who withheld from the children of Israel the straw for sun-baked bricks. Adobe construction also embodies strands of our southwestern history. When the Spaniards came to New Mexico they found the Indians using adobe, wood, and stone to house themselves. The Indians did not make bricks, but "puddled" the mud allowing each layer to dry before adding more. Adopting these materials the Spanish made moveable sun-baked bricks, formal fireplaces, and wooden doors. "Adobe" is a Spanish word derived from the Arabic "atob," which literally means sun-dried brick. The Spanish brought to the the Southwest the craft of forming the mud into blocks in wooden molds which is still used today.



Today's bricks are 14 inches long, 10 inches wide, and 4 inches high. They are still made with straw to make the dried mud more weather resistant, and also have a small bit of asphalt mixed in to stabilize them. The bricks can be bought at a reasonable price from a manufacturer who uses bulldozers to mix and pour the mud into the forms. After the mud is poured a board is drawn across the top of the forms to take away excess mud and make the surface flat. After the bricks are dried they are taken from the forms and stacked by hand. The average cost of a brick is about 60 cents. Because the weight of an adobe house is so much greater than that of a frame house, the ground must not only be cleared, but should be compressed before the foundation and bricks are laid. If the ground is not compressed there could be movement promoting cracks in the walls at some later time. Next the footing is dug with a back hoe and then hand tampered to compress the dirt once again. In the Albuquerque area the footing is laid about 18 inches below grade (the surface) to avoid the expanding and contracting that takes place when temperatures go below freezing. In the mountains and the colder regions of New Mexico the footing level will be deeper. Both the footing and the stem wall of an adobe home must be larger because of the extra weight of the walls. The footing and stem wall of a frame house are commonly 16" and 6" respectively. The footing and stem wall of an adobe house are commonly 24" and 14" respectively. Of course this increases the cost of adobe construction.



After the foundation is completed, the first layer or "course" of bricks must be laid. This course must be made of special adobe bricks that are made with more asphalt to make them waterproof. It is best is best to lay the adobe bricks in warm weather because the mud used as mortar will freeze. Ditch bank dirt is used for this purpose because it does not have too much clay or too much sand. The right consistency will shake off a shovel. The mud is applied with a shovel and trowel. Each course is laid the whole length of the walls at the same time with bricks overlapping at the corners. Story poles are set at the ends of the walls and support a string used to mark the next course of adobes. Lintels are beams of wood put over the windows and doors. They are often decoratively carved and serve as headers that help support the openings. Construction progresses and adobes are laid one brick at a time with a "more or less" attitude. While, in construction of a frame house, all of the structures and drywall must be measured and cut exactly to fit with precision. People who are sensitive to toxic substances prefer to build with adobe since their is no need to use chipboard filled with formaldehyde.



When the courses of adobes are high enough, bond beams are laid to tie all the walls together and the vigas are laid on top of this with more adobes in between them. The vigas, hewn from trees, make up the ceiling and are often seen sticking out of adobe houses. Traditionally they were not cut off at the walls simply because of the labor involved, but they have since become a notable architectural trait of the adobe house. Over the vigas, latias are laid at 90 degree angles to each other creating a pattern design. Latias are smaller hewn poles made of pine, spruce or aspen. Sometimes today one inch decking boards are used instead of latias because they are more economical. Twelve inches of fiberglass insulation is then installed between 2" x 6" sleepers which are sloped to give a gravel and tar roof drainage. This is called a pocket roof because the space between the ceiling and the roof provides an area for electrical wiring, recessed lighting, and insulation. A canale, or drain channel, is put in every ten feet or so to help any water drain from the roof.



If two inches of foam insulation is applied to the outside walls at this point it will increase the ability of the adobe walls to maintain an even temperature. This will bring a 14" adobe up to an R-value of 22. A screen is applied after that to help the plaster tack to the walls. Plaster is applied in three coats after the foundation, walls, ceiling and roof are completed. Plastering is said to be an acquired skill. Ninety percent of the cost of the plastering is in the labor.
In present day, the adobe house is for the very rich or the very poor, not because of the expense of the materials or the complexity of construction, but because of the expense or availability of labor. Adobe construction is labor and detail intensive. You must be rich enough to hire out the labor, or poor enough to have the time to do the labor yourself. A custom built adobe house will cost about $100 and up per square foot. An active solar design may add $20,000 to the final cost.



