Wednesday, December 5, 2012

Incorporating Environmental Metrics into Probalistic Seismic Performance

The Applied Technology Council (ATC) has made available for review a 90% draft of the ATC-86 report recommending approaches for incorporating environmental metrics into the ATC-58 probabilistic seismic performance methodology. The SEI Sustainability Committee has been asked to review the 80-page document. SEI-SC will provide comments by December 12th.

The work of implementing the recommendations in the ATC-86 report is funded in part by the Federal Emergency Management Agency (FEMA).

You may inquire about the review process by emailing Stay tuned for further updates on this interesting work by our member affiliated organization.
Wednesday, November 14, 2012

Structure and Carbon: How Materials Affect the Climate

The Carbon Working Group (CWG) is pleased to announce the release of their white paper titled, Structure and Carbon: How Materials Affect the Climate. CWG is a dedicated and concerned group of engineering professionals with design, industrial, and academic backgrounds. They are united in passion for addressing the causes of climate change today through professional practice.

The intent of this white paper is to serve as a primer on greenhouse gas emissions, the most important of which is carbon dioxide (informally referenced simply as “carbon”), for the structural engineering community and others with an interest in the carbon impacts of structural materials and systems. It explains:

  1. Why structural engineers must understand greenhouse gas emissions
  2. How the construction of building structural systems contributes to greenhouse gas emissions
  3. How we as a profession can help reduce the greenhouse gas emissions associated with structural systems.
Ultimately, the authors hope that this paper will spur actions that will reduce the greenhouse gas emissions associated with building structures. The materials in the built environment are a substantial source of anthropogenic carbon emissions, and structural engineers have unique opportunities to specify materials for construction projects that can significantly affect the contribution of each project to more climate changes.

The choices of structural engineers make a difference. The risk of destructive climate change impacts can be reduced by choosing and using building materials with climate change in mind. This white paper introduces some strategies structural engineers may use to reduce greenhouse gas emissions. Download the white paper here.

For further information on how to reduce structures' environmental impact, see the SEI Sustainability Committee’s  Sustainability Guidelines for the Structural Engineer (Kestner et al, 2010).
Tuesday, November 13, 2012

Carbon Working Group

The purpose of the Carbon Working Group (CWG) is to study the carbon impacts of structural materials and systems and to make recommendations for reducing the carbon footprint of the structural system. The CWG has recently produced a white paper intended primarily for practicing structural engineers that addresses the following topics. Download it here.

  1. Explain the importance of carbon and the meaning of carbon equivalents.
  2. Describe how, and during which parts of the lifecycle, carbon is embodied in the various primary structural materials (steel, concrete, wood, masonry).
  3. Discuss how the engineer can impact the carbon footprint of the structural system and building.
  4. Provide examples of carbon calculations comparing baseline cases and improved cases.
Saturday, September 29, 2012

Life Cycle Assessment Software Now Free Download

The Athena Impact Estimator® (IE) is the most widely used North American life-cycle assessment tool made for designers that allows one to choose the structural system and specification. In order to significantly increase the user base of the IE within the architectural/engineering design community, the software is now offered free of charge. Visit for more information and to download.

The SEI Sustainability Committee is recognized in Athena Institute’s recent press release for our contribution to improvements made to their latest version of the Impact Estimator® (Version 4.2.01, released Sept 2012).  The LCA working group of the committee issued a wish list to Athena in late 2011 and worked through the year to fulfill one of the top wish list items: the addition of composite floors (concrete-filled metal deck over steel beams) to the floor and roof assembly options. This effort took a bridging of Athena with AISC and ensuring the translation of data from AISC into the tool met the needs of structural engineering users. The LCA WG will continue to push for implementation of other wish list items in the next release.”
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Friday, September 21, 2012

Structure and Carbon: How Materials Affect the Climate


The following is excerpted from the Carbon Working Group's upcoming white paper:

The embodied impacts associated with building materials (including structural materials and other finishes and equipment) comprise a relatively small part of the total environmental impact over the life cycle of a structure, with impacts from heating and cooling typically far outweighing the materials impacts. In North America, the relative life-cycle carbon emissions due to building structural materials alone can range from 1 to 16 percent for a 50-year building life, depending upon the building type, energy efficiency, and location.

