Overillumination is the presence of lighting intensity higher than that which is appropriate for a specific activity. Overillumination was commonly ignored between 1950 and 1995, especially in office and retail environments.M.D. Simpson, ''A flexible approach to lighting design'', Proc. CIBSE National Lighting Conference, Cambridge, 8–11 April 1990, 182-189, Chartered Institution of Building Services Engineers Since then, however, the

interior design Interior design is the art and science of enhancing the interior of a building to achieve a healthier and more aesthetically pleasing environment for the people using the space. An interior designer is someone who plans, researches, coordina ...

community has begun to reconsider this practice. Overillumination encompasses two separate concerns: * Unnecessary electric lighting is expensive and energy-intensive. Lighting accounts for approximately 9% of residential electricity use and about 40% of commercial electricity use. * Excessive levels of artificial light may adversely affect health. These detrimental effects may depend on the spectrum as well as the overall brightness level of light. Overillumination can be reduced by installing

occupancy sensor An occupancy sensor is an indoor motion detecting device used to detect the presence of a person to automatically control lights or temperature or ventilation systems. The sensors use infrared, ultrasonic, microwave, or other technology. The ter ...

s, using natural sunlight whenever possible, turning off lights when leaving a room, or changing the type of lightbulb. Overillumination does not refer to

snowblindness Photokeratitis or ultraviolet keratitis is a painful eye condition caused by exposure of insufficiently protected eyes to the ultraviolet (UV) rays from either natural (e.g. intense sunlight) or artificial (e.g. the electric arc during welding) ...

, where high exposure to

ultraviolet light Ultraviolet (UV) is a form of electromagnetic radiation with wavelength from 10 nm (with a corresponding frequency around 30 PHz) to 400 nm (750 THz), shorter than that of visible light, but longer than X-rays. UV radiation i ...

causes physical damage to the eye. Underillumination (too little light; the opposite of overillumination) is associated with

seasonal affective disorder Seasonal affective disorder (SAD) is a mood disorder subset, in which people who have normal mental health throughout most of the year exhibit depressive symptoms at the same time each year. Common symptoms include sleeping too much, having li ...

Causes

Overillumination can be caused by several factors: * Illuminating an unoccupied area * Using electrical lights instead of natural light * Providing lighting for an occupied area, but with too much intensity * Installing too few electrical controls. This results in an area that must either be overilluminated or not illuminated at all. In addition, there are ancillary reasons why overillumination might be decided to be necessary. For example, retail stores with large windows will sometimes stay illuminated overnight as a method of crime prevention. While some aspects of illumination are readily controllable, such as turning off lights when exiting a room, others are determined by the architecture and construction of the building. For example,

skylight A skylight (sometimes called a rooflight) is a light-permitting structure or window, usually made of transparent or translucent glass, that forms all or part of the roof space of a building for daylighting and ventilation purposes. History Open ...

s decrease the amount of artificial lighting that is required during the daytime, but most buildings do not have them installed. In addition, too few light switches can also cause issues. If an office building with large windows only has one switch per floor, then electric lights will illuminate the perimeter areas (with abundant natural light) to same level as the interior zones (which receive less sunlight).

Health effects

Overillumination has been linked to various negative health effects. While some effects might happen because the color spectrum of fluorescent lighting is significantly different from

sunlight Sunlight is a portion of the electromagnetic radiation given off by the Sun, in particular infrared, visible, and ultraviolet light. On Earth, sunlight is scattered and filtered through Earth's atmosphere, and is obvious as daylight when t ...

,Lumina Technologies, Santa Rosa, Ca., ''Survey of 156 California commercial buildings energy use'', August, 1996Peter Boyce and Boyce R Boyce, ''Human Factors in Lighting'', 2nd ed., Taylor & Francis, London (2003) other symptoms might be caused by light that is simply too intense. In particular, overillumination has been linked to headaches,

fatigue Fatigue describes a state of tiredness that does not resolve with rest or sleep. In general usage, fatigue is synonymous with extreme tiredness or exhaustion that normally follows prolonged physical or mental activity. When it does not resolve ...

