LED Lighting Design Case Study: Using MK350S Premium to Meet WELL Certification Standards for Healthier Indoor Spaces

Step 1 — Understand the Environment First

Good lighting design begins before any fixture is selected. The first step is collecting and classifying the environmental data for the target space: what kind of activity happens there, who occupies it, and at what times of day?

Light source selection must account for three core parameters:

• Optical frequency: particularly high-frequency driving behavior and flicker risk
• Spectrum: including brightness, chromaticity, and radiant power
• Light distribution: near-field and far-field distribution characteristics

Different commercial and residential scenarios have significantly different requirements for color temperature and illuminance density. In commercial settings such as retail, offices, restaurants, and galleries, the lighting needs to serve both functional and atmospheric roles simultaneously.

In residential environments, the variation is equally significant. Living rooms, bedrooms, kitchens, and dining areas each call for different illumination angles and intensities to match the activity and the time of day.

Commercial lighting requirements by product category — mapped across color temperature and illumination density

Understanding these environment-specific requirements is the foundation. The WELL Building Standard builds on this foundation by adding a layer of scientific rigor — translating “good lighting” from a subjective judgment into a set of measurable, verifiable criteria.

Step 2 — WELL Certification: A Scientific Framework for Lighting

The WELL Building Standard addresses ten dimensions of indoor environment quality, including air, water, nourishment, thermal comfort, and — critically for lighting designers —light. For this case study, we focus on the two most directly relevant to LED lighting design and measurement:

• L03 — Circadian Lighting Design
• L08 — Electric Light Quality

These two chapters translate the three-layered human experience of light — visual, psychological, and physiological — into specific, testable requirements.

Step 3 — Designing for the Whole Person: Visual, Psychological, and Physiological Needs

Professional lighting design must serve occupants at three levels simultaneously. WELL certification provides the criteria for each.

WELL’s level of certification

Visual Experience — Color Rendering Quality (WELL L08)

Humans evolved under sunlight, and our visual system is calibrated to it. When artificial light renders colors poorly, it impairs spatial perception and makes it harder to accurately distinguish objects and surfaces. WELL Chapter L08 addresses this through requirements for Color Rendering Index (CRI) and the more comprehensive IES TM-30 metrics (Rf for fidelity, Rg for gamut).

The MK350S Premium measures both CRI and TM-30 directly in the field, giving lighting designers the data they need to confirm that specified luminaires meet WELL’s color rendering thresholds before a project is submitted for certification.

The MK350S Premium’s TM-30 mode displays Rf (color fidelity) and Rg (color gamut) readings on-site.

Psychological Experience — Color Temperature and Atmosphere

Color temperature profoundly shapes how people feel in a space. Warmer tones (2700–3000K) create a relaxing, intimate atmosphere suited to residential bedrooms or restaurant dining rooms. Cooler tones (4000–6500K) support focus and alertness, making them appropriate for workstations and task-oriented areas.

Comparison of light quality on living room comfort

But color temperature alone is not enough. WELL L03 adds a further requirement: that the light selected must also support the body’s natural circadian rhythm — which means considering not just how light looks, but how it acts on the human biological clock.

Physiological Experience — Circadian Rhythm and Flicker (WELL L03 + L08)

This is where WELL certification moves furthest beyond conventional lighting practice.

Circadian Lighting (L03 — Melanopic EDI)

Humans evolved with a natural light-dark cycle that regulates sleep, hormone secretion, metabolism, and mood. Prolonged exposure to indoor artificial lighting — which typically lacks the spectral and intensity characteristics of natural daylight — disrupts this cycle. Circadian rhythm disruption has been linked to obesity, diabetes, depression, breast cancer risk, and sleep disorders.

WELL L03 addresses this through Melanopic Equivalent Daylight Illuminance (melanopic EDI), a metric that quantifies how effectively a light source stimulates the intrinsically photosensitive retinal ganglion cells (ipRGCs) — the cells in the eye that drive the physiological clock.

Unlike traditional photopic lux, which measures light as the visual system perceives it, melanopic EDI measures the light that regulates the body’s circadian system. The two are different because the ipRGCs have a distinct spectral sensitivity, with peak response around490nm (blue-cyan range).

WELL L03 specifies:

• Tier 1: ≥ 136 melanopic EDI at workstations during daytime hours
• Tier 2: ≥ 250 melanopic EDI at workstations during daytime hours

WELL’s light levels

The MK350S Premium measures MEL Daylight Lux (equivalent to melanopic EDI) directly, and can also output EML (Equivalent Melanopic Lux) data, which can be converted using the standard relationship established by the WELL Building Standard.

The MK350S Premium displays MEL Daylight Lux (equivalent to melanopic EDI) directly on its screen.

Flicker Management (L08 — SVM and PstLM)

Artificial lighting frequently contains low-frequency flicker that is absent in natural daylight. Even flicker that is not consciously visible can cause eye strain, headaches, migraines, and — insensitive individuals — seizures. WELL L08 includes specific flicker requirements measured using SVM (Stroboscopic Visibility Measure) and PstLM (short-term flicker perceptibility).

The MK350S Premium includes a dedicated Flicker mode that measures both SVM and additional flicker metrics. When connected to the UPRtek uFlicker PC software, both SVM and PstLM readings can be viewed simultaneously — giving designers the complete picture required for WELL L08 compliance verification.

Connecting the MK350S Premium to the uFlicker PC software provides simultaneous SVM andPstLM readings for complete WELL flicker compliance verification.

Step 4 — On-Site Verification with the MK350S Premium

Specifying WELL-compliant luminaires based on manufacturer datasheets is a starting point — but not a guarantee. Actual installation conditions such as fixture positioning, dimming levels, room surface reflectance, and luminaire aging all affect the real-world light environment. WELL certification requires verified on-site measurement data to confirm that the installed system truly performs to standard.

The MK350S Premium is a field-ready handheld spectrometer designed for exactly this purpose. In a single device, it consolidates the measurements required to verify compliance with the key WELL lighting chapters:

This consolidation matters in practice. Rather than requiring multiple separate instruments for a WELL audit, lighting designers and commissioning engineers can carry a single portable device and move efficiently between measurement points throughout a building.

 Summary

Creating a healthy indoor light environment requires more than selecting the right color temperature or hitting a target lux level. It requires understanding the full range of human responses to light — visual, psychological, and physiological — and designing to meet quantified criteria for each.

The WELL Building Standard provides that scientific framework. The MK350S Premium provides the on-site measurement capability to verify it.

Together, they give lighting designers the foundation to move beyond “looks good” toward environments where the light genuinely supports the health and well-being of every person who works, learns, rests, or lives within them.