Disaster Resilience and Sustainability White Paper

Structural engineers can make a significant contribution to the sustainability of the built environment by considering disaster resilience in their designs. Download the SEI Sustainability Committee Disaster Resilience Working Group's definitive guide and learn how to design more resilient structures. Click here and look for the link to download at the bottom of the page.

Executive Summary

The importance of sustainability within structural engineering has become more widely accepted in recent decades. When structural engineers think of sustainability, they often limit their scope to material selection and recycling. Few structural engineers recognize the relationship between sustainability and disaster resilience, an area in which they can make significant contributions. Consequently, the aims of this report are to

1. Raise awareness of the relationship between disaster resilience and sustainability by discussing how a holistic view of sustainability must recognize the need for disaster resilience, and to
2. Provide a critical review of resilience-related efforts and resources available to practicing structural engineers and related professionals.

Sustainability encompasses three spheres: economic, environmental, and social. Within each of these spheres, sustainability requires providing for the needs of the present while allowing future generations to meet their own needs. Disaster resilience pertains to the ability to suffer less damage and recover more quickly from adverse events such as hurricanes and earthquakes. A resilient structure provides socially valuable services such as shelter and safety, even in the face of disaster, and it should do so while minimizing economic and environmental costs. Ignoring resilience during design can lead to structures that may seem green but that cannot reliably provide the services that we expect from them. Sustainability and disaster resilience are related in complex ways. Often times striving for one will help achieve the other as when a more robust structure reduces the environmental and economic cost of repairing extensive damage. Sometimes the two are at cross-purposes. For example, striving for material efficiency may render a structure less redundant, and hence less safe in a disaster.



The main section of this report discusses a variety of efforts to promote resilience and resources for resilient design. Some of these are prescriptive, offering a set of design rules more stringent than existing building codes. Others are performance-based, offering performance criteria and methods for predicting the performance. Prescriptive criteria are simpler, but do not explicitly assure better performance. Performance-based approaches allow the designer to provide specified improvements in performance, but this requires much more effort to achieve. Some of the efforts are voluntary and others are intended to become model codes. Voluntary efforts depend on the desire of the owner or developer to enforce the guidelines. Model codes aim to become law that all designers and builders must follow. Voluntary initiatives may become accepted more quickly and be more adaptable to changing times, but efforts to change model codes have the potential to effect change more broadly.

The report also discusses current efforts to quantify the connection between disaster resilience and sustainability through life cycle methods. There is no current agreement as to the best way of achieving this, nor are there standard tools for the structural engineer to use in everyday practice. However, it is important to remain aware of developments in this area, as it will likely become a common consideration in structural design. The structural engineer who stays abreast of developments, and even better, who contributes to them ñ will be at an advantage when these methods mature.



In the interest of encouraging positive and meaningful action, the report provides the following suggestions for structural engineers who are interested in supporting disaster resilience and sustainability:

1. Becoming better informed by using the references and links in this document.
2. Participating in the code adoption process to encourage resilient design standards.
3. Supporting legislation that requires or provides incentives for resilient construction.
4. Educating owners regarding the importance and value of resilient construction.
5. advocating with insurance companies and portfolio managers to offer decreased costs for better performing facilities.
6. Advocate with ASCE, SEI and other professional organizations to raise the profile of structural engineers.

Concluding the report is a thoughtful afterword on resilience and sustainability in developing countries. The afterword suggests considerations for those interested in projects in these countries and provides potential solutions to common challenges, some of which can inform design practices in developed countries such as the United States.

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How are disaster resilience, climate change, and sustainability related?

Sustainability has many definitions and applications. A long view of the future is one important aspect of sustainability. The Brundtland definition of sustainable development supports this by stating, “sustainable development is development that meets the needs of the present without compromising the ability of future generations to meet their own needs.” The application of sustainable development pertains to three different spheres of life: economic, environmental, and social. These are sometimes called the three pillars of sustainability. To be sustainable, a project must respect the three pillars over a long time span.

Disaster resilience refers to the ability to suffer less damage and recover quickly from adverse events. Both man-made and natural disasters occur quickly and can have significant consequences on portions of the built environment. There are many definitions of resilience, but most of them identify two key aspects: robustness and rapidity. Robustness is the ability to limit damage. Ductility, redundancy and integrity are important characteristics that help limit damage in structures. Rapidity is the ability to restore service to pre-disaster conditions quickly after the disaster. Disaster resilience is necessary for sustainability. A facility with many features that would otherwise render it sustainable will be of no use if it is heavily damaged in a disaster. Reconstruction would incur significant financial, social, and environmental impacts. These impacts must be considered in sustainability assessments. A resilient design ensures the usefulness and longevity of other sustainability features.

Climate change refers to any significant difference in the measures of climate that lasts for a significant period of time. These changes include those related to an increase in greenhouse gasses in the atmosphere, which contribute to global warming. The scientific community is in near unanimous agreement that global warming is anthropogenic, i.e., caused by humans. Some segments of the population dispute the cause, but few dispute that climate change is occurring. Whatever the cause, weather-related disasters are expected to increase in severity and magnitude in many parts of the world. Weather events of increased severity underscore the need for a resilient built environment. In more hostile climates, resilience must be a more important component of sustainability. Moreover, construction and maintenance activities generate greenhouse gasses that can accelerate climate change. Meaningful reductions of such impacts can have positive effects in mitigating the severity of climate change.

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Sustainably Designing for Acts of God

Yup, they thought about that too... Resources are available to aid the Structural Engineer in improving disaster resilience for building structures in flood plains, coastal regions, hurricanes, tornadoes, hail, and wildfires.

Flood plains

For flood damage resistance, structural components should comply with ASCE/SEI 24 as well as state building codes.

Coastal regions

Foundations located in FEMA Coastal Zone A should be designed to the same criteria as those located in FEMA Coastal Zone V. Levees and flood walls should not be considered flood protection when renovating or designing new buildings for resistance to flood damage. Additional recommendations include compliance with Appendix G of the International Building Code – Flood Resistant Construction.

Hurricane, tornado, and other high wind regions

For wind-damage resistance in general, buildings should be designed for an increase in basic design wind speed by 20 mph. Roof coverings, their attachments, and gutter attachments should comply with UL and FM standards.

In addition, if located in hurricane- or tornado-prone areas, use of exterior cladding that is susceptible to wind damage should be limited. Storm shelters should be provided for all building occupants when design wind speed is 160 mph or greater (in hurricane- and tornado-prone areas). Storm shelters should be designed according to ICC 500 – Standard for the Design and Construction of Storm Shelters.

If located in hurricane-prone areas, also use the above recommendations for buildings in flood plains and coastal regions.

Regions susceptible to hail

For hail damage resistance, if located in moderate-to-severe hail exposure areas, use of exterior cladding that is susceptible to hail damage should be limited.

Regions susceptible to wildland fires

For wildfire damage resistance, buildings should meet the requirements of the International Wildland-Urban Interface Code.

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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

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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.

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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.

Timing

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.

 

References

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).

 

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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.

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