Candace Gossen


Portland, Oregon






Moving into a new paradigm, the natural environment, there is a need to understand how energy is consumed. Current building practices make extensive use of wood, and tree growth cannot sustain the growing demand. To achieve sustainability we need to consider alternative methods of building construction and materials.

More than 90% of new single-family dwellings built consist of wood frame construction. What are the environmental benefits of using alternative building materials in the residential industry? This study using the Phoenix metropolitan area analyzes building materials such as adobe and rammed earth in comparison to the more conventional and traditional methods of residential construction in current practice today.

The construction industry accounts for over 11% of the total energy consumed in the United States annually.(1) Of this 11%, over half is for new building construction with single family structures at the top of the list. Embodied energy encompasses the direct and indirect processes of extraction, transportation, construction and operation of each structure that is built. An increase in embodied energy spirals to resource exploitation. The evolutionary implications are so destructive in nature that there is no culture in modern society that is not affected, and our demand for energy is directly related to consumption, environmental degradation and its supplier the power plant.

The choice of using local materials in residential construction could substantially change evolutionary patterns of a culture that is currently exploiting its resources. Survival depends on responsibility and accountability of our building practices.




Society is becoming more conscious about environmental sustainability and ecology, but economics often hinder even the best intentions. There should be a responsibility not only to create performance standards in operation, but also to choose building materials that have the fewest impacts on the environment. For example, a house that consumes less energy has less of an environmental impact. A house that demands fewer wood materials also destroys fewer trees that are necessary in the absorption of pollutants in our air.

Temperate forests are one of the largest absorbers of air pollutants in the world. For these forests to be ecologically efficient they would have to be able to absorb and clean an equal amount of air pollution that is produced. A tree quotient that would represent this ecological balance looks like this: Tree quotient =Total amount of trees: total amount of pollution compound absorbed from the atmosphere. For example 210 acres of trees are required to

remove the stack emissions released from the production of 1.4 million kilowatt hours (averaged for oil, gas and coal producing power plants).(10) If forest trees were planted every 6 feet on center, there would be an average of


1,200 per acre. Therefore multiplying the 1,200 trees x 210 acres = 252,000 trees required to absorb pollution from 1.4 million kilowatt hours/acre.

As we consider the environmental impacts of the residential construction industry, we can begin with the conventional design of a wood frame house. An average home of 2,000 sf would require 12,782 board feet of dimension lumber for the wall and roof framing. This 12,782 board feet = (17-24 trees) at 9.5" - 16" diameter x 60 feet tall would demand 20 trees to be cut down.(10)

In 1991 Phoenix, Arizona permitted and built 3,713 new single family residences. 90% of these were built of wood frame construction equaling 3,341 new houses. The total new houses were multiplied times 20 trees per house for a total of 66,834 trees required to be cut for the dimension lumber only. Completing the tree quotient, the 66,834 trees = 55 acres of trees. Therefore in 1991, 55 acres were lost that were required to control the pollution of 364,000 kilowatt hours. For an average household of 13,000 - 45,000 kwh consumed annually, this 55 acres would absorb and clean the stack emissions for approximately 8-27 houses.(10)

Power plants have both direct and indirect impacts on the air, land and water we need to exist. These resources are depleting, pollution is increasing, degradation is evident, and the population of the world continues to grow. There is an urgent need for alternatives to today’s building practices. The purpose of this study is to evaluate the relative environmental impacts of conventional building practices, and to suggest alternative approaches that are more environmentally compatible with their local environment.

Earth materials (e.g. dirt, adobe, and aggregate) are just one alternative to the consumption of trees for wood products used in residential construction. Adobe and Rammed Earth are building prototypes local to Arizona, and are also effective as thermal mass in the hot arid desert. They can help reduce the reliance on wood products and the environmental degradation involved in the processing of the wood material.



Eco comes from the Greek word "Oikos" meaning house, habitat or environment in relation to ecology. Culture relating to human ecology is a social paradigm

concerned with the study of spatial and temporal interrelationships between people and their economic, social and political organizations.

When we place these two words together in the form of Eco-culture we have a resurgence of a character, a new generation that is attempting to integrate the relationship of science concerned with organisms and their environment with a society of people. This renewed awareness stems from a grave desire for change, in an attempt to right the wrongs of conventional habits and behaviors addressing ecology of design to maintain a healthy planet. The characteristics of this eco-culture wherever feasible choose to use renewable energy sources. They believe that ecology and economics have a life-cycle of embodied energy and the costs include the environmental impacts of technology and the externalities as a result thereof. Conventional cultures live in short-term options, they tend to have little regard for global cultures, and destroy local commonalties. Eco-culture respects the traditional knowledge of existence and supports local materials and biodiversity.

