Structural Technologies - Green Building

Article by: Alan Bernstein AIA, ASLA, LEED AP

October 1, 2009



Jonathan Wirthlin, Structural Engineer, AIA Member, Structural Engineering Association of Southern California Sustainable Design Committee, and LEED AP with Coffman Engineers did an outstanding job presenting at the AIA COTE Committee Meeting of September 3, 2009, on how structural engineers can make a project green.



Wirthlin focused on commercial buildings. The Engineers role creates a substantial cost impact on all projects and there are very few LEED points associated with structural engineering. By savings on materials, additional engineering calculations and changes to the building code, the engineering for buildings can become greener. Wirthlin promotes the Green Globes approach rather then the LEEDS, because it is more comprehensive in its approach.


Greener Concrete

Currently a lot of concrete products that are not “green” still have some fly ash content in them. By increasing the fly ash content to 20 to 70% of the cement mixture we are reducing the amount of fly ash that goes to landfills. Fly ash is a byproduct of burning coal for energy, it use to be sent up into the sky before environmental regulations finally stopped or reduced the fly ash into the atmosphere. As a result there is a lot of fly ash in the chimneys coal fire plants. (The best way to reduce fly ash is to reduce coal fire plants.) If a 50% fly ash mixture where used widely, it would reduce the world’s CO2 production by 4% (that is big).



By adding fly ash to the concrete mix we are creating a concrete that works differently than regular concrete, it does not make it worse, and it is less expensive than cement. It takes longer to set and dry- so the engineer needs to create a time line for the “working strength” of the concrete so the job can continue while the concrete is still curing. It takes less water, requires different admixtures, and can have more shrinkage cracks.


Material Reduction

By using fewer materials we can reduce the environmental impact. But there will be more labor involved in carefully calculating each beam individually, as opposed to the current standard of consistent and repetitive beam sizes. This could also reduce the quantity of bolts, welds, reduce shear wall length, and change stud spacing to 24 or 32” on center.



By use of a higher strength concrete, material can be reduced by thinner slabs, shorter and thinner shear walls, reduce deflection, and ultimately building weight.



Using high strength steel is not very practical. Standard steel shapes usually use standard steel strengths. It would be better to reduce the steel weight by increasing the depth of the beams for less deflection and widths of the posts for more efficient strengths.



Less material can reduce construction cost. There will be a learning curve for labor to be more attentive to small and frequent detail changes. More detailed plans will require more construction management and coordination. Wood projects or advance framing techniques will probably benefit the most from these changes. Concrete would benefit the least.


Advanced Systems

Advanced systems like energy dissipaters, system isolators, buckling restrained braced frames and steel plate shear walls can reduce materials and effects of earthquake damage on buildings. These systems require additional engineering and cost.



To justify these costs we need to consider the Life Cycle the building? How long is the building to last? Would it be better to spend more on materials and have a longer building life? Can the building adapt to other uses? And what will be the impact on the building when the earthquake hits – tear it down or replace some isolators?


Green Aspects of Structural Materials

Current LEED credits for engineering are gained in these areas:

Fly ash counts as pre-consumer recycled content, MR4.

Significant use of fly ash has been awarded Innovation in Design credit, ID1.

Crushing existing concrete for aggregate counts as post consumer recycled content credit, MR4.

Using special aggregates, pozzolans and add mixtures can help achieve Innovation in Design credit, ID1.

Showing the extended life of the building may also help achieve Innovation in Design credit, ID1.

LEED does not look at the life cycle, flexibility or reuse of a building.



Recycled wood can go into particleboard, mulch, fuel and firewood. Larger members can be reused, but smaller members like 2x4s will split apart when nailed. Windows and doors can be recovered and reused. Wood is easily deconstructed and reused in some manner. Wood is the greenest building material. Trees store carbon. Wood comes from a “rapidly” renewable resource. The creation of lumber uses relatively low amounts of energy sometimes their own sawdust (biofuel) creates the energy to mill the timber.



Steel is the most recycled material in the world. Over 80% of the steel comes from recycled product. Reusing steel beams is fully practical. Steel can be constructed with deconstruction in mind by using less weld and more bolts. Avoid unusual or custom shapes that are more difficult to reuse. Steel is the strongest per volume building material used. Steel manufacturing has been dramatically cleaned up, most hazardous waste associated with manufacturing is being recovered and used beneficially. Steel is produced more efficiently yet still takes a lot of energy to melt.



Concrete can be reused as base material, gravel, aggregate for new concrete, and the steel can be recycled. Concrete slabs and walls cannot be recycled for structural use. Concrete has the largest carbon footprint. The production and pouring of one ton of concrete creates 1.25 tons of CO2 and significant heat. One 90-pound bag of cement creates 22291 cubic feet of CO2 (a volume equivalent to 28 cubic feet).



Using an existing building can be greener then building a new green building. When we consider all the waste from demolition, existing embodied energy in materials, labor, transportation and time in an existing building we can save more energy through reuse.

Reusing a building has social, economic and cultural impacts. Adding life, strength and safety to an old building often has less impact on the environment. Building design and structural systems should allow for easy reconfigurations and different uses. The envelope or curtain wall system should be removable to allow future renovated or modernized exterior. Simple building shapes would save in renovation costs.



