(Issue: February 2018)
Lighting Controls and Building Energy Codes
By Jack Curran
The combination of solid-state lighting technology and the expanded use of lighting control systems is once again changing the lighting industry. LED’s dual characteristics of instant-on and color changing (with multiple LEDs) combines perfectly with lighting control systems to provide unique functionality in many applications from color tuning of white light systems, to vertical farming applications. And the combination offers the ultimate in energy savings.
With the rapid introduction of LED technology, energy requirements for building lighting has been greatly reduced as LEDs are now the most efficient light sources available for general lighting applications. However, more can be done through the use of lighting control systems whether by simply adding dimming capability to offices, daylight harvesting function in classrooms or full building control, making use of a wide variety of sensors for feedback.
While the case for substitution of LEDs in place of traditional light sources makes for a straightforward economic payback, the additional use of lighting control systems is often not as easy a sell. In many cases, the push for lighting controls may depend on the applicable building codes to provide the additional incentive for building owners to make the investment (at least until more research is completed in the productivity advantages that I believe LED/control systems will provide). So, in this article we will take a brief look at how building energy codes relate to lighting control systems.
Background on Building Energy Codes
As with most commercial real estate applications, building codes drive much of what is installed. With respect to lighting controls, requirements for control systems are just starting to spread. If we look at building codes applied across the country, there are three standards: ASHRAE, International Energy Conservation Code (IECC) and—for those in California—Title 24. The story is more complicated by the fact that there are different editions of ASHRAE and IECC codes as shown in Figure 1.
Figure 1: Energy Building Codes by State
There is a vast range of differences when comparing the standards used by various states. Compare the 2003 version of the IECC still in use by the state of Wyoming to the 2015 version in use by 15 states such as Texas, Hawaii and New York. Codes for Alaska, Colorado and Connecticut also reference ASHRAE 90.1.2010, besides IECC-2012. For states that primarily reference ASHRAE codes, their editions range from 2007 thru 2013.
As a point of comparison, the Electrical Power and Lighting Systems
section of the IECC code was less than two pages in the 2003 edition, while the 2015 edition is almost 12 pages. The soon to be adopted 2018 edition consists of 15 pages on that topic. The 2018 edition also introduces the concept of Luminaire Level Lighting Controls (LLLC) and requires that such systems conform to performance standards similar to traditional lighting control systems as well as being independently capable of:
Monitoring occupant activity to adjust the lighting levels;
- Monitoring ambient lighting levels (both daylight and electrical) and adjust the lighting levels accordingly; and
- Configuration and reconfiguration of light setpoints, timeouts, dimming fade rates, sensor sensitivity adjustments and wireless zoning configuration for each control strategy.1
For IECC, emphasis on lighting control codes is focused on seven main areas:
Occupant sensor controls: automatically turn off lights within 30 minutes of occupants vacating the monitored space.
- Time-switched controls: a system capable of being programmed for seven different day types per week, having a “holiday” feature (turns off all lighting loads for at least 24 hours) and backup capabilities in case of power failure.
- Light reduction controls: a manual control that allows occupants to reduce the connected lighting load by at least 50 percent using one of the following methods:
a. Controlling all lamps/luminaires;
b. Dual switching of alternate rows of luminaires; alternate luminaires or alternate lamps;
c. Switch the middle lamp in a three-lamp luminaire;
d. Switch each lamp/luminaire.
- Manual controls: switches that are readily accessible to building occupants and located where the controlled lights are visible.
- Daylight-responsive controls: configured so they can be calibrated from within that space by authorized personnel. Those calibration mechanisms should be readily accessible and should dim lights continuously from 100 percent full output to 15 percent of full output.
- Specific application controls: which cover topics like display/accent lights, display cases, hotel/motel sleeping units, supplemental task lights, equipment for sale or used in education demonstrations, and non-visual applications (plant growth, food warming, etc.).
- Exterior controls: allows automatic turn-off of exterior lighting as a function of available daylight; or, in the case of building façade/landscape lighting, automatically shut off as a function of dawn/dusk and/or set opening/closing time and include controls configured to reduce lighting power by 30 percent between midnight and 6:00 a.m.
The 2013 edition of ASHRAE 90.1 focuses on the following nine elements with respect to lighting:
Local control: one or more manual and readily accessible lighting controls in the space that controls all the lighting in the space.
- Restricted to manual ON: none of the lighting shall be automatically turned on.
- Restricted to partial automatic ON: no more than 50 percent of the lighting power for the general lighting shall be allowed to be automatically turned on, and none of the remaining lighting shall be automatically turned on.
- Bilevel lighting control: the general lighting in the space shall be controlled to provide at least one intermediate step (between 30 and 70 percent) in lighting power or continuous dimming in addition to full ON and full OFF.
