Standardizing Melanopic Effects of Ocular Light for Ecological Lighting Design of Nonresidential Buildings—An Overview of Current Legislation and Accompanying Scientific Studies

Round 1

Reviewer 1 Report

In this paper, the authors present a detailed technical as well as medical overview of the scope and background information on how the standard DIN/TS 5031-100 came to be. In general, I think it is worthy of publishing. Some points should be included within the manuscript in order to improve the publication.

• In section 2.2 the authors describe the current state regarding the lighting of workplaces in the European Union (France, Germany) and in the USA. It would be useful if the authors analyze the current state of other countries.
• The authors write that “The effect of light on the biological human body system is mainly related to the parameters light spectrum, light distribution, irradiance, and their temporal sequences.” (lines 366-367). The way that these parameters affect the biological human body system should be commented on and analyzed in detail.
• A conclusion section should be added. In the conclusions section, the authors should summarize the main points of their study. The authors should explain the contribution of their study in comparison to approaches of other researchers. In addition, in the conclusions section, the authors should refer to the advantages of their method. They should emphasize and analyze them in detail.
• I would like to see a little bit more discussion of the melanopic equivalent lux (line 749).
• In table 1, the authors give information about some research projects. There is a gap. There is no related research project between the years 2013 – 2021?
• The manuscript could be substantially improved by relying and citing more on recent literature about lighting, lighting control, and health such as the followings:

- Doulos, L.T., Tsangrassoulis, A., Madias, E.-N., Niavis, S., Kontadakis, A., Kontaxis, P.A., Kontargyri, V.T., Skalkou, K., Topalis, F., Manolis, E., Sinou, M., Zerefos, S., Examining the Impact of Daylighting and the Corresponding Lighting Controls to the Users of Office Buildings. Energies 2020, 13(15), 4024. https://doi.org/10.3390/en13154024

- Oluwapelumi Osibona, Bethlehem D. Solomon, Daniela Fecht, Lighting in the Home and Health: A Systematic Review. International Journal of Environmental Research and Public Health 2021, 18(2), 609. https://doi.org/10.3390/ijerph18020609

Author Response

In this paper, the authors present a detailed technical as well as medical overview of the scope and background information on how the standard DIN/TS 5031-100 came to be. In general, I think it is worthy of publishing. Some points should be included within the manuscript in order to improve the publication.

• In section 2.2 the authors describe the current state regarding the lighting of workplaces in the European Union (France, Germany) and in the USA. It would be useful if the authors analyze the current state of other countries.

Since not all standards and laws of the respective countries are available in English, the authors had to rely on the input of the Chambers of Commerce of the respective countries for the preparation of this publication. More than 10 chambers were requested to contribute by creating a report and several accepted. However, it was only possible to produce a comprehensive result for the countries documented in the publication, simply because most of the requested countries do not have structured rules regarding Human Centric Lighting. However, referring to this comment, I have now taken a position on the fact under point 2. (line 391 – 395)

 

• The authors write that “The effect of light on the biological human body system is mainly related to the parameters light spectrum, light distribution, irradiance, and their temporal sequences.” (lines 366-367). The way that these parameters affect the biological human body system should be commented on and analyzed in detail.

The health correlations of the measured variables with the human body (and which interfaces are responsible for this) were described in depth under point 1.1.2. But I agree with the comment. The sentence makes statements that need to be explained and referenced. On second thought, I find the sentence out of place at this position and have deleted it. I have further added a reference to chapter 1.1.2. (line 417)

• A conclusion section should be added. In the conclusions section, the authors should summarize the main points of their study. The authors should explain the contribution of their study in comparison to approaches of other researchers. In addition, in the conclusions section, the authors should refer to the advantages of their method. They should emphasize and analyze them in detail.

I have added a Conclusion. Suitable content already existed in the discussion and was moved. I added two more paragraphs to meet the requirements stated by the reviewer.

• I would like to see a little bit more discussion of the melanopic equivalent lux (line 749).

I have added the most essential information about EML (line 552 – 562). Since it is not considered in DIN/TS 5031-100, it does not play a major role in this publication.

• In table 1, the authors give information about some research projects. There is a gap. There is no related research project between the years 2013 – 2021?

