LIGHTING Avoid designing environments that are biologically impoverished.
Lorraine Calcott
Lorraine Calcott IEng FILP IALD CLD MSLL MCIBSE MBSS is an internationally recognised lighting consultant with nearly 40 years’ experience in architectural, exterior, and healthcare lighting design. She is one of only a few Certified Lighting Designers (CLD) worldwide and a Fellow of the Institution of Lighting Professionals. Lorraine serves on the IALD Health and Wellbeing Committee as well as the Regulatory Committee and co-authored the 2025 IALD White Paper on integrative lighting. Her work focuses on spectrally responsible lighting design, ecological impact mitigation, and the relationship between light, mitochondrial health, and long-term human wellbeing. She advises healthcare estates teams, corporate organisations, and design professionals on evolving lighting strategies that balance energy efficiency with biological responsibility.
Research is ongoing. Early adopters will likely gain reputational, economic, and operational advantages.
4. Work with competent professionals Lighting design is no longer purely aesthetic or electrical – it is biological. Engaging a lighting professional who understands
integrative lighting principles, CIE guidance, and mitochondrial research is not a luxury – it is due diligence. The IALD White Paper emphasises responsibility. Minimising potential harm should be the primary goal of lighting design. Healthcare estates teams routinely commission specialists for fire engineering, acoustics, and infection control. Lighting deserves similar scrutiny.
Are we at a tipping point? The lighting sector has already accepted that glare, flicker, and circadian disruption matter. Standards are evolving, and research continues. The next phase may be spectral completeness. If future longitudinal research confirms that long-term
exposure to spectrally narrow lighting environments contributes to accelerated cellular ageing or metabolic dysfunction, the question will not be whether we knew – it will be why we ignored early signals. Healthcare estates professionals are uniquely positioned. They influence environments where biological resilience matters most. This is not about reversing progress. It is about refining it.
Conclusion: beyond compliance Compliance is the minimum threshold. Healthcare environments should aim higher. Energy reduction and maintenance efficiency are vital, but so is human health. We cannot recreate the sun indoors, but we can avoid designing environments that are biologically impoverished. Just as the solution to scurvy was not complex once
understood, the solution to light deficiency may ultimately prove straightforward: n More daylight n Better spectral balance n Smarter design.
The science is advancing. Guidance from CIE and CEN is evolving. The professional community – including
54 Health Estate Journal April 2026
IALD – has begun to formalise integrative lighting principles. The conversation is no longer optional. Healthcare estates teams who begin reviewing their lighting strategies now through the lens of light nutrition and spectral responsibility will not only meet regulatory expectations – they may help shape the next generation of healthier buildings.
Bibliography n Brown, T.M. et al. (2022). Recommendations for daytime,
evening, and night-time indoor light exposure to best support physiology, sleep, and wakefulness in healthy adults. PLoS Biology, 20(3), e3001571.
n CIE (2018). CIE S 026:2018 – System for Metrology of Optical Radiation for ipRGC-Influenced Responses to Light. Vienna: International Commission on Illumination.
n CIE (2023). CIE TN 015:2023 – Recommendations for Daytime, Evening and Night-time Indoor Light Exposure. Vienna: International Commission on Illumination.
n DIN (2021). DIN/TS 67600:2021 – Complementary Criteria for Lighting Design with Regard to Non-Visual Effects of Light. Berlin: DIN.
n Gkika, A. et al. (2025). Lighting Design for Health, Wellbeing and Quality of Light – A Holistic Approach to Integrative Lighting. IALD European Regulatory Affairs Working Group.
n IALD White Paper. Lighting Design for Health, Wellbeing and Quality of Light – A Holistic Approach to Integrative Lighting.
https://www.itdoes.co.uk/wp-content/ uploads/2025/07/2025-IALD-Whitepaper-Lighting-Design- for-Health-We-1-2.pdf
n Jeffrey, G. et al. (2018). Near-infrared light improves mitochondrial function in ageing retinal cells. Journal of Cellular Physiology.
n Roddick, A. et al. (2024). Effects of near-infrared radiation in ambient lighting on cognitive performance, emotion, and heart rate variability. Neurobiology of Sleep and Circadian Rhythms.
n Schlangen, L.J.M. and Price, L.L.A. (2021). The lighting environment, its metrology, and non-visual responses. Frontiers in Neurology.
n Whelan, H.T. et al. (2001). Effect of LED irradiation on wound healing. Journal of Clinical Laser Medicine & Surgery.
n Zimmerman, S. and Nunn, A. Publications on photobiomodulation and mitochondrial function in systemic health contexts.
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