Humans are creatures of habit and our behavior is a reflection upon that style of thinking that is currently creating more destruction and waste by-products such as pollution than our earth can regenerate into its life cycle. Eco-culture is perhaps our new paradigm to an immediate needed change.




Each object has a cycle called a "Life-cycle". It has a beginning, an ending, and a new beginning. Energy as matter is only transformed, it can never be rid of. The life cycle of an object, such as a piece of lumber for example begins with a tree. In its natural surroundings the tree grows supporting its needs and wastes and until we modify its environment, the tree continually sustains its ecosystem.

When the tree is cut for use, the process begins with the energy required for extraction. For example, the logging operation that cuts this tree is probably several hundred miles at least from the processing plant. The operation of extraction requires a network of logging roads, sawyers to cut the trees, diesel equipment to perform the cutting, skidding, loading and hauling. Semi-trucks now transport the timbers to a mill for further processing. At the mill the tree now cut into logs is put into a log handler, debarker, deck saw, head


rig, a twin band resaw, through a filing room, into edgers, trimmers, sorters, stackers, into computerized dry kilns and then eventually sent to a planing mill. Of this one tree only 75% is usable as milled lumber. The other 25% are scraps that are either burned, or processed with additives into sawnwood products, bark or sawdust. The lumber is further treated chemically and processed for shipment across the country. Again the lumber is loaded onto semi-trucks or rail cars for further transportation to a distributor.

Once arrived at the distributor, the lumber is further divided and shipped again by truck to a local retail supplier. At this point the consumer purchases the materials and again ships them to the building site. Upon reaching the site, the material which was once

a simple element, a tree, is now an extremely complex building material that has been transported several hundreds if not thousands of miles away from its home. It has been stripped, cut, bonded, shaped, treated and is now being used in the construction phase of the building project to make a shelter. It is during this construction phase that multiple layers of wood products bonded with adhesives and formaldehydes are sealed, painted and encased with more adhesives, solvents and chemicals to complete the shelter.

The constructed shelter stands and performs to the best of its ability. Throughout this life cycle of performance, the materials as they are layered, encased and standing, expand and contract under stress of our natural environment and to our human environment of desired comfort levels with the help of furnaces and air conditioners.

As the life of the product ages the wood is now either destroyed, recycled, reused, decays or is burned. Further transforming this life cycle yet into another life of other elements including bacterial, biological, and chemical.



In 1981 Richard Stein along with the Stein Partnership and the DOE produced "A Handbook of Energy Use for Building Construction." (1) In this handbook conventional habits and behaviors of the construction industry are accounted for. The research identifies the energy required for the manufacturing and delivering of raw materials to the construction job site for over 400 different building materials and products.


The construction industry accounts for over 11% of the total energy consumed in the United States annually. This 11% represents approximately 7,500 trillion Btu, which has the equivalent energy value of 1 billion barrels of oil. Within the construction industry, new building construction accounts for 5.19 percent of national annual energy consumption. The remaining 5.95 percent is distributed among new non-building construction (highways, railroads, dams, bridges, etc). (Stein, 1981)

The energy consumed by new building construction in the United States has two distinct categories. 15 percent of the total energy is used at the construction site, which equates to approximately 548 trillion Btu. The remaining 85 percent, or 2,925 trillion Btu is referred to as embodied energy, the energy required for the production of materials which are incorporated into buildings.


Embodied energy is the direct and indirect expense of energy to create an element for use in some form or another. Unfortunately there is still very little information concerning adobe, rammed earth, strawbale, and other techniques that use soil, aggregate and organic waste by-products.

In the following paragraphs human shelter is the subject of the research and the cultural habits and behavior of construction are observed with a counteractive look at a more ecological and sustainable way of creating shelters.




The Phoenix metropolitan area is one of the fastest growing cities in the United States. The majority of building construction is residential and is using fast, easy methods for economic gain that we see all over the country. This area is also plentiful in local materials for adobe and rammed earth construction, which could support a more sustainable use of natural resources and promote less environmental degradation. This research evaluates the environmental degradations of using local earth materials as a source of wall framing in residential construction rather than using the more common material wood. Each prototype is compared according


to its direct impact on the environment through measurable energy consumed, including air emissions, and projected land impacts from the use of fossil fuel energy. Results of this research show that building performance of a construction prototype is not the only consideration in choosing a construction material. It also shows that the entire energy path must be considered in order to make the proper choice for sustainability.

The four step "process" focuses on:

1) Extraction - of the simple element such as a tree and soil and all of the equipment necessary to do so.