, medically defined stress, anxiety, and decreases in sexual function.''Cambridge Handbook of Psychology, Health and Medicine'', edited by Andrew Baum, Robert West, John Weinman, Stanton Newman, Chris McManus, Cambridge University Press (1997) Susan L. Burks, ''Managing your Migraine'', Humana Press, New Jersey (1994) L. Pijnenburg, M. Camps and G. Jongmans-Liedekerken, ''Looking closer at assimilation lighting'', Venlo, GGD, Noord-Limburg (1991)Igor Knez, ''Effects of colour of light on nonvisual psychological processes'', Journal of Environmental Psychology, Volume 21, Issue 2, June 2001, Pages 201-208 Some studies attribute migraine headaches to overly intense light, while others linked it with certain spectral distributions. In one survey bright light was the number two trigger (affecting 47% of respondents) for causing a migraine episode. Fatigue is another common complaint from individuals exposed to overillumination, especially with fluorescent media. Likewise, overillumination can also cause stress and anxiety. In fact, natural light was preferred over purely artificial light by office workers from both eastern and western cultures.E. Nagy, Sachiko Yasunaga and Satoshi Kose, ''Japanese office employees' psychological reactions to their underground and above-ground offices'', Building Research Institute, Ministry of Construction, 1 Tatehara, Tsukuba-shi, Ibaraki-ken 305, Japan, Revised 13 April 1995. Available online 20 May 2004. In addition, overillumination can cause medical stressM.R Basso Jr., ''Neurobiological relationships between ambient lighting and the startle response to acoustic stress in humans'', Int J Neurosci. 2001;110(3-4):147-57, and even aggravate other psychological disorders like

agoraphobia Agoraphobia is a mental and behavioral disorder, specifically an anxiety disorder characterized by symptoms of anxiety in situations where the person perceives their environment to be unsafe with no easy way to escape. These situations can in ...

. The replacement of natural light with artificial light also decreases task performance under certain conditions.

Circulatory and circadian rhythm effects

Hypertension Hypertension (HTN or HT), also known as high blood pressure (HBP), is a long-term medical condition in which the blood pressure in the arteries is persistently elevated. High blood pressure usually does not cause symptoms. Long-term high bl ...

effects of overillumination can lead to aggravation of

cardiovascular disease Cardiovascular disease (CVD) is a class of diseases that involve the heart or blood vessels. CVD includes coronary artery diseases (CAD) such as angina and myocardial infarction (commonly known as a heart attack). Other CVDs include stroke, h ...

and

erectile dysfunction Erectile dysfunction (ED), also called impotence, is the type of sexual dysfunction in which the penis fails to become or stay erect during sexual activity. It is the most common sexual problem in men.Cunningham GR, Rosen RC. Overview of male ...

, which are outcomes of long-term cumulative exposure and associated systematic increases in blood pressure. The mechanism of this effect seems to be stress by related

upregulation In the biological context of organisms' production of gene products, downregulation is the process by which a cell decreases the quantity of a cellular component, such as RNA or protein, in response to an external stimulus. The complementary proce ...

adrenaline Adrenaline, also known as epinephrine, is a hormone and medication which is involved in regulating visceral functions (e.g., respiration). It appears as a white microcrystalline granule. Adrenaline is normally produced by the adrenal glands and ...

production akin to the

fight-or-flight response The fight-or-flight or the fight-flight-or-freeze response (also called hyperarousal or the acute stress response) is a physiological reaction that occurs in response to a perceived harmful event, attack, or threat to survival. It was first des ...

