Laura Isabel Ettedgui Magna Cum Laude Bachelor Of

LAURA ISABEL ETTEDGUI

MAGNA CUM LAUDE BACHELOR OF DESIGN IN ARCHITECTURE SPRING 2010

SUSTAINABILITY + INDUSTRIALIZATION: structural considerations in the design of the Solar Decathlon house LAURA ISABEL ETTEDGUI magna cum laude // b.design architecture // spring 2010

ABSTRACT

This project presents an assessment of various parameters for determining the sustainability of structures, particularly through an investigation into the structural materials. The guidelines of the Solar Decathlon competition provide a context and a model for the investigation. The competition highlights sustainability and industrialization as important themes, and research was conducted along these veins. As a modern buzzword, sustainability involves an ecological balance of resources, but it also carries the dimension of time in the longevity of the product. Therefore, research was conducted into life-cycle assessments for various industrialized structural materials. It was found that the energy consumed in the operation phase of a building far outweighs the embodied energy in the materials of the building. The project also investigates scales of modularity for the structure of the home, particularly in terms of the efﬁciency of shipping and assembly. The results of the research were applied to the structural and architectural design of the University of Florida Solar Decathlon house. LAURA ISABEL ETTEDGUI magna cum laude // b.design architecture // spring 2010

TABLE OF CONTENTS

INTRODUCTION [1]

1. SUSTAINABILITY IN BUILDING DESIGN [1]

a. signiﬁcance [1]

b. methods of assessment [2]

c. implementation [3]

2. STRUCTURAL MATERIALS [3]

a. life-cycle assessment [3]

b. life-cycle properties of structural materials [4]

c. importance with respect to total building impact [6]

3. SOLAR DECATHLON STUDIO [7]

a. guidelines [7]

b. research implications [7]

c. design applications [9]

CONCLUSIONS [11]

ACKNOWLEDGMENTS [13]

WORKS CITED [14]

[NOTE: I am a double major with civil engineering and am submitting a similar paper for honors in that discipline.] LAURA ISABEL ETTEDGUI magna cum laude // b.design architecture // spring 2010

INTRODUCTION

The Solar Decathlon Europe is an international competition between nineteen universities to build and operate a solar-powered house. The University of Florida is one of only two universities from the United States participating in the competition, which will be held in June 2010 in Madrid, Spain. A large team of students from eight different disciplines and four different colleges have been working on the project for over a year, beginning with the architecture design studio in the spring of 2009.

As a double-major in architecture and civil engineering, my particular focus for the Solar Decathlon project was the structural design of the house, which I developed through a research project into the structural sustainability. However, what began as an investigation into the sustainability of structural materials, particularly in terms of life-cycle assessments, resulted in the discovery of the relative insignificance of the embodied energy of individual components of a building with respect to the energy-efficiency of the building as a whole. This paper presents the research that led to this understanding, as well as the applications of these ideas to the architectural design process. For the particular case of the Solar Decathlon house, the results of this research were relevant to various design decisions, and helped elucidate the relationship between architectural and engineering decisions in the context of green building. The implications of this paperʼs findings found real-world application in the design of the Solar Decathlon house, culminating in actual construction for the competition itself.

1. SUSTAINABILITY IN BUILDING DESIGN a. signiﬁcance

Sustainability, in terms of the built environment, describes the energy-efﬁciency of a building. This efﬁciency can be achieved by a low energy input to its components, low energy consumption of the building itself, or mere longevity - a literal capacity of the building to last. While trendy - the study of sustainable building has been growing in popularity since the early 1990s (Zhang 669) - the movement for sustainable construction is rather timely, given the simultaneous deterioration of both the environment and the economy over the last few years.

The building sector is a major culprit in energy consumption as well as the generation of greenhouse gas emissions. Cited variously as constituting 30-40% or up to half of societyʼs total energy demand, buildings are responsible for about 44% of total material usage as well as about one third of all carbon dioxide emissions (Li 1414). Throughout the life of a building, “various natural resources are consumed, including energy resources, water, land, and minerals,” and the consumption of these is associated with the release of many kinds of pollutants back into the environment, which contribute to such problems as global warming, acidiﬁcation, and air pollution and “inﬂict damage on human health, primary production, natural

1 LAURA ISABEL ETTEDGUI magna cum laude // b.design architecture // spring 2010 resources and biodiversity.” There is a clear consensus that “reducing the environmental burden of the construction industry is indispensable to sustainable development” (Li 1414).

