A Greener Future Through Masonry

Words: John Cicciarelli

When it comes to building a more sustainable future, the construction and building materials sector has a lot of room for growth. According to the most recent data, construction and building-related emissions are responsible for 40% of greenhouse gas emissions. Eleven percent of these emissions can be directly attributed to building materials, presenting a significant opportunity to drive decarbonization through more thoughtful material selection and specification.

While different projects call for different materials to meet structural requirements, masonry is one of the most sustainable materials available. It offers several environmental benefits and can be incorporated into a project’s design through a variety of applications, from traditional brickwork to concrete masonry units (CMUs).

The Sustainability of CMUs
Work is already being done across the industry to support safe, durable, and environmentally friendly building practices. This includes efforts to establish more in-depth Environmental Product Declarations (EPDs), which provide specific material details to help manufacturers better quantify the environmental impacts of their products and enable builders to better understand the potential carbon footprint of their projects. CMUs, in particular, often have EPDs to back up their many sustainable attributes.

CMU Sustainability Benefits
Thanks to a combination of factors, CMUs present several environmental benefits for architects, specifiers, and builders looking to meet specific green goals and requirements, such as the AIA Materials Pledge, LEED, and more.

1.) Carbon Footprint Reduction: Carbon Sequestration

The emissions produced during the production, transport, and use of building materials is referred to as embodied carbon. When CMUs are produced, the concrete chemically binds to carbon dioxide (CO2) in the environment. This process is known as carbonation or sequestration, which is a central characteristic of concrete and an important component in the sustainability of CMUs.

As concrete is produced, it releases CO2. When the material begins to hydrate, sequestration begins, meaning the CO2 reacts and locks back into the matrix of the concrete itself. Dry-cast concrete like CMUs have a particular advantage when it comes to carbon sequestration because of their open structure. Recent studies conducted by the NCMA Foundation show that dry-cast concrete has significantly higher rates of carbonation than wet-cast concrete, representing a reduction in total embodied carbon. Continued research is being done on the carbon sequestration of CMUs, but these initial results demonstrate their sustainability potential for reducing carbon emissions.

2.) Transportation Reduction and Local Sourcing

Transportation has often been left out of the sustainability conversation as it relates to building products. However, CMUs present a unique opportunity to minimize transportation emissions and costs.

Because CMUs are produced locally, typically within 50 miles of a job site in the United States, builders can better comply with local sourcing requirements and reduce project timelines. With production in close proximity, the need for long-haul transportation is eliminated, resulting in reduced costs and emissions.

3.) Waste Reduction

CMUs are composed of Portland cement, water, and sand, which makes them easily recyclable by crushing and grinding the concrete into aggregate. Aggregate is then used as a base material in new projects, such as roads or concrete mixes. This helps with waste reduction since the concrete gets reused, rather than disposed of in a landfill. This also contributes to circularity initiatives, which ultimately avoid more direct carbon emissions.

The Value of Masonry EPDs
When architects need to quantify the sustainability benefits of a given product or material, they rely on Environmental Product Declarations, or EPDs for short. Backed by verified, third-party data, this documentation is the most reliable source of information on a product’s manufacturing process and environmental impact. They are crucial for measuring a building’s sustainability and pursuing sustainability requirements and certifications, such as LEED.

There are multiple tiers of EPDs that exist today, including single company/single product EPDs, which focus on a single product made by a single manufacturer; multiple product EPDs that highlight similar products from a single manufacturer; and EPDs for products that are not yet on the market, which are developed based on a valid EPD for a similar product.

There are also sector/industry average EPDs, the first of which was developed by The Concrete Masonry & Hardscapes Association (CMHA). Based on data from 35 producers and verified by ASTM International, this EPD sheds more light on the environmental impacts of masonry compared to alternative building products.

The masonry industry continues making strides in industry-wide and product-specific EPDs that paint a detailed picture of potential environmental impact. Certain manufacturers are working on plant-specific EPDs, some of which are already published in various regions. These more tailored EPDs provide data on specific products made in these regions, with more insights into that product’s life cycle and impact.

Looking Ahead
In the coming years, we’ll see more advances in green building materials and technology in the masonry industry, helping us to continue progressing sustainable building practices. In addition to the masonry industry, specific EPDs for dry mix and hardscape products are in the works, further enhancing sustainable options across the building products sector.

While codes or regulations may evolve over time, architects, builders, and specifiers need to remain committed to sustainability efforts in the design/build process to ensure a greener future.

A Greener Future Through Masonry

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