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HomeMy WebLinkAbout6 - Update MemoFebruary 6, 2408 TO: Landmarks Preservation Advisory Board FROM: James Hewat, Chris Meschuk SUBJECT: Update Memo Joint Planning Board Landmarks Board Meeting Verbal Update at meeting Draft White Paper on Embodied Energy in Historic Buildings See attached document. Please bring your comments to the meeting. New and Pending Land Use Review Applications See attached Planning Board Calendar See attached Stay of Demolition Status Summary, February 6, 2008 ~ :~,_~ , Qate.Stay- l~ri ed 4ate;of Ex iratinn ~ : , , ,~urrent Stt~~us Staff has contacted Ed Byrne (Attorney for the estate) to try to set up a meeting. He is trying to get all of the estate and 819 6th Street 1954 1/9/2008 5/17/2008 foundation parties involved to meet. A meeting has not been scheduled. The board will need to indicate by April if a initiation hearin is desired. Landmark Applications Update: • 800 Arapahoe: Will be reviewed by Council in June. • 5653 Baseline: Public hearing scheduled for April 1. • 4051 Broadway: Designation application received for the Barn, Designation hearing scheduled for April 2 ARTICLES AND INFORMATION: Monument at the 'lomb of the Unknornns at Arlington National Cemetery Gets a Reprieve Legi.slation Prevents Replacement & Mandates Study of Repair (7ptions, National Trust for Historic Preservation Press Release January 29, 2008 Status regarding reauthorization of the Colorado State Historic Preservation Tax Credit. Email from Dan Corson dated January 30, 2008. Monument at the Tomb of the Unknowns at Arlington National Cemetery Gets a Repriev... Page 1 of 2 The National Trust for Historic Preservation The National Trust provides leadership, education, advocacy, and resources to save America's diverse historic places and revitalize our communities. Press Release Monument at the Tomb of the Unknowns at Arlington National Cemetery Gets a Reprieve Legislation Prevents Replacement & Mandates Study of Repair Options Washington, DC (January 29, 2008) -The Monument at the Tomb of the Unknowns at Arlington National Cemetery, among the nation's most revered sites, has been given a reprieve. The National Defense Authorization Bill, signed into law yesterday by President Bush, includes an amendment sponsored by Senators Daniel Akaka (D-HI) and )im Webb (D-VA), passed unanimously by the Senate, which prevents replacement of the Monument pending a report to Congress about repair options. The National Trust for Historic Preservation has been fighting efforts by federal administrators to substitute a replica for the 48-ton marble block Monument, which has two cosmetic cracks. The bid to preserve the Monument involves a coalition of thousands of members of the National Trust for Historic Preservation and members of the public who have written to John Meltzer, Jr., superintendent of Arlington National Cemetery, and their members of Congress, along with National Trust partners the Arlington Heritage Alliance and APVA Preservation Virginia. The coalition is urging preservation over replacement because the two cosmetic cracks can be repaired and do not pose a threat to visitors or to the Monument. Language in the Defense Authorization Bill requires the Secretaries of the Army and Veterans Affairs to determine the feasibility of repairing, rather than replacing, the Monument and to report the findings to Congress within 180 days. The process of repair and proper care of the Monument would be similar to that undertaken at the Lincoln Memorial - a re-grouting of the cracks and use of only gentle cleaning methods instead of high-pressure power-washing. Stone preservation expert Mary Oehrlein explained this method of restoration to the staff of the Senate Armed Services Committee in testimony on September 13, 2007, saying, "The existing Monument can easily be repaired, as was done 17 years ago, using conventional conservation methods to re-grout the cracks. Once repaired, the fault lines would be virtually invisible from the public viewing areas." In a recent AOL on-line poll asking "should the monument be repaired or replaced," 87% of the more than 100,000 votes cast were in favor of repairing the memorial. "This is arguably the nation's most important war memorial and we are working to insure that it is preserved, not replaced," said Richard Moe, president of the National Trust for Historic Preservation. He added, "We are pleased that Senators Daniel Akaka and Jim Webb, along with our partners and citizens nationwide share our determination that the Monument be properly preserved and cared for." "Since World War I, the Tomb of the Unknown Soldier has served to commemorate and immortalize those who never returned from the