- Automatic daylight responsive controls for sidelighting: in any space where the combined input power of all general lighting completely or partially within [the primary sidelighted areas is 150W or greater/the primary and secondary sidelighted areas is 300W or greater], the general lighting in [the primary sidelighted areas / the primary and secondary sidelighted areas] shall be controlled by photocontrols.
- Automatic daylight responsive controls for toplighting: in any space where the combined input power for all general lighting completely or partially within daylight areas under skylights and daylight areas under roof monitors is 150W or greater, general lighting in the daylight area shall be controlled by photocontrols.
- Automatic partial OFF (full OFF complies): general lighting power in the space shall be automatically reduced by at least 50 percent within 20 minutes of occupants leaving the space.
8. Automatic full OFF: all lighting shall be automatically shut off within 20 minutes of all occupants leaving the space. A control device meeting this requirement shall control no more than 5000 sq. ft.
9. Scheduled shutoff: all lighting in the space not exempted shall be automatically shut off during periods when the space is scheduled to be unoccupied using either a time-of-day operated control device that automatically turns the lighting off at specific programmed times or a signal from another automatic control device or alarm/security system.
California Title 24
In effect since 1978, California’s Title 24 has lead the country in energy efficient lighting requirements. The latest 2016 edition has four main control specifications for non-residential building environments:
Time-Switch Lighting Controls
a. Automatic Time-Switch Controls
b. Astronomical Time-Switch Controls
c. Multi-Level Astronomical Time-Switch Controls
d. Outdoor Astronomical Time-Switch Controls
- Daylighting Controls
a. Automatic Daylight Controls
b. Photo Controls
- Occupant Sensing Controls
a. Occupant Sensors
b. Motion Sensors
c. Vacancy Sensors
d. Partial-ON Sensors
e. Partial-OFF Sensors
There are five mandatory categories for lighting controls in Title 24 for nonresidential applications:
Area Controls: manual controls separately controlling lighting in each area.
- Multi-Level Controls: which provide occupants with the ability to use all the light, some of the light, or none of the light in an area.
- Shutoff Controls: to automatically shut off or reducing light output of lighting when the space is vacant.
- Automatic Daylighting Controls: to provide separate control of some or all the lights in the daylight area from the lights that are not in the daylight area.
- Demand Responsive Lighting Controls: controls that are capable of receiving and automatically responding to a demand response signal.
Design Lights Consortium
Besides building codes, the Design Lights Consortium (DLC) is influencing lighting control growth with the introduction of a Qualified Products List (QPL) for control systems back in 2016. DC and Power over Ethernet (PoE) systems are excluded from the list. As of today, there are 27 systems listed on the DLC’s QPL. Just as with the QPL list for solid-state luminaires, having a lighting control system on the QPL allows local utilities to provide rebates and incentives to building owners for installing such systems. For products included on the list, DLC publishes two categories: Required Capabilities and Reported Capabilities. Required Capabilities and examples of Reported Capabilities are shown below.
- Networking of Luminaires & Devices
- Occupancy (and/or Traffic) Sensing
- Daylight Harvesting/Photocell Control
- High-End Trim
- Luminaire & Device Addressability
- Continuous Diming
Interior systems only
Exterior systems only
- Energy Monitoring
- Device Monitoring/Remote Diagnostics
- Type of User Interface
- Luminaire Level Lighting Control
- Personal Control
- Load Shedding (Demand Response)
- Emergency Lighting
- Plug Load Control
- External Systems Integration (e.g. BMS, EMS, HVAC, Lighting, API)
- Color Changing/Tuning
- Start-up and Configuration Party
While not typically a part of building codes, I thought it would be useful to provide an example of what I believe will be the major driver of lighting controls in the future—productivity. It is somewhat difficult to try to provide ROIs on productivity improvement for people, however, a lot of work has been done on trying to improve the growth and yield of plants. Researchers are finding that improved plant growth and yield can be improved by varying the spectral content and light intensity as a function of the stage of growth of the plant. For example, many flowering house plants need 12–14 hours of light per day for optimum growth. However, darkness also is important as it allows the plant to rest and triggers the flowering response. Other plants such as chrysanthemums and poinsettias need longer periods of darkness for optimum flowering. NASA studies have found that plants in general are more sensitive to the level of blue in the spectrum depending on the type and stage of growth of the plant.2
Today’s high-pressure sodium and metal halide growth lights are changing to the “purple” red/blue LED grow lights offered today by many manufacturers. Tomorrow’s vertical farming lighting systems will include the ability to shift the spectral content using lighting control systems. Particularly in the high value agriculture growth applications (e.g. herbs, cannabis, etc.). LED/lighting control systems will provide business opportunities for those in the lighting industry.
1 2018 International Energy Conservation Code, International Code Council, 2017.
2 Sole-Source Lighting for Controlled-Environment Agriculture, Mitchell and Stutte, NASA.
Jack Curran is President of LED Transformations, LLC. Jack is a regular LM&M contributor. You may reach Jack at email@example.com.