WELL Building Standards

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The lighting environments where humans spend their time impact their visual, circadian and mental health. Currently, lighting conditions in most spaces are designed to meet the visual needs of individuals but do not take into account circadian and mental health. This presents an opportunity for projects to provide lighting conditions required by humans for improved health and well-being. Integrating daylight and electric light to create lighting strategies focused on human health, along with traditional requirements for visual acuity and comfort, can lead to healthier and more productive environments. Understanding the specific needs and preferences of users in a space is integral to creating effective lighting environments. For example, patients in a hospital ward have different lighting requirements than individuals in an office environment. Understanding user needs in a space is key to creating a healthier space. Environments that take into account these lighting strategies and user needs can contribute to improvement of the overall mood and increase the productivity of employees.The WELL Light concept aims to provide a lighting environment that reduces circadian phase disruption, improves sleep quality and positively impacts mood and productivity.

There are 2 Preconditions (mandatory strategies) and 7 Optimization (optional strategies with a weighted point value) for the Light concept:

L01: Light Exposure

Provide Indoor Light



Choose between the following:

The project demonstrates, through computer simulations, that one of the following conditions are achieved:

  1. Regularly occupied spaces achieve one of the following targets:

  2. Calculations per IES LM-83-12 Calculations per Annex A of CEN 17037:2018
    Average sDA 200,40% is achieved for > 30% of regularly occupied floor area OR Target illuminance 19 fc is achieved for >30% of floor area throughout 50% of daylit hours of the year
  3. Common spaces that have unassigned seating for at least 15% of regular occupants at any given time achieve one of the following targets:

  4. Calculations per IES LM-83-12 Calculations per Annex A of CEN 17037:2018
    Average sDA 300,50% is achieved for > 75% of floor area OR Target illuminance 28 fc is achieved for >30% of floor area and average illuminance 9 fc is achieved for >95% of floor area throughout 50% of daylit hours of the year

One of the following requirements is met:

  1. At least 30% of the regularly occupied area is within a 20 ft horizontal distance of envelope glazing in each floor.

  2. Common spaces have unassigned seating and can accommodate at least 15% of regular occupants at any given time. At least 70% of all seating in the spaces is within a 16 ft horizontal distance of envelope glazing.

One of the following requirements is met:

  1. The envelope glazing area is no less than 7% of the regularly occupied floor area for each floor level.

  2. The floor plate is no more than 65 ft between opposite walls that each have transparent envelope glazing, and there are no opaque obstructions higher than 3.2 ft within a 20 ft horizontal distance of the transparent envelope glazing.

The following requirement is met:

  1. The project achieves at least one point in Feature L03: Circadian Lighting Design.


Choose between the following:

The project demonstrates, through computer simulations, that the following requirement is achieved:

  1. One of the following targets are met in each dwelling unit:

  2. Calculations per IES LM-83-12 Calculations per Annex A of CEN 17037:2018
    Average sDA 200,40% is achieved for > 30% of regularly occupied floor area OR Target illuminance 19 fc is achieved for >30% of individual unit area throughout 50% of daylit hours of the year

The following requirement is met:

  1. The envelope glazing area is no less than 7% of the regularly occupied floor area for each dwelling unit.

The following requirement is met:

  1. The project achieves at least one point in Feature L03: Circadian Lighting Design.

L02 Visual Lighting Design

Provide Visual Acuity



Choose between the following:

The following requirements are met:

  1. All indoor and outdoor spaces (including transition areas) comply with the illuminance thresholds specified in one of the following lighting reference guidelines:

    1. IES Lighting Handbook 10th Edition.
    2. EN 12464-1&2: 2011 or EN 12464: 2021.
    3. ISO 8995-1:2002(E) (CIE S 008/E:2001).
    4. GB50034-2013.
    5. CIBSE SLL Code for Lighting.

  2. The illuminance thresholds take into consideration the tasks and the age groups of the occupants

The following requirements are met:

  1. More than 50% of the occupants are under the age of 65.

  2. At least 90% of the project area is comprised of the following space types and meets the associated illuminance thresholds:

  3. Room Types Minimum Illuminance Threshold
    • Offices
    • Classrooms
    30 fc at task surface.
    • OfficesCirculation areas (including lobbies and atria)
    • Storage spaces
    10 fc at floor level.
    • Dining areas
    • Lounges
    • Restrooms
    10 fc at task surface.

The following requirements are met:

  1. Lighting is installed in kitchens and bathrooms to comply with the illuminance thresholds specified in one of the following lighting reference guidelines:

    1. IES Lighting Handbook 10th Edition.
    2. ISO 8995-1:2002(E) (CIE S 008/E:2001).
    3. GB50034-2013.
    4. CIBSE SLL Code for Lighting.