As technical systems, buildings are unique in terms of their relatively long life, as well as “their crucial role in the material and energy metabolism of the physical economy” (Assefa 1095). Sarja asserts that they are “the longest lasting and most important products of our society” (Sarja xi). Sustainable building design has the power to reduce the environmental impact of a building throughout its entire life (Wang 1415). Various parameters such as “reduction in energy input, lower environmental impact, lower waste production or maximum use of renewable energy” contribute to the overall sustainability of a building (Kumar 2450), as well as to the sustainability of our society in a world with limited resources.

b. methods of assessment

The overall sustainability of a built structure is impossible to quantify, but various “sustainability assessment toolkits” (Wang 1415) have been developed in the last couple of decades and are employed around the world (Assefa 1096). Some of the better-known of these include Leadership in Energy & Environmental Design (LEED) in the United States and Building Research Establishment Environmental Assessment Method (BREEAM) in the United Kingdom. Many of these systems involve a breakdown of various assessment categories or goals, including water efﬁciency and material choices. These categories are then assigned values, which are aggregated for the building in question to arrive at some standard of sustainability, such as LEED Gold or BREEAM Outstanding. “In this process fundamentally different aspects like indoor climate and energy use are added. Such a process implies subjective weighting with a number of shortcomings” (Assefa 1096). There are other systems, such as BEES and ATHENA, that are based on life cycle assessments and are considered more “objective evaluating models” (Zhang 669). The consideration of material choice is common to all of these assessment methods.

Fig. 1 : The advantages and disadvantages of some main sustainable assessment tools (Wang 1416)

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c. implementation

Despite the availability of “an enormous number of literature and sustainable design tools providing numerous sustainable design options,” the implementation of these tools is limited by inherent shortcomings in the tools themselves, as well as “by the affordability and risks the investors willing to take in practice” (Wang 1416). The most notable shortcoming of systems like LEED is the absence of life-cycle costs from the assessment scale. Life cycle assessment is considered to be an important link between the energy efﬁciency and ﬁnancial feasibility of green construction; it is “the best tool to combine both the long-term environmental and the economical evaluations of building designs,” it and should not be neglected (Wang 1416).

2. STRUCTURAL MATERIALS a. life-cycle assessment

Life cycle assessment is deﬁned as the ʻʻcollection and assessment of the inputs and outputs of any potential environmental impacts caused by the product system throughout its life cycleʼʼ (Mora 1330). The life cycle of a system covers everything “from the acquisition of raw materials to the ﬁnal disposal of products” (Zhang 669). Life cycle assessment is a well-known analytical procedure for assessing a productʼs sustainability (Gerilla 2779). The results are usually “presented in the form of aggregation of environmental loads or impacts related to the functional unit, without considering their distribution in time and space,” but they present a relatively “in-depth coverage of environmental impacts associated with design and building materials” (Zhang 669).

Blengini asserts that, “in order to achieve the best environmental solution and to define the right proportion between the natural and recycled raw materials that are necessary for the economic and social development of mankind, all life cycle phases, from-cradle-to-grave, must be considered” (329). A key aspect of the life cycle assessment, which is often difficult to anticipate, is the recyclability of the product in question at the end of its life. Thormark cites various studies from several countries of the recycling potential of buildings with results attesting to energy savings from 12 - 40% through recycling building materials (1020), while Blenginiʼs results demonstrate a recycling potential of “29% and 18% in terms of life cycle energy and greenhouse emissions, respectively” (319). It is clear that, “while building waste recycling is economically feasible and profitable, it is also sustainable,” and has the potential to outweigh the energy embodied in the materials themselves (Blengini 319).

