Luminaire life cycle
Sustainability rests on conservation and design quality
Energy efficiency and flexibility is achieved by lighting the open office area to a lower ambient light level and providing mobile-arm adjustable task lights at each desk to augment visual task illumination.
by Maninder K. Dhaliwal.
Sustainability can be defined as an attempt to provide the best outcomes for the human and natural environments, both now and into the indefinite future.
In order to study the total environmental impact of a product, life cycle assessment [LCA] is considered a standard method. It provides a way for identifying and evaluating the environmental effects associated with the life cycle of materials and services from “cradle-to-grave” or preferably, “cradle-to-cradle”. The luminaire life cycle includes multiple stages, beginning with extraction of raw materials and includes material processing, equipment and component production, transportation, use, maintenance and disposal.
For the stages of production and disposal the important factor the lighting professional should be aware of is the toxic impacts of luminaires. Mercury is an essential element in arc-tube chemistry in fluorescent and high intensity discharge sources. Figure 2.
Today, there are no known energy efficient substitutes for mercury in fluorescent lamps. However, exposure to mercury is understood to have severe neurological, renal, cardiovascular and immunological impacts on humans.
Environmental impact of mercury from the lamps is defined by a protocol called TCLP [Toxicity Characteristic Leaching Procedure]. It is a protocol of test methods used to characterize waste as either hazardous or non-hazardous for the purpose of disposal. Lamps with low mercury pass the TCLP test and can be safely disposed of as non-hazardous waste. All major lamp manufacturers produce low-mercury fluorescent lamps that are TCLP compliant, at little or no added cost. Even so, increased lamp recycling is recommended for TCLP-compliant products.
In the design profession, the use phase of the luminaire life cycle is of dominant interest - most importantly the lighting quality and energy consumption during life of the luminaire. In fact, sustainability for lighting has long been synonymous with energy efficiency. Figure 3.
Lighting accounts for approximately one-third of energy use in an average commercial building. Also, every 3.5 Kilowatts of energy used for lighting produces enough heat to require one ton of cooling by the mechanical system. Lighting energy consumption can be reduced by use of high efficiency lamps, electronic ballasts, and automated lighting controls such as occupancy sensors.
A lighting design strategy that integrates daylighting to minimize the dependence on electric lighting can also produce tremendous savings over typical lighting systems. New technologies such as T5 and T5HO fluorescents, high-colour rendering ceramic metal halides, dimming ballasts, and daylight dimming systems can provide even more savings.
No single organization has had more impact on the sustainable design industry in North America than the U.S. Green Building Council’s LEED (Leadership in Energy and Environmental Design) rating system. LEED has, for the first time, given the construction industry a workable and comprehensive tool for evaluating the “sustainability” of the construction, operation and maintenance of the built environment. Energy savings offer the most credits of any LEED category. Since lighting accounts for a large portion of the energy use of a typical building, energy effective lighting can contribute directly toward LEED certification.
Another important, but often ignored, aspect of sustainable lighting design is the quality of lighting design. Lighting supports the architectural vision, complements form, creates visual hierarchies, directs the eye, transforms spaces, provides drama, assists way-finding, and creates the ambiance. Good quality lighting also enables people to read, locate, identify, navigate, and otherwise perform well in their environment. Lighting enables us to interact with each other and the world around us. Figure 4.
Employers recognize that employees are their most costly and most valuable assets, therefore, human safety, comfort, and productivity issues are of great importance. The quality of the lighted environment greatly affects these issues. Hence, it makes business sense to design lighted environments that maximize the potential of the human assets. This can be achieved by providing illuminance conditions that enable the visual mechanism to perform better and nature the psychological needs by providing harmonious aesthetic places to work.
Part of the difficulty in separating poor quality from good quality lighting is that the human visual system is highly adaptable. Humans can put up with poor conditions for fairly long periods of time, but we can’t thrive under them. For example, it is possible to read a novel by moonlight, but to read under such a low light level will, over time, cause eye strain and fatigue. Another example is an open office area with light interior finishes lighted evenly by totally indirect pendants without any visual brightness or contrast. Although the quality of the lighting for reading and working is very good, the psychological impact of lack of sparkle and visual hierarchy will be un-stimulating, as with a perpetually overcast day.
Stantec’s Vancouver office incorporates many sustainable lighting design principles. As in most offices, the 55,000 sq.ft. LEED-Silver space must accommodate different forms of communication - written, visual, telephone, computer and face-to-face. The design concept was to provide a sustainable lighting solution for multiple visual tasks, and a stimulating working environment to enhance feelings of well-being, interest and enthusiasm.
The open plan office is illuminated to low ambient illumination levels that helped to achieve lighting power density of 30% below ASHRAE 1999. The mobile-arm adjustable task lights at each desk augment visual task illumination. This use of separate luminaire for task illumination gives workers a sense of place at a workstation in an otherwise open office.
Lighting is controlled by multiple control zones and perimeter zones can be shut-off in response to abundant daylight. A main building programmable timer automatically turns off all lights during non-business hours. Luminaires in all enclosed rooms - offices, copy rooms, washrooms, meeting rooms etc. are equipped with smart PIR occupancy sensors with user override capability. Conference rooms are provided with multiple control zones for varied visual tasks and dimming for daylight influx.
Standardization of lamp types to three [low mercury, TCLP-compliant linear fluorescent; compact fluorescent; and long-life tungsten halogen for accent lighting], helps with maintenance, lamp recycling and group re-lamping.
The essential elements of lighting design act to minimize the use of energy through: integrated design such as a team approach to finish selection; effective controls; optimizing the use of daylighting; specifying environmentally-preferable materials and equipment; ensuring system flexibility, maintainability, and durability; and providing for proper commissioning for the system.
Conference room lighting design incorporates all three standardized lamp types. Standardization of lamp types aids maintenance, lamp recycling and group re-lamping.
What’s ahead?
The future of sustainable lighting will include integrated, flexible lighting control systems such as DALI - an acronym for Digital Addressable Lighting Interface which is a worldwide standard for digital lighting control protocol that combines integration with other building management systems, full-range continuous dimming, flexibility for reconfiguring, and personal lighting controls using hand-held controllers or desktop computers allowing individuals to control lighting levels for maximum comfort and satisfaction.
Also, significant research is being conducted to study lighting with respect to circadian photobiology. Human health and well-being is controlled by a 24-hour circadian cycle, which, in turn, is found to be controlled by solar light exposure. The circadian system can become unsynchronized when light exposure is modified by work schedules or work environments, such as night shifts, or working in relatively dim indoor environments without access to natural light. This leads to fatigue, impaired performance, and reduced sleep quality.
It has been found that the circadian rhythms in humans can be stimulated by exposure to bright, well-timed electric light of relatively higher colour temperature. This exciting phenomenon has yielded promising results for laboratory conditions and probably stands to change the way that we will define sustainable lighting design.