However, a study of demolition records found that over 60% of the demolished concrete buildings were less than 50 years old, and roughly 10% were less than 25 years old. The numbers were even more striking for the steel-framed buildings: more than 80% of these buildings were less than 50 years old when demolished, and 40% less than 25 years old. For these short-lived buildings, the embodied impacts of the structural system could easily exceed 1/3 of the total life-cycle building impacts for buildings that are highly energy efficient.

The green building movement has primarily focused on improving operating efficiencies to reduce carbon emissions, and building energy efficiency is likely to improve. As a result, the relative embodied impacts of building materials will likely grow. To decrease our risk of exposure to disastrous climate-related events, we must not only reduce emissions from building operations but also reduce embodied emissions in building materials including structural materials. The success of this task depends in large part upon structural engineers who understand the emissions associated with the materials they use and who can use data, design, and material research to reduce the carbon emissions associated with their projects.
So structural engineers are faced with both a challenge and an opportunity.  

Use this site to learn about structural design's contribution to climate change, and become part of the movement for solutions.
Tuesday, September 18, 2012

How to Reuse a Floating Bridge

Seattle's 520 Floating Bridge
The Washington State DOT has required that the design-build team for a new bridge must reuse or recycle the existing bridge in a sustainable way. An international design ideas competition has been born of this challenge. Favorite options for reusing the existing pontoons have included floating docks, breakwaters, and piers. It's likely that the winner of the ideas competition will be more creative.

Results of the competition are to be announced live at the 2012 Seattle Design Festival and subsequently posted online. Log on to view the winning design. Did you have a better idea? What other design options come to mind? Please share your comments here.
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Tuesday, September 11, 2012

Coal Waste Processors Sue EPA

Coal waste products, like flyash, have long been used as complimentary cementitious materials to improve strength and durability of concrete while reducing cement content and therefore the embodied carbon of concrete. Until recently, even the EPA has been supportive of the commercial use of such materials. Now the EPA is taking a second look at the heavy metal content in these byproducts. A final ruling on whether to classify these materials as hazardous waste remains in limbo, but the uncertainty has angered the largest coal waste producers who have filed suit against the EPA demanding a deadline for the ruling.

Jim Vallette of the Healthy Building Network has published an interesting article outlining the positions of each side on this case. Online at

This issue was addressed in a previous blog article on this website: House Bill Takes on EPA Ruling Process
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Friday, September 7, 2012

Thermal Bridging in Concrete


The thermal bridging group is progressing on their next publication through ASCE. One new point of focus in this publication is thermal bridging through other materials. One common building material that is often overlooked as a thermal bridge is concrete. 

Although concrete isn’t nearly as conductive as steel, where it acts as a bridge it can still cause substantial energy loss. One of the most common examples of this is at balconies. Often the balcony is merely a cantilever of the main floor slab. Because of this, there is no continuous envelope or insulation barrier. In high rise condos and apartments, these can almost be visualized as fins on a radiator, as they behave in much the same way. 

One way to avoid or reduce this bridge is with a proprietary break. These systems are designed to still transfer the cantilever forces (shear and moment), while reducing the bridging to isolated stainless steel bars. Although widely used in Europe, these systems are not commonly found in the states. The Thermal Bridging group will be looking at these cantilever concrete conditions more closely in the next publication.

Thermal Bridging Working Group update by web liaison Raquel Ranieri, P.E., LEED AP BD+C. Read more recent articles about thermal bridging here.
Tuesday, September 4, 2012

The Value of Structural Engineering to Sustainable Construction


Numerous rating schemes have been proposed to incentivize green design, but how well do these codes relate to the building structures. The Institution of Structural Engineers set out to identify which green codes, if any, successfully addressed structures. Their report, titled The Value of Structural Engineering to Sustainable Construction, takes a methodical look at provisions in eight main categories common to most of the rating systems:
  1. Reuse
  2. Reduction of Portland cement
  3. Recycled content
  4. Responsible sourcing 
  5. Local sourcing
  6. Life cycle assessment
  7. Efficiency & future proofing
  8. Health implications
The conclusions are generally predictable, but the report does a nice job of recommending changes to improve the codes. Highest on the list are needed changes to those credits witch promote a perversion of the sustainable intent, like achieving full recycled content credit by using structural steel (over 90% post-industrial recycled content by nature) or using more interior finish for it's recycled content when a polished concrete wall would be perfectly fine. The best features of the report are the meticulously researched figures and user surveys. Anyone preparing a talk on sustainable structures should read this report for statistical backup to their conclusions.

