Tuesday, September 16, 2014

Top 10 LCA FAQs Bibliography

We’ve been asked about recommended reading. While there are over 50 references embedded in our Top 10 articles these are ones we agreed likeminded structural engineers should turn to first. Enjoy!

Anderson, J., Silman, R. (2009) “A Life Cycle Inventory of Structural Engineering Design Strategies for Greenhouse Gas Reduction,” Structural Engineering International, March 2009 Issue.

Arup (2010) “Embodied Carbon Study: Study of Commercial Office, Hospital and School buildings,” The Concrete Centre, United Kingdom.

Cole, R., Kernan, P. (1996). Life-Cycle Energy Use in Office Buildings, Buildings and Environment, 31 (4): 307-317

Comber, M.V. & Poland, C. (2013). “Disaster Resilience and Sustainable Design: Quantifying the Benefits of a Holistic Design Approach.” Proceedings, American Society of Civil Engineers- Structural Engineering Institute (ASCE-SEI) Structures Congress, Pittsburgh, PA.

Curran, M. A. (2006). Life cycle assessment: principles and practice. Cincinnati, Ohio, 80.

Fernandez, N. P. (2008). “The Influence of Construction Materials on Life-Cycle Energy Use and Carbon Dioxide Emissions of Medium Size Commercial Buildings” Victoria University of Wellington, Wellington, New Zealand.

Hsu, S. (2010) “Life Cycle Assessment of Materials and Construction in Commercial Structures: Variability and Limitations,” Massachusetts Institute of Technology, Cambridge, Massachusetts.

Kaether, Burridge (2012) “Embodied CO2 of Structural Frames”, The Structural Engineer.

Kneer, E., & Maclise, L. (2008). “Consideration of Building Performance in Sustainable Design: A Structural Engineer’s Role.” Proceedings, Structural Engineers Association of California (SEAOC) Annual Convention.

Konig, H. Kholer, N. Kreissig, J. Lutzkendorf, T. (2010). A life cycle approach to buildings: principles, calculations, design tools. Radaktion DETAIL, Munich.

LEED (2012) Reference Guide for Green Building Design and Construction v4 Draft. USGBC.

Ochsendorf, J., et al. (2011) “Methods, Impacts, and Opportunities in the Concrete Building Life Cycle,” Massachusetts Institute of Technology, Cambridge, Massachusetts.

Preservation Green Lab (2011) The Greenest Building: Quantifying the Environmental Value of Building Reuse, National Trust for Historic Preservation. [Accessed July 11,2014 from http://www.preservationnation.org/information-center/sustainable-communities/green-lab/lca/The_Greenest_Building_lowres.pdf]

Ramesh, T., Prakash, R., Shukla, K.K. (2010) “Life cycle energy analysis of buildings: An overview,” Energy and Buildings, 42 1592-1600.

Simonen, K. (2014) Life Cycle Assesment, New York, Routledge.

Webster, M., Kestner, D., Parker, J., Waltham, M.. (2007) “Deconstructalbe and Reusable Composite Slab,” Winners in the Building Category: Component – Professional Unbuilt, Lifecycle Building Challenge
Sunday, September 14, 2014

ASCE International Conference on Sustainable Infrastructure 2014

For those of you who do engineering for infrastructure, the International Conference on Sustainable Infrastructure is in Long Beach, California, November 6-8, 2014. It is hosted by ASCE.www.asce.org/icsi2014
This is the first international conference of its kind. The call for papers has closed.

Buzzwords from the program include: climate change, extreme events, risk, resiliency, adaptation, envision rating system. 

More from the program:
This conference is not about how to be sustainable. If it were, we would tell you not to waste your time. Instead, and more appropriately, this conference is about how to deal with the consequences of non-sustainability, that is, how to plan, design and construct infrastructure for a new and increasingly harsh operating environment. Today, engineers, academicians and other practitioners are facing difficult and unprecedented challenges in addressing a new reality for infrastructure design. Decade after decade of non-sustainable economic development is changing the environmental conditions under which infrastructure is supposed to operate. It is also changing the cost and availability of critical resources such as fresh water and energy. How we as engineers and scientists deal effectively with these changes is the most important challenge of the 21st century. This international conference is the first of its kind. We have brought together people from across the world; people who are building the knowledge base and developing the requisite policies and practices to handle the challenge of a changing operating environment. We designed the conference for practitioners, enabling them to engage with others, exchange ideas, and see the full spectrum of activities in infrastructure design for this new reality. 

You can also meet members of the Sustainability Committee of the Coasts, Oceans, Ports and Rivers Institute (COPRI) of ASCE. Contact Angie Lander at ASCE for more information on the committee.
Monday, July 28, 2014

Q10: What is greener, building reuse or new construction?

Reusing existing buildings has many potential benefits, but might constructing new buildings offer greater life-cycle environmental advantages?

