Lighting the way to 90.1

By A. J. Glaser, Lighting Controls Assn. and HUNT Dimming, Fort Collins, Colo. May 1, 2009

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ASHRAE/IES 90.1, Energy-Efficient Design of New Buildings Except Low-Rise Residential Buildings , along with the International Energy Conservation Code (IECC), is used as a standard for energy-efficient commercial building construction throughout the United States. Today, most states have adopted 90.1 or IECC as their commercial energy code, have a code based on one of them, or maintain a state-specific code with similar requirements. Currently, the United States presents a patchwork of energy codes that are either state-specific or based on ASHRAE 90.1-1999, 2001, 2004, or 2007; or IECC 2003, 2006, or 2009.

Right now, 90.1-1999 is the national energy standard of record for state code adoption in the United States. As of July 2004, all states were required to implement a commercial energy code that is at least as stringent as 90.1-1999. At press time, 37 states and significant jurisdictions in other states have complied. On Dec. 30, 2008, the Dept. of Energy recognized 90.1-2004 as the new national energy standard, which will become effective Dec. 30, 2010. Currently, 24 states already have a building energy code in place that meets or exceeds 90.1-2004, meaning 13 states will likely catch up in 2010 and 13 will not comply for various reasons, such as “home rule” state constitutions.

Meanwhile, under the stimulus package enacted into law in February, the DOE is offering nearly $17 billion to the states for a variety of measures related to production of renewable energy, energy and conservation research, and other programs. To qualify for a share of the money, the state government must work toward implementation of a commercial energy code that is at least as stringent as 90.1-2007 and develop a plan for achieving 90% code compliance.

The Commercial Buildings Tax Deduction is based on exceeding 90.1-2001. U.S. Green Building Council LEED for New Construction v.2.2 is based on 90.1-2004, while LEED 2009 is based on 90.1-2007. Federal construction is governed by a code that is based on 90.1-2004; by executive order, all federal facilities must meet 90.1-2004’s mandatory requirements and go at least 30% beyond its lighting power densities wherever economically justified. (The stimulus is intended to help fund these modernization projects.)

Interestingly, the IECC, not 90.1, is the code adopted in most states. Like 90.1, IECC is now updated every three years and, in recent years, both standards have converged in some aspects. Significantly, IECC has recognized 90.1 as an alternative compliance standard, giving designers the option to choose either version by section (mechanical, lighting, etc.). This means a project’s mechanical engineer could use IECC while the lighting designer could use 90.1, which offers some additional flexibility in lighting compliance. IECC 2009 changes that, however, by requiring the design team to choose one standard or the other for all building systems. This will mean the lighting designer will need to lobby upfront with other project designers for which code or standard will be used, which in some cases results in less design flexibility.

ASHRAE 90.1-2004 versus 1999

Regarding lighting, 90.1-2004 includes minor text clarifications and additional exceptions while incorporating three major changes compared to 90.1-1999. These three changes are:

  1. Complete replacement of interior lighting power density allowances: The lighting power densities in 90.1-2004 have been completely revised and are generally 13% to 50% lower than those in 90.1-1999 (on average 20%, according to DOE).

  2. Revised exterior lighting power density allowances: Exterior lighting power allowances are dramatically expanded in 90.1-2004, covering 17 applications from parking lots to drive-up windows. The requirements are split into “tradable” and “non-tradable” applications; with regard to interior power limits, power can be traded among the tradable applications for design flexibility.

  3. Addition of occupancy sensor requirements: The 90.1-2004 standard changes the “space control” requirements by identifying three applications where an occupancy sensor is a required control to turn the lights off within 30 minutes of the occupant leaving the space:

  • Classrooms (with significant exceptions)

  • Conference/meeting rooms

  • Employee lunch and break rooms.

ASHRAE 90.1-2004 adds, “These spaces are not required to be connected to other automatic lighting shutoff controls.”

The 2004 standard also presents a new exit sign wattage requirement (“internally illuminated exit signs shall not exceed 5 W per face”), eliminates “by occupant intervention” as a method of automatic shutoff (included in error in 90.1-1999), and recognizes “a signal from another control or alarm system that indicates the area is unoccupied,” among other changes.

ASHRAE 90.1-2007 versus 2004

In terms of lighting, 90.1-2007 does not alter the lighting power density limits but contains a significant number of refinements.

Light fixture wattage: The 2007 standard says the wattage of light fixtures with permanently installed or remote ballasts or transformers is either the input watts of the maximum lamp/ballast or lamp/transformer combination or the input watts of the maximum labeled wattage of the light fixture. The new latter option recognizes fluorescent lamp/ballast systems with multi-tap or multi-level-type ballasts; fixtures can be labeled to indicate maximum lamp wattage, and this value can be used for compliance.

Line-voltage track: The installed lighting power for line-voltage track lighting is either 30 W/linear ft, or the wattage limit of either the system’s circuit breaker or another permanent current-limiting device on the system. This rewards use of low-wattage track fixtures such as ceramic metal halide by recognizing a load closer to the actual lighting design. Solutions include subpanels with current-limiting breakers and current-limiter track connectors with a resettable breaker that trips if the connected load exceeds the current limit.

Furniture-mounted task lighting: A number of nongeneral, separately controlled types of lighting do not have to be counted as part of the installed interior lighting power, such as lighting in casino gaming areas. The 2007 standard adds furniture-mounted task lighting that both is controlled by automatic shutoff and has an integral or nearby wall-mounted switch to the list of exceptions. This change reinforces the intent that all lighting, including task lighting, should comply with the energy code as long as it’s part of the original design.

Exterior lighting shutoff: All exterior lighting not specifically exempted by 90.1 must have automatic shutoff either when sufficient daylight is available or the lighting is no longer required to be operating during the night. Lighting designated for dusk-to-dawn operation therefore must be controlled by a photosensor (daylight) or astronomical time switch (scheduling). The 2004 version says that non-dusk-to-dawn outdoor lighting must be controlled by an astronomical time switch. The 2007 version amended this to specify that non-dusk-to-dawn fixtures can be controlled by either a time switch or a combination of an astronomical time switch and a photosensor. Allowing light fixtures with combined control increases flexibility by allowing the user to decide which is best for the application.

Additional lighting power: Finally, the 2007 version clarifies that additional lighting power is allowed only if the lighting is controlled separately from the general lighting and automatically shut off during nonbusiness hours. It eliminates additional lighting power for video display terminal applications (such as offices with computer screens). And it significantly revises additional lighting power allowances for retail display lighting based on four types of retail sales areas.

What’s next?

While 90.1-2007 does not include many major changes, change is in the air nevertheless. ASHRAE is already working on the 2010 version, and many changes have been proposed and approved for the lighting section, with others currently working their way through the process.

ASHRAE 90.1-2010, for example, may require lighting controls for daylighted spaces (following IECC, which began addressing daylighting control in IECC 2009), manual-on operation for occupancy sensors, incentives for nonmandatory controls, and controls commissioning.

Author Information
Glaser is president of the Lighting Controls Assn. ( ) and HUNT Dimming. He has worked in the lighting industry for 25 years. He is an active advocate for the controls industry as a Lightfair speaker and commentator.

At A Glance

For more information about energy codes, including what code is in effect in your state, visit . For more information about lighting and energy codes, particularly lighting control options to satisfy code requirements, visit the Lighting Controls Assn. at , which offers a number of white papers and a free online course.