Download the report at:

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Thursday, August 30, 2012

Disaster Resilience in Congress

Disaster resilience has recently caught the attention of the United States Congress. Representatives Davis (R-KY) and Diaz-Balart (R-FL) introduced a bill proposing tax credits for resilient construction. The bill refers to the FORTIFIED program by the Insurance Institute for Business and Home Safety.

In other action, the National Institute of Building Science recently provided testimony to the Congressional Transportation and Infrastructure Committee's Subcommittee on Economic Development. Intitute President Henry L. Green, Hon. AIA, reiterated that mitigation efforts save about four dollars for every dollar spent; argued for increased collaboration between federal agencies; and proposed suggestions for improved code development, adoption, and enforcement.

Article by Disaster Resilience Working Group web liaison Tonatiuh Rodriguez-Nikl, Ph.D., P.E. Check out other recent articles about disaster resilience.
Wednesday, August 22, 2012

Like a Radiator: Thermal Bridging

Some architectural gems have recently taken a lot of heat for loosing a lot of heat. Thermal bridging is a pervasive problem for all structures with monolithic slab cantilevering balconies. The authors of this article hosted at have turned their infra-red camera's on Chicago's iconic Aqua tower. Beyond simply highlighting shortcomings, some more efficient alternatives are proposed.

Link provided by committee member Kathrina Simonen, R.A., S.E, LEED-AP, assistant professor at the University of Washington.

Sunday, August 19, 2012

Sustainable Infrastructure Update

The recently revived Infrastructure Working Group (IWG) strives to engage the structural engineering community outside of building designers in an effort to disseminate the fundamental concepts of sustainability that are applicable to all types of structures.

While the LEED rating system has pushed building designers to develop and apply their fundamental principles of sustainability, the lack of such a driver within the bridge, tunnel, dam, levee, and other industries has left a gap in the sustainability fundamentals of its engineers. The IWG is working to fill that gap by raising awareness about sustainability project rating systems such as Envision and Greenroads that are applicable to transportation and other non-building type structures.

Envision is a newly released system developed to help evaluate the sustainability of civil infrastructure. It was created by the Institute for Sustainable Infrastructure (ISI) which was founded by the American Society of Civil Engineers (ASCE), the American Council of Engineering Companies (ACEC), and the American Public Works Association (APWA). The rating system uses a holistic approach to educate owners and project teams on the aspects of sustainability and offers guidance on how to ensure each aspect receives due consideration. Projects are evaluated based on 55 credits within 5 categories: Quality of Life, Leadership, Resource Allocation, Natural World, and Climate and Risk.

More information about Envision and ISI can be found at

Post submitted by committee member Marty Chorkey.
Wednesday, August 15, 2012

10 Steps to Greener Concrete


According to the World Business Council for Sustainable Development (WBCSD), “concrete is the most widely used material on earth, apart from water, with nearly three tons used annually for each man, woman, and child.” Most structural engineers are familiar with efficient design practices for working with concrete, but there are sustainable considerations that should also be taken into account. There are at least three areas in which the characteristics of concrete can be used sustainably:

1.     Exposed concrete can be used as both an interior or exterior finish, thereby reducing the additional material cost of cladding, painting, installing drop ceilings and sheeting, etc.
2.     Concrete structures intrinsically have more thermal mass – a property that enables heat energy to be absorbed, stored, and later released, giving greater comfort in the both the heat of summer and the cold of winter.
3.     Carefully considered mix designs can reduce the embodied carbon intrinsic to concrete, improve long-term durability, and still provide sufficient workability.

Unfortunately, the production of portland cement releases a high volume of carbon. Approximately 40% of embodied carbon is associated with powering the extremely hot furnaces needed for the transformation. Cement manufacturers are experimenting with ways to become more efficient. (4) Structural engineers can specify that cement be sourced from plants scored by the Energy Star Industrial Focus Program with an Energy Performance Indicator (EPI) above 75.

