Supplementary Data, Figures and Calculations

Figure A. All the spectra that was considered for the model shown in figure 4. Melanopic Lux weighting function (black) and the Circadian Stimulus weighting functions (cool in blue and warm in gold). All spectra and weights are normalized.

Figure B. Spectra from figure A, broken down into Warm Spectra of 3500K and warmer for evaluation. These spectra were used to determine the vertical foot-candles required to meet the daytime criteria for the CS = 0.3 and the WELL criteria of 150 and 200 melanopic lux, utilizing the “warm” CS weighting function (yellow) as well as melanopic lux weighting function (black), respectively. All spectra and weights are normalized in this graph.

Figure C. Spectra from figure A, broken down into Cool Spectra from 4000K to 6500K. These spectra were used to determine the vertical foot-candles required to meet the daytime criteria for the CS = 0.3 and the WELL criteria of 150 and 200 melanopic lux, utilizing the “Cool” CS weighting function (blue) as well as melanopic lux weighting function (black), respectively. All spectra and weights are normalized in this graph.

Figure D. Illustration of the individual melanopic to photopic (M/P) ratio of the spectra shown in figure A. M/P ratio is similar to the Melanopic Ratio determined in figure 2. Individual data points are shown in blue and trend lines are shown here to demonstrate the effect of color rendering on M/P ratio.

Calculation Examples:

Equivalent Melanopic LuxUsing the calculators, I chose a 3500K spectrum, I’ve uploaded this and several other commonly found spectra in a calculator. That calculator can be found here

In this first example we will look how much vertical light you need to achieve the WELL standard criteria of 150 melanopic lux. It is a very simple equation shown here:

Melanopic lux=Photopic Lux×Melanopic Ratio

In order to determine melanopic lux, we need a melanopic ratio. We can get that from the calculator above. From figure E, we see a 3500K spectrum with a melanopic ratio of 0.83

Figure E. WELL calculator with a 3500K spectrum uploaded into it. This calculator with preloaded spectra can be found here

150 Melanopic lux example:

Base Equation: Melanopic lux=Photopic Lux×Melanopic Ratio

Plug and Chug target melanopic lux (150) and melanopic ratio (0.828):

150=Photopic Lux×0.828

Divide both sides by melanopic ratio (0.828) to solve for photopic lux:

1500.828

=Photopic Lux× 0.8280.828

Answer: 181=Photopic Lux

Convert to Foot-candles: 1 foot−candle=10.76 Lux

Answer in Foot-candles: 181 lux= 18110.76

foot−candles=16.8 foot−candles

Circadian Stimulus example:Using the LRC calculator, I upload the same 3500K spectra from the previous example onto the LRC’s online calculator. Here what you do is play with the lux in order to achieve a CS 0.3. See figure 3 for

details. This determines your vertical illuminance target.

Figure 3. LRC Circadian Stimulus Calculator with a 3500K Spectrum uploaded into it. Here there are two factors that I’ve boxed in red. The “input” is the amount of lux you have. The output is the CS value. In this image, the CS = 0.300 and the light level required to meet this criteria is 179 lux.

In this example from figure 3. We requite 179 lux in order to achieve a CS = 0.300. This should be your target in your design.

Converting to foot-candles:

179 lux= 17910.76

foot−candles=16.6 foot−candles