## 5 Conclusions  
We propose that illumination designers study real environments with commercial lights and evaluate the light from visual and nonvisual perspectives to determine a method to improve design feedback based on photometric parameters and in accordance with the current normative. Quantitative models have been proposed to evaluate light's nonvisual effects, resulting in confusing calculations, interpretations, inter-comparisons, and applications. It is important to develop a lighting design method that takes into account visual considerations according to current international standards and that can be easily interpreted and achieved independently of the nonvisual metric used. In this study, we define the parameter MAF, which is SPD-dependent and which facilitates the quantification and comparison of different metrics of circadian effects and visual appearance. These different circadian effects are discussed and contrasted using case studies to establish a pattern that lighting designers can follow in their illumination projects with commercial lights. Our paper introduces a simple protocol that should enable even novice designers to develop lighting projects using basic photopic and melanopic parameters with commercial luminaires and lamps. The proper method for light measurement is preferably based on the SPD of the light source. The described conditions and control systems are critical to estimate the effects and to construct robust optic models. To study the effect of light on health, a multidisciplinary approach is required. Light and illumination are based on illuminance and color appearance. The spectral action of the photoreceptors with their three cone types and rods and that of the ipRGCs are completely different. The melanopsin function and illuminance equivalent to D\({}_{65}\) considered by the CIE, the equal-energetic illuminant considered by WELL, and the CL\({}_{\text{A}}\) or CS parameters of Rea are widely accepted as methods for light measurements at the corneal level in laboratory studies, although Chartered Institution of Building Services Engineers (CIBSE) and the BRE Group concluded in a literature review that the existing recommendations in the WELL Building Standard and DIN SPEC 67600 should be treated with caution. However, a standard for the visual field and environmental illumination does not exist in terms of spectral resolution. The most important contributions of this study are summarized as follows:
* Simple equations are proposed to calculate circadian lighting from values of photopic illuminance. The relationships are EDI \(=\ 1.104\times\text{MAF}\times\text{E}_{\text{photopic}}\) and \(\text{EML}=1.218\times\text{MAF}\times\text{E}_{\text{photopic}}\) with \(\text{MAF}=\frac{\int_{-380}^{780}\text{SPD}(\lambda)\times\text{S}_{\text{mol }}(\lambda)\text{d}\lambda}{\int_{-380}^{780}\text{SPD}(\lambda)\times\text{V}( \lambda)\text{d}\lambda}\), which are calculated for a variety of lamps. The Rea proposal should be considered as it has previously been described. These equations can provide quick feedback for lighting manufacturers and designers regarding healthy circadian effects, and the correspondence between both metrics is easily determined. * An example of our method's application is provided using numerical simulation data obtained with DIAlux. Various lighting conditions are described, including different types of luminaire, various combinations of room surface reflectance, various orientations of the visual axis, and the observer's age. * Three ways are described to obtain the best photopic and melanopic illuminance levels in lighting projects:
* Substitute the simulated Ev value obtained with the illumination program to obtain the minimum allowed MAF, CL\({}_{\text{A}}\), and CS that can include LEDs in the luminaires. If the LEDs do not reach this value, other LEDs with a higher proportion must be selected. * Modify the design of the luminaire; another luminaire with a more extensive profile should be used if it contributes a higher E\({}_{\text{V}}\).