Overillumination

This cosmetics store has lighting levels over twice recommended levels and sufficient to trigger headaches and other health effects

Over-illumination is the presence of lighting intensity beyond that required for a specified activity. The context of over-illumination can be: higher intensity light than needed, illumination with unnatural frequency spectra or temporal extension of lighting beyond times of use. Over-illumination with excess intensity was common between 1950 and 1995, especially in office and retail environments; only recently has the design community recognized the consequences of over-illumination, both in terms of energy wastage and adverse health effects. Inappropriate spectral usage is primarily an issue for health and annoyance, while delivery of lighting to unoccupied spaces is purely waste.

Since lighting consumes 20 to 40 percent of commercial electricity use, depending upon region, the toll of unneeded energy consumption in the U.S. alone exceeds 700 million barrels of oil per year, based upon estimates that almost half of commercial lighting may be wasted (including unneeded overnight lighting of office buildings, forsaking certain available natural light, usage of improper spectra, underutilization of occupancy sensors, delamping and under-using discretionary light controls).

Adverse health effects from excessive lighting or incorrect spectra can manifest in the form of headaches, fatigue, annoyance, medical stress, Sexual effects, increased risk of certain carcinomas, high blood pressure and other cardiovascular disease. Some of these effects are under further study to understand more precise pathways.

Numerical definition of over-illumination

Some big box retail stores have over-illumination

Generally speaking over-illumination occurs when light levels exceed 500 lux for incidental lighting, exceed 800 lux for general office use or exceed 1600 lux for special purpose use such as microchip etching quality control. The term over-illumination first came into reasonably broad use in the early 1990s, when considerable realization of its effects by the lighting, health and energy conservation fields. Production of glare is a de facto indication of over-illumination, since that causes optical processing conflicts and confusion to the brain in translating optical inputs. The reason over-illumination is sometimes grouped with incorrect spectra is that the health effects are linked, and also because incorrect spectra (such as fluorescent globes) provide too intense illumination in certain frequency bands compared to other bands. The desired spectrum is that of natural light, which the body is expecting and which is used to set the circadian rhythms of all higher forms of animal life.

Causes of over-illumination

Lighting unoccupied areas is responsible for significant energy wastage. A 2005 survey of commercial buildings indicates that only about five percent of structures utilize any form of occupancy sensor, a device that has been available for over 15 years. More remarkably office buildings are often illuminated on overnights and weekends. A survey of building managers indicates this practice was primarily for the convenience of the janitors, so that they would not have to bother turning lights on and off during night shifts when janitorial work was carried out! Timers are also available to switch light banks off at prescribed times, a practice particularly useful to prevent outdoor lights from staying on during daylight. One survey of 156 California building managers revealed that average daylight use of outdoor lighting was one to two hours, and the reason for such wastage was most commonly attributed to the failure of building maintenance personnel to reset timers for each season (e.g. quarterly reprogramming that takes approximately two minutes per timer).

California fitness club using mostly natural light to achieve healthy and energy efficient outcome

Forsaking use of natural light is often a design decision made by the architect or his subcontractor. Overlooking opportunities for skylights is a major defect of many building designs, but lack of coordination of interior light banks with natural exterior light is an even more common error. At a minimum, the building design should offer sufficient independent light banks so that building occupants may select the most suitable combination of natural to augmented light. Very frequently entire floors of office buildings are designed with only one switch, so that perimeter areas near natural light are illuminated with the same level of artificial light as the dimmest interior zones. This lack of independent controls also would require an entire office floor of say 10,000 square feet to be fully illuminated if one office worker stays late for evening work. To demonstrate that this result can occur with the most eminent of architect, The Frank Lloyd Wright designed Marin County Civic Center was designed for only one or two switches serving very large floor footprint office pools. This outcome cost Marin County several thousands of dollars per annum in unneeded electricity costs. While the energy wastage effect is notable, the health consequences are of greater significance, because numerous studies have shown the importance of matching the color spectrum of sunlight when illuminating the workplace.

Omitting occupancy sensors is an error primarily for bathrooms, conference rooms and storage areas. This is an energy wastage issue and not a health issue. The payback time of most occupancy sensors is in the range of two to five years, and yet first cost economics prevent the installation of occupancy sensors in the majority of cases where they would save energy and bulb maintenance costs.

Failure to delamp or use available lighting controls is a common issue associated with over-illuminated buildings. Many instances of “designed in” over-illumination can be corrected by simple actions of building managers, following an illumination survey. In many instances over-illumination can be solved by removing a fraction of the globes or fixtures from a ceiling lighting system. In other cases a lighting retrofit can be conducted to replace older, less energy efficient fixtures with newer ones. Lighting retrofits can also be designed to reduce over-illumination; retrofits have typical payback periods of two to four years. In simpler cases many fluorescent ceiling illumination systems have multiple switch settings that allow tuning of the light intensity delivered, the most common version of this control being the "three-way switch". 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 own lighting level

Common T8 fluorescent lighting fixture frequently used in office environments

Non-lethal health effects

Non-lethal health effects of over-illumination or improper spectral composition of light are as follows: increased headache incidence, worker fatigue, medically defined stress, anxiety, and decrease in sexual function. These will all be dealt with within non-lethal effects, except for sexual dysfunction, which while not deadly, is most closely associated with the hypertensive effects and addressed under the circadian rhythm discussion under lethal effects..