There are several limitations to the life cycle assessment methodology. Some of its basic hypotheses, such as the time stability of the product system, are not reliable due to the long lifetime of buildings and building products. While life cycle assessment accounts for the embodied energies of building materials, it does not account for the functional qualities of

3 LAURA ISABEL ETTEDGUI magna cum laude // b.design architecture // spring 2010 different materials or the overall performance of the building, and functions “such as thermal comfort in winter and summer, indoor air quality, etc., cannot be taken into account” (Verbeek 1037). Zhang also asserts that inherent characteristics of life cycle analysis make it “very difﬁcult to include all environmental factors of buildings in LCA [Life Cycle Assessment] framework, especially the indoor climate” (674-675). Life cycle assessment evaluates environmental damage at the large scale of ecosystems, so qualities like indoor climate and the effect of building surroundings are bypassed .

b. life cycle properties of structural materials

The life cycle properties of structural materials vary greatly by manufacturer, location and scale of implementation, but some general trends were gleaned from extensive research. First of all, it is interesting to note “the phenomenon of increasing embodied energy with decreasing annual energy consumption,” that is, low-energy buildings tend to require more materials and have higher embodied energies (Verbeek 1040 - see table below).

Fig. 2 : Embodied energy and annual consumption energy for different construction types (Verbeek 1039)

Wood frame construction is generally favored over massive construction by life cycle studies, provided that the wood be recycled or reused (Verbeek 1040). Gustavsson says that “previous studies have shown that the use of wood for construction generally results in lower energy use and CO2 emission than does the use of concrete,” and his studies conclude that “the use of wood building material instead of concrete, coupled with greater integration of wood by-products into energy systems, would be an effective means of reducing fossil fuel use and net CO2 emission to the atmosphere” (940). However, both of these studies only compared wood construction with concrete or masonry construction. When steel was thrown in the mix, it gained an edge over wood in its associated construction energies (Cole - see Fig. 3 and 4).

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The Solar Decathlon house, in particular, had to be designed to be disassembled and assembled multiple times, so steel was the only reasonable choice for the structure of the house among readily available industrialized materials.

(Left) Fig. 3 : (a) Construction/Embodied Energy (Including Worker Transportation); (b) Construction/Embodied Greenhouse Gas Emissions (Including Worker Transportation) (Cole 346) (Right) Fig. 4 : (a) Average Construction Energy for Wood, Steel and Concrete Assemblies; (b) Average Construction Greenhouse Gas Emissions for Wood, Steel and Concrete Assemblies (Cole 347)

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Fig. 5 : Environmental proﬁles for a range of building materials (Harris 757)

c. importance with respect to total impact of building

A life cycle perspective on total energy use must include the energy associated with operation of the building in addition the the buildingʼs embodied energy (Thormark 1019). Verbeek examined life cycle assessment studies on building as a whole from several countries and noted that, despite the differences in building typology and building tradition, “all case studies emphasize the importance of the operational phase, when comparing the environmental impact of the different life cycle phases of a building” (Verbeek 964). So, despite the phenomenon mentioned earlier whereby “extremely low energy dwellings demand an extra input of materials and products, such as extra insulation or photovoltaic modules” (Verbeek 964), the energy efﬁciency of the building as a whole, in terms of operation throughout its life, carries far more weight than the embodied energy of its components.

“The contribution analysis of the life cycle inventory of the four reference dwellings shows the relative small importance of the embodied energy of a building compared to the energy consumption during the usage phase. For common dwellings that comply with the legal energy performance level, the total embodied energy corresponds to 1/3 to ¼ of the primary energy consumption during 30 years of use of the building. Only extremely low energy buildings might have a total embodied energy higher than the energy use of the usage phase. All these results lead to the important conclusion that considerations on reducing the embodied energy of extremely low energy houses can be an interesting issue for future research, but that in the ﬁrst place, effort should be paid to the reduction of the energy consumption during the usage phase, as this phase still has the largest potential for improvement, both for new and old buildings.” - (Verbeek 967)

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Thormark conﬁrms this, citing numerous international studies to assert that operational energy accounts for approximately 85–95% of a buildingʼs total energy use (1019). The primary environmental impact of buildings is global warming, and the operational phase of a buildingʼs life is largely responsible for this due to the high level of natural resource consumption and of pollution during this period (Zhang 675). In terms of carbon emissions in particular, Gerilla found that “carbon emissions from the operation stage constituted about 79% of the total emissions,” while construction and maintenance/disposal accounted for 12% and 9% of the total life cycle, respectively (2781), and explained that “much of the environmental impacts from building a house are on the Global Warming Potential because much of the emissions come from carbon emissions” (2783). These effects can be signiﬁcantly mitigated by extending the design life of the building, giving a 14% reduction in carbon emissions, or by using solar energy in the operational phase of the building, resulting in a whopping 73% reduction in total life cycle carbon emissions (Gerilla 2783).

