Energy Code for Lighting Retrofits

The creators of the ASHRAE/IES 90.1 energy standard set an aggressive goal for the 2010 version, published in November 2010: 30 percent energy savings over the 2004 version. According to a detailed analysis conducted by the Department of Energy, they hit it. Commercial buildings designed to ASHRAE/IES 90.1 2010 are expected to achieve 32.6 percent site-energy savings and 30.1 percent energy-cost savings compared to buildings compliant with 90.1 2004, excluding plug loads.

In terms of lighting, the new standard means dramatic changes. While previous versions showed a progressive evolution since 1999, the 2010 version feels, in many ways, like starting from scratch. The lighting section, for example, contains lower interior lighting power density (LPD) limits for buildings and expanded outdoor LPD requirements by lighting zone, dramatically expanded lighting control requirements, coverage of lamp and ballast retrofits, and commissioning.

It is important to note that ASHRAE/IES 90.1 is not an energy code. It is a standard written in code-ready language that jurisdictions can adopt as or adapt for their energy code. The 2010 version is expected to be initially adopted in the states that are most progressive toward energy conservation.

An expansion of the lighting alterations section now covers lamp and ballast retrofits in both indoor and outdoor applications. If a building owner replaces lamp-ballast systems representing 10 percent or more of the connected lighting load in an indoor space or outdoor area, the owner must comply with the standard’s LPD limits (expressed in watts per square foot) and automatic shutoff requirements. This would require the addition of scheduling, occupancy sensor or some other recognized type of shutoff control for the renovated spaces. Requiring controls in retrofits may change the economics of some retrofit projects while requiring electrical contractors who perform lamp and ballast retrofits to attain a high level of proficiency with lighting control application, installation and functional testing.

Also of interest to electrical contractors is a new requirement for functional testing of lighting controls and systems, as contractors are typically required to provide these services (the standard requires that the construction documents identify who will conduct and certify the testing). Specifically, all specified lighting controls and associated software must be calibrated, adjusted, programmed and ensured to operate in accordance with construction documents and manufacturer installation instructions. Specific requirements are identified for occupancy sensors, programmable schedule controls and photosensors. For example, the party conducting the functional testing must confirm that the placement of occupancy sensors and their sensitivity and timeout settings will provide acceptable performance (e.g., turn the lights off only when the space is not occupied).

Related to commissioning is another requirement for certain documents to be turned over to the owner within 90 days of system acceptance, including as-built drawings of the lighting and control system, operating and maintenance manuals for all lighting equipment, a recommended relamping program, a schedule for inspecting and recalibrating lighting controls, and a complete narrative of how each lighting control system is supposed to operate, detailing its recommended settings.

Now let’s talk about the meat of ASHRAE/IES 90.1, which is the caps on LPD by whole building and individual space type as well as mandatory lighting control requirements. While a review of the LPD modeling method resulted in LPD caps being raised for some space types, caps were lowered in a majority of building and space types, making the standard more stringent than preceding versions. This modeling was based on assumptions about readily available technology and current IES light level recommendations. That being said, it is arguable that the lower the LPD caps go, the more expertise is required to satisfactorily serve two masters: the energy code and building occupants, who will benefit from a high-quality lighting environment.

That leaves lighting controls, and the changes here are dramatic. The automatic lighting shutoff exemption for buildings smaller than 5,000 square feet is gone. Building owners are required to install automatic lighting shutoff, covering both indoor and outdoor lighting, with all interior automatic controls restricted to manual-on or auto-on to 50 percent operation; bilevel switching for stairwells and space control; occupancy sensors in a broad range of space types; daylight harvesting in daylighted spaces; and other requirements covering specific applications. Furthermore, a list of advanced control options, such as automatic continuous daylight dimming, are identified with power adjustment factor credits for basic space types, such as office, meeting, retail and public spaces. These factors can be applied to adjust space LPD caps, rewarding adoption of these advanced control strategies with a higher design lighting power allowance.

In all, the new ASHRAE/IES standard is more comprehensive, stringent and complicated, and it contains provisions that are likely to directly affect electrical contractors. To obtain a copy of the standard, visit the ASHRAE bookstore at

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

About the Author

Craig DiLouie

Lighting Columnist
Craig DiLouie, L.C., is a journalist and educator specializing in the lighting industry. Learn more at and .​

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