ASHRAE STANDARD 90.1 Energy-Efficient Design of New Buildings Except Low-Rise Residential Buildings establishes minimum standards for designing energy-efficient buildings. In January, ASHRAE released 90.1-2007, and states could begin the process of adopting it, verbatim or amended, as their energy code.

Clarifications and refinements with a major revision for additional power allowances are new.

“The majority of the lighting changes are enhancements to the language to provide clarity for facilitating appropriate and effective application of the standard’s requirements,” said Eric Richman, senior research engineer for the Pacific Northwest National Laboratory/U.S. Department of Energy and current chair of the 90.1 Lighting Subcommittee.

Below are highlights of several key lighting changes. All comparisons to the previous version of 90.1 refer to 90.1-2004.

Section 9.1.4.

This section defines what wattage should be used for lighting fixtures in the installed interior lighting power calculations. Previously for track lighting, if low-voltage track was specified, the maximum wattage of the track system was the transformer wattage, while line-voltage track was penalized with a minimum of 30 watts per linear foot.

This section now recognizes the wattage of a circuit breaker connected to the system and the wattage of other current-limiting devices.

Track lighting subpanels enable multiple lengths of track to be applied to one current-limited circuit and control of other loads such as low-voltage track and nontrack lighting. Track current-limiters are installed at the supply end of each track section. If the connected load exceeds the current limitation, a reset breaker trips.

Section 9.2.2.3.

The wattage of furniture-mounted task lighting is now excepted from the installed interior lighting power total as long as it is controlled by automatic shutoff plus either an integral switch or a suitable wall-mounted control device. This means connecting the task lighting to a scheduling panel or occupancy sensor.

“The intent has always been to include all lighting, including task lighting, in energy code compliance as long as it is part of the original illumination design,” Richman said. “This change is intended to encourage the use of controls and provide some relief of a potentially confusing application point.”

Section 9.4.1.3.

Exterior light fixtures not intended for dusk-to-dawn operation previously had to be controlled by an astronomical time switch. Under 90.1-2007, these fixtures can be controlled by either a time switch or a combination of a time switch and a photosensor. Richman said this change was for the sake of practicality and flexibility.

Section 9.6.2.

The biggest changes are in this section, which covers additional lighting power allowance that can be claimed for applications, such as retail and decorative lighting when using the space-by-space method.

First, language is included that strengthens 90.1’s intent that additional allowances can be used only for nongeneral lighting. Second, the additional lighting power allowed for applications with video display terminals, such as computer screens, has been discontinued, limiting open and enclosed office spaces to a total 1.1W per square foot. Finally, additional lighting power allowances for retail spaces have been revised dramatically.

According to Standard 90.1-2007, separately controlled, nongeneral lighting installed in sales areas used to highlight merchandise can claim additional lighting power as shown in the table.

“The section has been completely revised to provide a simpler method of calculating an additional retail display lighting allowance—based on floor area—and make it clearer when a specific allowance would apply. The inclusion of four merchandise levels instead of just two also incorporates additional application clarity,” Richman said.

What’s next?

Major changes may be coming in 2010, such as requirements for expanded exterior lighting, more automatic shutoff, daylight harvesting controls and for controls commissioning, and advanced control incentives.

To purchase a copy of 90.1-2007, visit the ASHRAE bookstore at ashrae.org. To learn more about energy codes in general, visit energycodes.gov.

DILOUIE, a lighting industry journalist, analyst and marketing consultant, is principal of ZING Communications. He can be reached at www.zinginc.com.