More recent studies were added to the table. They have not been added in the first place, as they are not cited in the standard and did not contribute to it.

• The manuscript could be substantially improved by relying and citing more on recent literature about lighting, lighting control, and health such as the followings:

- Doulos, L.T., Tsangrassoulis, A., Madias, E.-N., Niavis, S., Kontadakis, A., Kontaxis, P.A., Kontargyri, V.T., Skalkou, K., Topalis, F., Manolis, E., Sinou, M., Zerefos, S., Examining the Impact of Daylighting and the Corresponding Lighting Controls to the Users of Office Buildings. Energies 2020, 13(15), 4024. https://doi.org/10.3390/en13154024

- Oluwapelumi Osibona, Bethlehem D. Solomon, Daniela Fecht, Lighting in the Home and Health: A Systematic Review. International Journal of Environmental Research and Public Health 2021, 18(2), 609. https://doi.org/10.3390/ijerph18020609

Lighting control is definitely relevant to user health, but constitutes a separate engineering discipline. The paper is already very long and is intended to deal extensively with the melanopic effect. The current occasion of the review is the publication of the described DIN standard, in which lighting control plays no role. Oluwapelumi has written a literature review for light in living spaces. The title of our publication excludes residential buildings. Nonetheless, I have incorporated the suggested sources (line 407, line 366).

 

Author Response File: Author Response.pdf

Reviewer 2 Report

Overall, it is a well-written review paper, with a good effort in summarizing the melanopic metrology and the issues in standardization. However, the circadian literature review and critical discussion could be more in-depth, especially for a review paper. The authors should refer to CIE S 026/E:2018 (rather than 2015) and discuss the limitations of melanopic metrics. Melanopic (or “circadian”) metrics are only a proxy of NIF effects of light – and not a very good one–, while there are several other mechanisms that might affects alertness, sleep quality etc. Therefore, standardizing half-baked metrics is not beneficial to occupants, and might hurt energy conservation and visual comfort. The authors have mentioned some of these discussions. In the USA, the building certification institutions (WELL, UL) are recommending the use of circadian metrics that are not independently proven to estimate NIF effects of light on occupants. The big takeaway of this paper should be the necessity of further investigation without enforcing understudied metrics. While researchers are free to propose, test, and validate metrics, care must be taken when adopting these metrics to guidelines and standards.

 

A key part of the discussion related to standards is the choice of circadian metrics. While WELL adopted Lucas and colleagues’ earlier equivalent melanopic lux (EML) as a metric in their standard, Lucas et al. and other eminent circadian researchers published the CIE document (2018) advising the use of circadian measures based on SI units (rather than their early proposal EML). There might be a case for standardization to improve lighting in architectural spaces, while researchers continue to propose/improve circadian metrics. Therefore, it is vital to test the performance of these metrics and compare them. Authors can refer to some of the studies that compare difference circadian measures (e.g., EML, melanopic irradiance, m-EDI, CS, M/P):

• Lowry, G. D. (2018). A comparison of metrics proposed for circadian lighting and the criterion adopted in the WELL Building Standard. In CIBSE Technical Symposium, Stretching the Envelope. CIBSE.
• Bodrogi, P., Vinh, Q. T., & Khanh, T. Q. (2019). Correlations among lighting quality metrics for interior lighting. Lighting Research & Technology, 51(8), 1192-1207.
• Durmus, D. (2021). Multi-objective optimization trade-offs for color rendition, energy efficiency, and circadian metrics. In Light-Emitting Devices, Materials, and Applications XXV (Vol. 11706, p. 117061J). International Society for Optics and Photonics.
• Busatto, N., Dalla Mora, T., Peron, F., & Romagnoni, P. (2020). Application of Different Circadian Lighting Metrics in a Health Residence. Journal of Daylighting, 7(1), 13-24.