2) Transportation - including all vehicles, rail and truck and their consumption of fossil fuels.

3) Step three identifies the energy embodied in the building materials and the construction sector. The study analyzes the actual Btu’s expended per wall construction material created. For a relative comparison to energy, it is further translated into Btu’s per gallon of gasoline.

4) The fourth category of the process is the actual performance of the built shelter. It includes the energy used to operate the house on an annual basis, given in kilowatt-hours.

This last category was simulated and computed using at DOE2.1Dprogram entitled "Energy Consumption Analysis of a Typical Residential Unit with Different Wall Materials."(10)

Air emissions including CO, Nox, HC, Pm, Co2 and So2 are emissions from the machinery necessary to process each building prototype, whether it be from stationery diesel, mobile diesel, electric generated equipment or electric generated power. These figures were taken from various sources. (2,3,4,5)

Land, water, trees and fossil fuel impacts are all included in Table 4 which are relative to coal operated power plants.(7) In the paper titled "Land requirements for the Solar and Coal Options," it is noted that the total land disturbed due to the operation of Navajo Generating Station is 6.62 ac per NW. (7) This includes all land affected for the generating station site, ash disposal area, evaporation ponds, well field and pipeline, station access roads, railroad, transmission lines, mines and limestone source. Navajo Generating Station was chosen for this study due to the consistent operation of this plant, information available and more closely related to electric power supply to Phoenix through this generating station.

The water statistics in Table 4 also relate to the generation of power. The figure cited as 0.790 gal per

kwh expended is the total evaporation of water. This number is applied to the total electric consumption per building prototype. The tree loss is relative to the amount of board feet required per prototype. This affects the amount of trees per individual houses built in Phoenix during the study year.

Fossil fuel consumption is listed according to two sub-titles, diesel and coal. The diesel noted is the direct consumption per piece of equipment necessary to process each natural element into a building construction material and into a finished product of a built house. The coal is relative to Navajo Generating Station and the amount required to supply electric power.(6)





beginning with the extraction process, one must find the proper soil mixture in order to create an adobe brick. In Arizona, adobe soil is plentiful, especially near the Phoenix area. The equipment used in mechanical adobe processing are mostly electric generated and produce approximately 5,000 bricks per 6 hour shift. Production is random depending on the demand from construction. The operation cited in this study operates at 115,000 kwh monthly, or 5,750 kwh per 5,000 bricks for one house constructed.(10) In the construction phase it is noted that the energy embodied per adobe brick = 2,500 Btu’s at 5,000 bricks per house = 12.5 million Btu’s expended. In relation to fossil fuels, the energy embodied in 5,000 bricks would equal 116 gallons of gasoline. The operation of the adobe house consumes approximately 11,069 kwh annually. Using Navajo Generating Station statistics from a document "An Evaluation of Alternative Control Strategies to Remove Sulfur Dioxide and Carbon Dioxide at Existing Large Coal-Fired Facilities" Report EA 1989, per kwh there is 10,239 Btu’s expended.(2) Therefore an adobe house would equal 113,335,491 Btu’s expended divided by 22.07 million Btu’s per ton of coal = 5.135 tons of coal per one year of operation.(10)


The process for rammed earth has two options, either to transport in the aggregate needed, or to dig out the site. It is common to use ‘5/8"minus’ aggregate which is a byproduct of the granite mining process. The diesel equipment necessary in this process consumes 2,500 gallons of diesel in 8 days, which is 33 gallons per house constructed. Ninety-Six tons of aggregate is


needed for each house, as compared to 1,472 tons produced daily. The emissions are based on mobile vehicles in figures by ADEQ.(4) The construction of the walls consumes 100 gallons of diesel with the emissions given on the flow chart. The fourth procedure, operation of the constructed house would consume 9,639 kwh annually, although the DOE2.1D program only allowed for 13 inches width of the walls. In comparison a normal rammed earth wall is 24 inches wide. Using again the statistics from Navajo Power Plant, this documents the rammed earth prototype as using 4.47 tons of coal annually.



There is quite an extensive network involved in the timber industry and that is why this study was quite specific in documenting only milled lumber used in the framing of a house. For an average 1,500 sf house there is 14,307.6 bf used in the walls and roof. In comparison both the adobe and rammed earth prototypes used 1,900 bf for the roof framing only.

There are generally 12-16 sawyers daily that work for one particular cut or sale area. As an average there is among 6-25,000 bf cut daily over 160 acres in 7days.(8) Diesel is used as an energy source and the statistic base is the same as used for adobe and rammed earth. Total skidding, loading, and hauling for production of one house consumes 119.52 gallons of diesel per 14,307.6 bf of lumber, or 20 trees.

