The Man at Work Collection--Studies in Sustainability

Installment Nine:  “From Lanterns to LEDs -- A Look at the Evolution of Sustainable Lighting”

By Deborah L Jackman, PhD, PE, LEED AP™

glass blowers making lantern mantles.jpg

Glassblowing, 1932,

by Hugo von Bouvard (1879-1959), oil on canvas

A Brief History of Lighting:

          It is easy for us to forget that humans have only had access to artificial lighting for about two hundred years.  Prior to the early 19th century when gas lamps began to be introduced into some major cities in the United States and Europe, people lived a very different life—a life whose rhythms were governed largely by the rising and setting of the sun.  A. Roger Ekirch, a historian on the faculty of Virginia Tech, writes of life before artificial lighting in his best-selling book, At Day’s Close: Night in Times Past [1]. Ekirch’s research reveals glimpses into a human culture awash in superstition and fear, with many people refusing to leave their homes at night, convinced they would encounter demons, witches, or even Satan himself.   In large cities, like London or Paris, street crimes, committed by roving gangs of thugs, were rampant after dark.  The street crime rate in cities is estimated to have been as much as ten times greater prior to 1800 than today, when adjusted for differences in population.  People’s patterns of recreation and sleep also varied greatly from today, with activities requiring light, such as reading and writing, confined largely to daylight hours, and hence, largely reserved for the upper classes, who could afford leisure time during the day.  While candles and torches have existed for centuries, such devices require constant tending and were the source of fires, which in a time of limited fire-fighting ability, were feared by people perhaps even more than the alleged demons lurking in the dark.  Furthermore, candles tended to be expensive and the working classes usually used tapers instead. (Tapers consisted of a reed dipped in animal fat which would burn for only short periods of time and which smoked excessively.)  Even those in the upper classes who could afford high-quality bee’s wax candles would have had to burn as many as 100 candles simultaneously to achieve the same illumination as can be achieved today with a single 60 Watt incandescent light bulb.  

          Human society began to change significantly starting in the mid 18th century as  oil lanterns came into common use. Oil lanterns allowed for a more controlled burn, better fire safety, and more predictable, longer lasting light levels.  Then, starting in the early 19th century, gas lamps began to be used in large cities.  Cities installed the infrastructure to supply gas derived from coal and oil into people’s homes via a system of pipelines.  In rural areas, oil lanterns were gradually replaced by kerosene lanterns.  The subsequent increased demand for kerosene spurred the growth of the oil and gas industry, with the most prized early product of oil refining being kerosene, rather than gasoline.  It was only later on, after the Model T was introduced in the early 20th century, that gasoline overtook kerosene as the most sought after product of petroleum refining.   Our subject painting, Glassblowing, depicts artisans blowing glass mantles for use in the manufacture of kerosene lanterns.  Kerosene lanterns persisted as a major source of artificial light well into the early 20th century in rural America, prior to the rural electrification programs carried on as part of the New Deal.

          The biggest leap in the development of artificial lighting occurred with the development of the incandescent light bulb.  Light is produced in the incandescent light bulb by passing electrical current through a tungsten filament in a vacuum. When heated by an electric current, the tungsten glows, producing light. The absence of oxygen in the evacuated space keeps the filament from oxidizing. While Thomas Edison is traditionally credited with the invention of the incandescent light bulb, it existed in various forms well before Edison.  Much of the early research on incandescent bulbs centered on finding a suitable material for the filament—a material that would glow or “incandesce”, which was able to be manipulated easily during the manufacturing process, and which was cheap and durable.  Edison did propose a number of improvements to the device, starting in the early 1880s.  However, his major breakthrough came in 1905, when he patented an improved ductile tungsten filament, very similar to what we use today. Whatever his role in the actual invention of the light bulb, Edison was indisputably the major force in its commercialization.   Incandescent light bulbs represented a huge improvement over earlier forms of illumination because they operated without an actual flame.  This reduced the fire hazard associated with the use of artificial lighting immensely--a feature of increasing importance as America became more urbanized, with higher population densities crowded into fire-prone urban housing units. 