 

It is obvious that circadian photometry is a wild-west right now. It is important to keep readers up-to-date with the most recent scientific findings. The authors should refer to the recent review papers:

• Zeitzer, J. M. (2018). When is a proxy not a proxy? The foibles of studying non‐image forming light. The Journal of physiology, 596(11), 2029.
• Spitschan, M. (2019). Melanopsin contributions to non-visual and visual function. Current opinion in behavioral sciences, 30, 67-72.
• Vetter, C., Pattison, P. M., Houser, K., Herf, M., Phillips, A. J., Wright, K. P., ... & Glickman, G. (2021). A Review of Human Physiological Responses to Light: Implications for the Development of Integrative Lighting Solutions. LEUKOS, 1-28.
• Schlangen, L. J., & Price, L. L. (2021). The Lighting Environment, Its Metrology, and Non-visual Responses. Frontiers in Neurology, 12, 235.
• Tähkämö, L., Partonen, T., & Pesonen, A. K. (2019). Systematic review of light exposure impact on human circadian rhythm. Chronobiology international, 36(2), 151-170.
• Safranek, S., Collier, J. M., Wilkerson, A., & Davis, R. G. (2020). Energy impact of human health and wellness lighting recommendations for office and classroom applications. Energy and Buildings, 226, 110365.
• Rossi, M. (2019). Conclusions and possible guidelines for circadian lighting design. In Circadian Lighting Design in the LED Era (pp. 257-277). Springer, Cham.
• Vetter, C. (2020). Circadian disruption: What do we actually mean?. European Journal of Neuroscience, 51(1), 531-550.
• Houser, K. W., Boyce, P. R., Zeitzer, J. M., & Herf, M. (2020). Human-centric lighting: Myth, magic or metaphor?. Lighting Research & Technology, 1477153520958448.

 

Authors can also improve the paper further by referring to another important limitation of the circadian metrics: the lack of environmental considerations, which affect the stimulus at the eye. The spectral reflectance of walls and other surfaces are known to change the circadian metrics that reach the eye, but current metrics do not take these into account:

• Cai, W., Yue, J., Dai, Q., Hao, L., Lin, Y., Shi, W., ... & Wei, M. (2018). The impact of room surface reflectance on corneal illuminance and rule-of-thumb equations for circadian lighting design. Building and Environment, 141, 288-297.
• Durmus, D. (2019). Impact of Surface Reflectance on Spectral Optimization for Melanopic Illuminance and Energy Efficiency. In Optical Devices and Materials for Solar Energy and Solid-state Lighting (pp. PT2C-5). Optical Society of America.
• Bellia, L., Pedace, A., & Barbato, G. (2014). Indoor artificial lighting: Prediction of the circadian effects of different spectral power distributions. Lighting Research & Technology, 46(6), 650-660.

The manuscript seems to abruptly cut off. A final “Conclusions” chapter would improve the paper, by wrapping up the discussion and reiterating the major points of the article.

 

Minor comments:

• Using facts as subheading is pretty strange. While “engineering facts” and “medical facts” are true to our limited knowledge, they might certainly change in the future depending on results of research studies.
• Figure 1 and 3 axes labels are missing.
• Traditionally, CCT values do not require comma (e.g., 5000 K).
• The authors should avoid random capitalizations. Only proper nouns are capitalized (e.g., circadian stimulus instead of “Circadian Stimulus”).
• The statistics on lone 36 (419.9 hr per third quarter) is a little awkward. A more relatable stat would be hr per day or hr per week.
• Human centric lighting is not a technical term. It is mostly used by lighting manufacturers to sell products.
• Units are not capitalized when spelled out, even though they might be proper names (with the exception of Celsius). For example, it is either 3000 K, or 3000 kelvin.
• Correction in sentences 175-176. It should be: illuminance (unit: lux) instead of "illuminance (lux)" and the same for luminance.

Author Response

Overall, it is a well-written review paper, with a good effort in summarizing the melanopic metrology and the issues in standardization. However, the circadian literature review and critical discussion could be more in-depth, especially for a review paper. The authors should refer to CIE S 026/E:2018 (rather than 2015) and discuss the limitations of melanopic metrics. Melanopic (or “circadian”) metrics are only a proxy of NIF effects of light – and not a very good one–, while there are several other mechanisms that might affects alertness, sleep quality etc. Therefore, standardizing half-baked metrics is not beneficial to occupants, and might hurt energy conservation and visual comfort. The authors have mentioned some of these discussions. In the USA, the building certification institutions (WELL, UL) are recommending the use of circadian metrics that are not independently proven to estimate NIF effects of light on occupants. The big takeaway of this paper should be the necessity of further investigation without enforcing understudied metrics. While researchers are free to propose, test, and validate metrics, care must be taken when adopting these metrics to guidelines and standards.

