Applying measured spectral data for light sources has been a driver for Lark, first with skies (v1.0), then electric lights (v2.0), and now the sun (v3.0). Our research shows the color of the sun transitions from warmer spectrums at sunrise and sunset (e.g. orange, red) to cooler spectrums (e.g. blue) at its zenith, which can largely impact non-visual light stimulus. This cycle can be simulated with full-spectrum lighting in any indoor environment for improved health and wellbeing.

Another innovation in Lark v3.0 includes adding opsin 5 (neuropsin) to the toolkit; v1.0 was the first simulation tool to include opsin 4 (melanopsin) along with opsin 1 (photopsin). Neuropsin, which is sensitive to short-wavelength violet light, has been linked to human growth and metabolism. We simulated light received by a baby in the Newborn Intensive Care Unit (NICU) of Cincinnati Children’s new Critical Care Building as a test to understand the health impacts of different daylight and electric lighting options. We show through simulation that ZGF’s NICU design achieves adequate visual and non-visual illuminance for photopic, melanopic, and neuropic stimulus at the patient isolette with spectral light sources mimicking key wavelengths, including violet and blue light, across the visible spectrum found in sunlight and skylight.

Lark v3.0 allows for custom spectral power distributions for the sky, sun, electric lights, glazing, and finish materials. The workflow can be used by architects, lighting designers, manufacturers, researchers, and public health officials to test any configuration of daylight and electric lighting for any building type. Other Lark v3.0 features include:

• Calculate non-visual light stimulus for opsin 5 (neuropsin) in addition to opsin 4 (melanopsin)
• Accurately color the sun with measured spectra  
• More options to color the sky
• Improvements to how the visible spectrum is divided in to 3 and 9 channels
• Utilities building Radiance sky files and processing spectral data

This effort took two years gathering sky and sun spectra; improving sky and spectral data processing; coloring the sun with measured spectra; learning about emerging opsin biology with Cincinnati Children’s Hospital Medical Center (CCHMC) Drs. James Greenberg and Richard Lang; and integrating all of this data into a tool and paper presented at the International IBPSA 2023 Conference in Shanghai, China.

As part of ZGF’s ongoing partnership with the UW ARC program, each year we identify a research project that an architectural intern from the program finds of interest and joins our team for a year to complete the research in parallel with their university work. Our most recent interns, Bo Jung, M.Sc., and Zining Cheng, M.Sc., led by Dr. Mehlika Inanici, worked on the research and development of Lark v3.0.

Check out the YouTube tutorial here.

Acknowledgements

We’d like to thank Dr. James Greenberg and Dr. Richard Lang from Cincinnati Children’s Hospital Medical Center for providing information on neuropsin, human development, and metabolism; ZGF Partners Todd Stine and Victoria Nichols for their continued support of applied research in circadian lighting, daylight measurement at Gould Hall, and the Lark Spectral Lighting project; University of Washington College of Built Environments Dean Renée Cheng and ARC Program Manager Teri Thomson Randall for their leadership and support of the daylight spectral measurement at Gould Hall; Sara Cao at the Lang Lab for sharing research and scripts for daylight measurement. Additional thanks to Deborah Gumm, Julia Leitman, Kelly Chanopas, and Lahmi Kim at ZGF.

References

Lark v0.0.1-1.0:

Inanici M., Brennan M., and Clark E. “Spectral Daylighting Simulations: Computing Circadian Light.” International Building Performance Simulation Association (IBPSA) Conference, Hyderabad, India, 2015.

Copyright 2015-2022 University of Washington (Mehlika Inanici, Ph.D.) and ZGF Architects LLP < Lark Spectral Lighting v1.0.

Lark v2.0            

Gkaintatzi-Masouti M., Pierson C., Van Duijnhoven J., Andersen M., Aarts M. "A simulation tool for indoor lighting design considering ipRGC-induced responses." BuildSim Nordic Conference, Copenhagen, Denmark, 2022.

Copyright 2022 EPFL, Oregon State University (Clotilde Pierson, Ph.D.) and Eindhoven University of Technology (Myrta Gkaintatzi-Masouti, M.Sc.) < Lark Spectral Lighting v2.0.

With contributions from ZGF Architects LLP Ed Clark and Marty Brennan for the electric lighting simulation workflow and contributions from Priji Balakrishnan, Ph.D. and Alstan J. Jakubiec, Ph.D. for the implementation of the Perez sky model.

Lark v3.0

Jung B., Cheng Z., Brennan M., Inanici M. "Multispectral Lighting Simulation Approaches for Predicting Opsin-driven Metrics and their Application in a Neonatal Intensive Care Unit." IBPSA 2023 Conference, Shanghai, China, 2023.

Copyright 2023 University of Washington (Bo Jung, M.Sc., Mehlika Inanici, Ph.D., Zining Cheng, M.Sc.) and ZGF Architects LLP < Lark Spectral Lighting v3.0.