Author: Mark Webster; Contributors: Adam Slivers, Matthew Comber

Reusing existing buildings instead of constructing new buildings has many potential benefits, including:
  • Reducing the use of new materials and their associated environmental impacts by extending the lifetime of materials that have already been manufactured and are in use.
  • Protecting undeveloped land by reducing the pressure to construct new buildings and infrastructure on it.
  • Reducing construction and demolition waste.
  • Maintaining the cultural heritage of our existing building stock.

But even so, might constructing new buildings offer life-cycle environmental benefits compared to reusing existing buildings? What if new buildings are more energy efficient than the alternative reused buildings?

Let’s look at three studies, summarized in Table 1, that use life-cycle assessment methodology to compare building reuse to new construction. These studies show much depends on assumptions regarding operational energy use and lifespan.

Empty Homes Agency

The British Empty Homes Agency, a charity working to fill unoccupied homes, compared the global warming impacts of three refurbished homes to three new homes over a 50-year time period [EHA 2008]. All six case studies are actual projects, so the embodied impact estimates are based on actual bills of material. The authors selected the 50-year time period as the assumed time between major refurbishments.  

The average CO2 emissions over 50 years are 155 kg/ft2 of floor area for the new construction and 150 kg/ft2 for the rehabilitation projects. If the authors had selected a 75-year time-frame, the results would have been similar (211 vs. 219 kg/ft2). While the reused homes use more energy per square foot per year (an average of 2.76 vs. 2.23 kg/sf/yr), the embodied impacts are so much lower that at the end of the 50-year or even the 75-year time-frames the differences in total emissions are small.

Athena Sustainable Materials Institute

The Athena Sustainable Materials Institute (ASMI) conducted a study for Parks Canada of four actual rehabilitation projects [ASMI 2009]. ASMI compared the energy use and carbon emissions for the four buildings to the impacts of demolishing the buildings and constructing similar new buildings. Unfortunately the authors did not attempt to quantify the embodied impacts associated with renovation of the existing buildings.

For the base case, which assumes the new buildings meet the Canadian energy code, the average CO2 emissions for the new and rehabilitated buildings over a 50-year period are almost identical: 251 kg/ft2 for the rehabilitated buildings vs. 253 kg/ft2 for the new buildings. Only the existing Winnipeg building had better energy performance than the assumed new replacement building; the assumed new buildings had lower energy use in the remaining three cases.

Preservation Green Lab

The Preservation Green Lab (PGL) of the National Trust for Historic Preservation conducted the largest and most thoroughly documented study comparing reuse and new construction. The Greenest Building: Quantifying the Environmental Value of Building Reuse examines the life-cycle impacts of seven reuse vs. new construction scenarios in four different cities [PGL 2011]. The study’s findings are exceptionally well documented and available for public scrutiny on the organization’s website.

The PGL assumed for the new construction scenarios that the existing building was demolished and includes the demolition impacts in the LCA results. The PGL used actual renovation projects to estimate the embodied impacts of renovation activities. The study quantifies 17 environmental impacts, including climate change.

For its base case, PGL assumed that both the reuse and new construction options have equal energy consumption. To evaluate the possibility that the new construction options may be more energy efficient than the reuse options, PGL also compared the reuse vs. new cases assuming 30% less energy use in the new buildings. While PGL used a 75-year time-frame for its base case, it also looked at time-frames ranging from 1 to 100 years.

Looking at just the commercial office building and single-family residence analyses in Chicago and Portland:
  • If the reuse and new options have equal energy consumption, the 50-year CO2 impacts are 12% to 17% less for the reuse option.
  • If the new options are 30% more energy efficient than the reuse options, the 50-year CO2 impacts are 1% to 12% less than the new options. In other words, even assuming significantly better energy performance for the new options, the differences in climate change impact over 50 years are relatively small. Over a 75-year time-frame, the 30% more energy-efficient new buildings emit 5% to 16% less carbon than the less efficient reused buildings.
Discussion and Conclusions

The three studies were conducted or commissioned by entities that generally support building reuse. Nevertheless, the studies appear to be well planned and conducted. The usefulness of the Athena study is limited by its neglect of the embodied impacts of the existing building renovations. Many existing buildings will require significant upgrades to make them as energy efficient as new construction, and the embodied impacts of these upgrades should be considered. The PGL study found that the materials-related carbon emissions for the rehabilitated office building, for example, accounted for 12% of the total life-cycle emissions over 50 years, compared to 22% for the new construction.

The studies generally support the conclusion that over a 50-year life cycle, the environmental impacts of reuse are less than the impacts of new construction when use-phase energy consumption is similar in the two options (Figure 1). Even when the new construction options have significantly better energy efficiency, the differences in life-cycle impacts are not that large in many cases, and fall within the expected range of uncertainty associated with life-cycle assessment studies.

Because the outcome of new vs. reuse comparisons depends upon so many variables, readers are encouraged to make use of readily available LCA tools and utility data to make their own project-specific assessments. The Athena Environmental Impact Estimator and the U.S. Energy Information Administration (EIA) are good starting points.