The discussion chapter was extended and more critical content was added. CIE S 026 citation was updated in the new version of the manuscript. Limitation of metrics were discussed in the discussion section.

A key part of the discussion related to standards is the choice of circadian metrics. While WELL adopted Lucas and colleagues’ earlier equivalent melanopic lux (EML) as a metric in their standard, Lucas et al. and other eminent circadian researchers published the CIE document (2018) advising the use of circadian measures based on SI units (rather than their early proposal EML). There might be a case for standardization to improve lighting in architectural spaces, while researchers continue to propose/improve circadian metrics. Therefore, it is vital to test the performance of these metrics and compare them. Authors can refer to some of the studies that compare difference circadian measures (e.g., EML, melanopic irradiance, m-EDI, CS, M/P):

• Lowry, G. D. (2018). A comparison of metrics proposed for circadian lighting and the criterion adopted in the WELL Building Standard. In CIBSE Technical Symposium, Stretching the Envelope. CIBSE.
• Bodrogi, P., Vinh, Q. T., & Khanh, T. Q. (2019). Correlations among lighting quality metrics for interior lighting. Lighting Research & Technology, 51(8), 1192-1207.
• Durmus, D. (2021). Multi-objective optimization trade-offs for color rendition, energy efficiency, and circadian metrics. In Light-Emitting Devices, Materials, and Applications XXV (Vol. 11706, p. 117061J). International Society for Optics and Photonics.
• Busatto, N., Dalla Mora, T., Peron, F., & Romagnoni, P. (2020). Application of Different Circadian Lighting Metrics in a Health Residence. Journal of Daylighting, 7(1), 13-24.

A paragraph about melanopic lux and equivalent melanopic lux was added and the differences between these measurement methods were taken into account. I added three out of four of these citations. As EML is not part of DIN/TS 5031-100 it was not addressed in detail in the first place (line 554 – 564).

It is obvious that circadian photometry is a wild-west right now. It is important to keep readers up-to-date with the most recent scientific findings. The authors should refer to the recent review papers:

• Zeitzer, J. M. (2018). When is a proxy not a proxy? The foibles of studying non‐image forming light. The Journal of physiology, 596(11), 2029.
• Spitschan, M. (2019). Melanopsin contributions to non-visual and visual function. Current opinion in behavioral sciences, 30, 67-72.
• Vetter, C., Pattison, P. M., Houser, K., Herf, M., Phillips, A. J., Wright, K. P., ... & Glickman, G. (2021). A Review of Human Physiological Responses to Light: Implications for the Development of Integrative Lighting Solutions. LEUKOS, 1-28.
• Schlangen, L. J., & Price, L. L. (2021). The Lighting Environment, Its Metrology, and Non-visual Responses. Frontiers in Neurology, 12, 235.
• Tähkämö, L., Partonen, T., & Pesonen, A. K. (2019). Systematic review of light exposure impact on human circadian rhythm. Chronobiology international, 36(2), 151-170.
• Safranek, S., Collier, J. M., Wilkerson, A., & Davis, R. G. (2020). Energy impact of human health and wellness lighting recommendations for office and classroom applications. Energy and Buildings, 226, 110365.
• Rossi, M. (2019). Conclusions and possible guidelines for circadian lighting design. In Circadian Lighting Design in the LED Era (pp. 257-277). Springer, Cham.
• Vetter, C. (2020). Circadian disruption: What do we actually mean?. European Journal of Neuroscience, 51(1), 531-550.
• Houser, K. W., Boyce, P. R., Zeitzer, J. M., & Herf, M. (2020). Human-centric lighting: Myth, magic or metaphor?. Lighting Research & Technology, 1477153520958448.

The papers were implemented as follows: Vetter, Houser, Tähkämö (line 375), Rossi (line 925), Schlangen (line 83), Vetter (line 70), Safranek (line 404). Thank you very much for sharing.