            Perhaps the most amazing feature of the incandescent light bulb is its longevity.  In a world where technologies are launched, mature, and become obsolete over the period of a few years, or at most a few decades, incandescent bulbs have remained a viable commercial product for nearly 110 years.  They are cheap to make and easy to use. However, from a technical standpoint, they are very inefficient producers of light.  Of the electrical power consumed to operate an incandescent light bulb, only about 5% of it is converted to light.  The remaining 95% is converted to heat energy.  That means that the traditional incandescent light bulb is actually a much better heater than it is a light! Thus, in this era of increased awareness of the importance of energy efficiency, the venerable incandescent bulb is finally being phased out, in favor of alternatives which include Compact Fluorescent Lamps (CFLs) and Light-Emitting Diodes (LEDs).

          Compact Fluorescent Lamps (CFLs) were first introduced commercially in the mid 1990s. They operate on the same principle as the more traditional tube style fluorescent lamps, except the tube is bent to fit into a space approximately the same size as a standard incandescent bulb.  Various chemical phosphors are excited by the electric ballast at the base of each bulb, and when excited, they luminesce, creating light.  CFLs became common place in the first decade of the 21st century, when various rebates and other purchasing incentives, coupled with education programs on how the use of CFLs would save consumers money on utility bills, provided many consumers with an incentive to purchase them as replacements for incandescent bulbs. They are much longer lasting and energy efficient than incandescent bulbs, but suffer from other shortcomings, which are discussed in greater detail below.

The newest type of artificial light source is the Light-Emitting Diode (LED).  LEDs are solid state semiconductor devices that emit a photon of a single wavelength (color) of light when an electric current passes through them.  Single LEDs have been in use since the 1970s as panel indicator lights on electronic devices.  However, it has only been in the last decade that LED based devices have been developed that can be used as replacements for incandescent light bulbs in task lighting applications. LED light bulbs are made up of many individual LED units in a variety of colors which combine to provide sufficient light intensity and color spectrum (collectively a white light.)  They are still quite expensive relative to both incandescent bulbs and CFLs, but show great promise to ultimately fully replace incandescent bulbs over the next years because of their good quality of light, their long life, and their energy efficiency.

Environmental Impacts of Artificial Lighting:                              

Before we look specifically at new developments in artificial lighting and at alternatives to the incandescent light bulb, we need to investigate some of the environmental impacts of artificial lighting.   This investigation informs the search for the best and most sustainable modern lighting systems.

1.    Energy efficiency--Nearly all Americans are aware of the government mandated transition that is currently underway to phase out incandescent light bulbs.  And most are also aware of the primary reason behind the phase-out--the need to become more energy efficient.  Indeed, energy efficiency is the major driver in many industries today, as society strives to become more sustainable by reducing the production of green house gases through greater energy conservation. Lighting consumes 22 to 25% of all electricity used in the United States and therefore represents a major opportunity for energy savings. As noted above, only 5% of the energy consumed by an incandescent light bulb is converted to light.  This is in contrast to compact fluorescent bulbs, which use only 25 to 35% as much electricity as incandescent bulbs to produce the same illumination and last 10 times longer [2].  Even more impressive are light emitting diodes (LEDs), which use 20% as much electricity as incandescent bulbs for the same illumination levels and last 25 times longer [3]. Clearly, on the basis of energy efficiency alone, the LED-based light fixture represents the way of the future.      

