Germicidal lights earn first LEED credit for clean air quality

Notkin Mechanical Engineers of Seattle, mechanical engineer for the new city hall project at Sammamish Commons, applied for and received the LEED credit from the USGBC for utilizing UVC Emitters in the air-handling units downstream of the system’s cooling coils to improve indoor air quality (IAQ) and reduce energy and maintenance costs. The UVCs are manufactured by Steril-Aire, Inc., Burbank, Calif.

Notkin project engineer Darren Schwend says that studies have shown UVC light systems to be a cost-efficient way to address indoor air quality, energy consumption and other operational issues. “Sammamish Commons incorporates a city hall, police station and other office and public space, so it was very important to reduce the risk of human exposure to microorganisms that can potentially occur in public buildings," he notes.

Heating and cooling for the 45,000-sq.-ft. building are provided by two packaged rooftop air-handling units (AHUs). Both variable-air-volume units feature DX and hot-water coils that can provide 100 percent economizer cooling. The UVC devices are single-ended (SE Series) emitters designed for rooftop systems and mounted to the units’ exteriors. The lamps penetrate into the system through 1-in. holes in the exterior, but the power supply remains external.

The UVCs emit enough energy to penetrate any microbes present and kill or deactivate their DNA and RNA so that they cannot grow and replicate. The UVCs continuously clean the coils, reducing or eliminating scheduled coil cleaning as maintenance and enabling the coils to operate more efficiently than fouled coils, which also can reduce airflow. Mechanical maintenance includes changing the lamps and filters annually or as needed.

Sevda Baran, project manager for Sammamish Commons, says the air quality in the facility has been excellent. “We are very satisfied with the IAQ and operational benefits, and we are excited to be the first project to use this technology for LEED credit.”

Baran says the facility runs the lights 24/7. He plans to replace the bulbs annually as recommended by the manufacturer to ensure that the UVC system maintains the germicidal output needed to prevent mold from growing on the coils or infectious viruses and bacteria from circulating through the air.

According to the USGBC, Innovation in Design points are awarded to LEED projects that “develop new solutions, employ new technologies, educate or realize exemplary performance in another area." In addition to the Innovation in Design point for the UVC system, the Sammamish Commons project earned overall LEED Silver certification. Architect for the project is ARC Architects, Seattle.

Robert Scheir, president of Steril-Aire, which pioneered the use of UVC in air-handling systems, says, “The inclusion of UVC in the LEED rating system is precedent-setting and will reward other building owners, designers, engineers and contractors who take advantage of this technology in the future."