3. SOLAR DECATHLON STUDIO a. guidelines

The Solar Decathlon studio constituted the initial design phase of University of Floridaʼs Solar Decathlon house, which will be constructed in Madrid for the competition in June 2010. The Solar Decathlon Europe is an international competition between 19 universities to build and operate a solar-powered house. It is called a “decathlon” because the houses are evaluated in ten different categories (see Fig. 6). This paper is conﬁned to a discussion of the subjects addressed during the studio, namely, Architecture and Engineering in terms of Sustainability and Industrialization.

Important restrictions of the Solar Decathlon competition include a small maximum square footage, solar energy standards, and the condition that the house be shipped overseas. The structure of the Solar Decathlon house accounts for issues of spatial ﬂexibility, transportation, passive and active energy systems, and modularity of assembly. The primary design objective for the structure of the house was the balance and reconciliation of these requirements within the small frame of the home.

b. research implications

The purpose of this project was to explore the relationship between architectural and structural engineering decisions under the restrictions of sustainability and industrialization. Research was conducted into the various methods of assessing sustainability, the life cycle costs of various structural materials, and their relative importance with respect to the total environmental impact of a building.

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Fig. 6. Scoring table for the Solar Decathlon Europe 2010 competition [illustrated by author]

The ﬁndings of the analysis of various building sustainability studies have made it clear that, while material choice is important, particularly in terms of recyclability, the overall efﬁciency of a building carries substantially more weight in terms of energy consumption. Buildings are damaging to the environment, primarily through the large amount of associated carbon emissions, and the use of solar energy during the operation of the building has the potential to have a huge impact on the life cycle carbon emissions of a structure. As Thormark summarized, “It can be concluded that in order to reduce total energy use in buildings, it is of great importance in the design phase of new buildings to not only reduce operational energy needs but to also pay attention to the choice of building materials as well as the recycling aspects,” and it is especially important “to provide for disassembly” (1025).

Solar power was already a given for this house. A positive net energy balance was a stated goal of the competition, and there was a deﬁnite need to design for disassembly and reassembly since the house needed to be shipped overseas. The shipping itself would throw off an entire life cycle assessment of the house itself, considering the amount of energy expended in transportation alone, but it provided an additional design restriction that could contribute to the overall sustainability of the house as a prototype.

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(top) Fig. 7 : Florida Cracker House (middle) Fig. 8 : North view of UF Solar Decathlon house [Rendered by David To and Clay Anderson] (bottom) Fig. 9 : Plan development from Dog Trot plan, left to right [Illustration by author]

c. design applications

An important strategy of sustainable building design involves maximizing use of renewable energy, which “can be achieved by maximizing the use of solar energy through passive building design and maximizing the use of alternative sources of energy” (Kumar 2450). The Cracker House, a vernacular style of architecture in northern Florida and other regions of the southern United States, served as a model for passive design (see Fig. 7). Built well before the use of electricity, the Florida Cracker House kept inhabitants cool through various passive design techniques, including large overhangs for shade and a breezeway for ventilation.

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These elements were adopted and reinterpreted in the design of the Solar Decathlon house. The plan of the Dog Trot house, the basic Florida Cracker house, shown in Fig. 9, was adjusted to accommodate the more modern spatial requirements of the Solar Decathlon house.

The Solar Decathlon house design maintained the two separate volumes of the house from the Dog Trot, thereby minimizing the amount of space needing to be conditioned at any given time. The larger volume is the living module, including the more social functions of the house: the kitchen, dining, and living areas. The smaller volume houses the more private areas of the house, namely, the bedroom, bathroom, and mechanical space.

Another strategy of sustainable building design is modularity of the structure at various scales: “the development of building works in a modular fashion makes the repairing action of modifying materials or parts of works possible” (Mora 1329), as well as facilitating the design for disassembly and shipping. The steel frame was designed in 8 ft x 16 ft modules, which accommodate standard, industrialized, prefabricated materials, and can be conﬁgured in various groupings to accommodate different numbers and preferences of occupants (see Fig. 13).