Authors can also improve the paper further by referring to another important limitation of the circadian metrics: the lack of environmental considerations, which affect the stimulus at the eye. The spectral reflectance of walls and other surfaces are known to change the circadian metrics that reach the eye, but current metrics do not take these into account:

• Cai, W., Yue, J., Dai, Q., Hao, L., Lin, Y., Shi, W., ... & Wei, M. (2018). The impact of room surface reflectance on corneal illuminance and rule-of-thumb equations for circadian lighting design. Building and Environment, 141, 288-297.
• Durmus, D. (2019). Impact of Surface Reflectance on Spectral Optimization for Melanopic Illuminance and Energy Efficiency. In Optical Devices and Materials for Solar Energy and Solid-state Lighting (pp. PT2C-5). Optical Society of America.
• Bellia, L., Pedace, A., & Barbato, G. (2014). Indoor artificial lighting: Prediction of the circadian effects of different spectral power distributions. Lighting Research & Technology, 46(6), 650-660.

This is a very good input for the discussion section. I added a paragraph about it and included two of these citations (line 904 -925)

The manuscript seems to abruptly cut off. A final “Conclusions” chapter would improve the paper, by wrapping up the discussion and reiterating the major points of the article.

A conclusion section was added to the document.

Minor comments:

• Using facts as subheading is pretty strange. While “engineering facts” and “medical facts” are true to our limited knowledge, they might certainly change in the future depending on results of research studies.

I changed it to “contexts”

• Figure 1 and 3 axes labels are missing.

The figures have been updated.

• Traditionally, CCT values do not require comma (e.g., 5000 K).

The commas for Kelvin values have been removed.

• The authors should avoid random capitalizations. Only proper nouns are capitalized (e.g., circadian stimulus instead of “Circadian Stimulus”).

I checked the document, but I did not find many. Please, if you spot such a mistake, feel free to tell me.

• The statistics on lone 36 (419.9 hr per third quarter) is a little awkward. A more relatable stat would be hr per day or hr per week.

A more familiar expression has been added (line 37).

• Human centric lighting is not a technical term. It is mostly used by lighting manufacturers to sell products.

The term was changed whenever necessary. I added the word marketing (line 56) and I changed it to biologically effective (line 603)

• Units are not capitalized when spelled out, even though they might be proper names (with the exception of Celsius). For example, it is either 3000 K, or 3000 kelvin.

Thank you. Since it is also a name, I was not aware.

• Correction in sentences 175-176. It should be: illuminance (unit: lux) instead of "illuminance (lux)" and the same for luminance.

 Changed as suggested

Author Response File: Author Response.pdf

Reviewer 3 Report

The article presents a detailed technical and medical overview of the new standard DIN/TS 5031-100.

The authors use a state of the art on projects about ecological lighting design of the past 20 years in order to put in evidence the sustainable lighting design as an interdisciplinary matter: engineering design, medicine and architecture.

Taking into account that this is a Review Paper I am very pleased of the amount of study that the authors presented in the paper.

I was very happy, as an engineer, to see the comments, discussions, debates, that the authors presented in their Review Paper. 

Maybe a short paragraph could be introduced in the 1.1.1.  Engineering facts, regarding the HCL in Airports.

The paper is a significant contribution to the field.

Congratulation

Author Response

The article presents a detailed technical and medical overview of the new standard DIN/TS 5031-100.

The authors use a state of the art on projects about ecological lighting design of the past 20 years in order to put in evidence the sustainable lighting design as an interdisciplinary matter: engineering design, medicine and architecture.

Taking into account that this is a Review Paper I am very pleased of the amount of study that the authors presented in the paper.

I was very happy, as an engineer, to see the comments, discussions, debates, that the authors presented in their Review Paper. 

Maybe a short paragraph could be introduced in the 1.1.1.  Engineering facts, regarding the HCL in Airports.

Thank you so much for the kind words. I added a paragraph about the special needs of the environment “airport” (line 232 – 246)

The paper is a significant contribution to the field.

Congratulation

 

Author Response File: Author Response.pdf

Round 2

Reviewer 2 Report

Thank you for the changes and improving your paper.

A small note: random capitalization of non-proper nouns include "Design of Experiment," "Human Centric Lighting."

This manuscript is a resubmission of an earlier submission. The following is a list of the peer review reports and author responses from that submission.