Modern Building Services

20 MODERN BUILDING SERVICES APRIL 2021 LIGHTING FEATURE LIGHTING H uman Centric Lighting (HCL) is an increasingly common topic for discussion among facility executives. HCL has already been employed in facilities to increase occupant wellness bymaintaining their circadian rhythms and improve productivity by stimulating the natural cycle of melatonin and cortisol.While its adoption is currently limited tomore upscale facilities, lighting control technology is rapidly advancing with cost of ownership declining and will likely be attainable for most facilities by 2023. HCL encapsulates the lighting design tenets that aim to maximize the health and wellbeing of the building’s occupants. In practice this includes compliance with the guidelines for light level and quality, to avoid glare and flicker while maximizing colour rendition and often takes the design a step further by mimicking the natural day/night cycle to entrain the body’s circadian rhythm. Although no standard for circadian lighting is currently available through the American National Standards Institute (ANSI), International Electrotechnical Commission (IEC), or International Organization for Standardization (ISO), both Underwriters Laboratories (UL) and the International WELL Building Institute have published guidelines for day-active people. Pain and headache reports Considerations for healthy lighting should begin with the guidance that is easiest to implement, such as ensuring proper light levels and reducing the possibility of introducing lighting with non- visible flicker. Flicker is an often overlooked yet critical element to consider for any LED-based lighting design. High flicker rates, caused by the modulation of the AC power line, have been associated with headaches, eye strain and fatigue, and a study published in Current Pain and Headache Reports attributed visual triggers such as flicker to 38% of reported migraines. Advancements in electronic ballasts for fluorescent lamps drastically reduced the flicker that was associated with their magnetic ballast predecessors; however, many LED products inadvertently re- introduced these high flicker rates. A simple method for determining whether an LED lamp is designed to eliminate flicker is to look for UL- verified “Low Optical Flicker” LEDs, which are certified to produce less than 1% flicker. Taking lighting systems to the next level of wellness means incorporating dimming and colour-tuning to allow occupants to finetune their localized lighting tomeet their preferences and automated systems to entrain, or to get in sync with occupants’ circadian rhythms. According to Human-Centric Lighting: Foundational Considerations and a Five-Step Design Process, the non-visual benefits associated with a properly entrained circadian rhythm range from improvements in sleep quality to a healthier immune system. Numerous studies have demonstrated that these same benefits are amplified when HCL is employed in assisted living facilities and nursing homes. A study led by the Lighting Research Centre, titled Tailored lighting intervention improves measures of sleep, depression, and agitation in persons with Alzheimer’s disease and related dementia living in long-term care facilities, found that lighting designed to increase daytime circadian stimulation significantly improved night-time sleep efficiency, reduced nocturnal wandering, and alleviated evening agitation in patients with Alzheimer’s disease and related dementia. Circadian lighting, a subset of HCL, capitalizes on light’s role in numerous biological cycles. As the primary “zeitgeber” or “time giver” for the circadian system (the body’s internal clock), light helps align one’s body to the 24-hour sleep-wake cycle. This is achieved by altering the brightness and colour temperature of indoor lighting throughout the day to mirror the rising and setting of the Sun. Brighter light and higher or cooler colour temperatures suppress melatonin, keeping us alert and productive, while dimmer light and lower or warmer colour temperatures have the opposite effect and help induce states of relaxation. The research article Circadian Rhythm Disruption and Mental Health explains how circadian rhythm entrainment or disruption is intricately linked to mood and associated psychiatric disorders. The researchers also found that individuals suffering from disrupted circadian rhythms are at a higher risk for cardiovascular disease, certain cancers, and diabetes. Control system Fortunately, the only technologies necessary to mimic natural light indoors are dimming and colour tuning LEDs paired with a control system that allows for manual finetuning or automated light adjustments. Colour-tuning options are currently most prevalent with wireless systems, which are more than capable of meeting circadian lighting requirements. However, wireless systems often introduce their own issues with security and programming/use complications, so many facilities look to wireline or powerline communication protocols. Until recently, low- voltage and phase-cut controls were the only options available. While low-voltage dimming systems are highly efficient they don’t offer colour-tuning capabilities, and facilities without existing low-voltage wiring will bear the additional cost of running new wires. Phase-cut controls can similarly incur additional expenses by introducing noise to the line. Advancements in powerline control have enabled colour tuning and dimming via a simple retrofit of existing lighting systems, with no commissioning required. Instead of modulating the powerline, and Christopher Johnston , Director of Total Sustainability, Energy Focus, Inc. shares the impact lighting design has on health & wellbeing. Delivering Human-Centric Lighting to the Masses