A frame house might go up in two months, while a 3000-3500 square foot adobe might take nine to ten months to construct, Typically, adobe walls range in thickness from 10 to 30 inches with 14 inches being the mean. A frame house will have 4 inch walls and about 5% of the house will be consumes in the walls. The walls of an adobe house will absorb 15-20% of the total space because of their thickness.

ENVIROMENTAL DESIGN ELEMENT
Rammed Earth

Rammed/Stabilized Earth

When you take into account energy efficiency, environmental responsibility, price, comfort, longevity, inherent beauty and architectural power, there is simply no better value in today's home buying market.

But before you make the final commitment to build with earth, there are a few important points you need to think about. The advantages, of course, are numerous and we've taken the opportunity of describing them for you below. There are also certain characteristics of the walls that some people think of as limitations (although to others these same features are considered enhancements). It's critical to us that you be fully aware of these characteristics so that if you do build with earth both your experiences during construction and your appreciation of the finished product will be as rewarding as possible.

The Benefits

Thermal Flywheel Effect

The ability of a solid earth wall to store energy for long periods of time results in interior temperatures that change very little from day to night. Mass walls absorb solar energy during winter days and then re-radiate that energy to offset nighttime heat losses within the building. In the summer months, the mass of the walls absorbs excess heat generated during the day, keeping the inside spaces surprisingly cool, then releases that stored heat to the clear night sky. In a properly designed and oriented building, this can mean significant savings in heating and cooling bills. And because the energy that controls the temperature inside the building radiates directly from the mass of the walls, the quality of the comfort inside is noticeably different than in a space regulated through mechanically altered air. Couple a mass wall with a hydronic radiant slab to achieve the most quiet, uniform, and dust-free heating system available.

Indoor air quality

Earthwalls improve the quality of the indoor environment. Unlike wood-frame buildings, packed full of potentially harmful manufactured materials which can outgas hazardous fumes for months, an earth walled building with a natural finish emits no toxins whatsoever.

Longevity, durability, and low maintenance

Walls built of raw earth in China, Africa, and even the cold wet climates of northern Europe continue to provide shelter after several hundred years of use. With the addition of modern stabilizers, concrete foundations, and steel reinforcing, we can say in total confidence that our earth walls will last for many centuries. And like all other masonry wall systems, whether they are brick, stone, or concrete, exterior maintenance is virtually eliminated.

Fire and insect resistance

Two important reasons for choosing to build with solid earth walls are that they are fireproof and resistant to damage from termites and other insects. Both these factors contribute to greater longevity, of course, but they can also mean an important increase in safety for you and for future occupants

Intangible qualities

One of the most appealing aspects of a house with thick earth walls is the indescribable feeling you get just being inside. There is a certain calmness that simply can't be duplicated with lightweight building materials, no matter what the architecture. Whether it is simply the energy of thermal mass, the healthful air of a natural environment, the quiet that results from the sound absorbing nature of the solid earth, or some other less identifiable quality, there is something special happening inside.

Environmental responsibility

Perhaps the best reason to build with earth is the boost it can give to the health of the planet. Earth is an unprocessed, widely available building material with virtually no side effects associated with its harvesting or use. Since an earth walled building saves construction and energy resources, doesn't pollute, and lasts practically forever it a wise investment in the future of the planet.

The Frequently Asked Questions

Structural integrity

The first question people usually ask about earth walls is, "How do they respond to earthquakes?" The answer is that earthquake safety is our number one concern. In fact, it was the very first engineering task we addressed twenty years ago when the modern renaissance of rammed earth began. Today, there are several different design approaches we employ depending on the design of the building, the method of construction, and the proximity to an earthquake fault. In some cases, individual panels of earth are enclosed within a framework of cast-in-place concrete. In others, the earth walls are fully reinforced with an integral grid of steel reinforcing rods. A third approach is a continuous solid earth wall topped with a bond beam of reinforced concrete. Whatever the engineering design, every wall system is in full compliance with local building codes, including projects built in seismic zone four localities. Each is constructed to the highest standards of workmanship and quality control.

Weathering characteristics

The second most frequently asked question is, "What happens when it rains?" The answer is that if the soil is selected properly and the wall constructed according to specifications, the finished product is as resistant to deterioration as the parent rock from which the soil came, and in some cases even more so. Tests conducted on samples of finished walls demonstrate that stabilized earth can be completely saturated for months at a time without any deterioration whatsoever. Because not all soils are ideal, and because earth loses its insulative properties when it becomes wet, in climates where rainfall can be extreme, walls should be protected against saturation with ample roof overhangs and raised foundations.