The remaining 60% of embodied carbon in cement is a result of calcination, the intrinsic chemical reaction whereby limestone is transformed into clinker, on the way to becoming cement. Therefore, the primary means of greening concrete is to reduce the amount of portland cement in the mix.

Fortunately structural engineers can have great control over the mix designs selected. Some relatively simple steps can be taken to ensure that more sustainable concrete mixes are used on your job site. These can be simplified into four rules of thumb: (5) reduce water content, (6) use complimentary cementitious materials (CCMs), (7) use the maximum aggregate size, and (8) specify proper strengths.

Reduce water content. Keep the water/binder ratio low, and although less cement is used, the same strength can be achieved. A low w/b is also good for durability. Based on the relationship of specific gravity between concrete and water, a w/b ratio greater than 0.32 is most likely to result in free water that is not bound to the binder paste. This results in unwanted voids and drying shrinkage as the free water evaporates (instead of being consumed in the chemical reaction).

High slump is often desirable for workability. (9) Fly ash and superplasticizers help improve workability without increasing water. The spherical shape of fly ash acts as a physical lubricant and thus aids in cement hydration. Water-reducers likewise increase slump, however, too much of these admixtures can cause segregation and excessive bleed water. A good rule of thumb is to limit the water-reducers or superplasticizers to 2 percent of the mass of the binders.
Fly Ash (Meryman 2007)

Use complimentary cementitious materials (CCMs). Fly ash, slag, natural pozzolans, and ultrafines can be used in lieu of portland cement. Many such materials have less embodied carbon or are recycled industrial byproducts. The basic chemical reaction between portland cement and water produces calcium hydroxide (CH).  Many CCMs then react with the CH to produce calcium silicate hydrate (C-S-H), which provides a much stronger bond, particularly around the aggregates.

With regard to durability, C-S-H is known to be a much denser product and therefore less permeable. Non-cement binders also tend to reduce the heat of hydration. Although specific alkali-silica reactions are known, CCMs generally enhance both strength and durability. (10) For a more in-depth analysis of durable mixes, designers can utilize the Life-365 freesoftware from the National Ready Mix Concrete Association (NRMCA).

Use the maximum aggregate size. This reduces the surface area that the binder paste needs to cover thereby keeping the past volume lower. Normally available aggregates are stronger than the surrounding hardened paste.

Specify proper strengths. Choose target strengths at ages that realistically reflect the needs of the project. Recall the above described chemical reaction involving CSMs: C-S-H takes longer to develop and the conventional 28-day period may not be sufficient. If possible, specify 56 or even 90 day strength. This gives mix designers at the batch plant more freedom to utilize some CCMs.

The above recommendations were sourced from SustainabilityGuidelines for the Structural Engineer, Chapter 3.2 – Concrete. Current and former SEI Sustinability Committee Members influential in authoring the referenced chapter include: Helena Meryman, Sarah Vaughan, Alan Kren, and Iyad Alsamsam. This summary is by Ken Maschke, P.E., S.E., LEED A.P., associate with Thornton Tomasetti in Chicago, IL.
Saturday, August 11, 2012

Life Cycle Assessment

The Life CycleAssessment (LCA) Group is working toward educating structural engineers on the meaning and professional application of LCA criteria, procedures, and measurements in order to make environmentally conscience decisions on the use of structural materials.

Life cycle assessment (LCA) is a method of measuring the total environmental impact of a product or process, from acquisition of raw materials to end-of-life.  For structural materials, the life cycle generally includes extraction, manufacture, transport, construction, maintenance, re-use and recycle opportunities and end-of-life including demolition and disposal. Thus LCA provides the most complete picture of environmental effects inherent to choosing certain structural materials.  It is analogous to performing environmental accounting on the structural materials in order to choose the most environmentally friendly design solution over the anticipated standardized life of such materials.

LCA has four basic stages or evaluation components; goal and scope definition, inventory analysis, impact assessment, and interpretation.   The inventory analysis can utilize such catalogs as the U.S. Life-CycleInventory Database prepared by the National Renewable Energy Laboratory, and the Inventory of Carbon and Energy ('ICE') prepared by the University of Bath.  The analysis can be done in software programs such as Athena Eco-Calculator and the SimaPro.  In addition, some companies are coming out with their own proprietary software for post processing the data and inventories based upon specific circumstances. 

