Embodied Carbon: What Fabricators Should Know
A Q&A with Mike Hammond, Manager, Technical Support
At Vitro Architectural Glass, it is part of our mission to continually raise the industry standard for sustainability and be part of conversations around environmental responsibility. One of today’s hot topics in the realm of sustainability is embodied carbon: what it means, how to measure it and what manufacturers can do to offset its impact.
Earlier this year, Mike Hammond, manager, technical support and the Vitro sustainability team issued new educational resources and information to help glass industry professionals better understand what embodied carbon is and why it has become such a focus for the industry. Now, he’s breaking down what Vitro Certified® Network members should know about embodied carbon, Environmental Product Declarations (EPDs), and the role of low-e glass in carbon reduction.
Q: What is embodied carbon, and how is it measured?
A: Perhaps the most comprehensive way to measure embodied carbon in glass (or any building product) is Global Warming Potential (GWP). This measure takes all the energy used to create a product and converts it into kilograms of equivalent carbon dioxide, expressed as the term “CO2-eq.” The purpose of this is to help stakeholders and sustainability programs more effectively gauge the environmental performance of glass and other products manufactured for buildings.
It takes a lot of energy to make glass. The process involves heating a melting furnace to 3,000 degrees Fahrenheit, and, as a result, most of the embodied carbon in an insulating glass unit (IGU) – about 75% – comes from producing flat glass lites. Of the remaining, 13% comes from heat strengthening or tempering the glass, 10% comes from the IGU fabrication process itself, and just 2% comes from the process of adding low-e coatings.
Q: Are there significant ways to reduce embodied carbon in IGUs?
A: Truly, if you wanted to reduce the embodied carbon in an IGU, you would go back to the old single-pane windows. Of course, we know that that’s not the right thing to do from a comfort and aesthetics standpoint, nor is it going to offer long-term carbon reduction.
Consider this: there has been significant conversation in the glass industry about moving from double-pane to triple-pane IGUs for better insulation performance. This is going to increase the amount of embodied carbon in the unit, simply because it includes more glass. However, the energy savings that you will receive during the operational lifetime of the building is going to far exceed the embodied carbon content.
Q: What is Vitro doing to reduce the embodied carbon in its architectural glass?
A: Vitro is committed to doing its part to lower the embodied carbon in glass, as this will, in turn, make the impact of operational carbon reduction happen even quicker. Some of the steps we’ve taken are:
- Developing expertise in furnace control systems to reduce variability of melting temperatures and fuel consumption
- Adding new specialized post-ignition burners to further reduce greenhouse gas emissions
- Using variable frequency drives on cooling fans to reduce energy use
- Utilizing recycled cullet (both pre- and post-industrial) to reduce fuel consumption
- Converting all facility lighting to LED, which reduces electric consumption by as much as 80% vs. incandescent lighting
- Using oxy-fuel technology at three plant locations in the U.S., which can reduce energy consumption in glass melting furnaces by up to 20% and cut greenhouse gas emissions in half
It’s also important to note the role energy-efficient glazings play in offsetting the impact of embodied carbon. Vitro’s energy efficient Solarban® and Sungate® glasses are perhaps more valuable in reducing the overall carbon footprint of a project than operational changes in glass production.
Q: Can low-e coatings play a role in reducing embodied carbon?
A: Technically, no, low-emissivity (low-e) glasses do not reduce embodied carbon. However, while raw glass typically has a higher amount of embodied carbon because of its manufacturing processes, high-performing low-e glasses can help reduce the impact of that carbon through operational carbon reduction.
We understand that low-e glasses like our own Solarban® and Sungate® glasses can help reduce operational carbon by lowering a building’s solar heat gain (SHG) and increasing interior daylighting, which places less of a demand on artificial lighting. By applying low-e coatings to architectural glass, the operational carbon can absolutely be reduced to the point that you quickly “pay” for the embodied carbon emitted by making the glass itself. By focusing solely on embodied carbon, we may lose sight of that, so it’s very important to keep low-e coatings in mind when considering the “big picture” impact of a building’s carbon footprint.
Q: What are EPDs, and what should fabricators know about them?
A: Environmental Product Declarations (EPDs) are documents that provide detailed data about the life-cycle impacts of Vitro Glass products on the environment and may be used as credentialing for LEED® and other green building certification programs.
It’s important to understand how to properly read, interpret and utilize data that is published in EPDs. The purpose of an EPD is to provide information on the environmental impact of the product over the life cycle, and they typically rely on estimations of impacts and can therefore differ across product lines and reported impact. In the context of evaluating embodied carbon, EPDs will likely offer the most value in interpreting how a given product was manufactured and what steps manufacturers are taking to reduce energy expenditures.
Among glass suppliers, Vitro has been a leader in the realm of sustainability and environmental considerations, and we were the first North American manufacturer to publish third-party verified EPDs for our flat glass and processed glass products. However, there is going to be a push for more manufacturers to make EPDs available as regions like California introduce more sustainability legislation, which is why we want to ensure our fabricators have access to Vitro’s information and know how to interpret it.
To download Vitro’s uncoated and processed glass EPDs, visit the embodied carbon page on out website.
For more information about embodied carbon in glass, please contact Mike Hammond at mhammond@vitro.com.
