Reducing Embodied Carbon

July 10, 2023

University of Houston Exterior Image Photography by Joe Aker

Did you know buildings are responsible for 39% of annual global greenhouse gas emissions? Operational carbon – the emissions from the ongoing use of a building – contributes to 28%, while embodied carbon – the amount of carbon released in the extraction, manufacturing, transportation, maintenance, and disposal of materials – is responsible for 11% of pollutants.  

At Page, we know reducing embodied carbon is just as important as minimizing the building’s operational emissions, so we use tools and benchmarks to create better-performing, more resilient, more equitable, and more ecologically minded facilities. For example, our University of Houston College of Medicine design reduced embodied carbon by 28%. 

Initiatives like the Federal Building Performance Standard are setting impressive benchmarks to reduce operational energy use, but pinpointing areas to curtail embodied carbon is pertinent for mitigating climate change. 

Driving Design Decisions: Approaches for Healthier Facilities 

A Life Cycle Analysis (LCA) measures and improves the carbon impact of our designs, which drives informed decisions aimed at reducing a facility’s ecological footprint. The LCA calculates the embodied carbon from a product or an entire building. For simplicity, let’s first consider a single material: steel. The LCA investigates the emissions generated from sourcing the raw materials, producing and manufacturing the steel, and transporting the product to the building site. This process is then repeated for each material used onsite. 

Building modernization and reusing materials are the most effective strategies for reducing a building’s embodied carbon. Recycled materials have a lower footprint because the carbon to make the product is already spent. When the material is reused, the emissions from the transportation and refabrication process are significantly smaller than opting for a new product. Choosing reused steel, for example, can reduce a facility’s embodied carbon by 55%.  

Structural materials – concrete and steel – are responsible for 10% of global carbon dioxide emissions. Using concrete mixes with a high percentage of supplementary cementitious materials dramatically minimizes high-embodied carbon. For example, Portland cement, the main ingredient of concrete, is carbon-dense, so an alternative approach replaces cement with slag – a hydraulic cement formed from grinding granulated blast furnace slag and a small amount of Portland cement or calcium sulfate. This commonly used mixture can improve workability, durability, and strength of the concrete.  

Case in Point: Making Significant Emission Reductions  

From the beginning of design to the end of commissioning, the University of Houston’s new College of Medicine achieved substantial carbon reductions. Page’s Building Science team collaborated with the structural engineer, Walter P Moore, to reduce embodied carbon by 28%.  

Using a multi-pronged strategy, the team substituted partial cement in concrete structural members, used all recycled steel in the rebar and exterior shading devices, and reused an extracted tree on site to become the millwork within the project. Vaughn Construction, the general contractor, also diverted 89% of the total construction waste and demolition, preventing 8,600 cubic yards of waste from ending up in the landfill. 

University of Houston New College of Medicine Interior Space

Additionally, the interiors team worked relentlessly to specify finishes with Environmental Product Declarations (EPDs) and Health Product Declarations (HPDs). An EPD is a document that provides information on a product's life cycle analysis, and an HPD is a report disclosing possible health effects and hazards. The team also incorporated low-emitting materials, which do not release significant pollutants into the environment, leading to better indoor air quality.  

The University of Houston project team was a creative powerhouse, working to make intentional and rigorous carbon-emission reductions and propelled the university toward their goal of creating a brighter, healthier future. Reducing embodied carbon is an essential part of mitigating climate change, and it requires a concerted effort from all of us. As we accelerate efforts to decarbonize, what changes can be made to create a more sustainable and resilient future?