Courtesy AGC Glass

A single-family home built for multiple generations.

A condominium complex in an urban setting, designed to attract millennials who want to be in the city.

A high-rise commercial building that houses multiple tenants in a variety of different businesses and professions.

When it comes to energy efficiency as it relates to any building’s performance, the stakes have never been higher. Ever-evolving building codes continue to set stricter standards for every kind of structure.

For architects, that means finding inventive ways to design a compelling, eye-catching building that has it where it counts—particularly when it comes to the components of the building envelope. In every instance, windows are an important part of this energy efficiency equation.

Setting the Standard

University of Kentucky student residence in Lexington, KY.
Courtesy AGC Glass University of Kentucky student residence in Lexington, KY.

When it comes to commercial windows, individual municipalities and governments across the country choose to adopt and enforce the standards of one of two organizations: the International Energy Conservation Code, or ASHRAE.

In both cases, these organizations set the standards for key performance criteria in specifying building envelopes.

One is U-factor, which measures the heat gain or heat loss because of temperature differences between the interior and exterior.

The second is solar heat gain co-efficient, or the level of solar radiation admitted into the building through the glass pane. A lower SHGC rating means the glass transmits less solar heat and has greater ability to shade the inside environment. This has direct impact on the thermal efficiency of a building and on energy required for (and resultant cost to operate) HVAC units to keep occupants warm in the winter and cool in the hotter months.

Rising to the Challenge

Thompson Hotel, Nashville, TN.
Courtesy AGC Glass Thompson Hotel, Nashville, TN.

Through research and innovation, glass manufacturers have consistently brought products to market over the past two decades that meet the highest and most stringent standards for both U-factor and SHGC. This has empowered architects, designers, specifiers, and building owners to meet or exceed energy and performance standards for a building by specifying windows made of high-performance glass.

As an example, architects can specify certain low-E glass products on the market right now that are 98% effective in driving down U-Factor in standard insulated-glass products. These products have truly changed the paradigm.

At the same time, the evolution of the technology for such advancements has reached a point of critical mass. Pushing the envelope to achieve even better U-factors or SGHCs requires trade-offs. For instance, the transmission of available natural light into an indoor environment—a key priority—can be negatively impacted.

An Innovation Revolution

The next frontier for high-performance windows looks much different than today’s model. New technology will change how windows perform and function.

Courtesy AGC Glass

Dynamic windows are an example. They are engineered with shading systems that can adjust light transmission based on building performance requirements or occupant preferences. Such windows can dramatically increase comfort and the efficiency of the building envelope.

Vacuum-insulated glass is another innovation that takes it a step further: Manufacturers can improve a window’s thermal performance by creating a very small space between two panes of glass, ensuring that no gas enters the space.

Ultimately, the nature of the conversation is changing when it comes to glass and energy efficiency. This will require a revolution in thinking for everyone involved in the design of a building.

Learn more about the latest innovations from AGC Glass. Visit