2.    Toxicity and Resource Depletion—Energy efficiency is only one component of how sustainable a product is.  As we have seen in other essays in this series, the best way to assess the overall sustainability of a product is via a life cycle assessment of that product.  Life cycle assessment takes into account not only how much energy is consumed during the use of the product, but also how much energy is consumed during the manufacture of the product (i.e. embodied energy), and how much hazardous waste or toxic chemicals are generated during the life cycle of the product.  When one looks at incandescent, fluorescent, and LED lamps in the life cycle assessment context, the picture is more nuanced than when considering energy efficiency alone.  According to researchers Lim, Kang, Ogunseitan and Schoenung [4] both CFLs and LEDs are categorized as hazardous waste under current federal regulations when disposed of at end of life due to excessive levels of lead leachability and their high content of copper, mercury, and zinc.  Incandescent bulbs, in contrast, are not so classified.  Lim, et al., also looked at the level of resource depletion that occurs during the production of the three light sources.  They concluded that CFLs and LEDs have higher resource depletion and toxicity potential than the incandescent bulb due primarily to their high aluminum, copper, gold, lead, silver, and zinc content. When compared on an equivalent quantity basis (taking into account and correcting for their different lifetimes), CFLs were found to have 3 to 26 times higher potential impact than incandescents, and LEDs 2 to 3 times higher impacts than incandescents.  This group of researchers only looked at resource depletion and hazardous waste impact of the three lighting sources.  They did not do a complete life cycle assessment which would factor in the reduced energy impacts of LEDs and CFLs.

The most interesting result of my research into these impacts is that a data base search did not reveal any journal articles in which a comprehensive life cycle assessment comparing the three light sources and including both energy use (operational and embodied) and toxics generation potential was conducted. Clearly, this is an area ripe for additional research. Were the operational energy consumption of these three light sources factored into a comprehensive life cycle assessment, one can surmise that LEDs would be shown to be at least as or more sustainable than incandescents.  Even though they have a 2 to 3 times higher resource depletion and hazardous waste generation potential than incandescents, the avoided pollution (both in terms of green house gases and toxics emitted by power plants) of the lower energy consumption of LEDs would likely off-set their environmental downside.  The case for CFLs is less clear because while more energy efficient than incandescents, their up to 26 times higher potential hazardous waste and resource depletion impact would require a great deal of avoided pollution from their energy use to off-set these impacts.  When compared directly to LEDs, CFLs are clearly the inferior choice, having less energy efficiency and higher negative environmental impacts.  In any case, the sustainability profile for both LEDs and CFLs can be significantly improved if an effective waste management system for collecting used bulbs is developed.  This will require a significant amount of consumer education and a change in the behavior of the general public, who in many cases still dispose of spent CFLs in their general trash, despite being instructed not to.  Perhaps some sort of cash deposit system, like that that used to be in effect for beverage containers in the 1960s and 1970s, could incentivize consumers to properly recycle LEDs and CFLs.  

          3.    Light Pollution—Another negative impact of our use of artificial lights is that of light pollution.  Light pollution is the alteration of light levels in the outdoor environment (from those present naturally) due to man-made sources of light [5]. The increase of light levels at night is more than just a nuisance that produces unattractive glare or interferes with activities that require a dark sky, such as star gazing.  Inappropriate levels of light during the night have been shown to be damaging to a number of nocturnal species of animals who depend upon darkness as part of their normal life cycle.  It is also a danger to humans, whose circadian rhythms can be disrupted, leading to sleep disorders and general health problems. So serious has this problem become that scientists and concerned citizens have founded the International Dark-Sky Association, an  organization whose purpose is to educate people about and help to reduce light pollution [6]. An excellent article by Gaston, Davies, Bennie, and Hopkins [7] summarizes the current state of the efforts to reduce light pollution.  They first summarize the various forms of light pollution: 1) glare and over-illumination (caused by excessive brightness of a light source); 2) light clutter (excessive grouping of light sources); 3) light trespass (unwanted direct lighting of an area); and 4) skyglow (increased night sky brightness produced by upwardly emitted and reflected light).  They then proceed to analyze and discuss the various ways to reduce light pollution.  These include such measures as zoning ordinances which prohibit artificial light in certain environmentally sensitive areas; reducing the duration of lighting; reducing the intensity of light to minimum levels needed for safety and human activity; reducing light trespass and skyglow through properly designed directional lighting; and broadening the spectrum of lights used to more nearly mimic those found in nature.  In terms of the three types of lighting devices under consideration here, LEDs offer some distinct advantages related to light pollution as discussed in greater detail below. 