battlefield," said Senator )im Webb. "Though cracked this monument represents the patriotic spirit of all of the brave unidentified men and women who have fought and died in America's wars. I am pleased that, with the President's signature today, the decision to replace this memorial has been postponed. I look forward to reviewing a full assessment of the memorial's damage and recommendations for moving forward judiciously." Senator Daniel K. Akaka, Chairman of the Senate Veterans' Affairs Committee, said, "I am pleased that our amendment will require an assessment of the feasibility and advisability of repairing the Monument rather then replacing it with a replica. Like the Liberty Bell and the Star-Spangled Banner, the Monument at the Tomb of the Unknowns is a national treasure that has been weathered by time. It is a tangible tribute to the service of those who do not return from battle and a place for their families and others to contemplate their absence. We must ensure that we first explore all options and move with great caution before making any decisions that would irrevocably affect this solemn place of remembrance." The National Trust for Historic Preservation is anon-profit membership organization bringing people together to protect, enhance and enjoy the places that matter to them. By saving the places where great moments from history Monument at the Tomb of the Unknowns at Arlington National Cemetery Gets a Repriev... Page 2 of 2 - and the important moments of everyday life -took place, the National Trust for Historic Preservation helps revitalize neighborhoods and communities, spark economic development and promote environmental sustainability. With headquarters in Washington, DC, nine regional and field offices, 29 historic sites, and partner organizations in all 50 states, the National Trust for Historic Preservation provides leadership, education, advocacy and resources to a national network of people, organizations and local communities committed to saving places, connecting us to our history and collectively shaping the future of America's stories. For more information visit www.nationaltrust.ora Contact Information Phone: 202-588-6141 ru nthp.org • Press Releases • Speeches 1765 Massachusetts Ave, NW, Washington, DC 20036-2117 • tel: 202.588.6000 • 800.944.6847 • fax: 202.588.6036 ©2008 National Trust for Historic Preservation. All rights reserved. Privacy Statement ~ Terms of Use Site Review Comments for 20281St'' Street The Boulder County Tax Assessor record for this property indicates the vernacular wood frame Bungalow was constructed in 1908. Research undertaken in 1995 during the historic survey of the property has also revealed that in the 1930s the house was owned by Thomas E. Barry who arrived in Boulder in 1876 as a child, and for many years worked as a plumber in the city. Barry is also believed to have served as Water Commissioner for the City of Boulder. Staff is of the opinion that the property is eligible for designation as a local landmark for its architectural significance as awell-preserved example of vernacular frame Bungalow design and is historically significant for its association with early Boulder resident Thomas E. Barry. The house has also been identified as a potentially contributing building to the identified Whittier Historic District. As such, a condition of Site Review approval for the redevelopmerit of this property would be the preservation of the building(s) and the applicant's submittal of a completed application to landmark the property as per policy 2.33 Preservation of Historic and Cultural Resources of the Boulder Valley Comprehensive Plan. Staff has reviewed the proposal to rehabilitate, add to, and connect the house and adjacent garage. The location and scale of the proposed addition seem generally consistent with the General Design Guidelines for Boulder's Historic Districts and Individual Landmarks, however the treatment of the addition and remodel of the house and garage may be inconsistent with these guidelines and the historic preservation ordinance. Likewise, the application should be formally reviewed by the Landmarks Board (or its designated design review committee) to establish whether the treatment of the house and adjacent garage are appropriate. Staff recommends that the developer submit a completed landmark application to designate the property as soon as possible so that we can schedule a designation hearing. This will allow for the Landmarks Board to review - the proposed landmark and boundary in the context of the exterior changes on the property and that the subsequent Planning Board review will include the Landmark Board's comments and recommendations. Please note that the historic preservation