A new national energy standard took effect on Dec. 30, 2010. On that day, all states had to certify to the U.S. Department of Energy (DOE) that they had a commercial building energy code in place at least as stringent as ASHRAE/IES 90.1 2004 or justify why they could not comply. The new standard supersedes ASHRAE/IES 90.1 1999, recognized as the national energy standard since 2004.

As of Jan. 5, 2011, 34 states were in compliance, with 20 going even further by adopting ASHRAE 90.1 2007, according to EnergyCodes.gov. Seven states were not in compliance, still using a code based on an older, less stringent standard. And nine continued to have no statewide energy code for reasons such as home rule constitutions, which require energy codes to be enacted at a more local level of government.
Energy codes set minimum standards for design and construction and can significantly affect building system lifecycle costs. Electrical contractors often find themselves in the position of making design decisions and, therefore, should be aware of energy code requirements for new construction and renovations.

ASHRAE/IES 90.1, Energy Standard for Buildings Except Low-Rise Residential Buildings, is actually not an energy code. Rather, it is a standard written in code-ready language that jurisdictions can adopt or adapt as their commercial building energy code. Today, most states have adopted either 90.1 or the International Code Council’s (ICC) International Energy Conservation Code (IECC) as their energy code, have a code based on one of them, or publish a state-specific code with similar requirements.

More states have adopted IECC than 90.1, but IECC references 90.1 as an alternative compliance standard. Each standard is updated every three years but not on the same schedule (2003, 2006, 2009 for the IECC and 1999/2001, 2004, 2007 and 2010 for ASHRAE/IES). As a result, different versions of the same standard are in effect in different jurisdictions. Even with a national energy standard, the United States is essentially a patchwork of energy codes, which can make things confusing. Further, ASHRAE/IES 90.1 is referenced in a number of energy conservation and sustainability programs, including LEED (90.1 2007), ASHRAE 189.1 green building standard (90.1 2007), the Commercial Buildings Tax Deduction (90.1 2001), the Commercial Lighting Solutions web tool (90.1 2001–2007), ASHRAE Advanced Energy Design Guides (90.1 1999), federal stimulus energy grants (90.1 2007), and federal construction and upgrades (90.1 2004).

ASHRAE/IES 90.1 2004 applies to new construction and major alterations (i.e., renovations). Basically, if a lighting system is altered—that is, half or more of the lighting fixtures are replaced—the building owner must comply with the standard’s lighting power requirements. If this occurs and existing controls are replaced, the standard’s space control requirements must be met.

For construction, ASHRAE/IES 90.1 2004 is broken into two major sections, covering (1) mandatory requirements for lighting controls, tandem wiring and exit signs and (2) prescriptive compliance paths for producing a lighting design within a maximum allowable lighting power value for the given building or space type. Significant updates to the 1999 version include the following:
• Correction to automatic lighting shutoff section eliminating manual control option and recognizing shutoff signal from another building system
• Required use of occupancy sensors in certain lunch, meeting and classrooms
• New internally illuminated exit sign wattage requirement, limiting power to 5 watts per face
• Complete replacement of interior lighting power allowances
• Revised exterior lighting power allowances

Contractors reading ASHRAE/IES 90.1 for the first time will see the phrase “lighting power density” (LPD) used frequently. This term describes the amount of lighting power allowed in the building or space based on its area, expressed as maximum allowable watts per square foot. ASHRAE/IES 90.1 imposes caps on maximum allowable LPDs in whole buildings (if the building area method is chosen by the designer) or per space type (if the space-by-space method is used).

The interior LPD limits in ASHRAE/IES 90.1 2004 are, on average, 20 percent lower than the 1999 version, based on modeling with assumptions about available technology, IES-recommended light levels and common design practice. In other words, highly efficient lighting equipment had become widely available, so it was believed that good design was already satisfying the lower LPD caps.

Also, exterior LPD requirements were expanded to cover 17 outdoor applications from parking lots to drive-up windows. The outdoor values are split into “tradable” and “nontradable” applications; for example, with indoor lighting power using the space-by-space method, power can be swapped among tradable applications for a higher level of design flexibility.

Next month, this column will visit the latest version of ASHRAE/IES 90.1 (2010), published last November, which contains significant changes.


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