(top) Fig. 10 : Current ﬂoor plan of the UF Solar Decathlon house [from construction drawings, Chris Sorce] (middle) Fig. 11 : South view of the UF Solar Decathlon house [Rendered by David To and Clay Anderson] (bottom) Fig. 12 : Exploded axonometric view of SD house components [Rendered by Clay Anderson]

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Fig. 13 : Grouping conﬁgurations of the modules of the UF Solar Decathlon house [Rendered by Paige Mainor and Clay Anderson]

CONCLUSIONS

The format for the Solar Decathlon studio involved a number of unusual constraints, including the numerous rules of the competition itself, the acknowledgment of far more realistic parameters than a typical design studio (given that it was ultimately built at full scale), and the collaboration of a dozen architecture students on a single design. While the ﬁnal design for the house was relatively simple, and it underwent many changes throughout the course of the project, the number of constraints still fostered a creative design process through the extent of problem-solving and compromises required.

The scope of the Solar Decathlon project is far greater than the scope of this paper, and it is difﬁcult to discuss discrete pieces of the project without discussing the whole effort because it has been so collaborative. Nevertheless, the research that was conducted into the assessment of sustainability, and the practice of applying the ﬁndings to both architectural and engineering decisions for the project, were productive and successful. The structural design of the house managed to accomplish its various requirements, particularly the modularity, the facilitation of disassembly,

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Fig. 14 : Urban grouping conﬁgurations of the UF Solar Decathlon house [Rendered by Clay Anderson] and the support of the systems necessary to make it a low-energy building.

While the current tools for assessing the sustainability have there various shortcomings, sustainable building design is still a young field that is continually growing and developing. Life cycle assessments are valuable in determining the large-scale environmental impact of buildings, and new methods such as Integrated Life Cycle Design are being developed to incorporated the valuable information from life cycle assessments into the development of design parameters that account for the effectiveness of building configurations at a smaller scale. “Integrated life cycle design is still at a phase of rapid development, and this is the start of the final formulation of a new integrated design process and methodology, which in future will serve as a general design culture. The next step on this path will be an integration of the design, management and maintenance planning of buildings and civil infrastructures into a comprehensive life time engineering. The practical implementation can be carried out through international and national standards, guidelines and computer tools.”(Sarja xii)

We are in the midst of a significant reevaluation and adjustment of the way we build, and competitions like the Solar Decathlon Europe are bringing these concerns to an international audience. While the roles of “architect” and “structural engineer” seem disparate in the current workplace, the field of green building may provide a new grounds for collaboration; “not only is the work of structural engineers changing, but the form of their co-operation with clients, architects, building service system designers and producers is needed.” (Sarja 5) The experience of the Solar Decathlon studio was the first of many collaborative design endeavors for all its participants, and while the design process was more confined, it afforded everyone the opportunity to employ the skills acquired in previous studios to more realistic design problems.

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ACKNOWLEDGMENTS

The work of the Solar Decathlon studio, and of the entire team since then, is fundamentally collaborative. While image credits are listed throughout the text, I would like to acknowledge the participation in the design effort of all the other members of the Solar Decathlon studio:

Clay Anderson Sarah Appleyard Chris Chappell Andrew Herbert Paige Mainor Sean Morgan Katie Orr Alex Ruhnau Chris Sorce David To as well as all of the many dedicated students on the Solar Decathlon team.

Chris Anderson Sabine Jean Francois Alex Palomino Brooks Ballard Brian Kim Jason Parker Jacob Beebe Rachel Kopek Kevin Priest Mina Bevan Samantha Kuphal Isabel Quintana Luke Booth Jake Landreneau Jacklyne Ramos Joanna Brighton Marcela Laverde Max Scott Isaac Church Amy Long Wyatt Self Rachel Compton Robert Lyons Jessica Tomaselli David Cowan Laura Meeks Lucky Tsaih Dale Freel Robert Menasco Ian Trunk Amy Guidos Matt McKinnon Pete Vastyan Darren Hargrove Geoff Miller David Wasserman Jeanette Holloway Ryan Moose Erin White Katie Huber Ryan Murray Jordan Wise Jeff Humpal Mike Osterling Amanda Young Aaron Hynds Ryan Padgett Erika Zayas

I would also like to acknowledge Dereck Winning, who spearheaded this project, and the faculty responsible for this project: Dr. Robert Ries and Dr. Jim Sullivan of Building Construction; Dr. Maruja Torres of Interior Design; and, ﬁnally, Bradley Walters and my research mentor Mark McGlothlin of Architecture, who led this studio.

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