ordinance (9-11-5(a)) states that once a completed application made by the property owner is received, a public hearing must be heard by the Landmarks Board between 60 & 120 days of the application date. Please contact James Hewat at 303.441.3207 if you have questions, or need more information regarding this matter. Page 1 of 1 Chris Meschuk -Fwd: Status of State Historic Preservation Tax Credit Reauthorization From: Chris Meschuk Subject: Fwd: Status of State Historic Preservation Tax Credit Reauthorization "Corson, Dan" <Dan.Corson@chs.sWte.co.us> 1/30/2008 11:26 AM Dear Local CLG Contact: The reauthorization of the state historic preservation tax credit expiring on January 1, 2010 is currently pending before the House Finance Committee that heard testimony from six witnesses, four of them property owner users of the credit, on Wednesday, January 23, 2008. The committee vote will not be taken until next Wednesday, February 6, 2008. Only one recommended amendment survived drafting. That is the amendment to eliminate the annual requirement for CLGs to pass a resolution stating whether or not it desires to locally review projects in a certain year. The bill number is HB 08-1033. There are five "no" votes expected on the eleven member committee. The committee chair whose vote it necessary for passing currently intends to offer an amendment that will preclude taking the credit in years in which state revenues are expected to be below a certain threshold. This may preclude use of the credit as an incentive for designation and rehabilitation if its use will be speculative. However, that amendment may be necessary for a favorable vote at the committee level. Assuming the bill goes forward the next step is a vote by the entire House of Representatives that may accept or not accept the committee chair's amendment. If the bill makes it through the House, then it starts over in the Senate with a committee hearing. If the bill is not successful this year, there is another year to try for reauthorization before it expires. If reauthorization does not occur, projects in process will not be eligible for the credit for any work done starting on January 1, 2010. Please let me know if you have any questions. I will continue to keep you updated. Dan W. Corson Intergovernmental Services Director Colorado Historical Society 1300 Broadway Denver, Colorado 80203 (303) 866-2673 dan.corson @ chs.state.co.us www.coloradoh istory-oah p.org Embodied Energy: An Overview As discussion of energy efficiency, energy conservation and 'green building' rises, so does interest in embodied energy; Embodied energy refers to the total energy cost of a material; specifically, how energy is expended from the extraction of the raw material to the demolition or recycling of the building. The focus of this paper is look at how various groups define and quantify embodied energy and how that information is used. Embodied energy is not a new concept, but it has received recent attention with the incr._east3~t~~nterest in designing energy efficient buildings. According to the American Institute of-Architects' Environr~lental Resource Guide, more than 30% of America's energy==use gties to the conction and maintenance of buildings.' When assessing ham=~ efficient a building is, it is necessary to look beyond the ann.~al operational casts-(i.e. lighting, cooling, and heating), and consider factors such as tf~t -lifespan of a;aterial and the energy required to manufacture and transportthose_i~tate€ials..: While there are rty, ways to rsiw~'~sure errik3odied energy, there is not a universally accep ~ methoi~ogy for quantifying embodied energy usage. The most widely used def°` " n embodied energy is "the energy consumed by all of the prose;3assocla~c~with the dr~rduction of a building, from the acquisition of n{tral resources ~.to product- delivery. This includes the mining and manufaet%1~T;_ing of matert~s and equipment, the transport of the materials and the administra4ive functions." Though all the of the definitions identify a embodied energy as being the total energy required to manufacture a certain material, there is a large discrepancy in determining where the process begins and ends. For example, a strict method of quantification, called Gross Energy Requirement (GER)3, accounts for the energy required to nourish and transport workers to the site for material extraction (mining, logging, etc), the energy embedded in the urban ~ Mumma, Tracy. Reducing [he Embodied Energy of Buildings. Home Energy Magazine. 