Circadian rhythm A circadian rhythm (), or circadian cycle, is a natural, internal process that regulates the sleep–wake cycle and repeats roughly every 24 hours. It can refer to any process that originates within an organism (i.e., Endogeny (biology), endogeno ...

disruption is primarily caused by the wrong timing of light in reference to the circadian phase. It can also be affected by too much light, too little light, or incorrect spectral composition of light. This effect is driven by stimulus (or lack of stimulus) to photosensitive ganglion cells in the retina. The "time of day", the circadian phase, is signalled to the

pineal gland The pineal gland, conarium, or epiphysis cerebri, is a small endocrine gland in the brain of most vertebrates. The pineal gland produces melatonin, a serotonin-derived hormone which modulates sleep, sleep patterns in both circadian rhythm, circ ...

, the body's

photometer A photometer is an instrument that measures the strength of electromagnetic radiation in the range from ultraviolet to infrared and including the visible spectrum. Most photometers convert light into an electric current using a photoresistor, ph ...

, by the

suprachiasmatic nucleus The suprachiasmatic nucleus or nuclei (SCN) is a tiny region of the brain in the hypothalamus, situated directly above the optic chiasm. It is responsible for controlling circadian rhythms. The neuronal and hormonal activities it generates regula ...

. Bright light in the evening or in the early morning shifts the phase of the production of

melatonin Melatonin is a natural product found in plants and animals. It is primarily known in animals as a hormone released by the pineal gland in the brain at night, and has long been associated with control of the sleep–wake cycle. In vertebrates ...

(see

phase response curve A phase response curve (PRC) illustrates the transient change (phase response) in the cycle period of an oscillation induced by a perturbation as a function of the phase at which it is received. PRCs are used in various fields; examples of biolog ...

). An out-of-sync melatonin rhythm can worsen

cardiac arrhythmia Arrhythmias, also known as cardiac arrhythmias, heart arrhythmias, or dysrhythmias, are irregularities in the heartbeat, including when it is too fast or too slow. A resting heart rate that is too fast – above 100 beats per minute in adults ...

s and increase

oxidized Redox (reduction–oxidation, , ) is a type of chemical reaction in which the oxidation states of substrate change. Oxidation is the loss of electrons or an increase in the oxidation state, while reduction is the gain of electrons or a d ...

lipid Lipids are a broad group of naturally-occurring molecules which includes fats, waxes, sterols, fat-soluble vitamins (such as vitamins A, D, E and K), monoglycerides, diglycerides, phospholipids, and others. The functions of lipids include ...

s in the

ischemic Ischemia or ischaemia is a restriction in blood supply to any tissue, muscle group, or organ of the body, causing a shortage of oxygen that is needed for cellular metabolism (to keep tissue alive). Ischemia is generally caused by problems wi ...

heart. Melatonin also reduces

superoxide In chemistry, a superoxide is a compound that contains the superoxide ion, which has the chemical formula . The systematic name of the anion is dioxide(1−). The reactive oxygen ion superoxide is particularly important as the product of the ...

production and myeloperoxide (an

enzyme Enzymes () are proteins that act as biological catalysts by accelerating chemical reactions. The molecules upon which enzymes may act are called substrates, and the enzyme converts the substrates into different molecules known as products. A ...

in neutrophils which produces

hypochlorous acid Hypochlorous acid (HClO, HOCl, or ClHO) is a weak acid that forms when chlorine dissolves in water, and itself partially dissociates, forming hypochlorite, ClO−. HClO and ClO− are oxidizers, and the primary disinfection agents of chlorine so ...

) during ischemia-reperfusion.R.J. Reiter, Cardiovascular Research; 58:10-19 (2003)

Energy and economic considerations

Using too much lighting will lead to higher electricity consumption, and therefore higher electricity costs, for the owner of the building. The solution to this issue is multi-faceted because there are several causes of too much light.

High-intensity light

First, overillumination occurs when the intensity of lighting is too high for a given activity. For example, an office building might have many sets of fluorescent lights to keep the area illuminated after sundown. During the daytime, however, large windows might allow for abundant amounts of natural sunlight to enter the office. Therefore, keeping all of the fluorescent lights illuminated during the daytime might cause unnecessary costs and energy consumption.

