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Circadian lighting design

Features>Light>54. Circadian lighting design

54. Circadian lighting design

Exposure to light regulates the circadian rhythm, which determines sleep and wake cycles. To promote alertness and activity, the human circadian cycle is most sensitive to lights of high frequency and intensity. Conversely, lights of low frequency and intensity signal the body to decrease energy and prepare for rest.

This feature provides lighting conditions that reinforce the natural patterns of the human circadian cycle. The Equivalent Melanopic Lux (EML) is a measurement of light's effects on the circadian cycle. EML can be used to determine how interior lighting conditions may be optimized to support the circadian function. See Tables L1 and L2 in Appendix C for more information on how to calculate the EML of individual lamps and larger spaces.

Part 1: Color Rendering Index

To accurately portray colors in the space and enhance occupant comfort, all electric lights (except decorative fixtures, emergency lights and other special-purpose lighting) meet the following conditions:

a.80 Color Rendering Index Ra (CRI, average of R1 through R8) of 80 or higher.
b.80 Color Rendering Index R9 of 50 or higher.
Part 2: Melanopic Light Intensity in Living Environments

In all bedrooms, bathrooms, and rooms with windows, one or more fixtures provide the following:

a. 250 or more equivalent melanopic lux as measured facing the wall in the center of the room 1.2 m [4 ft] above the finished floor. The lights may be dimmed in the presence of daylight, but are able to independently achieve these levels.
b. Evening lights provide not more than 50 equivalent melanopic lux (to the extent allowable by code) as measured 0.76 m [30 inches] above the finished floor.
Part 3: Melanopic Light Intensity in Breakrooms

Workplaces where employees spend most of their time in spaces with light levels limited by work type (such as restaurant servers or hospital ward workers) have break rooms which meet the following requirement:

a. Lights provide a maintained average of at least 250 equivalent melanopic lux as measured on the vertical plane facing forward at surfaces 1.2 m [4 ft] above finished floor. The lights may be dimmed in the presence of daylight, but are able to independently achieve these levels.
Part 4: Melanopic Light Intensity in Learning Areas

At least one of the following requirements is met:

a. Early education, elementary, middle and high schools, and adult education for students primarily under 25 years of age: Light models (which may incorporate daylight) show that at least 125 equivalent melanopic lux is present at 75% or more of desks, on the vertical plane facing forward 1.2 m [4 ft] above finished floor (to simulate the view of the occupant). This light level is present for at least 4 hours per day for every day of the year.
b.139 Ambient lights provide maintained illuminance on the vertical plane of equivalent melanopic lux greater than or equal to the lux recommendations in the Vertical (Ev) Targets in Table 3 of IES-ANSI RP-3-13, following the age group category most appropriate for the population serviced by the school. For example, art studios in elementary school, middle school, or high school are provided with 150 equivalent melanopic lux from the electric lights.
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Applicability Matrix

Core & Shell Tenant Improvement New Construction
Part 1: Color Rendering Index - O O
Part 2: Melanopic Light Intensity in Living Environments - - -
Part 3: Melanopic Light Intensity in Breakrooms - - -
Part 4: Melanopic Light Intensity in Learning Areas - - -
Commercial Kitchen Schools Multifamily Residential Restaurant Retail
Part 1: Color Rendering Index O O O O O
Part 2: Melanopic Light Intensity in Living Environments - - O - -
Part 3: Melanopic Light Intensity in Breakrooms - - - O O
Part 4: Melanopic Light Intensity in Learning Areas - O - - -

Verification Methods Matrix

Letters of Assurance Annotated Documents On-Site Checks
PART 1 (Design)
Color Rendering Index 		Architect
PART 2 (Performance)
Melanopic Light Intensity in Living Environments 		Performance Test
PART 3 (Performance)
Melanopic Light Intensity in Breakrooms 		Performance Test
PART 4 (Design)
Melanopic Light Intensity in Learning Areas 		Architect

139

American National Standards Institute and Illuminating Engineering Society of North America. American National Standard Practice on Lighting for Educational Facilities. New York, NY: Illuminating Engineering Society of North America; 2013. RP-3-13.
54.4.b

ANSI/IES RP-3-13 provides Table 3 for recommended maintained illuminance targets for the vertical plane stratified by observer age. Table 3b recommends a target value of 150 lux on the vertical plane in art studios for observers <25 years of age.
174

American National Standards Institute and Illuminating Engineering Society of North America. American National Standard Practice for Office Lighting. New York, NY: Illuminating Engineering Society of North America; 2012. RP-1-12.
54.1.b

ANSI/IES American National Standard Practice for Office Lighting (RP-1-12) provides recommended maintained illuminance targets for various types of spaces by age group. For reception desks, RP-1-12 recommends a maintained target of 150 lux for ages 25-65.
Features>Light>54. Circadian lighting design