1995 s Commonwealth Scientific and Industrial Research Organization Materials Greenhouse.gov 1 infrastructure (roads, water lines, electricity), as well as such expenses as the lighting in the office where the architectural drawings are drafted. Accounting for `upstream energy' is usually impractical to measure and complicated by a lack of definitive boundaries. A more general approach, Process Energy Requirement (PER)4 measures on{y the energy directly re{ated to the manufacture of the materials, including but not limited to the energy required to extract the raw material (through logging, mining or quarrying), transportation of the material to a factory, refinement or manufacturing of the product, trnsportation to the site, assembly of the building, and the energy required to smble or demolish the building. As informal derivatives of the PER, t~oi'e. are tee common methods in analyzing embodied energy; 1) Process Analy`stsY,'f,~~Input-Output Analysis, and 3) Hybrid Analysis. Each of the aforementioned a les is merely an element of analysis; having little to do with'~~ ~ or scope lie analysis, which will be discussed in detail in later sections- Process Analysis -This ?~aopular procedure ordinarily identifies a system boundary for direct a indtr.~et-energy The boundary scope must be defined spatially as vkej` by a==~(neframe - ~ example, a spatial scope would be a parceln~f land or a ~o~e no~~ncluding the land; the timeframe's scope pertains to how far~'upstream the'?energy flow is going to be analyzed. The advantage of ,process analysis is in the degree of accuracy possible for the precisely defined system to which it relates (i.e. energy used to process aluminum from a particular factory). Unfortunately the method is impractical in analyzing the energy inputs more than two stages 'upstream' of the process being analyzed and indirect energy at every level is unaccounted. For this reason, the actual embodied energy in a particular project may be much higher than what the method suggests. ° Greenhouse.gov 2 Input-Output Analysis -This method ultimately measures energy by tracing economic flows of goods and services between economic entities. Consumption is measured in a ratio of energy to monies. Energy measurements are derived from energy costs of various activities related to the project under analysis. For example, gasoline can be quantified in a monetary amount or by the energy that can be produced by that amount of gasoline. One benefit of this particular method of analysis is the ability to compare the energy-price of various materials using their specific monetary values. Hybrid Analysis -The final method is a hybrid of the two formerthods. Input- output analysis is used to define the -major enemy pathways_ process analysis is subsequently used to find the ene~-y embedded iri a particular material. This particular method prAVides the corr~ehensive data of the three options as the inadequacies of tl~ ether methods;- v~hen used alone, are compensated for. The disadvantage=f.- the hybl'id analysis. is its lack of credibility. Few people understand the meter-Qdologies involved which typically makes the process inaccurat_,ulrtr~fiable: Vyhen credibility can be assumed, this method is gives the stngest results f~~embedded energy analysis. 5 ~`a Embodied Energy Resource Review The following section summarizes the sources used for this paper. Some are government funded while others are private companies or groups. In general, the information is consistent, with the exception of how to quantify embodied "energy. The numbers vary greatly, but the objective remains the same: it is important to take into account the energy required to assemble (and 'Best, Rick and Gerard de Valence. Design and Consvuction: Building In Value. Elsevier. 3 disassemble) a building and use that reasoning when determining the energy efficiency of a building. A particularly comprehensive resource is the information provided by the Australian Greenhouse Office (AGO), self-described as 'a joint initiative of the Australian Government and the design and construction industries', published as part of a guide for homeowners to build and live in sustainable homes. `Your Home Technical Manual' provides information on how to~design, preserve or buy a sustainable home b listin uidelines and y g g rural information about sustainability, energy use and costs of improvin~~youur home fo be more energy efficient. - -:x= :R AGO defines embodied energy as `the energy'i;oirned by all of the processes associated with the production i>zf a building, frJ{ the acquisition of natural resources to product delivery. Ths< i~r~t[i,~ the min ~ =°and manufacturing of < materials and equipment, the transport of mYa#~,tafs and the administrative functions'6 (i.e. heath,<.oling and 'lighting). Renovation and maintenance throughout the built~c's life`also included in this calculation. Internatior~F ~;;v cte IRO, fhd Commonwealth Scientific