Leaving lights turned on

Likewise, not switching off the lights when exiting a room will also cause higher energy consumption. Some people avoid frequently turning off CFL bulbs because they think that doing so will cause them to burn out prematurely. While this is true to a certain extent, the US Department of Energy recommends that 15 minutes is an appropriate time frame. Another concern is that turning on a fluorescent bulb consumes large amounts of energy. While fluorescent bulbs do need more energy to turn on, the amount of electricity consumed is equal to only a few seconds of normal operation. Sometimes people do not turn off lights for other reasons, such as an office worker whose company actually pays for the electricity. In these cases

building automation Building automation (BAS), also known as building management system (BMS) or building energy management system (BEMS), is the automatic centralized control of a building's HVAC (heating, ventilation and air conditioning), electrical, lighting, ...

provides more control. These solutions provide centralized control of all lighting within a home or commercial building, allowing easy implementation of scheduling, occupancy control, daylight harvesting and more. Many systems also support

demand response Demand response is a change in the power consumption of an electric utility customer to better match the demand for power with the supply. Until the 21st century decrease in the cost of pumped storage and batteries electric energy could not be ...

and will automatically dim or turn off lights to take advantage of DR incentives and cost savings. Many newer control systems are using wireless mesh open standards (such as

ZigBee Zigbee is an IEEE 802.15.4-based specification for a suite of high-level communication protocols used to create personal area networks with small, low-power digital radios, such as for home automation, medical device data collection, and othe ...

), which provides benefits including easier installation (no need to run control wires) and interoperability with other standards-based building control systems (e.g. security).

Architectural design and the type of light bulbs

Architectural design can also provide ways of reducing energy usage. There are technological aspects of

window A window is an opening in a wall, door, roof, or vehicle that allows the exchange of light and may also allow the passage of sound and sometimes air. Modern windows are usually glazed or covered in some other transparent or translucent materia ...

design where window angles can be calculated to minimize interior glare and reduce interior overillumination, while at the same time reducing solar heat loading and subsequent demand for air conditioning as energy conservation techniques. For the

Dakin Building The Dakin Building is an architectural award-winning class A office building on the San Francisco Bay in Brisbane, California. Serving as a corporate headquarters building for several companies of national prominence, it was built from the profit ...

Brisbane, California Brisbane (pron. , unlike Brisbane, Queensland, Australia) is a small city located in California in the northern part of San Mateo County on the lower slopes of San Bruno Mountain. It is located on the southern border of San Francisco, on the ...

the angled window projections effectively provide permanent sunscreens, obviating interior blinds or shades. Ideally, the design of a building would create multiple switches for the overhead lighting. Adjusting these settings would allow the optimal light intensity to be delivered, the most common version of this control being the "three-level switch", also called A/B switching. Much of the benefit of the excess illumination reduction comes from a better ratio of natural light to fluorescent light that can result from any of the above changes. Research has been conducted showing worker productivity gains in settings where each worker selects his or her own lighting level.H. Juslen, M. Wouters M and A. Tenner, ''The influence of controllable task-lighting on productivity: a field study in a factory'', Appl Ergon., Mar 7; 2006 Lastly, the type of light bulbs that are installed has a significant effect on energy consumption. The efficiency of light sources vary greatly. Fluorescent lights produce several times as much light, for given power input, as incandescent lights do, and LEDs are continuing to improve beyond that. Shades vary in their absorption. Light-colored ceilings, walls, and other surfaces increase ambient light by reflecting.

References

External links

Lighting in Offices, a Simple Guide to Health Risk Assessmment
Occupational Safety and Health Branch, Labour Department, Government of Hong Kong, 2003
Lightmare
- fighting the road safety issue of high-intensity headlights {{Public health Environmental science Light pollution Lighting Low-energy building Pollution