Everything Lighting OEMs Need to Know About the WELL Building Standard

The WELL Building Standard was launched in late 2014 with the goal of prioritizing the health and wellness of building occupants. It is most easily described as LEED for healthy buildings.

Like LEED, WELL operates on a scoring system in multiple categories, including air, water, and light. Some features are preconditions for certification, while others are optimizations. Depending on the number of features that pass, a project can be certified as WELL Silver, Gold, or Platinum.

WELL is quickly becoming an unstoppable force. In summer 2017, just 2.5 years after launch, there were 100 million square feet of projects completed or in progress worldwide. As interest has grown in healthy environments, the next 100 million will undoubtedly come even more quickly.

The Light Concept

Light is one of the seven major concepts covered in the WELL Building Standard. The primary goals of the Light Concept are:

  • supporting healthy circadian rhythms
  • promoting visual acuity and safety
  • maximizing visual comfort

While much of the Light Concept is concerned with the lighting design of a space, including access to natural light, there is an opportunity for lighting and controls manufacturers to offer products that are ready for WELL projects.

UL recently launched Wellness Certification, a marker for product compatibility with the WELL Building Standard. For lighting and controls manufacturers, this could serve as a signal to lighting designers that your product can be included in a WELL project. Note that a compatible product can be included in a WELL project even without UL Wellness Certification.


In the following three sections, I break down some important WELL terms and concepts.

Precondition vs. Optimization

Some WELL features are preconditions, which means they are required for certain project types, no matter if the project is destined for WELL Silver, Gold, or Platinum.

For example, the Circadian Lighting Design feature, part 1 is a precondition for New and Existing Buildings and New and Existing Interiors. Preconditions are marked with a P on applicability matrices.

Applicability Matrix for the Circadian Lighting Design feature

Other features are optimizations. Optimizations are not required for WELL Silver. However, 40% of applicable optimizations are required for WELL Gold and 80% are required for WELL Platinum.

As an example, the Color Quality feature, part 1 is an optimization for all project types. Optimizations are marked with an O.

Applicability Matrix for Color Quality pilot programs

Pilot Programs and Features

The three primary project types defined by WELL are:

For the most part, only the first two project types are relevant to lighting and controls manufacturers.

There are additional pilot programs for commercial kitchens, retail environments, restaurants, educational facilities, and multifamily residential complexes.

Pilot programs may have pilot features or parts associated with them. For example, Light at Night is a pilot feature for multifamily residential projects. It is not currently relevant to any other programs.

Equivalent Melanopic Lux

Equivalent Melanopic Lux (EML) is a measurement of the effect of light on the human circadian rhythm. It is similar in concept to the more widely-used Circadian Stimulus metric, but computed in a different manner.

WELL uses EML as a metric to evaluate the circadian impact of both natural and artificial light. More specific details about EML can be found in Tables L1 and L2 on this page.


In the remainder of this article, I highlight specific aspects of WELL features that lighting and controls manufacturers should be aware of.

Visual Lighting Design (Controls)

Part 1 of the Visual Lighting Design feature governs light levels and control capabilities. This precondition requires that an ambient lighting system is zoned in independently controlled banks no larger than 500 ft² (46.5 m²) or 20% of the open floor area of a room, whichever is larger.

Part 1 (along with parts 5 and 6) also allows for dimming in the presence of daylight, although it is not required.

Circadian Lighting Design (Luminaires)

The Circadian Lighting Design feature defines EML values for different activity zones, including work areas, living environments, breakrooms, and learning areas. In general, light sources that provide high EML (125–250) in the lighting design are specified for daytime activities, while sources with low EML (<50) are preferred for nighttime activities.

Electric Light Glare Control (Luminaires)

The Electric Light Glare Control feature attempts to minimize glare emitted by artificial light sources. Part 1 covers shielding angles for luminaires. Lamps with luminance values of at least 20,000 cd/m² must be shielded. Specific requirements are outlined on this page.

Additionally, part 2 defines luminance values for luminaires above desks, workstations, and seating areas. Any luminaire located more than 53° above the center of view must have a luminance less than 8,000 cd/m².

Solar Glare Control (Controls)

The Solar Glare Control feature seeks to relieve fatigue and discomfort associated with glare from natural light. Parts 1 and 2 require shading for windows meeting certain conditions. Glare minimization strategies may include manual or automatic interior shading, exterior shading, or variable opacity glazing, among others.

Color Quality (Luminaires)

Unlike Title 24, WELL does not require 90 CRI light sources. The Color Quality feature is an optimization that calls for a minimum CRI (Ra) of 80 and minimum R9 of 50. Note that most 80 CRI sources do not achieve this R9 value.

CRI Color Palette. Image: Wikipedia

To understand why R9 is important, note that R1 through R8 (the colors used to calculate CRI Ra) are all pastel hues. R9 is a deep red color. A light source can have a high CRI (Ra) and emit very little red—something people find undesirable. Thus, R9 becomes a priority for the appearance of people and objects within a space.

Automated Shading and Dimming Controls (Controls)

The Automated Shading and Dimming Controls feature is an optimization that can ensure glare control and energy reduction. Part 1 calls for windows larger than 6 ft² (0.55 m²) to have shading devices that automatically engage when outside sunlight could cause glare.

Part 2 calls for general illumination to automatically dim to 20% or less (or switch off) when a space is unoccupied. In addition, the lighting must dim continuously in response to daylight.

Light at Night (Luminaires & Controls)

The Light at Night pilot feature, part 3 specifies safe nighttime navigation lighting for multifamily residential projects. This optimization specifies nightlights on the path between sleeping areas and the closest bathroom, as well as within bathrooms.

Nightlights must:

  • be located no higher than 14 inches from the ground to the center of the luminaire
  • be motion activated
  • have a manual on and manual off option
  • not emit wavelengths below 550 nm
  • not produce more than 15 lumens

Circadian Emulation (Luminaires & Controls)

The Circadian Emulation pilot feature attempts to mimic the daily changes in spectrum and intensity of the sun. This optimization is a pilot feature for multifamily residential projects.

Part 1 of this feature covers circadian lighting. In all bedrooms, bathrooms, and residential rooms with windows, the lighting system must be automated such that:

  • users are able to define a bedtime and wake time
  • between the wake time and 2 hours before bedtime, the lighting must provide at least 250 EML on average
  • between 2 hours before bedtime and bedtime, the lighting must provide 50 EML on average, or less

Part 2 covers dawn simulation. In all bedrooms, the lighting system or a lighting device must allow a settable wake time, and gradually increase from 0 to at least 250 EML over at least 15 minutes.


Next Steps

Now you should have an idea of what the WELL Building Standard asks of lighting and controls manufacturers. Many products may only require small modifications to be compatible with WELL’s various preconditions and optimizations.


I am very passionate about the human-centric lighting space and the boost provided by WELL.

I help companies create healthy lighting products. If you are considering strategy or product development in the human-centric space, visit my website greg.lighting or get in touch directly.


Note that the WELL Building Standard is subject to change at any time, and the information presented in this article may become out-of-date.