Lighting is an essential element of our everyday life and one of the most important components of architectural design both in terms of atmosphere and quality of life. In conventional approach to an interior lighting plan, several people contribute to the final design and layout of the ceiling and lighting, from architects and interior designers who define aesthetic, mood and ceiling design to electricians and engineers who identify the appropriate amount of light, power and electrical circuits needed for the space. Throughout this whole process, focus is often on functionality, design and initial cost with no attention to energy consumption and the environmental and health effects of the lighting plan. In the conventional approach to lighting design, decisions and the type of lighting are very much influenced by functionality, time and cost of the project, factoring in only the first cost and not the life-cycle cost of the luminaries and the overall lighting system.
Sustainable lighting is part of the comprehensive sustainable and green building initiatives in an integrative process that takes into consideration the life-cycle assessment and life-cycle cost (LCC) of artificial lighting. The life-cycle approach includes the initial cost of purchase and installation but also the operation and maintenance cost as well as the environmental and health effects of the design over its life cycle and even during demolition.
In this article we want to bring forward the discussions and the recent interests of many builders and designers on sustainable and energy-efficient lighting and some of the practices recommended by LEED (U.S. Green Building Councill) to combat light pollution and light trespass.
LEED & Light Pollution
One of the LEED system credits for energy consumption and preservation is high efficiency lighting and a sustainable lighting plan to reduce light pollution. Light pollution is defined as excessive and misdirect artificial light with negative environmental effects such as interference with astronomical observations and research, disruption of ecosystems and energy waste. Light pollution has also been a big area of focus lately as it has adverse effects on our health and is sometimes linked to sleep disorder, depression, obesity, breast cancer and other negative health related issues. Controlling light pollution and light trespass has positive impacts on our environment but also saves energy and money in the long-run when looking at the LCC of design rather than the initial cost.
A good lighting plan in a high-performance green building addresses the amount of light that is needed to safely perform a task and yet reduces light pollution. The green lighting plan considers 3 forms of light pollution: off-light, glare and light trespass. Light trespass is the unwanted light where it's not needed. The truth is that most of traditional exterior lightings have been designed poorly and, in some cases, they are totally unnecessary, they are mostly unshielded which means light goes anywhere and everywhere and result in excessive energy consumption and higher operation and maintenance costs long-term.
Unshielded and no cut-off lights send out light in every direction into the sky and produce a lot of waste whereas the fully cutoff light fixtures are low-glare and help direct light down so they illuminate the project site rather than the surroundings and the sky.
Backlight Upplight Glare (BUG) method is a rating system specified by IES (Illuminating Engineering Society) which takes the back-light, up-light and glare measurements of lighting systems into account when measuring light trespass of a luminaire. Different light fixtures have different BUG ratings and the lower the BUG rating the lower the light trespass. considering the BUG system in the design phase of the lighting plan brings awareness to not only the amount of candle foot needed (and required) for a specific task/area but also how much trespass the lighting fixtures produce and how much they contribute to glare and light pollution of the interior and exterior design. When designing the lighting plan, evaluate both lighting the area on a horizontal plane as well as lighting the project area upward.
A great way to address light pollution is by limiting the use of artificial lights to when absolutely needed. Motion lighting systems and switches ensure artificial lighting is used only when there is traffic. Smart light switches like automatic light shut-offs are another great way to control light consumption and pollution especially for offices and commercial buildings and yet they save us money long-term when looking at life-cycle cost. Of course, there are other factors contributing to green lighting such as, among many other, the temperature and type of the lighting fixtures and the brightness level of the luminaries.
LEED & Interior Lighting Quality
One of the key components of interior design is the access to and quality of natural lighting which can contribute to positive health benefits, reducing light pollution and energy consumption and lowering energy costs. A sustainable interior lighting plan allows connection with the outdoor and utilizes the natural lighting in the best way possible which can result in significant savings in both energy consumption and energy cost. Natural lighting and blurring lines between interior and exterior impacts the space lighting quality but also air quality and has been linked to productivity and happiness, improving cognitive skills like learning and memorizing and better mood and energy especially in kids with autism. Also, the traditional lighting like compact fluorescent lights are high in bad chemicals like mercury and do not only contribute to climate change and energy waste but the toxins and chemicals released when generating electricity pollute the air and negatively impact the interior air quality and our health especially in children.
Of course, lighting plan goes hand in hand with the overall interior (and exterior) palette which includes colors, textures, materials and the type of paint. Choosing the right paint and colors for walls and floors of the space contributes to the green building and energy consumption and light pollution. Sustainable design goes beyond the functionality aspects of the design and brings to attention the social and economic attributions in all stages of design from planning to design and layout to construction, consumption and post-consumption life of products and materials.
Edited by Aidin Belganeh