Auto-tuning Daylight with LEDs: Sustainable Lighting for Health and Wellbeing

While human life expectancy may be increasing due to advances in public health, technology and medicine, there are serious questions as to whether the quality of human life can keep up with this increase in longevity. Postindustrial society is experiencing a proliferation of light-related disorders and diseases specifically because our technologically-based society can operate 24 hours per day in illuminated indoor environments. Furthermore, illuminating interiors with electric lighting poses a dual dilemma: the energy efficiency of electric light versus natural daylight together with the impact of light itself on human health and wellbeing. This paper investigates sustainable design at the nexus of health, energy and technology by considering relationships between light and human health. By discussing the physiological effects of light on the body, the need for natural daylight in the human environment for improved cognitive functioning will be demonstrated. Because people spend a large portion of their time indoors, especially the elderly, unless a room is oriented to maximize light from the sun, it is necessary to illuminate the interior environment using electric light sources. However, artificially illuminating the indoors poses a sustainability issue because electric lighting is one of the largest contributors to energy consumption by buildings in the United States. Designing for older adults in health care environments, especially the elderly with age-related fragility, declining cognitive functioning and symptoms of dementia, is a particularly significant design challenge and one in which lighting can play a crucial role. To address both issues of health and sustainability, an energy-conserving diurnal daylight-matching LED luminaire is being developed to improve health outcomes for the elderly at St. Francis Country House near Philadelphia, Pennsylvania.