and Industrial Research Organizatrptt.,desc~i>xes itself as `Australia's national science agency; delivering: olutions for9nbusiness, energy and transport, environment and natural recd°urces, health, information technology, telecommunications, manufacturing and mineral resources.' Embodied energy is also defined by CSIRO as `the energy consumed by all of the processes associated with the production of a building, from the acquisition of natural resources to product delivery, including mining, manufacturing of materials and equipment, transport and administrative functions'. The importance of embodied energy is emphasized in that `energy embodied in existing building c http://www.greenhouse.gov.au/yourhome/[echnical/fs3l.htm 4 stock in Australia is equivalent to ten years of the total energy consumption for the entire nation.'' The choice of materials impacts the total energy required to construct a building and while there are other means of quantifying energy use, embodied energy is particularly helpful in determining the CO2 emissions of a building. As buildings are becoming more energy efficient in their operation, the embodied energy is approaching half the lifetime energy consumption.8 Research by CSIRO has found that the average household contains about 1,000 GJ (gigajoules) of energy embedded in the materials used in its construction. This is equivalent to about 15 years of operational energy use. For a house that lasts 100 years this is over 10 percent of the energy used in its life. AGO does not accept one specific means of quantification, but summarizes that quantification is dependent on `boundaries' or where the process begins and ends. The AGO recognizes that while it is effective, the Gross Energy Requirement (GER) assessment method is usually impractical to measure. Conversely, the Process Energy Requirement (PER) measures only the energy that is directly related to the manufacture of the material, which usually accounts for 50-85% of the Gross Energy Requirement, and is though it is more feasible to measure, it is difficult to assign a specific value to a material because of other factors such as: efficiency of the individual manufacturing process, the fuels used in manufacture and transport of the materials and amount of recycled product. CSIRO asserts that the numbers can vary greatly, and should only be taken as a rough estimate. .ice . 4 q ~ P - oY. a ~~x ,ter. °t, Timber frame, timber weatherboard, 188 plasterboard lining ~ http://www.cmmt.csiro.au/brochures/tech/embodied/index.cfm s http://www.cmmt.csiro.au/brochures/tech/embodiedlindex.cfm 5 Timber frame, clay brick veneer, 561 plasterboard lining Timber frame, aluminum weatherboard, 403 plasterboard lining Steel frame, clay brick veneer, 604 plasterboard lining Double clay brick, plasterboard lined 906 Cement stabilized rammed earth 376 FLCOI?S Elevated timber floor 293 110 mm concrete slab on ground 645 200 mm precast concrete 644 T beam/infill ~:;C:Orr_ Timber frame, concrete tile, 251 plasterboard ceiling Timber frame, terracotta tile, 271 plasterboard ceiling Timber frame, steel sheet, 330 plasterboard ceiling A sample of the embodied energy required in different wall assembly figures Source: Australiar Greenhouse Office ?_007/Lawson 7996 A relationship is drawn between embodied energy and operational energy. For example, large masonry walls have high embodied energy but the associated operational costs would be reduced. On the other hand, much less material is required in steel frame construction than heavy timber frame construction, but wood has much less embodied energy than steel. It is important, then, to look at an entire building assembly when assessing the embodied energy. Benefits/Implications of Assembly and Material Assessment 6 The Australian Greenhouse Office offers the following suggestions as guidelines to reduce embodied energy: • Design for long life and adaptability, using durable low maintenance materials • Ensure materials can be easily separated, save materials by building suitably sized house and using recycled materials, specifying standard sizes, modify or refurbish instead of demolishing or adding • Use locally sourced materials • Select low embodied energy materials, give preference to materials manufactured using renewable energy sources and to ask suppliers for information on their products and share this information ~lIQO~ M The site stresses the importance m r ~o--'' - A of recycling and reusing building so 0 40 materials, stating that "reuse of ro 9 zo - building materials commonly G Y~I Alumini;gym s,P~~ ~~~~s saves about 95% of embodied r~*ii3foicE~m?nt pro~;ucts energy that would otherwise be ~ Re~U~ ~ R~z~t~c~essisi~ wasted". The feasibility depends on the