LCA assessment tools move beyond simplistic assumptions and determine true environmental impacts.  Measurements of LCA include multiple metrics including quantifying the environmental ‘costs’ (e.g. CO2emissions) of each item, the energy required to produce the items (embodiedenergy) and various measurements of how these impacts relate to larger scale environmental concerns (e.g. global climate change)

The main goals of the group include:

1.   Providing information and resources to the structural engineering community on applications of LCA in building and infrastructure design. 
2.   Improving LCA software to better represent environmental impact reductions we know can be made from structural design and specification.
3.  Engaging structural engineers in the incorporation of LCA into green building and infrastructure rating systems and building codes.

Currently, the group is working on publishing their response to the top 10 most encountered questions, as experienced by LCA Committee members within their practice of structural engineering.
Wednesday, August 8, 2012

Thermal Breaks for Brick Shelf Angles


The Brick Industry Association (BIA) has an article in their most recent issue of Brick in Architecture magazine which includes information and detailing of thermal breaks for brick shelf angles in veneer construction over cold-formed steel.  

The article begins on page 9; the section entitled “Thermal Design” begins near the end of page 13, and the details are on pages 12 and 13.
BIA has recommended that AISI reference this article in their upcoming rewrite of the steel stud brick veneer design guide; I found out about it in a memo received this morning with a BIA review of the old design guide.
Provided by committee member Don Allen, P.E.
Friday, August 3, 2012

Carbon White Paper Coming Soon

The committee’s Carbon Working Group white paper, "Structure and Carbon: How Materials Affect the Climate" will explore how carbon dioxide and other emissions contribute to climate change, how the manufacturing of the structural materials in buildings creates such emissions, and the ways that structural engineers can make changes in their current practice to reduce greenhouse gases.  In a nutshell, we aim to quantify the carbon footprint of structure, and provide tools for designers to reduce it.

The paper covers the modern structural materials: concrete, steel, masonry, wood, and fiber-reinforced polymers. Carbon footprint data is based on life cycle assessment research conducted for industry trade groups and research consortiums such as AISC, PCAAthena, and CORRIM. In addition to reporting raw emission numbers, we show how the data can be used to study material optimization on an example floor plate.  We also discuss uncertainty in the data collected, to make users aware of current limitations and to promote further study.

"Structure and Carbon: How Materials Affect the Climate" is in its final review phase. Look for its public release on this website later this year.

Post by Carbon Working Group liaison, Adam Slivers, P.E., S.E., Associate at KPFF Consulting Engineers in Seattle, WA.

Wednesday, August 1, 2012

Gray to Green: How to Make Cleaner Concrete

Sustainable concrete has captured the imagination of always provocative Popular Mechanics. A recent web article explores radical new ways to green concrete. Most structural engineers are well versed in supplemental cementitous materials like fly ash and blast furnace slag, but have you considered rice husks, sewage sludge, and geopolymers? The article also suggests using prcelain from recycled toilets for aggregate and hempcrete blocks as an alternate to CMU. Finally, a PM article wouldn't be complete without some exploration of space. Strategies are discussed for converting moonrocks to traditional or sulfur-based concretes.
Friday, July 27, 2012

Thermal Bridging Working Group Update


The Thermal Bridging Working Group is actively trying to spread awareness of thermal bridging, and how structural engineers can address it, to help make more efficient building envelopes and reduce unnecessary energy losses. This has been aided with their recent publication in AISC’s ModernSteel Construction. Learn more about this free resource on our previous post or download the file electronically from MSC

Detailing to prevent or reduce thermal bridging is much more mainstream outside of the United States, so the group is working to bring local consultants up to speed, and make all designers aware of the issues and impacts associated with envelope details. A recent article in Building Science emphasizes the importance of proper detailing to prevent thermal bridges, and points out some common details. This article by Joseph Lstiburek can be found here.