What about Radon?

Radon is in fact never confined to any one soil but rather originates deep underground in certain rock formations and passes directly through the mineral soil and the top soil as it escapes to the atmosphere. Radon is of concern when air tight houses are mistakenly constructed on top of these formations.

How much do they cost?

Houses with walls of solid earth will cost slightly more than a comparably designed house with wood-frame walls. As explained above, they are both a better product and a better investment. How much more they cost will depend on your site, the height and complexity of the wall system, the available soil, and the seismic safety factors. Generally the cost increase ranges between 5% and 10%.

The Limitations

The Nature of the Process

Stabilized earth construction, whether it is traditional rammed earth or the new PISÉ process, is still a made-by-hand product. As such, it exhibits all the inconsistencies and variations that characterize any handmade item.
The color and texture of the finished wall will vary from spot to spot. Some areas may be rough and less well-consolidated than others. Shrinkage cracks, honeycombing, and voids are inevitable. Tolerances for line and level are typically more forgiving than for manufactured building materials. In short, a brand new earth wall looks old the minute the formwork comes off.

For the homeowner who desires this old world look, earth walls are a natural. To one who seeks the comfort, security, and energy efficiency of affordable thermal mass, without the patina of antiquity, a wide range of washes and plaster finishes can be applied to the interior wall surfaces.

The truth is, the way the walls look straight off the formwork may not be to your liking, and we recommend that you include the price of a plaster finish in your construction budgeting. If, as the rest of the building takes shape, the natural finish walls enhance the look of the interior in your eyes, then the money reserved for plastering can be invested in some other upgrade to the building finishes.

Efflorescence

In some cases, especially when walls are constructed during wet, cold weather, free lime in the soil mixture can migrate to the wall surfaces, causing a powdery white stain to appear. Efflorescence can be minimized during the curing process by covering the walls with polyethylene if prolonged wet weather is anticipated. Although it is difficult to remove completely, a washing with a mild muriatic solution will greatly reduce the staining.

Exterior waterproofing

Stabilized earth walls, like rock, are slightly porous. In arid regions, the exterior surfaces should require no waterproofing whatsoever. In areas where snow or wind driven rain can be severe, moisture may penetrate all the way to the inside surface of the walls during prolonged storms. In these regions, we recommend sealing the exterior walls, either all of them or only those which are expected to take the brunt of the storm and are not adequately protected by roof overhangs.

Interior wall sealing

Some walls, especially those made with very fine-grained soils, may have a tendency to dust slightly on the inside surfaces. With these soils, and when plaster is not being applied, we recommend applying a coat of clear penetrating sealer such as Ramseal, a product made especially for stabilized earth walls. Even without a dusting condition, a clear sealer can make it easier to keep the natural earth walls clean.

ENVIROMENTAL DESIGN ELEMENT
Gabion Baskets

Gabion baskets are a highly effective, resource efficient, and relatively inexpensive type of retention or check dam structure.

Gabion baskets are rectangular spaces defined by wire-mesh and filled with stone. When stone is readily available, environmental impacts are reduced due to the small embodied energy of the metal mesh (as opposed to concrete) and minimal energy required to transport the gabions and stone to a site. As well, the decommissioning of gabion baskets produces little waste as the gabions are 100% recyclable metals and the stone is local material.

Advantages

Gabions can be purchased in various sizes to suit the height and width of drop required.

Economical, especially if field stone is available.

Less costly (economic, environmental) than rock chutes, especially if rock must be trucked in.

Easy to transport, assemble and install on-site.

Channel gradient is reduced, encouraging soil deposition and vegetative growth.

Gabions are flexible, allowing settlement or frost movement without fracture.

Little maintenance is required and they can remain as permanent structures.

Disadvantages

Gabion rock (75–125 mm) can be difficult to obtain at some quarries.

Baskets are not widely available.

Basket wire can deteriorate after several years.

They are limited to intermittent flows and small drainage areas.

Design parameters limit their practical uses to between 0.3 – 1 m vertical drops, intermittent flows up to 1.5 m3/s, and depth and width of spillway of 0.15–0.5 m and 0.6–2.4 m respectively.