material; for example, reprocessing aluminum saves up to 95% of the embodied energy, but only 20% for glass. Urban Ecology Australia's is anon-profit educational association that offers a terse definition of embodied energy as `the mining and manufacturing of materials and equipment, the transportation of the materials and the administrative functions'. Urban Ecology cites both the RMIT- Greening the built Lifecycle and the Australian Greenhouse Office's `Your Home Technical Manual'. The UEA is also a proponent of recycling building materials, citing that recyclable materials allow receiving buildings to share some of their embodied energy with delivering buildings, thus providing more building years for the same energy 7 input. Durable materials are preferred because they will extend the buildings' life, and therefore reduce the yearly embodied energy. Canadian Architects is a monthly publication that reviews project designs and features articles on current practice, building technology, and social issues affecting architecture. It has been in continuous publication since 1955 and, in part, offers information on sustainability, in a section called `Measure of Sustainability', the purpose being `An attempt to describe the negative impacts, or conversely the goodness of fit, between human activities or interventions, ecology and the environment. Measures vary between disciplines and those used in economics, for example, may be quite different from others used in areas such as sociology. For architecture, several useful measures have been developed by researchers, and the simpler measures are then often combined into composite measures which attempt to more fully assess the sustainability of architectural intervention.'9 Included in the Measures of Sustainability are embodied energy, operating energy, energy (absolute energy efficiency) and durability and externalities. The overview of embodied energy includes a definition, means of measurement, quantification of approximately how much embodied energy is in a building, and an assessment of whether embodied energy is a suitable means of measuring a building's total costs. Canadian Architects (CA) divides embodied energy into two categories: initial embodied energy and recurring embodied energy. Initial embodied energy is concurrent with the generally accepted definition of `the non-renewable energy v http://www.canadianarchitect.com/ast%perspectives sustainibility/measures of sustainablity/measures_of _sustainablity_intro. htm g consumed in the acquisition of raw materials, their processing, manufacturing, transportation to site, and construction'. The initial embodied energy is divided into two sub-categories: Direct energy -the energy used to transport building products to the site, and then to construct the building Indirect energy- the energy used to acquire, process, and manufacture the building materials, including any transportation related to these activities Recurring embodied energy represents the non-renewable energy consumed to maintain, repair, restore, refurbish or replace materials, components or systems during the life of the building. This method of breaking up energy into components is unique and also helps to measure the embodied energy of a building in a more feasible way. The CA's quantification of embodied energy is measured as `a quantity of non-renewable energy per unit of building material, component or system'. This could be in megajoules, gigajoules per weight (kg or ton) or area (square meters or feet). "Implicit in the measure of embodied energy are the associated environmental implications of resource depletion, greenhouse gases, environmental degradation and reduction of biodiversity. As a rule of thumb, embodied energy is a reasonable indicator of the overall environmental impact of building materials, assemblies or systems. However, it must be carefully weighed against performance and durability since these may have a mitigating or compensatory effect on the initial environmental impacts associated with embodied energy."10 ~o http://www.canadianarchitect.com/asf/perspectives sustainibility/measures of sustainablity/measures of _sustainablity_embodied.htm 9 Canadian Architects have summarized the research of Cole and Kernan, completed in 1996 as a basis for the theoretical approach towards embodied energy (see Appendix A). The assessment of embodied energy is concluded by questioning the effectiveness of using embodied energy as a tool to quantify the total energy embedded in a building. The CA concluded that embodied energy is a valid tool as long as the method is not viewed in absolute terms. CA's assessment of resources suggests that materials can vary greatly depending on the