New California Energy Code Pushes Daylighting Methods for Nonresidential Buildings
June 6, 2012

by Erica Terrini, eterrini@glass.com

An energy efficiency code that includes several provisions related to both glazing and daylighting has been passed by the California Energy Commission (CEC).

Among the revised requirements is a provision that vertical windows in nonresidential buildings “have a west-facing area no greater than 40 percent of the gross west-facing exterior wall area, or 6 feet times the west-facing display perimeter, whichever is greater; and a total area no greater than 40 percent of the gross exterior wall area, or 6 feet times the display perimeter, whichever is greater.”

Several specific exceptions are listed for vertical windows that use chromogenic or dynamic glazing.

The standards also include a major focus on daylighting, and specify that in climate zones 2 through 15, conditioned enclosed spaces and unconditioned enclosed spaces that are greater than 5,000 square feet and that are directly under a roof with ceiling heights greater than 15 feet, shall meet specific daylighting provisions. The section also requires skylit daylit areas and additional sidelit daylit areas (primary and secondary) to be included in building plans. Exceptions include locations such as “auditoriums, churches, movie theaters, museums, and refrigerated warehouses.”

Skylights in these areas, for instance, must “have a glazing material or diffuser that has a measured haze value greater than 90 percent, tested according to ASTM D1003 (not withstanding its scope) or another test method approved by the Commission.”

The focus on daylighting is based on a 2002 study related to the topic, according to information from the CEC.

“Thoughtful design of buildings using daylight can improve lighting quality, increase productivity and reduce energy consumption. Since over 60 percent of commercial building floor space is single story or on a top floor, toplighting with skylights or other rooftop apertures will be the method of choice for daylighting much of the commercial building stock,” according to the 2002 Commission case study.

The study also had addressed the environmental impacts of commercial daylighting.

“Commercial skylights are primarily a plastic glazing held in place with an extruded aluminum frame,” according to the study. “They displace a similar area’s worth of roofing product and are often mounted on a wood site assembled curb … A very small amount of these materials are used to save large amounts of electricity … Peak demand savings from daylighting lead to reduced emissions from peaking power plants.”

The goal of the new standards is to make buildings in California more energy-efficient and thus reduce energy costs and pollution, according to the CEC.

"Improving the energy efficiency of buildings in which we will live and work will save Californians energy for decades," says energy commissioner Karen Douglas. "These Standards will help save consumers money on their utility bills, keep them comfortable in their homes, and reduce greenhouse gas emissions through better, more efficient buildings."

The latest release of the standards provide 30 percent more energy efficiency for nonresidential construction than the previous version, according to the CEC.

The 2013 Building Energy Efficiency Standards that the California Energy Commission adopted May 31 is part of the California Building Code, which is state law enforced by local building departments. The standards are scheduled to go before the California Building Standards Commission for approval in December 2012. The standards are scheduled to take effect January 1, 2014, according to the CEC website.

This story is an original story by USGlass magazine/USGNN™. Subscribe to USGlass magazine.
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