Despite being immovable, buildings must be incredibly versatile because the standards that influence their design are ever-changing. Continually, architects and designers are urged to consider the energy footprint a building leaves behind for both environmental and financial reasons.
According to the nonprofit organization Architecture 2030, building operations can account for more than 40 percent of energy consumption, with construction and building materials making up an additional 6 percent.
Energy codes are necessary to reduce energy consumption, and architects and designers must pay heed to codes pertaining to construction practices, materials, equipment and systems and window efficiency when planning new buildings. These professionals should consider three overarching trends related to energy codes and sustainability standards that have emerged in recent years.
Because politicians are making the curb of energy consumption a central part of their political platform to help decarbonize the country, more states are adopting energy codes. As of 2024, most states have adopted a standardized energy code.
ASHRAE 90.1 is the primary code with the greatest impact on glass and glazing. This organization sets the standard for performance and sustainability.
Although a handful of states have not adopted a statewide energy code or fully enforced ASHRAE 90.1 or a code with similar benchmarks, many have adopted the 2010 version of ASHRAE 90.1. Some states, including Oregon, California, Nevada, Florida and Massachusetts, have adopted the latest 2013 version of ASHRAE 90.1 or utilize an energy code that exceeds the energy efficiency recommendations outlined by ASHRAE standards.
Other states have adopted codes from the International Code Council (ICC). The ICC is an association dedicated to the development of standards to construct safe, affordable and resilient structures. ICC codes provide a minimum baseline standard for structure safety and energy efficiency.
ASHRAE 90.1 is the code with the most direct impact on glass and glazing usage for windows in buildings with four stories or higher.
While state adoptions of ASHRAE 90.1, the International Code Council (ICC) and similar codes have increased, the standard has also become more stringent. In fact, the Energy Use Intensity (EUI) targets required by ASHRAE 90.1—which is calculated by dividing the total energy consumed by the total gross floor area of a building—has been cut in half since the code’s inception.
Energy codes are written to improve energy efficiency to better preserve the environment. The ICC and ASHRAE codes represent a pragmatic approach to addressing the climate zone of the building. The U-value and solar heat gain coefficient (SHGC) targets are based upon a model using 40 percent window and 60 percent wall.
Higher efficiency requirements mean glazing and fenestration are receiving increased scrutiny. Window-to-wall ratios are actively being analyzed for optimal reductions. Designers must look at the performance of the entire window, which also includes the frame. New requirements for U-values and solar heat gain coefficient (SHGC) limits are creating demand for high-performance glass and glazings. For more information, see “Understanding Framing and Performance Values.”
Additionally, the Inflation Reduction Act (IRA) of 2022 and the U.S. General Services Administration (GSA) set standards for low embodied carbon (LEC) products. These standards require that products must offer a Type III EPD and an ENERGY STAR® Score as well as an embodied carbon content that is less than 1,401 kilograms of carbon dioxide equivalent (kg CO2e).
By these standards, LEC products can fall into three different product categories according to embodied carbon content:
| Product Category | Embodied Carbon Content |
| Acceptable | 1,401-1,371 kg CO2e |
| Preferred | 1,371-1,332 kg CO2e |
| Most Preferred | < 1,331 kg CO2e |
The GSA has indicated that it will prioritize products from manufacturers that meet the top 20% ("Most Preferred") LEC material category. While this standard does not offer a renewable certification, its criteria are now requisite for naming a product “low embodied carbon” in the building products industry – especially for projects pursuing additional certifications or compliance with local and national green building standards. For additional information, please see “Low Embodied Carbon (LEC) Standards.”
As energy codes become more stringent, and more states adopt mandatory energy codes, voluntary sustainability and energy efficiency programs also are increasing.
The United States Green Building Council reports that its Leadership in Energy and Environmental Design (LEED) certification program has seen a steady, gradual increase in project registrations from 2000 through the release of LEED v4 in 2016 – with LEED v5 expected to be released in 2025. In fact, the current version of LEED endorses the Cradle to Cradle Certified® program, indicating a stronger commitment to material health and improving the impact of buildings on the well-being of humans and the environment. For more information on top sustainability certifications across the industry, see “Sustainability Certifications and Standards.”
Product manufacturers like Vitro Architectural Glass also are publishing third-party verified Environmental Product Declarations (EPDs), which are voluntary transparent reports issued by companies regarding the life-cycle impacts of their products on the environment. To learn more about EPDs, see “Understanding EPDs.”
With the mission to reduce the impact buildings have on the environment, energy codes are dynamically driving the way glass and coatings are used. Progressively higher mandates in energy efficiency are pushing manufacturers to look beyond traditional aesthetics and are giving birth to a new generation of higher-performance glass paired with new glazing technology.
One such glass advancement is vacuum insulating glass (VIG), which combines vacuum technology and high-performance glass substrates into an insulating glass unit (IGU) with exceptional insulation performance, even rivaling that of traditional walls. These units feature slim construction and light weight that allow them to be incorporated into virtually any traditional (and even non-traditional) glazing system, window frame or curtainwall application. To learn more about VIG technology, see “VacuMax™ Vacuum Insulating Glass (VIG).”
For more information about Vitro’s commitment to sustainable products and practices, please visit vitroglazings.com/sustainability. To download EPDs for Vitro’s flat and processed glass products, see “Sustainability Documentation.” For any other glass questions, please contact Vitro Glass or call 1-855-VTRO-GLS (1-855-887-6457).