Application of healthful lighting: Research progress and prospects

Abstract

Light is a key component for life on Earth. Lighting quality is thought to be one of the most important factors influencing people’s work and living conditions in building spaces. A complete standardization system has been established on the basis of comprehensive research concerning visual performance and comfort under lighting situations with traditional lighting technology; this has played an important role in guiding the proper design and application of lighting environments. In the past decades, science and technology related to lighting have advanced significantly in the following areas. (1) Technology has transformed lighting with the development of light emitting diodes (LEDs), which are now a practical source for general illumination. The unique properties of LEDs, such as their small size and availability in saturated colors ranging from red, green, and blue to different tones of white, offer tremendous new application possibilities. Because most existing quality measures for such applications are derived from research with and referring to the use of diffuse fluorescent lighting, there has been significant concern with respect to the feasibility of current measures for evaluating indoor lighting with LED lighting systems. (2) Vision and biological sciences have achieved a deepening knowledge of the complex relationship between light and health, adding both opportunities and responsibility to the work of those who design lighting systems, and have heightened public awareness with respect to how lighting affects our lives. Intrinsically photosensitive retinal ganglion cells (ipRGC) send light information via the retinohypothalamic tract (RHT) directly to the suprachiasmatic nucleus (SCN) of the hypothalamus and other targets in the brain; they have given lighting research and applications a brand-new connotation to provide the right light for the right person in the right place using the integration of LED lighting and smart lighting control technology to provide occupants with healthful lighting environments that provide safety, comfort, and human wellbeing. In this paper, on the basis of a systematic review of recent advances in the areas of lighting, and vision and the implications of healthful lighting, the following suggestions concerning research and the implementation of healthful lighting in China are given. (1) The widening application of LED technology and its connotations for healthful lighting, as well as the challenges faced by existing lighting quality measures, need to be studied. A healthful lighting evaluation system needs to be established with improved evaluation criteria for glare, color quality, and temporal light artifacts. In addition, a better understanding of the mechanisms of non-visual effects needs to be acquired in the areas of vision, neurophysiology, and psychology. (2) From the point of view of the dynamic characteristics of its intensity and spectrum, daylight is the optimal light source for healthful lighting. Therefore, the integration of daylighting technology, smart lighting control, and LED lighting will be the most effective method to realize this concept in real applications without resulting in high levels of energy consumption and discomfort associated with a fluctuating and nonuniform daylight distribution. (3) The core connotation of healthful lighting is its human-centric feature. Individuals differ widely in their visual capabilities and needs; this is not considered in current lighting recommendations, which have been developed on the basis of average results, usually for able-bodied young adults. Globally, with the increasing proportion of older people and people with visual impairments, the suitability of lighting recommendations based primarily on research with younger populations is being questioned. For healthful lighting, the development of suitable lighting technologies or design practices to assist diverse populations is necessary for healthful lighting applications.