High-Performance Glass and LEED

Various types of high-performance glass contribute to LEED points in four categories. Following are the number of points possible in specific categories and examples of glazing systems that can contribute to those points. EAc1: 1-19 points for NC or 3-21 for CS. Optimize Energy Performance. Thermally broken window and curtain-wall systems with optional thermal upgrades. EAc2: 1-7 points for NC, 4 for CS. On-Site Renewable Energy. Fully integrated solar energy systems to produce electricity. MRc4.1: 1-2 for NC, 1-2 for CS. Recycled Content – 10% (post consumer + ½ pre-consumer) MRc4.2: NA. Recycled Content – 20% (post consumer + ½ pre-consumer). Aluminum extrusions for windows can be made of at least 30 percent recycled material. MRc5.1: 1-2 for NC, 1-2 for CS. Regional Materials – 10% Extracted, Processed and Manufactured within 500 miles of project site. MRc5.2: NA. Regional Materials – 20% Extracted, Processed and Manufactured within 500 miles of project site. EQc2: 1 for NC, 1 for CS. Increased Ventilation. Window operation types can help to create airflow patterns. EQc6.2: 1 for NC, 1 for CS. Controllability of Systems (Thermal Comfort). Automated windows; operable window systems. EQc7.1: 1 for NC, 1 for CS. Thermal Comfort – Design. Operable and automated window systems. EQc8.1: 1 for NC, 1 for CS. Daylight and Views. Sun control systems can optimize day-lighting and exterior views. EQc8.2: 1 point 1 for NC, 1 for CS. Daylight and Views. Glazing options can optimize views to the outside while satisfying the project’s structural and thermal needs. IDc1.1-1.4: 1-5 for NC, 1-5 for CS. Innovation in Design. High-performing façade systems could help to provide performance that exceeds LEED-NC requirements.

Putting it All Together—BIPVs and Pre-Wired Curtain Walls

While the contribution of high-performance glazing is key, it can be even more successfully leveraged as part of a whole system approach to the energy design of a building. Industry experts say that significant energy reduction in a building—up to 60 percent—can be achieved from factors like early planning, high-efficiency HVAC systems, extra insulation, daylighting, energy-efficient lighting, rooftop energy production, and energy storage. Achieving the final 40 percent of energy reduction is the real challenge and requires a paradigm shift and/or new technologies.

Building Integrated Photovoltaics (BIPV)

Current technology is creating an opportunity to integrate PV into residential and commercial structures in an important new way allowing the entire building exterior to become a power generator. A building integrated photovoltaic (BIPV) system consists of integrating photovoltaic modules into the building envelope, such as the roof or the façade. By simultaneously serving as building envelope material and power generator, BIPV systems can provide savings in materials and electricity costs, reduce the use of fossil fuels and emission of ozone depleting gases, and add architectural interest to the building.

Leveraging PVGU and advanced architectural glazings, the BIPV product replaces the standard vision glass or skylights, with a glass product that converts direct sunlight into energy. BIPV systems are incorporated into the design of a building in the early planning stages. The architect works with photovoltaic engineers and other experts to create an aesthetically pleasing, effective design. BIPV technology can be installed in lieu of regular building materials, thereby saving money on construction. For example, glass with specialized solar cells embedded can be used on the facade of a building instead of conventional glass.

Still in its infancy, the global market for BIPV technology was estimated by market firm BCC Research at 1.2 GW in 2010 and was poised to more than double in size for several years to 11 GW by 2015. Another research firm, NanoMarkets, estimates that the total market for BIPV glass will reach $6.4 billion (USD) in revenues in 2016 compared to $1.5 billion in 2012. The report estimates that global appetite for BIPV curtain wall will grow dramatically through 2020, when the EU will require all new construction to be net-zero energy buildings.

According to research from Jesse Wolf Corsi Henson, AIA, LEED AP, BIPV spandrel applications can contribute more than 15 percent of annual electricity needs for highly efficient office buildings throughout major U.S. climate zones—an amount that existing roof-mounted PV systems for tall buildings do not achieve. While current research reveals the energy production limits associated with their vertical application, the net-zero energy goal suggests a reconsideration of BIPV facades. Currently available PV module products can allow building planners, architects, engineers and contractors the option of employing façades as major energy generators. Potential future studies could include the impact of additional BIPV spandrel on the east and west building facades. Further development of BIPV strategies and products is required in order to create and adapt tall buildings into net-zero annual energy consumers.