  2. For spaces where lighting is not installed, the following is provided to all tenants:

    1. lluminance thresholds for common tasks conducted in spaces
    2. Specifications, quantity and location of light fixtures required to meet light levels based on sample layout

L03 Circadian Lighting Design

Meet Lighting For Day-Active People (Max: 3 Points)



For workstations used during the daytime, electric lighting is used to achieve the following thresholds:

  1. The following light levels are achieved for at least four hours (beginning by noon at the latest) at a height of 18 in above the work-plane for all workstations in regularly occupied spaces:

  2. Tier Threshold Threshold for Projects with Enhanced Daylight Points
    1 At least 150 EML [136 M-EDI(D65)] OR The project achieves at least 120 EML [109 M-EDI(D65)] and L05 Part 1 or L06 Part 1 1
    2 At least 275 EML [250 lux M-EDI(D65)] OR The project achieves at least 180 EML [163 M-EDI(D65)] and L05 Part 1 or L06 Part 1 3
  3. The light levels are achieved on the vertical plane at eye level to simulate the light entering the eye of the occupant.


The following requirements are met in each dwelling unit:

  1. Electric lighting is used to achieve the following light levels:

  2. Tier Threshold Threshold for Projects with Enhanced Daylight Points
    1 At least 150 EML [136 M-EDI(D65)] OR The project achieves at least 120 EML [109 M-EDI(D65)] and at least 2 points in Feature L05: Enhanced Daylight Access 1
    2 At least 275 EML [250 lux M-EDI(D65)] OR The project achieves at least 180 EML [163 M-EDI(D65)] and at least 2 points in Feature L05: Enhanced Daylight Access. 3
  3. The light levels are dimmable. If automated lighting is used, it is automatically dimmed after 8:00 pm.

  4. The light levels are achieved in living rooms and kitchens at a height of 55 in in the center of the room. If workstations are present, light levels are achieved at a height of 18 in above the work-plane.

L04 Electric Light Glare Control

Manage Glare From Electric Lighting (2 Points)



Choose between the following:

Each luminaire (excluding wall wash fixtures, concealed fixtures and decorative fixtures installed as specified by the manufacturer) within all regularly occupied spaces meets one of the following requirements when measured at light output representative of the following regular use conditions:

  1. 100% of light is emitted above the horizontal plane.

  2. Classified with Unified Glare Rating (UGR) of 16 or lower.

  3. Luminance that does not exceed 6,000 cd/m2 at any angle between 45 and 90 degrees from nadir.

  1. The following requirement is met in all regularly occupied spaces:

  2. Unified Glare Rating (UGR) of 16 or lower.


Choose between the following:

All luminaires within regularly occupied spaces (excluding wall wash, concealed and decorative fixtures installed as specified by the manufacturer) meet one of the following:

  1. 100% of light is emitted above the horizontal plane.

  2. Classified with Unified Glare Rating (UGR) of 19 or lower.

  3. Luminance that does not exceed 6,000 cd/m2 at any angle between 45 and 90 degrees from nadir.

All regularly occupied spaces meet the following requirement:

  1. Unified Glare Rating (UGR) of 19 or lower.

L05 Daylight Design Strategies

Implement Daylight Plan (Max: 2 Points)



The following requirement is met:

  1. The project demonstrates that the following conditions are achieved in each floor:

  2. Tier Interior Layout Façade Design Points
    1 70% of all workstations are within 25 ft of transparent envelope glazing. Visible light transmittance (VLT) is greater than 40%. OR Envelope glazing is no less than 15% of the regularly occupied floor area or individual unit. Visible light transmittance (VLT) of windows is greater than 40%. 1
    2 70% of all workstations are within 16 ft of transparent envelope glazing. Visible light transmittance (VLT) is greater than 40%. OR Envelope glazing is no less than 25% of the regularly occupied floor area or individual unit. Visible light transmittance (VLT) of windows is greater than 40%. 2

The following requirement is met:

  1. One of the following requirements is met in each dwelling unit:

  2. Tier Vertical Envelope Glazing Requirements Points
    1 Vertical envelope glazing is no less than 15% of the floor area of each dwelling unit. Visible light transmittance (VLT) is greater than 40% 1
    2 Vertical envelope glazing is no less than 25% of the floor area of each dwelling unit. Visible light transmittance (VLT) is greater than 40% 2

Integrate Solar Shading (Max: 2 Points)



The following requirements are met in regularly occupied spaces:

  1. All vertical transparent envelope glazing has shading that meet one of the following:

Tier Type of Shading Points
1 Manual shading controllable by regular occupants at all times. Shades are regularly opened once a day for all days that the project is in use 1
2 Shading is automated to prevent glare 2

The following requirements are met in dwelling units:

  1. All vertical transparent envelope glazing has shading that meets one of the following:

Tier Type of Shading Points
1 Manual shading is controllable by regular occupants at all times. 1
2 Shading is automated to prevent glare. 2

L06 Daylight Simulation

Conduct Daylight Simulation (Max: 2 Points)



The project demonstrates, through computer simulations, that the following conditions are achieved in each floor:

  1. Regularly occupied spaces achieve one of the following targets:

  2. Tier Calculations per IES LM-83-12 Calculations per Annex A of CEN 17037:2018 Points
    1 Average sDA300,50% is achieved for > 55% of regularly occupied floor area OR Target illuminance of 28 fc is achieved for >50% of regularly occupied areas throughout 50% of daylit hours of the year 1
    2 Average sDA300,50% is achieved for > 75% of regularly occupied floor area OR Target illuminance of 28 fc is achieved for >50% of total area and average illuminance 9 fc is achieved for >95% of total area throughout 50% of daylit hours of the year 2