Of importance for climate change is the timing of the carbon emissions (Figure 2). New construction generally releases more carbon emissions than rehabilitation at the start of the life-cycle. Even in cases where the new construction uses less energy, it can take many decades for the new buildings to “pay back” that investment and equalize their emissions with the reuse alternatives. If the new and reuse options have similar energy efficiency, that pay-back may never happen. Those construction-related near-term emissions have a more serious impact on climate change than the emissions that occur farther in the future. Q3 also discusses this.

Beyond the Property Line

None of the studies attempt to quantify reuse benefits that occur beyond the building footprint. Existing buildings are more likely to be in existing neighborhoods with existing infrastructure, such as water, sewer, gas, and electricity. New buildings are often constructed on greenfield sites where these utilities must be constructed to service the buildings. Furthermore, I expect that existing buildings are more likely to be served by public transportation than new buildings, and more likely to be in denser neighborhoods. Therefore the daily users of these reused buildings may not have to travel as far to reach them and may have more alternative transportation options. A valuable research project would be to quantify these non-building impacts associated with the reuse vs. new construction alternatives. I expect the results would strengthen the argument that reuse is often environmentally preferable.


Athena Sustainable Materials Institute (2009). A Life Cycle Assessment Study of Embodied Effects for Existing Historic Buildings, prepared for Parks Canada in association with Morrison Hershfield Limited (http://www.athenasmi.org/wp-content/uploads/2012/01/Athena_LCA_for_Existing_Historic_Buildings.pdf).

Empty Homes Agency (2008). New Tricks with Old Bricks: How Reusing Old Buildings Can Cut Carbon Emissions (http://www.emptyhomes.com/empty-homes-publications-and-toolkits/empty-homes-publications/).

Preservation Green Lab (2011). The Greenest Building: Quantifying the Environmental Value of Building Reuse (http://www.preservationnation.org/information-center/sustainable-communities/green-lab/lca/The_Greenest_Building_lowres.pdf).

Thursday, February 13, 2014

Reporting from Greenbuild

The green building community gathers annual to share ideas and promote new innovation at the Greenbuild International Conference and Expo. The 2013 conference was held in Philadelphia, PA, November 20th through the 22nd. New SEI Sustainability Committee member Lori Koch was there to inspire attendees to "reThink Wood."

(Lori Koch, November 25, 2013) I had a great time at Greenbuild. I was working the reThink Wood Pavilion in the expo hall, and got to spend a good deal of time talking to attendees about using wood in sustainable structures. 

One of the big draws to our booth was the model of a 40-story tower that had a hybrid structural system of concrete and CLT (cross-laminated timber). The prospect of wooden skyscrapers really intrigued a lot of people, and led to some great discussions. 

I was lucky enough to have some down time to walk around the expo hall and see some of the other exhibitors (and I was lucky enough to win an iPad mini from the Office Depot booth!). One of the more impressive displays was the Kohler RV, it had working models of about a dozen different toilets and the rep talked about the lower water consumption models they have available. It was very interesting just from a standpoint of being a fixture that we all use every day, yet give very little thought to what’s at work with the system (or maybe that’s just me being a narrow-minded structural engineer!). 

I also got a chance to talk to folks interested in sustainable buildings from nearly every angle: wood products, steel producers, plumbing fixtures, educational programs, windows… the list goes on and on. It was a great experience and I’m looking forward to doing it again next year.
Tuesday, January 28, 2014

Learn to Design Thermal Breaks at the 2014 Structures Congress

Many of a structural engineer's common design tasks may affect the energy efficiency and environmental performance of a building. Designing exposed projections of the supersturcture, supporting enveloping facades, and attaching exterior equipment can create a conduit for thermal bridges between the outside and conditioned envelope of a building.

A preconference workshiop titled Design of Sustainable Thermal Breaks has been planned on the afternoon before the start of the this year's Structures Congress in Boston, Massachusetts. The workshop will focus on providing practicing engineers with state-of-the-art strategies implementing thermal break connections. Design and construction examples by the SEI Sustainability Committee's Thermal Bridging subcommittee will be presented. You probably won't find these tips in typical structural engineering texts.

Additionally, an architect and a mechanical engineer will discuss why thermal break connections are important aspects of building science. They will also describe how overall energy modeling effects ASHRAE's recent reporting on building envelopes.

The 2014 ASCE/SEI structurs congress is April 3-5, 2014, at the Sheraton Boston Hotel and Hynes Convention Center.

Register for the preconference seminar here

MODERATOR: Mark Webster, P.E., LEED AP BD+C, Simpson Gumpertz & Heger Inc.


  • James A. D’Aloisio, P.E., SECB, LEED AP BD+C, Klepper Hahn & Hyatt
  • Dave DeLong, S.E., LEED AP, Halvorson & Partners
  • Andrea Love, Building Scientist, Payette
  • Russ Miller-Johnson, P.E., Engineering Ventures
  • Raquel Ranieri, S.E., LEED AP, Walter P Moore & Associates
  • Chris Schaffner, P.E., LEED Fellow, The Green Engineer
PLEASE NOTE: Application for AIA Educational Credits has been submitted, but is not yet confirmed.

Additional Registration Fee: EB: $99 / ADV: $175 / ONS: $250
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