location, manufacturer, and construction methods. The publication stresses that as more energy efficient and `zero-carbon' houses become more common and subsequent operational energy is dramatically decreased, consideration of embodied energy becomes more important. Ultimately, CA suggests quantifying embodied energy can be a useful tool, but it is not the only component of determining the impact a building has on the .environment. The Architectural League of New York describes its project `Ten Shades of Green' as an exhibition on architectural excellent and environmental responsibility. The project evaluates the impact architecture has on the environment, and encourages designers and architects to do their part in reducing their impact of the world's resources. "Buildings account for nearly half the energy consumption of developed countries, and therefore are the major cause of global warming, the most tangibly urgent of environmental problems'." Ten Shades of Green offers ten steps for creating `fully green architecture'; among the ten steps is an analysis of embodied energy. While the exhibit showcases buildings that meet one of more of these 10 criteria, the focus of this paper is on the various definitions of embodied energy and how it is quantified. ~ ~ http://www.tenshadesofgreen.org/1 Oshades.html 10 Ten Shades of Green defines embodied energy as `all the energy required to extract, manufacture and transport a building's materials as well as that required to assemble and 'finish' it. 12 The project, like the publication from Canadian Architects, stresses that as green architecture, zero-carbon houses and more energy efficient buildings emerge, more emphasis is put on embodied energy. A simple overview is provided on the quantification of embodied energy, based on wood as requiring 640 kilowatt-hours per ton and then compares it to other common building materials. For example, the embodied energy of brick is 4 times (4X) that of wood, concrete (5X), plastic (6X), glass (14X), steel (24X) and aluminum (126X). It encourages the conservation and restoration of old buildings, the use of local materials to decrease transportation energy, and `loose fit' design methods, which give a building flexibility in adaptive reuse. The Architectural League of New York provides a concise summary of embodied energy and outlines other steps in reducing the impact we have on the world's resources. Embodied Energy in Historic Preservation It is argued that the conservation of embodied energy in a historic structure becomes an added benefit to the social and cultural value of historic buildings. Oftentimes, the design of historic buildings took into account solar orientation, window placement, high ceilings and the use of durable materials. These design features are still beneficial today and can be incorporated into a `green' design. In addition to the energy cost of demolishing a building, there is also the cost of energy invested in historic buildings. Historic structures are commonly constructed of brick, plaster, concrete and timber; materials which consume a relatively low amount of energy. Many modern buildings utilize plastic, steel, vinyl and aluminum in addition to the aforementioned materials. The more contemporary materials are some of the most consumptive in terms of embodied energy, and should be used wisely. Even when materials are used in 12 hitp://www.tenshadesofgreen.org/lOshades.html 11 the construction of a new building that are similar to those found in historic buildings, increased pressure on resources makes those materials more expensive in terms of embodied energy than they were in the past though increased transportation and labor costs. The demolition of a historic building and subsequent replacement by a modern structure wastes valuable embodied energy that cannot be easily justified by lower annual operating costs.13 In theory, energy savings can only be realized when the sum of energy used in the construction of a new building and the destruction of the old building is less than the energy cost of operating the old building over the rest of its useful life.14 In many instances, the most energy efficient option is to rehabilitate an old building to be more efficient in the context of operational energy. The option not only `reuses' the embodied energy, it also saves the energy that would be required to demolish the building and preserves a historic link to the past. Conclusion ' Ultimately, embodied energy assessment and analysis is an effective way of comparing the environmental impacts of decisions made in the built environment, specifically; the construction, demolition, preservation, or adaptation of structures. Embodied energy studies provide a platform to determine the best use of overburdened natural and manufactured resources and provide options for adaptive reuse, growth management, and conservation. As quantification of embodied energy is still an inexact science, attention must be paid to the manner in which comparative analysis is made and the invariability of assessment methods. Considering that 40% of carbon emissions are attributed to buildings15, an important factor to consider when designing new construction is how much useful 13 Rypkema, Donovan. Economics, Sustainability, and Historic Preservation. 