Lighting the way

As part of the Energy Policy Act of 1992, the U.S. Dept. of Energy (DOE) established ANSI/ASHRAE/IESNA 90.1-1989 as the federally mandated minimum design and construction standard for commercial buildings throughout the United States. And with lighting efficiency—a major component of overall building system efficiency—as energy-efficient lighting technologies evolve, the code also e...


As part of the Energy Policy Act of 1992, the U.S. Dept. of Energy (DOE) established ANSI/ASHRAE/IESNA 90.1-1989 as the federally mandated minimum design and construction standard for commercial buildings throughout the United States. And with lighting efficiency—a major component of overall building system efficiency—as energy-efficient lighting technologies evolve, the code also evolves.

In addition to establishing the new standard, the legislation empowered the DOE to review future updates to ANSI/ASHRAE/IESNA 90.1 (commonly called Standard 90.1), and determine if those updates should be adopted on a federal level. In 2002, the DOE did just that, adopting Standard 90.1-1999 as the new federal standard, and in doing so, set a two-year deadline for all 50 states to adopt commercial energy codes at least as stringent as Standard 90.1-1999. Roughly half of the states adopted the standard by the deadline. To date, 14 states have not adopted energy codes as stringent as Standard 90.1-1999, not including three states that have had significant adoptions of the standard by local jurisdictions within the states.

It should be noted that some states use the International Energy Conservation Code (IECC) instead of Standard 90.1, upon which IECC is based. Each year, the two change stringency requirements, so it is difficult to know which to follow.

Since that time, two new versions of Standard 90.1 have evolved: ANSI/ASHRAE/IESNA 90.1-2001 and ANSI/ASHRAE/IESNA 90.1-2004. Understanding these two versions, as well as which of the standards, if any, is being adopted by particular states or local municipalities, is an important responsibility of consulting engineers.

Lighting effects

A collaborative effort of ASHRAE and the Illuminating Engineering Society of North America (IESNA) members developed Standard 90.1-1999 and later versions set energy standards in three primary areas:

  • Building envelope

  • HVAC/water heating

  • Lighting.

According to a report issued by the Lighting Controls Assn., lighting accounts for 50% of electrical energy use in most buildings constructed before 1986. In new buildings that meet Standard 90.1-1999, lighting accounts for only 30% of electrical energy use. Also, according to the Energy Cost Savings Council, energy-efficient lighting generates an average project payback period of 2.2 years and a 45% return on investment, a better payback than other energy-saving building system technologies. This dramatic reduction in overall electric consumption points toward the importance energy-efficient lighting technologies play within the three areas the standard addresses.

Many of the standard’s requirements, as they pertain to lighting controls, have gone unchanged in the 2001 and 2004 versions. The biggest differences with regard to lighting concern allowable lighting power density, which has become more stringent in recent versions.

For example, within office settings, the limitation on wattage per square foot went from 1.5 W/sq. ft in Standard 90.1-2001 to 1.0 W/sq. ft in Standard 90.1-2004. That change creates a push to seek out higher efficacy lighting in new construction projects.

The Energy Policy Act of 2005 was established to further increase the adoption of energy-efficient technologies in existing buildings by establishing tax incentives. The Energy Efficient Commercial Buildings Deduction allows as much as $1.80/sq. ft tax deduction for energy-efficient building systems, but no amount higher than the cost of the system, for buildings designed for 50% energy cost savings relative to a building designed within the scope of Standard 90.1-2001.

As an alternative to considering the efficiency of the whole building, the tax law also allows businesses to individually measure the efficiency of each of the three building systems considered in the standard. Each of these areas may qualify for up to a $0.60/sq. ft deduction for its contribution to the 50% savings.

While Standard 90.1-2004 has seen less application in federal law or the U.S. tax code, its initial focus served as a minimum requirement to qualify for the USGBC LEED certification program.

Left largely unchanged in the 2001 and 2004 versions of Standard 90.1 is the requirement for automatic lighting shutoff in commercial buildings larger than 5,000 sq. ft. The standard provides three methods for automatic lighting shutoff: time of day schedule control, occupancy sensing, and signal from other systems indicating space is unoccupied. Exceptions are given for buildings with lighting intended for a 24-hour operation, lighting in spaces where patient care is rendered, and places where safety would be compromised.

Also left unchanged from Standard 90.1-1999 are space control requirements, which stipulate that each enclosed space by ceiling-heightpartitions shall have at least one space control device to control an area up to 2,500 sq. ft for spaces 10,000 sq. ft or less, or an area up to 10,000 sq. ft for spaces greater than 10,000 sq. ft. Examples of compliant space controls include:

An occupancy sensor that turns lighting on and off with occupancy in offices, restrooms, conference rooms, employee lunch rooms, and classrooms.

A switch to override the schedule for as long as 4 hours during the off schedule, for lighting on a time-of-day schedule control.

Multi-scene controls in classrooms or conference rooms, which was featured in ASHRAE 90.1-2004.

The big picture

While it’s important for engineers to be mindful of energy codes and standards in their respective states, this should not be the only consideration when specifying lighting controls in a commercial building. While designing to a modern energy standard achieves energy savings, it may not meet the needs of those using the building. Dimming controls in offices, multi-scene controls in classrooms and conference rooms, and conveniently located keypads are a few ways that lighting controls make the building more functional and convenient for occupants.

But before employing a specific lighting control strategy, take the time to speak with suppliers who offer a wide breadth of lighting control options to verify how such a strategy will mesh with other energy saving initiatives that are employed. It will be time well spent and a key cog in achieving both functionality and energy and cost savings.

Author Information

Eddie Hickerson is responsible for energy code and lighting control training for Square D/Schneider Electric, as well as developing and administering support tools. With 20 years of experience in the lighting industry, Hickerson has served the lighting ballast design industry and as a product manager of fluorescent lamps and ballasts.


Of all the engineering disciplines, one can argue that lighting has made the most practical strides in complying with energy efficiency standards.

For more information, useful Web sites include the following• Lighting Controls Assn.,

• The Building Codes Assistance Project,

• Illumination Engineering Society of North America,

• For tax deductions,

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