The lighting industry continues to evolve with control enabled LED systems allowing man-made lighting environments to be both energy efficient and fully customizable. This article seeks to shed some light on the illumination standards community. We’ll introduce the institutions that deliver national standards and explore how lighting requirements vary in different settings.
Illuminance: Amount of light striking a surface.
Luminance: Amount of light a source is emanating.
Lumen (L): One foot-candle falling on one square foot of area – a measure to describe the quantity of light given off from a source
Foot-candle (FC): Amount of light that a one-lumen candle creates exactly one foot away (Figure1).
Lux: The amount of light that one lumen of light creates one meter away. Similar to a foot-candle, but for the metric system (Figure1).
Horizontal Illuminance: The amount of light hitting a horizontal surface (floor, desk or table).
Vertical Illuminance: The amount of light striking a vertical surface (wall or photo display).
Candlepower: A measure of how much light is produced at the source (also referred to as Candela). One can convert candlepower to foot-candles, and vice versa (Figure2).
Wattage (W): A measurement of energy consumed by a light.
Lighting Power Density (LPD): Power usage per square foot (typically measured in watts). Commonly used to describe building energy requirements.
Color Rendering Index (CRI): Measurement of how well a light source reveals the colors of an object compared to a reference light source (defined as having a CRI of 100) with the same color temperature.
There are several institutions and enforcement agencies that govern, update, and continually research the principles of lighting and illumination.
North America Illuminating Engineering Society (IESNA) is one of the top illumination recommendation agencies for the United States. Their mission is to enhance the lighting world and foster a network of illumination professionals. From manufacturing and distribution to architecture and design, the IESNA represents a diversified body of experts in the lighting industry.
The IESNA handbook outlines lighting standards and design recommendations. The guidelines within this manual are well established in American design for commercial, government, industrial and residential lighting applications. The IESNA provides lighting principles in the context of foot-candles for a range of areas (based on usage).
The IESNA offers recommendations for both horizontal and vertical illuminance in the form of Average Maintained Foot-Candles and Range of Maintained Foot-Candles. Illuminance recommendations are largely dependent on function of the space.
While vision intensive areas like commercial offices are expected to maintain higher average foot-candle levels (30-40 FCs), low usage areas like parking structures have a relatively low foot-candle threshold (1-5 FCs). In the industrial realm, a “difficult” assembly line should yield an average maintained illuminance of 100 FCs.
The required maintained foot-candles can be measured at the desk level, floor level, or workspace area, depending on the facility and application. The appendix of this article contains information summarizing foot-candle levels by the Energy Trust of Oregon and Lighting Design lab.
Design Lights Consortium (DLC) is another top institution for light quality standards. The DLC Qualified Products List (QPL) provides a comprehensive catalogue of luminaires that have met industry specifications for non-residential properties. Many projects require DLC listed products, as it provides an excellent form of pre-qualification for light suppliers.
Lighting Facts is a U.S. Department of Energy (DOE) program that showcases tested LED products. The program offers a simple yet compelling reference for comparing different luminaires. Lighting Design Lab provides energy conservation education, and also offers interim qualified approval for products being reviewed by DLC or Energy Star (an EPA voluntary program that helps identify energy efficient products and buildings).
LED strength and efficiency continues to improve, and research is currently underway for efficiencies as great as 250 lumens per watt (more than twice the industry average). The development of organic LEDs (OLEDs) for mass use is also on the horizon.
LED technology represents the majority of lighting research being performed. In 2015, LEDs accounted for 81% of the 227 progress submissions sent to the IES. There were no submissions for improvements in traditional lighting technologies (incandescents, HIDs and CFLs) in 2015. The growth stagnation of traditional light sources is a clear indication of the market shift.
As the illumination industry pivots towards LEDs, community experts are reconsidering the standards and measurements that were developed to assess traditional lighting technologies. For example, the CRI measurement has come under scrutiny for its limitations and new color quality measurement systems have been proposed.
Governing bodies like the DOE set guidelines regarding energy efficiency for residential and commercial areas. The emergence and adoption of LED lights have accelerated the DOE’s ability to emphasize energy reductions in a manner that is cost-effective.
The Energy Independence and Security Act (EISA) of 2007, required that common light bulbs be approximately 25% more efficient (Table1). In 2016, basic LED incandescent replacements have energy consumptions below 10W (40-90% more efficient), and boast minimum lifetimes of 5,000-50,000 hours.
California, New Hampshire, and Hawaii have taken the EISA one step further and are leading the way for non-residential building lighting requirements. California began energy efficiency standards in 1977 that saved their residents $74 billion in reduced electricity bills (California Energy Commission, 2016).
CA Title 24, signed into legislation in July of 2014, ushered in additional restrictions for new construction and lighting retrofits. Lighting retrofit projects are now required to meet the same standards as new construction for controls and LPD. Exceptions are made for buildings replacing less than 40 ballasts, or in cases where less than 10% of lighting will be replaced.
Some of the Title24 requirements for lighting include:
• Multi-level control in nonresidential areas over 100 square feet
• "Partial on/off" occupancy sensors in corridors, stairwells, and warehouse aisles
• Auto shut off control for security and egress lighting
• LPD reductions in office and retail spaces, including outdoor lighting
The Occupational Safety and Health Administration (OSHA) enforces standards for lighting, along with many other workplace safety guidelines. Some of the OSHA lighting regulations include wiring requirements and minimum clearances on light fixtures.
OSHA also issues control standards for lighting outlets, artificial lighting principles, and emergency lighting regulations. The overwhelming majority of public buildings within the United States have similar, if not identical, emergency exit signage which is all mandated to be marked with the word “Exit” and have functionality even through a power failure (Walker, 2016).
The lighting standards within the United States have changed to adjust for the market shift towards LED technology. Organizations like the IES and DLC have adopted new lighting baselines. These emerging industry standards lead to enhanced worker safety and productivity, via regulations enforced by institutions like the DOE and OSHA.
As the energy efficiency of lighting continues to grow, state governments seek to reduce their overall carbon footprint via reduced electric consumption. With power consumption between 40-90% below that of traditional lighting installations, LEDs are at the forefront of U.S. energy independence.
Excerpt from Foot-Candle Lighting Guide taken from IES Handbook (Energy Trust of Oregon, 2013)
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