4.    Color Rendition—Color rendition refers to the appearance of various objects illuminated by a light source, compared to how those same objects appear in natural sunlight. Certain light sources with poor color rendition make objects appear unnaturally red, yellow or blue. In general, the best light sources for general use are those that mimic the wavelengths present in natural sunlight (a fairly broad spectrum).  In certain non-critical, limited applications, lights having poor color rendition (such as low pressure sodium lamps often found in underground parking structures) can be used, if their energy efficiency, cost, and durability outweigh color rendition considerations.  But, for most sustained activities involving humans, broad spectrum lights are more efficacious and healthier for occupants.  Color rendition has been quantified by lighting designers through the Color Rendition Index (CRI) [8].  A CRI of 100 is considered the perfect light source in terms of color rendition, with natural sunlight having essentially a CRI of 100.  One of the advantages of incandescent bulbs is that their color rendition is excellent (CRI approximately equal to 100).  At the other end of the CRI spectrum are specialty lighting sources, such as the yellow low pressure sodium lamps discussed above, which actually have a negative value of CRI, so poor is their color rendition.  CFLs have historically been criticized for casting a blue tint on objects, although some of the “warm white” CFLs that are available are designed to somewhat minimize this blue tint.  A typical CFL has a CRI of between 50 and 70.  A positive feature of LEDs is their CRI, which while not as good as incandescents, is an improvement over CFLs.  CRIs of between 80 and 90 are typical for today’s LED lamps.   

Future Directions for More Sustainable Lighting Systems:

          What are the future trends in lighting?  The first is clearly a drive toward increased energy efficiency.  For this reason, the most common lamp will be the LED.  As discussed previously, it is more efficient than the incandescent bulb, has fewer environmental impacts than CFLs, has a very long life, and has reasonably good color rendition.  It is currently quite expensive, but costs are projected to drop as manufacturing is ramped up and production volumes increase.   The CFL--the most common energy-efficient alternative to the incandescent bulb in use currently--will likely vanish once LEDs become more cost competitive.  Most lighting experts agree that the CFL is an interim technology.  It suffers from a number of shortcomings in addition to its negative environmental impacts and mediocre color rendition.  Additional shortcomings include a lack of directionality and poor dimming capabilities.  The “dimmable” CFLs currently on the market generally perform poorly, exhibiting a narrow range of light intensity modulation and an audible buzzing sound while in operation. Perhaps most surprisingly, and despite the current phase-out of conventional tungsten filament incandescent bulbs, other types of incandescent lamps will likely continue to be used for specialized applications.  For example, halogen lamps (a type of incandescent bulb which is somewhat more energy efficient than tungsten-based incandescent bulbs) will continue in production and will be the preferred lighting source where exceptional color rendition is needed, such as in art museums, photography studios, and for commercial displays.

According to nationally-recognized lighting designer James R. Benya [9], additional future lighting trends will include:  

o   More efficient luminaires–the luminaire is the technical term for the light fixture that the lamp (i.e. the bulb) is placed in.  New luminaire designs promote directional lighting and effective shading. Light is directed onto the required task, and shading to mitigate light pollution is incorporated into the design.  Energy is also conserved because overall levels of illumination can be reduced, with light focused more efficiently on task areas.  LEDs are particularly compatible with this new concept in luminaire design because they are highly directional and exhibit little light scatter.

o   Integrated use of daylighting – Obviously, the most sustainable form of light is sunlight.  It costs us nothing and has no negative environment impacts.  In fact, humans who work in a day-lit environment report a greater sense of well-being than those who work under artificial lights.  The problem with extensive use of daylighting in the past has been that it is ephemeral, with optimum light levels only lasting for a few hours at most, depending on building orientation.  The rest of the time, the space is either over-lit or under-lit.  Modern control systems that employ light sensors and automated shading devices can optimize light levels in a room.  When daylight levels are high, all artificial lights are automatically turned off, conserving energy, and are gradually turned back on, in modulated fashion, as daylight dwindles.  If daylight levels are too intense, automated shading devices are used to adjust light levels to optimum intensity.  Daylighting, coupled with advanced control systems, offers an opportunity to reduce the need for artificial lights dramatically, provided a building is designed with suitable architecture and with daylighting as a design objective.