The project demonstrates, through computer simulations, that the following conditions are achieved:

  1. Each dwelling unit achieves one of the following targets:

  2. Tier Calculations per IES LM-83-12 Calculations per Annex A of CEN 17037:2018 Points
    1 Average sDA 300,50% is achieved for > 55% of the regularly occupied floor area OR Target illuminance 28 fc is achieved for >50% of individual unit area throughout 50% of daylit hours of the year 1
    2 Average sDA 300,50% is achieved for > 75% of the regularly occupied floor area OR Target illuminance 28 fc for >50% of individual unit area and average illuminance 9 fc is achieved for >95% of individual unit area throughout 50% of daylit hours of the year 2

L07 Visual Balance

Balance Visual Lighting (1 Point)


Choose between the following:

Ambient lighting in all regularly occupied spaces meets at least three of the following requirements:

  1. Horizontal and vertical luminance contrast ratios for an ambient light system is no more than 10 between adjacent independently controlled zones.

  2. Illuminance uniformity ratio of at least 0.4 or 1:2.5 (minimum light level: average light level) is achieved on any horizontal task plane within a space.

  3. One of the following:

    1. A lighting automation system is in use and automatic changes in lighting characteristics, such as light levels, changes in color and distribution take place over a period of at least 10 minutes.

    2. A lighting automation system is not in use.

  4. The Correlated Color Temperature (CCT) in each room for similar fixtures is consistent (±200 K) at any point of time.

Lighting is designed by a lighting professional and takes into account the following considerations:

  1. Luminance ratios on vertical and horizontal adjacent zones.

  2. Illuminance uniformity on horizontal task planes.

  3. Changes in lighting characteristics, such as light levels, changes in color and distribution.

  4. Color temperature of lights used.

L08 Electric Light Quality

Enhance Color Rendering Quality (1 Point)



All luminaires in occupiable spaces (except decorative fixtures, emergency lights and other lighting for signage) meet at least one of the following color rendering requirements. If tunable white lighting is used, the requirements are met at 1,000K intervals from the lower end (with a minimum of 2,700K) to the higher end (with a maximum of 5,000k):

  1. CRI (Ra) ≥90.

  2. CRI (Ra) ≥ 80 with R9 ≥ 50.

  3. IES Rf ≥ 78, IES Rg ≥ 100, -1% ≤ IES Rcs,h1 ≤ 15%.



All luminaires (except decorative fixtures, emergency lights and other special-purpose lighting) meet at least one of the following color rendering requirements:

  1. CRI ≥ 80.

  2. IES Rf ≥ 75, IES Rg ≥ 95, -7% ≤ IES Rcs,h1 ≤ 15%


Manage Flicker (2 Points)

All luminaires (except decorative lights, emergency lights and other lighting for signage) and their controls within occupiable spaces meet at least one of the following requirements:

  1. Classified as “reduced flicker operation” per California Title 24, when tested according to the requirements in Joint Appendix JA-10.

  2. Recommended practices 1, 2 or 3 as defined by IEEE standard 1789-2015 LED.

  3. Pst LM ≤ 1.0 and SVM ≤ 0.6 for indoor applications per NEMA 77-2017 or Commission Regulation (EU) 2019/2020.

L09 Occupant Lighting Control

Enhance Occupant Controllability (Max: 2 Points)


Meet the following for all spaces:

Ambient lighting systems meet the following requirement:

  1. All regularly occupied spaces contain lighting zones as shown in the table below (note: individual rooms smaller than the areas below and/or that have occupancies less than those listed in the table are considered separate zones):

    Tier Number of Zones Number of Zones Points
    1 One per 650 ft2 OR One per 10 occupants 1
    2 One per 320 ft2 OR One per 5 occupants 2

Each lighting zone meets the following requirements:

  1. Lighting systems have at least three lighting levels or scenes that allow for changes in light levels

  2. ​​​​​​Lighting systems have the ability to change at least one of the following:

    1. Color.
    2. Color temperature.
    3. Distribution of light by controlling different groups of lights or through preset scenes.

  3. All regular occupants have control over their immediate lighting environment through at least one of the following:

    1. Manual controls (e.g. switches or control panels) located in the same space as each lighting zone.
    2. Digital interface available on a computer or phone.

  4. Lighting for presentation or projection walls are separately controlled.


Provide Supplemental Lighting (1 Point)


For All Spaces except Dwelling Units Meet the following:

The project meets the following requirements:

  1. Supplemental light fixtures (e.g., task lights) are provided upon request to all employees at no cost and requests are fulfilled within eight weeks.

  2. At least one supplemental light fixture is available for trial purposes.

Supplemental light fixtures that meet the following requirements:

  1. Light levels are controllable by occupants, independently from the ambient lighting system.

  2. The location of the light is adjustable by users of the workstation.

  3. Under intended use, the light-emitting element is not visible to users.

Visit the WELL website for more information.