Facade Embodied Carbon Reduction Strategies

Facades are increasingly being recognized as a major contributor to whole-building embodied carbon. While designers know how to reduce the embodied carbon of structural systems, the embodied carbon reduction potential of facades is currently largely unrealized. This paper examines how designers can make an impact through design decisions and specifications, addressing top questions investigated during design:

1. How do different opaque assemblies and glazing assemblies compare in terms of embodied carbon?
2. How can we reduce the embodied carbon of facades through material optimizations?
3. How does the window-to-wall ratio impact facade embodied carbon?
4. How do we effectively implement embodied carbon reduction strategies?

The embodied carbon of facades is largely driven by cladding materials, IGUs, aluminum, and steel, so these materials offer the greatest opportunities for carbon reductions. For cladding materials, sourcing from certain manufacturers can significantly reduce embodied carbon. For IGUs, the embodied carbon penalty is the strongest for overall glass thickness and the smallest for coatings, and some manufacturers distinguish themselves through innovative manufacturing techniques. For aluminum, the sourcing location can be a stronger driver of embodied carbon than recycled content. For steel, the manufacturing process and recycled content are the main levers.

Strategies to reduce facade embodied carbon are not always implemented because they can impact cost and aesthetics more than reducing the embodied carbon of concrete or steel. In addition, the lack of product-specific EPDs for products like aluminum extrusions makes it difficult to demonstrate reductions and take credit for them as part of LEED certification. Nonetheless, because facades are a major part of whole-building embodied carbon, we need to overcome these implementation hurdles by assessing options early in design, better understanding the operational and embodied carbon tradeoffs, coordinating from early design through construction, and advocating for more material transparency.