In the meantime, the group is working on their next publication, which is a larger guide to thermal bridging. This new guide will focus on all material types including wood, masonry, and concrete. They are also hoping to arrange some presentations throughout the country over the next year. Stay posted for more information regarding upcoming speaking dates.

Article by Thermal Bridging Working Group web liaison Raquel Ranieri, P.E., LEED AP BD+C, senior associate with Walter P Moore in Los Angeles, CA. For more information about the Thermal Bridging Working Group please refer to our website.
Wednesday, July 25, 2012

Diaster Resilience Part of Sustainability Too

The Ray and Dagmar Dolby Regeneration Medicine Building at University of California, San Francisco. (Bruce Damonte, courtesy Rafael Vinoly Architects)
Surviving and thriving after natural events like earthquakes, storms, and tsunamis is a key component of sustainability. Although designers have previously placed more emphasis on material selection and energy performance, there's no disputing that buildings that survive extreme events are more sustainable than those that must be rebuilt. This article in the Pacific Standard further explores disaster resilient AND sustainable structural engineering. 
Friday, July 20, 2012

Coming Soon: New White Paper on Disaster Resilience


The Disaster Resilience Working Group is hard at work on a white paper that highlights the connections between disaster resilience and sustainability.  The document is still evolving but is starting to take form.  The white paper is expected to be finished by late 2012 and released to the public in mid-2013 after undergoing peer review.

The first chapter defines the main concepts and highlights the impacts of disasters and the importance of hazard mitigation.  The second chapter provides concise but useful considerations for resilient structural design and points the reader to resources for technical guidance.  The next chapter provides an international perspective with a discussion of disasters in developing countries.  A final chapter is planned with case studies to provide examples for some of the concepts presented in the paper.  

The Disaster Resilience Working Group is interested in gaining members that are willing to help with the white paper or looking to champion additional projects related to sustainability and resilience.  The Sustainability Committee has an open solicitation for new members, more.  Interested individuals are encouraged to apply for membership and indicate how they can contribute to the working group.  

Article by Disaster Resilience Working Group web liaison Tonatiuh Rodriguez-Nikl, Ph.D., P.E., Assistant Professor in the Department of Civil Engineering at California State University, Los Angeles. For more information about the working group please contact Tona at
Monday, July 16, 2012

Hajjar & Webster Design for Deconstruction

What if aging buildings could be dismantled and their components reused? Jerry Hajjar, Northeastern University, and Mark Webster, Simpson Gumpertz & Heger, have received a $250,000 research grant from the National Science Foundation to study design for deconstruction. Using structural clamps to attach precast plank to steel girders is one of the concepts to be evaluated. Read more about their work on the news@Northeastern web publication.
Saturday, July 14, 2012

Announcing the SEI Sustainabillity Committee's New Web Presence


The Sustainability Committee of the American Society of Civil Engineers’ Structural Engineering Institute (ASCE-SEI) has re-launched their website with a new, more dynamic and interactive format. The goal of the new website is to provide current information, promote discussion, and build connections between organizations and individuals interested in sustainable structures.

The new site will present weekly updates from the committee’s technical working groups. Web 2.0 features will make it easier to interact with the site and allow visitors to share interesting links with their personal networks.

The SEI Sustainability Committee was formed in 2005 with the following mission to:

·      Advance the understanding of sustainability in the structural community
·      Incorporate concepts of sustainability into structural engineering standards and practice.

In 2010 the committee published a 300-page book titled Sustainability Guidelines for the Structural Engineers, available for purchase through ASCE Press. The book provides guidelines and advice to structural engineers, identifying the important role that structural engineers play in sustainable development.

Structures take up an enormous amount of material resources and energy in their manufacture, transport, construction, and end-of-life disposal. Efficient material use and specification contributes greatly to the sustainability of a project. Superstructure is also typically the first item constructed on site and can therefore inhibit or enhance the subsequently installed systems that greatly affect operational energy performance. Finally, structural engineers are in a position of influence within the design team, connecting the purse strings of the developer to the activities of the builder. Communication and decisions made with the design-build team ultimately determine whether a sustainable project will be pursued.

To learn more about structures and sustainability continue to explore this site. The SEI Sustainability Committee welcomes all design professionals.

For additional information about the website’s features and the public roll-out please contact the website working group lead, Ken Maschke,
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