ASHRAE 90.1-2013 steps up lighting control requirements

Lighting controls, when added to a commercial building’s lighting system, can increase energy efficiency.




Learning Objectives

  • Learn how energy is used in commercial buildings, and how significantly lighting contributes to energy use.
  • Understand how lighting control saves energy in commercial buildings.
  • Learn the key mandatory lighting control requirements in the ASHRAE 90.1-2013 energy efficiency standard.

Daylight sensors communicate with digitally addressable dimming ballasts to provide automatic, daylight responsive control in areas with significant useful daylight. Courtesy: Lutron Electronics Co. Inc.As the building industry moves (albeit slowly) toward net zero energy-a key U.S. Dept. of Energy goal-the industry is recognizing that lighting controls play a crucial role in energy conservation. According to the U.S. Dept. of Energy, lighting is, by far, the largest end user of electricity in commercial buildings. It consumes 38% of a building's total electricity use-approximately the same as space heating, cooling, ventilation, office equipment, and computers combined.

Lighting controls can drastically reduce that appetite. They can eliminate 60% or more of the wasted lighting energy in buildings, while enhancing occupant comfort and productivity. They provide flexible control over the lighting in a space, and support energy savings by reducing the amount of power or amount of time the lighting system is in use. Energy, after all, is the multiplicative product of (in this case lighting) power used and time it is used. Lighting controls reduce both power and time.

Energy codes and standards

One of the nation's top three building energy codes and standards-Part 6 of California Energy Commission's Title 24, the International Energy Conservation Code (IECC), and ANSI/ASHRAE/IES Standard 90.1: Energy Standard for Buildings Except Low-Rise Residential Buildings-are used by nearly every state as the basis for local building energy codes. These codes and standards provide the minimum acceptable energy performance requirements for new construction or major renovations of commercial buildings, and they emphasize the importance of using lighting controls to conserve energy.

Sometimes referred to as America's primary commercial energy code, the latest version of ANSI/ASHRAE/IES Standard 90.1 was published in October 2013 and is known as Standard 90.1-2013. It provides the minimum requirements for the energy-efficient design of buildings, other than low-rise residential buildings.

Rita Harrold, director of technology for the Illuminating Engineering Society(IES), said in an ASHRAE news release that achieving the stringency goals established for the 2013 standard presented a challenge in reducing the requirements for lighting. "While interior lighting power densities (LPD) were reevaluated and most lowered, there continues to be an ongoing concern about maintaining quality of lighting installations for occupant satisfaction and comfort while achieving energy savings," Harrold said. "The focus in the 2013 standard, therefore, was not just on lowering LPDs, but on finding ways to achieve savings by adding more controls and daylighting requirements as well as including lighting limits for exterior applications based on jurisdictional zoning."

Below are highlights of some of the mandatory lighting control requirements in the new Standard 90.1-2013:

Local control

Each interior space must have at least one lighting control device (such as a manual switch or a dimmer) to control the lighting in that space.

Each control device shall be readily accessible and located so the occupants can see the controlled lighting and can only override the scheduled lighting shut-off by a maximum of two hours.

Automatic shut-off or scheduled shut-off

Lighting in the following spaces must be automatically shut-off (typically using vacancy sensors) within 20 minutes of vacancy:

1. Classrooms and lecture halls
2. Conference, meeting, and training rooms
3. Employee lunch and break rooms
4. Storage and supply rooms of 50 to 1000 sq ft 5. Rooms used for document copying and printing
6. Office spaces up to 250 sq ft
7. Restrooms
8. Dressing, locker, and fitting rooms

Lighting in all other spaces must have either an automatic lighting shut-off control (e.g. an occupancy sensor) that turns off the lights within 20 minutes of vacancy, or scheduled lighting shut-off during periods when the space is scheduled to be unoccupied (e.g. a timeclock).

Manual-on or partial automatic-on

Lighting in most spaces must have either a manual-on lighting control or an automatic-on lighting control configured to turn the lighting on to not more than a 50% light level. This effectively requires manual-on/automatic-off controls, or up to 50% auto-on capability for automatic controls. These controls also turn the lights off automatically after the occupants leave the space, and are commercially available as "vacancy sensors" or "multi-level" occupancy sensors. Automatic-on to full is allowed in some spaces, including public corridors and stairwells, restrooms, primary building entrance areas and lobbies, and areas where manual-on operation would endanger safety or security.

Bi-level lighting control

Most areas in commercial buildings must provide at least one light level between 30% and 70% of full lighting power in addition to off. This can be done by continuous or stepped dimming, or stepped/dual switching of luminaires or lamps, while maintaining a reasonably uniform level of illumination throughout the area.

Occupancy sensor switches help achieve local control and automatic shut-off by turning lights off when an area is unoccupied. Courtesy: Lutron Electronics Co. Inc.Automatic daylight responsive control for sidelighting and toplighting

An automatic reduction in lighting power in areas where the daylight can help illuminate the space will be required in most areas that are sidelighted (with windows) or toplighted (with skylights). General lighting in daylight areas using more than 150 W of power shall be controlled using continuous dimming or with at least one control point of 50% to 70% of design lighting power, a second control point between 20% and 40% of design lighting power, and a third control point that turns off all the controlled lighting.

Automatic partial-off

Lighting in stairwells and corridors shall be reduced by at least 50% after 20 minutes of all occupants leaving the space.

Exterior lighting control

Permanently installed outdoor lighting must be controlled by a photocontrol or astronomical time switch (timeclock) that automatically turns off the lighting during daylight hours. The new standard also requires that façade and landscape lighting be turned off between midnight and 6 a.m., or in conjunction with business opening and closing times. Other outdoor lighting, such as advertising signage, must operate at 70% power (or lower) between midnight and 6 a.m., or in conjunction with business closing and opening times, or when no activity has been detected for 15 minutes.

Other requirements

The examples above represent a portion of the new ASHRAE Standard 90.1-2013 requirements related to lighting control. Other energy efficiency requirements for the electrical and lighting systems include automatic receptacle shut-off (to control task lighting and other plug loads), parking garage lighting control (automatically reduced lighting power when daylight is present and/or during periods of vacancy), energy monitoring (to monitor whole-building energy usage and breakout lighting, HVAC, and plug loads separately), and functional testing requirements (to ensure that the lighting controls operate as intended).

Lastly, the standard provides additional lighting power allowances, above and beyond the minimum mandatory controls for that space, for using advanced lighting controls. The additional lighting power allowance may be used anywhere in the building, not just in the space with the additional controls. The energy use attributed to these allowances typically represents one half of the expected energy savings from these advanced lighting controls.

Lighting controls are vital components for helping us meet the increasingly stringent energy code requirements-requirements which help our nation meet its energy conservation goals in an energy-starved world.

For more information on building energy codes and standards, visit

Pekka Hakkarainen is vice president at Lutron Electronics, working in government and industry relations, including codes and standards activities. He was the chair of the Lighting Systems Division of the National Electrical Manufacturers Association (NEMA), is a member of the ASHRAE 90.1 Committee, and is a member of the IES. Pekka received a BA/MA degree from Cambridge University, England, and a PhD from MIT.


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