Again special thanks to Jonathan Wirthlin of Coffman Engineers for his presentation.

Thanks to Jonathan Vogel, President of Spectra Contract Flooring for hosting our meeting and providing food. We are always looking for new attendees, please contact Blaire Seibert, AIA, LEED AP, Verde Concepts via email blair@verdearchitects.com for the date and time of our next meeting. Looking forward to seeing you there.



Reminder, The Greenbuild 2009 International Conference and Expo will be held in Phoenix Arizona, November 11 –13. This is a great conference and an incredible number of exhibits about all things green. It attracts a mix of people from all aspects of the construction industry and related fields. Visit www.usgbc.org for further information.





Alan Bernstein is a licensed Architect, licensed Landscape Architect, U.S. Green Building Accredited Professional (LEED, AP) and Certified Green Building Advisor. For questions or comments contact Alan Bernstein at (818-707-9215) or email at alan@abarchitects.com



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Mike Pearson Masonry Contractor Los Angeles

CMU Walls - Concrete Masonry Units

The Carolinas Concrete Masonry Association (CCMA) was established in the year 1979. It includes concrete block providers in southern Virginia, North Carolina and South Carolina and companies supplying cement, mortar mix, aggregates, equipments, services to the masonry industry and admixtures. Its objectives are creating a superior standard in the manufacturing of concrete masonry, collecting information and publishing bulletins of educational and promotional character, and encouraging the use of concrete masonry products.

The Carolinas Concrete Masonry Association is an important trade association. It is devoted to encouraging the use of concrete masonry products. It also supports its members by giving them opportunities for networking, as well as support in marketing, research and government relations. This association focuses on the enhancement of product knowledge of masonry block applications in the industry for concrete retaining walls and commercial buildings. The CCMA website is an important resource for builders, architects and engineers. More and more people are using the website for this purpose.

Concrete masonry units are in great demand because of the durability, structural advantages, economics, energy efficiency, minimal maintenance and fire-resistance that they provide. Brick, marble, concrete block and limestone are the common materials used in masonry construction. Masonry contractors use this kind of material for constructing steps, walkways, durable brick patios, walls and masonry structures. Masonry construction is highly durable, but many factors can affect the durability and appearance of the masonry construction including the quality of material and mortar used, the quality of the workmanship, and the way the materials are laid.

Retaining walls are also built by residential masonry contractors. These walls are vital for proper drainage as well as maintaining a level grade for your landscape. By using cement blocks, concrete or any kind of field and rock stones, masonry contractors can provide a wide variety of landscaping choices. Retaining wall blocks provide great compressive power. Some concrete blocks offer even greater power for masonry structure as they have cores with steel reinforcement.

Concrete masonry units are large rectangular blocks utilized in the construction of retaining walls or other structures. Concrete blocks make laying the block walls much quicker as these units are much larger than bricks. In addition, concrete blocks have lower water absorption rates than bricks. Concrete blocks are used as a structural core for the walls of factories, garages and industrial buildings. Sometimes, river rock can be utilized as a surface layer.


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Mike Pearson Construction, Inc. - CMU Wall and Retaining Wall Contractor Los Angeles

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Concrete Masonry and Sustainability

CCMA stands for Carolinas Concrete Masonry Association. It is a non-profit trade organization. This association focuses on promoting the premium utilization of technical information, masonry materials, the benefits as well as economics using masonry and codes for the commercial and housing construction markets.

Carolinas Concrete Masonry Association offers not only education but also promotional assistance and advocacy to all its members. Concrete masonry product has advanced characteristics. It does not have any negative impacts on the environment. Furthermore, it has insect and fire resistant characteristics.
Using this environment friendly product for creating new looks become superior. There are couples of reasons why to use concrete masonry. First, one is the Green building and another is Sustainability.

First, we will look at what is the sustainability. It is the tolerance capability to experience, suffer or undergo without yielding or surrendering. Throughout its all the stages in the life span from raw material manufacture to destruction, concrete is an ally of the environment. Concrete masonry builds the rust free structures that will never burn or rot. They help to build long-lasting structures having great durability. It is very amazing to know that concrete building products have twice or thrice times the life span as compared to other building materials. That is why they are used for sustainable house construction. Day by day, these products are gaining increased popularity.

Another interesting thing about concrete masonry is it stays cool in the summer season and hot in the winter season. This is because the thermal mass of concrete permits it to store up the energy. Furthermore, utilization of concrete masonry products can help to save the utility bills over than 3%. Limestone is the most significant raw material used in the cement of concrete masonry. Moreover, the mineral ‘limestone’ is found in great quantity in nature. However, various waste by-products from different steel mills, manufacturing units and power plants can be used for the production of concrete.

Like wood, when exposed to the elements, concrete does not rot or warp. Its sustenance capability to all weather damages makes it to have a longer life. With concrete masonry used for building house, there are fewer chances of termites, rodents and ants to invade your home.

Sustainability of the concrete masonry makes it useful for long lasting and resistant construction. CCMA provides assistance to enhance the entire industrial viewpoint and knowledge towards the use of masonry products. It focuses on the use of block masonry applications for concrete viable buildings, paving walls, concrete masonry, retaining walls, etc. for further enhancement in the construction sector. It has helped to change our vision towards the utilization of several products, which are environment friendly.

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