Once the timbers are cut then they must be milled. The procedure for milling follows in diagram and consumes 3.3 bf/kwh of production.(9) Multiplying for 14,307.6 bf for requirements of one house that would equal to 47,215.08 x 10,239 Btu’s = 21.9 tons of coal for electric generated power.

The transportation of this cut timber and lumber was traced by consumption in Arizona versus import and export factors. It was found that most of the lumber used in the state is from the Pacific Northwest mills. To transport to Arizona there are two methods, by rail and by truck. The total traveled miles from Oregon is 1,419 miles by one train comprising 100 cars and 4 engines on average depending on the total weight of cargo.(9)

The construction of the framing for a wood frame house embodies approximately 105,376,199 Btu’s that is equivalent to 970 gallons of gasoline.(1) Today only 74% of an actual timber is usable. For an average 16" diameter by 16’ long log, approximately 199 bf is obtained.

The operation of a wood frame house is dependent on other elements beside just the dimension lumber, including plywood, insulation and finish materials. In the DOE2.1D program all current R values represent what is called locally "a climate crafted home" built to save 25% of the energy consumption of competitive homes. After construction, the wood frame house wold consume approximately 12,236 kwh annually, or 125,284,404 Btu’s equaling 5.67 tons of coal yearly.




This study requires a comparative analysis rather than a definitive answer or choice of a better prototype. The study concludes that:

  • Rammed Earth option #1 (to excavate the site out) had the fewest environmental impacts.
  • A rammed earth house operates with the least energy consumed on an annual basis for the Phoenix area.
  • The largest consumption of energy is from electric generated machinery.
  • Largest amounts of air emissions are from electric generated power.
  • Land degradation and water evaporation must be considered in electric generated power, which is relative to the operation of the construction industry.
  • The fewest amounts of trees required were equal for adobe, and rammed earth, with a ratio of 7:1 for a wood framed house to an adobe and rammed earth house (this includes lumber for the roof framing only)

Fossil fuels were consumed for all three prototypes, diesel for on site machinery and coal for electric generated power. The least impact is the more efficient piece of machinery.

The adobe and rammed earth houses require more labor but require less in costs of materials as compared to wood framing.







Table 4a Comparative Analysis of Individual Prototypes






lbs. (unless other wise noted)























ADOBE indv












option #1












option #2


























Eco-culture and sustainability have a basic understanding that exists regardless in how we apply cell production to biology, bacterial re-generation to agriculture and the need for shelter to architecture. It is to choose wisely, to be accountable for all that we create and be responsible for the future generations to come. Value local culture and its appropriateness. There are specifics provided by climate, flora, fauna, water, air and land mass. Sustainability is adapting a culture not from imposition on the outside, but rather from within. Local knowledge that becomes habit and behavior is accountable and responsible with each and every person and their place. Current building practices are destructive and non-returning into our life-cycle. How we create our shelters is just one significant step to sustainability.




  1. Stein, R.G., 1981. Handbook of Energy Use for Building Construction, USDOE/CE1220220-1. March 1981.
  2. Environmental Protection Agency, 1989. An Evaluation of Alternative Control Strategies to Remove Sulfur Dioxide and Carbon Dioxide at Existing Large Coal-fired Facilities. NEDS Point Source Listing 1985. Report 1989-January 3, 1989.
  1. Arizona Department of Environmental Quality, 1992. Emission Factors for Gasoline and Diesel
  2. Powered Industrial Equipment. Emission Factor Ratings, Table 3.3-1.

  3. Arizona Department of Environmental Quality, 1990. Air Quality Control for Arizona. Office of Air Quality. Annual Report, August 1991.
  4. Arizona Corporation Commission. Interview with David Berry, by author. Written interview, October 1992.
  5. Environmental Inspection Agency, 1992. Cost & Quality of Fuels for Electric Utility Plants 1988, Arizona Public Service, Co. Phoenix. 1988
  6. Table 50 gas units. FERC Form 1.

  7. Pasqualetti, M. and Miller, Byron A., 1984. Land Requirements for the Solar and Coal Options. The Geographical Journal, volume 150, number 2, July 1984.
  8. Arizona Public Service & Arizona Electric Power Cooperative operated units: data from LCP filing in April 1989.
  9. Georgia-Pacific. Clemet Falls, Oregon 1992. Interview with Peter Hess, Norm Edwardson, by author. Telephone interview January 1992.
  10. Gossen, C. 1993. Adobe, Rammed Earth and Wood: An Energy-Based Environmental Analysis of Residential Construction in Phoenix, Arizona. Arizona State University Library. May 1993.

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