o   “Just enough light levels”-- Recent advances in understanding human physiology have allowed us to know how much light is needed for various tasks.  Any light in addition to required levels is wasted energy. Hence, we can design around the optimum levels needed for various tasks, and can eliminate excess wattage.  To allow for differences in light levels needed by different individuals, due to variations such as age, visual acuity, etc., task lighting can be designed with adjustable controls, so that occupants can dim or increase light levels to accommodate individual preferences.

o   Infrared sensors (IR) and/or motion sensors for outdoor lighting -- The use of outdoor path and security lighting contributes to light pollution, even if it is properly shaded to minimize light trespass.  One technique that will become increasingly common in the future will be to integrate IR or motion sensors into the control systems for outdoor lights.  When people are not present, such systems will be turned off completely.  This will further reduce light pollution and also save energy.  LED life is not adversely affected by on/off cycling like incandescents are, so there is no  downside to turning them off as much as required.

     Public recognition of the need for sustainable lighting systems is as critical as having the technology required to implement them.  As education about the importance of sustained periods of darkness to Earth’s ecology and to human health increases, public interest in better designed and controlled lighting systems will increase.  Many counties and municipalities have already incorporated light pollution codes into their zoning ordinances. For example, Cochise County, Arizona, has a particularly detailed and comprehensive Light Pollution Code on their website, http://cochise.az.gov/cochise_planning_zoning.aspx?id=476 .  Many other areas are promoting voluntary light reduction campaigns, coupled with education about the need for reduced and/or better designed lighting.  The Hudson Highlands area of New York state provides a good example of such a voluntary approach, http://www.hhlt.org/lightPollution.html .   While we will never return to the periods of deep darkness experienced by our ancestors before the advent of artificial lights, the world of the future will most likely be somewhat less brilliantly lit than the developed world of the late 20th and early 21st century that many of us are used to.  Even the most light-polluted city in the United States--Las Vegas, Nevada, with its lighting excesses (e.g. the infamous Las Vegas Strip)--has recently installed new LED streetlights, designed to save energy and reduce glare.   That says it all.

I will love the light for it shows me the way, yet I will endure the darkness because it shows me the stars.

Og Mandino

References and Further Reading:

  1. Ekirch, A. Roger (2006), At Day’s Close: Night in Times Past. W.W. Norton and Company.  ISBN-10: 0393329011.
  2. United States Department of Energy (October 17, 2013), Fluorescent Lighting.   Retrieved from http://energy.gov/energysaver/articles/fluorescent-lighting .
  3. United States Department of Energy (July 29, 2012), LED Lighting. Retrieved from http://energy.gov/energysaver/articles/led-lighting .
  4. Lim, S., et al, “Potential Environmental Impacts from the Metals in Incandescent, Compact Fluorescent Lamp (CFL), and Light-Emitting Diode (LED) Bulbs,” Environmental Science and Technology, Vol. 47, No. 2, January, 2013.
  5. Hollan, J., “What is Light Pollution, and How Do We Quantify It?Darksky2008 Conference Paper, Vienna, August 2008.
  6. http://darksky.org/
  7. Gaston, K., Davies, T., Bennie, J., and Hopkins, J., “Reducing the Ecological Consequences of Night-Time Light Pollution:  Options and Developments,” Journal of Applied Ecology,  Vol. 49, p. 1256-1266, 2012.
  8. Guo, X. and Houser, K.W., “A Review of Color Rendering Indices and Their Application to Commercial Light Sources,“ Lighting Research and Technology, Vol. 36, No. 3, p. 183-197, September 2004.
  9. The Energy Center UniversitySM Short Course , Lighting and Daylighting: Design, Controls, and Technology, Oconomowoc, Wisconsin, October 2, 2013. 

 

      In the Summer of 2014, look for Installment Ten of this series.  The issues surrounding making the world’s fisheries sustainable will be explored using the work Fishermen Hauling in their Nets at Sea by French artist Georges-Jean-Marie Haquette as inspiration.