2005 14 McIlwain, John and Knox McIlwain. Out with the New and in with the Old. ITLI. 2007 15 http://www.nationaltrust.org/green/about.html 12 energy will be wasted with the demolition of an old building. On average, embodied energy accounts for 20% of a building's energy use during a 50-year cycle; equivalent to 10 to 20 times the annual energy use.16 During an assessment of Toronto homes, completed by a Canadian research group, it was concluded that the average house had an embodied energy roughly equal to a quarter of the energy needed to sustain that house for 40 years." Simply demolishing a building to build a new `green' structure is not energy efficient and the decreased operational costs will not outweigh the energy wasted with the demolition of the structure. - _ - - _ . - -~R - , r~~ sY.. 16 Recovery Insulation- Embodied Energy Mumma, Tracy. Reducing the Embodied Energy of Buildings. Home Energy Magazine. 1995 13 Appendix A E~ve'ope 2R ~?r`t s ~ 2'~~x ~ ~ r ~[rucc~,res "Research carried out by Cole and Kernan(1) using a =T~ ~ model based on Canadian construction of a generic 4 ~ > ; . ~ kY ~ ,.~t ~ 620 m2 (50,000 ft2) three-storey office building with 5?=~'`,', ~ underground parking, considered three different r serves ~ construction systems (wood, steel and concrete), and c ~ FiniShB4 za„ ~ f~: ,s^~ yielded the following results for average total initial Site 4'Jorx con ~aC1iOn embodied energy. (Note: Data were averaged for the 6°Jo three construction systems as the overall differences Average Total Initial Embodied Energy 4.82 GJ;m' between the building types were not significant. Breakdown of Initial Embodied Energy by Typical Office Building Components Averaged Over Wood, Steel and The building envelope, structure and services Concrete Structures [Cole and Kernan, contribute fairly equally and account for about 1996) three-quarters of total initial embodied energy. The finishes, which represent only 13% of the embodied energy initially, typically account for the highest .increase in recurring embodied energy. Embodied energy may not be significantly different between building systems (e.g., wood versus steel versus concrete), however, the environmental impacts associated with one material versus another can be dramatically different. (2) It is interesting to consider the relationship between site work (b% of initial embodied energy) and services (24%). The reallocation of embodied energy, and hence project budget, from conventional services to the site management of storm water, for example, may have a negligible effect on initial embodied energy, but the impact on recurring embodied energy may prove significant. Additional benefits downstream of the building at the community infrastructure level should also be considered. This points to one of the shortcomings of embodied energy analysis, which typically ends at the property tine and is somewhat unwieldy in dealing with a broader context. When recurring embodied energy in buildings is considered, yet more interesting relationships are revealed from the work of Cole and Kernan. First, to the credit of civil engineers, the structures of buildings normally do not expend recurring embodied energy, lasting the life of the building. By year 25, however, a typical office building will see an increase of almost 57% of its initial embodied energy due mostly to envelope, finishes and services. By year 50, recurring embodied energy will represent about 144% of the initial embodied energy, and it 14 was projected that by year 100, this proportion would rise to almost 325%. This relationship is a direct result of what is referred to as differential durability, where the service lives of the various materials, components, and systems comprising the building differ dramatically. The current preoccupation with lower first costs in buildings reveals its disregard for sustainability when viewed from a building life cycle perspective.i18 , ~ r _ ~~:,x ~ ~ m _ _ $ ~ - ~ gg~~ sm^"`~~ M ~ 5,a S, s+a~~~d ~ f. , a~_: roc v ~ 'i .,m -;:.n« r::ar- 18 http://www.canadianarchitect.com/asf/perspectives_sustainibility/measures _of sustainablity/measures of sustainablity embodied.htm 15