built for decarbonization
a proven path to lowering carbon.
SOURCE: ORCO Block
CMU uniquely combines low-embodied carbon, rapid carbon sequestration and resilient performance in a single system.
EVERY DESIGN CHOICE IS A CARBON CHOICE.
Nearly 40% of construction’s carbon comes from building materials. CMU offers a practical way to lower that impact without jeopardizing longevity.
Concrete masonry units are more than a time-honored building block—they’re an increasingly carbon‑conscious choice that architects eloquently use to explore color, texture, scale, proportion, and pattern. With their long lifespan, minimal maintenance, natural thermal mass, fire resistance, and ability to sequester carbon, CMUs reduce environmental impact while supporting resilient, locally sourced construction.
— Lance C. O’Donnell, o2 Architecture
CAPTURES CARBON FAST. KEEPS IT FOREVER.
Research shows CMU continues absorbing CO2 throughout its service life and beyond.
absorbed in
the first month
absorbed
by year two
CARBON-SMART BY DESIGN
Credit: Concrete Masonry & Hardscapes Association
CMU’s climate advantage comes from its dry-cast manufacturing process: low water, less cement, and a unique concrete matrix which enables faster CO₂ sequestration. Their hollow shape uses less volume of concrete in wall assemblies and maximizes surface area for carbon uptake.
LEARN ALL ABOUT THIS
IN OUR FREE,
ON DEMAND 3-PART SERIES.
Enter your email to sign up
for our Embodied Carbon Series
THE MOST SUSTAINABLE STRUCTURES
ARE THE ONES THAT LAST.
Built to last for generations, CMU’s durability reduces the need for replacement — lowering lifecycle emissions over time.
emissions are up to 75% lower than light-frame construction. *Department of Energy, 2024.
RESOURCES
Explore the resources below for more insights on how to incorporate concrete masonry to enhance the resilience of your designs.
reality check
Q1: Is concrete block a high-carbon material?
No. Concrete masonry units (CMU) have all the durability and resiliency of concrete structures with significantly lower embodied carbon. Their dry-cast manufacturing process uses less cement and water, producing a unique concrete matrix that accelerates natural CO₂ sequestration. In addition, their hollow design uses less total concrete in the wall assembly when partially grouted and provides more surface area for carbon uptake.
Q2: How does CMU compare to other building materials?
CMU is durable, recyclable, and long-lasting. Buildings often exceed 100 years of service life, which reduces the need for replacement materials and lowers use phase carbon impact over time.
Q3: What innovations make today’s CMU low carbon?
Many producers are integrating supplementary cementitious materials (like fly ash or slag) that can cut embodied carbon by up to 40%. Some are also piloting CO₂ curing, a process that can allow for lower carbon cements to be used, and may also enhance natural carbon sequestration rates and performance.
Q4: Can CMU help achieve net-zero building goals?
CMU’s thermal mass can reduces heating and cooling demand, in some cases by up to 50%. When paired with passive design strategies, it supports net-zero operational energy goals.
Q5: How does CMU reduce construction waste?
When the modularity of the units is incorporated into the dimensions of the building and openings, jobsite waste is minimized. If units do end up as construction waste, they can be reused or crushed for and used as aggregate, reducing demand for virgin resources.
Q6: How does concrete masonry contribute to indoor air quality?
CMU is an inherently non-emitting material. CMU contains no added urea-formaldehyde, minimal volatile organic compounds (VOCs), and does not off-gas over time. Its inorganic composition also resists mold, rot, and mildew, helping maintain a stable, healthy indoor environment without contributing to airborne contaminants.
Q7: Why does local sourcing matter for carbon impact?
Most CMU is produced within 50–100 miles of projects, strengthening local economies and cutting transportation emissions compared to materials that are imported or hauled long distances.
Q8: How long do CMU buildings last, and why does that matter for carbon?
Concrete masonry buildings are exceptionally durable—many last 100 years or more with minimal maintenance. That long service life means fewer replacements, repairs, and rebuilds, which avoids the additional embodied carbon that would come from manufacturing and transporting new materials. Simply put, the longer the building lasts, the less new carbon needs to be invested over its lifetime.
Q9: What happens to CMU at the end of its life?
CMU is recyclable. It can salvaged for new construction crushed into aggregate for new concrete, or reused as road base supporting a circular economy.
Q10: Where can I learn more about CMU and carbon?
Visit the Block Design Collective for the full story on carbon, performance, and design guidance.
