Concrete Masonry is Sustainable
Most designers know that masonry is inherently a green building material. Masonry has many attributes that contribute to its sustainability including protection against rot, mold, and termites. Greater resilience translates into lower maintenance costs and reduced use of virgin materials. Masonry’s strength and ability to withstand severe weather and fire are helping to meet new demands for climate-resistant building materials. Moreover, concrete masonry’s (CMU) thermal mass benefits can reduce energy bills and improve thermal comfort in buildings. CMU has come a long way, since the term “cinder block” was coined, and there are many aesthetic options for both structural CMU and non-structural veneers. A polished CMU gives a contemporary, sleek look, where matte ground finishes are subtler, and split units give a rugged “rock-like” feel. With a wide range of materials, textures, and colors available, the design possibilities of CMU are endless.
What makes masonry sustainable?
Masonry is strong, resilient, durable, sound-reducing, and beautiful. One of the most important sustainable attributes of CMU is thermal mass, or its ability to absorb and store heat. In the northeast, the best way to utilize thermal mass is to help hold the temperature of conditioned spaces. The energy code recognizes the benefits of thermal mass. In the 2012 IECC, for climate zone 5, the prescriptive requirement for a mass wall is a U-factor of 0.078 (R-11.4). Comparing this to a wood framed assembly, which has a U-factor requirement of 0.064 (R-20), or to a metal building with a U-factor requirement of 0.052 (R-26), utilizing thermal mass reduces the amount of wall insulation required.
Methods to improve masonry’s sustainability
CMU has a lower cement content than other concrete, since it gains additional strength through vibration and compaction. In addition, the environmental footprint can be reduced further using supplementary cementitious materials, or SCMs. One commonly used SCM in the northeast is slag, a byproduct from steel production.
Jandris embraces sustainability
Many CMU producers are looking for ways to go above and beyond designer’s expectations by introducing new elements of sustainability into their manufacturing practices. Committed to taking a leadership role, Jandris has made several changes to their manufacturing process over the last decade, which has improved plant efficiency and lowered their environmental impact. They utilize use thermal mass to cool the facility, have lowered their kiln oil consumption by half and introduced a closed loop system in their wet finishing facility to conserve water. Since installing solar panels, they have offset CO2 emissions by 949 tons. Jandris has also upgraded their manufacturing process to consume less Portland cement while maintaining required CMU strengths, further lowering CO2 emissions. Jandris has also invested in developing 3rd party verified EPDs for each mix design, which has helped identify potential inefficiencies in their operations.
The next frontier in sustainability: sequestered CO2
In March 2015, Jandris installed CarbonCure’s CO2 recycling technology into their Gardner, MA plant. Jandris is among 36 concrete producers across Canada and the US that is using this innovative technology to make better building products. CarbonCure’s technology recycles CO2 from smokestacks and injects it into masonry during mixing, where it gets converted into solid calcium carbonate. This means the CO2 is chemically converted into a stone within the masonry, and will never be released. The resulting masonry products have a lower carbon footprint, and are now being specified by leading designers in Massachusetts.
What does this mean for my projects?
CMU is a sustainable building material that has endless design possibilities. Look for the second article in this two-part series which will dive into how CMU can contribute to points in the new LEED v4 framework.
Note: This article is part one of a two-part series. View part two here.
LEED Green Associate, provides technical and design services for A. Jandris & Sons, Inc., a family owned structural and architectural concrete masonry manufacturer located in Massachusetts. A. Jandris & Sons is the first CMU manufacturer on the East Coast to have 3rd party verified environmental product declarations (EPDs) for each of their mix designs. Heidi was the Chair of the National Concrete Masonry Association’s (NCMA) EPD Task Group which developed the product category rules for the concrete masonry industry, and is current chair of the NCMA Education Committee. She grew up immersed in the industry, and earned a Bachelor of Architecture degree from Pratt Institute in Brooklyn, NY.
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LEED Green Associate and Vice President of Sustainability at CarbonCure Technologies, helps architects, engineers and developers meet their needs for sustainable concrete. She has helped company licensees issue the first Environmental Product Declarations (EPD) and Health Product Declarations (HPD) in the concrete industry. She is a Canadian Standards Association-certified GHG (greenhouse gas) inventory quantifier, LEED Green Associate and sits on the board of directors for the Health Product Declaration Collaborative and formerly the Atlantic Chapter of the Canada Green Building Council. Wagner holds a BSc from McGill University, an MSc in Chemistry and an MBA from Dalhousie University.
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