Migraine headaches are known to be triggered by excessive light. In one survey over-illumination was listed as the number two trigger for migraines, with 47 % of the respondents reporting bright light as the principal trigger of their migraine episode. Not only does bright light induce headache, but incorrect spectra (for example, too great an emphasis upon fluorescent as opposed to natural light) contribute to incidence of headache.

Fatigue is a common complaint from individuals exposed to over-illumination, especially with fluorescent media. Some studies have shown that the flicker and over-illumination combined in some fluorescent systems yield particularly high fatigue incidence. Research on circadian rhythm in humans indicates that one reason for fatigue stems from the incorrect color spectrum of fluorescent light. For example, the brain of a worker under intense fluorescent light for eight hours perceives itself to have been in total darkness and hence is preparing to sleep under its circadian setting.

'Stress and anxiety are frequent outcomes from working in a setting of intense (especially fluorescent) lighting. Research has shown that annoyance from bright light leads to medical stress<L. Pijnenburg, M. Camps and G. Jongmans-Liedekerken, Looking closer at assimilation lighting, Venlo, GGD, Noord-Limburg (1991)</ref>. It is clear that brighter, less spectrally correct light induces clinically measurable stress, and it is suggested that for children this over-illumination may interfere with the learning process. For example, in dysgraphia, a defect of learning to write, children experiencing any form of stress are subject to greater incidence of this learning disability. Fluorescent lighting has also been linked to aggravating other psychological disorders such as agoraphobia.

Major health effects

Hypertension effects of over-illumination can lead to aggravation of cardiovascular disease and erectile dysfunction, which impacts are outcomes of long term cumulative exposure and associated systematic increases in blood pressure. The mechanism of this effects seems to be stress by related up-regulation of adrenalin production akin to the fight-or-flight response. When adrenalin is released into the bloodstream it causes vasoconstriction, a known precursor to both hypertension and erectile dysfunction. Analogous female sexual side effects are thought to result in the female anatomy from reduced blood flows.

Circadian rhythm disruption is an effect of too much light, too little light or incorrect spectral composition of light. This effect is driven by stimulus (or lack of stimulus) to the pineal gland, the body’s photometer, that thence signals the brain as to time of day. In total light deprivation or total darkness the body’s clock is thrown off, if the light condition persists for too long a time. The principal adverse outcome seems to arise from workers subject to intense fluorescent light, which is poorly matched to the spectrum of sunlight. The body translates this condition as total darkness and resets the circadian clock incorrectly. Not only does this result in fatigue, but also immuno-supressive behavior that has been shown to be linked to increased cancers. Bright light inhibits production of melatonin, a substance shown to reduce cardiac arrythmias and to reduce oxidized lipids in the ischemic heart. Melatonin also reduces superoxide production and myeloperoxide (an enzyme in neutrophils which produces hypochlorous acid) during ischemia-reperfusion.

Energy and economic considerations

The total energy wastage of over-illumination is roughly 1.5 billion barrels of oil per annum. Most of the excess occurs in the U.S. and Europe. Japan, while highly industrialized, has a very different ethic in terms of avoidance of unneeded light; this equation has been changing in Toyko itself in the past two decades. One of the major reasons that such wastage is tolerated is that the person who bears the cost is usually not the one making day to day decisions about lighting. Building managers and not building owners usually structure such things as janitorial use of lighting, setting or installation of timers, choice of lighting globes. Another poor management practice in the U.S. is a leasing structure where the tenant, who makes operational decisions on lighting use, pays none of the electrcity costs, a form of lease common in about one half of the situations today.

There are also myths which continue to propagate, occluding better lighting decisions. One myth is that there is a greater cost of turning on fluorescent systems than keeping them running. This myth must have been invented by electricity suppliers because it has no basis in fact. Another myth simply states that electrical costs of lighting are a constant not a variable. At this point hundreds of buildings in the U.S. have been audited and lighting use altered, demonstrating that 30 to 50 percent of lighting costs can be eliminated. For example one California study indicated that generally 40 to 80 percent of lighting energy costs could be eliminated, sometimes requiring hardware investment with an average payback time of less than two years. Obviously the highest savings can be generated for buildings in the planning stage or where major remodeling will occur. A final myth is that more light is better. Health data disprove such an assertion, and this statement only has applicability in rare situations today where the original lighting is very low or where unusual technological manufacturing processes (such as microchip etching) demand high illumination levels.

See also

• Energy conservation
• Hypertension
• Light pollution

External links

• [http://www.lightforhealth.com/canadian.pdf Case Study of Incorrect Lighting Spectra on Poor Performance of School Children}
• Government of Hong Kong Health Effects of Lighting in the Workplace