How many hours a day do you spend under the sun? If you’re the average office employee, that time would be limited to some one to two hours on a sunny morning when you rush off to work; the few minutes during your lunch break if you eat outside your office and the one hour from 5:00 to 6:00 pm when leave your office and head back home.
That’s about three hours or less of natural and healthy sunlight, and it jibes with studies in the West that show most people spend 90 percent of their lives indoors.
And sunlight can indeed be healthy—it activates Vitamin D, for example—as long as it’s absorbed in moderation. The corollary is that most city dwellers spend most of their days indoors. That means our eyes rely mostly on artificial indoor lighting (which can sometimes be too dim) to get things done. Our eyes, therefore, tend to live in darkness everyday.
But how bright should artificial lighting or illumination be so it doesn’t harm our eyes? How healthy is artificial lighting for our eyes? And is there such a thing as “healthy artificial lighting?”
Moderate and regular exposure to “good sunlight” (generally accepted as sunlight before 10:00am and after 4:00pm on a sunny day) does have healthy benefits. One of these benefits is that sunlight helps stimulate the production of more red blood cells thereby increasing the blood’s oxygen content. The sun’s ultraviolet rays are also antiseptic and can kill some germs on our skin, according to some sources.
Moderate and regular sunlight exposure might actually protect the skin by increasing its natural resistance to the harmful effects of ultraviolet light instead of aging damaging the skin. And, as many of us already know, ultraviolet light converts cholesterol in the skin to Vitamin D. This vitamin is essential for the proper absorption of calcium by the body and thus in the prevention of osteoporosis.
A number of scientific studies support findings that natural daylight helps hospital patients recover faster, improves their mood and helps promotes well being. One striking discovery is that the health of patients close to windows tends to improve quicker. As you can see, sunlight in moderation is healthy.
Lux and lumens
Technically speaking, full or the brightest sunlight has an “illuminance” of some 100,000 to 120,000 lux per square meter at the Earth's surface. “Illuminance” is the total visible light (or “luminous flux”) present in a given area. It’s measured by the metric unit called “lux.” A lux can also be defined as one lumen per square meter. The lumen, in turn, is the metric unit of luminous flux.
The 120,000 lux generated by brightest sunlight is intense and should be since it floods immense areas of the earth’s surface. The family living room, however, needs only a very tiny fraction of this total: an illuminance of just 50 lux. That 50 lux can be achieved by a single compact fluorescent lamp (CFL) of 40 watts that produces 1,650 lumens and is available at hardware stores and major retail outlets.
In contrast, offices need more illuminance (up to 500 lux on the table surface) and therefore more lights for the good quality lighting employees need to work effectively at their computers and at clerical work. Factories obviously need more illuminance in their work areas than do offices for safety reasons.
Christine Sicangco, a professional “lighting designer” and one of the pioneers in this now expanding profession, said there isn’t a hard a fast rule as to the degree of illuminance in a room or how bright a room should be.
“If I were to do the lighting design of a family room, my use of lights would depend on who the occupants are or are they elderly or young; their lifestyle; their needs and the tasks they do,” she said. “You also have to take into account the height of the ceiling and the reflectivity of the walls.”
As an example, she noted that today’s kitchen is morphing into a living room and family room since family members tend to congregate here regularly for meals and chit chat. Children also seem to like studying in kitchens (probably because it’s a yummy food source).
To light a kitchen/living room/family room ensemble, an illuminance of 400 to 500 lux (similar to office lighting) would be appropriate considering the many activities that take place here. She said her kitchen is one of these triple function rooms; it’s lit by six paired 26 watt ceiling CFLs for “general lighting,” which makes for a brightly lit room. She uses “dimmers,” however, to regulate the brightness of her general lighting.
One can also use traditional fluorescent lamps for general lighting. But select the newer “T5 lamps” that last longer and are cheaper in the long run rather than the old “T10” lamps with ballast still found in many Filipino homes. In the case of Sicangco’s kitchen/living room/family room ensemble, two 28 watt T5 fluorescent lamps should give about the same illuminance as the CFLs she currently uses.
Sicangco’s living room is an altogether different affair, however. She sees her living room as a place to relax. Hence, the room has no bright ceiling lights such as those in her kitchen. Instead, her living room light sources are generated by floor lamps with low watt CFLs and accent lighting, which together add up to some 50 lux, and make for a relaxing setting.
But if you want more light in your home, don’t use more powerful ceiling lights or add more CFLs or fluorescent lamps to your general lighting. Use “task lighting,” according to Sicangco. Task or job lighting consists of table and floor lamps (with CFLs) that only illuminate the area where they’re needed and not the entire room. That saves money by cutting electricity costs.
“Why would you want lighting that generates over 500 lux?” Sicangco asked. “”It’s a waste of energy and you won’t need it that much.”
The conventional wisdom that more artificial light is better is a myth, according to some sources. Mounting medical evidence shows “over illumination” could actually be bad for your health. Among the ill effects attributed to over illumination are more headaches, increased worker fatigue and more stress.
Good lighting contributes greatly to person’s sense of well-being and can positively affect office worker satisfaction and productivity, according to the International Association of Light Designers (IALD), an international association that promotes the virtues of professional lighting design.
IALD says lighting designers are resource for innovative, practical and economically viable lighting solutions. They understand the role of lighting in architecture and interior design and rely on their extensive experience and knowledge of lighting equipment and systems to enhance and strengthen design.
A new and sustainable form of generating illuminance harnesses sunlight. Called “daylighting,” this “green” concept means lighting an indoor space with daylight from windows and skylights and not relying solely on artificial lighting.
Daylighting saves energy as it uses less electricity, and could avoid the perceived adverse health effects caused by over-illumination from artificial lights. Some experts believe artificial office lighting plus daylighting can attain an illuminance ranging from 2-3,000 lux without significantly increasing energy costs. Daylighting is also another solution to the challenge of using artificial lighting to duplicate the visual advantages of sunlight.
Most offices, however, continue to turn to artificial lighting to produce the clear visibility needed for safe and efficient work. This approach ignores a growing body of evidence that seems to suggest artificial lights can cause health problems due to under-illumination (research shows poor lighting can cause depression) and over-illumination (clinical studies show excessive levels of artificial light could lead to health problems).
The need to bring the healthy benefits of sunlight indoors has led to a marketing gimmick in the West called “full-spectrum lighting.” Although current medical research tends to disprove the most outlandish full spectrum lighting claims (that it replicates sunlight and purifies the air, for example), this phenomenon highlights a growing consumer concern indoor lighting should be “healthy,” or about as important to a family as the healthy food they eat.
Scientific articles about full-spectrum lighting compiled by the National Research Council of Canada Institute for Research in Construction, a Canadian government research and development agency, conclude that full-spectrum lighting does not confer any benefits as regards performance, mood or health compared to typical cool-white fluorescent lighting.
Sicangco concurs with this conclusion. “I don’t think full spectrum lighting is healthy,” she said. “If you need Vitamin D, go out into the sunlight.”
Good indoor lighting protects your eyes from the dangers of under- and over-illumination. It also helps protect you and your family members from accidents, and the visual risks associated with old age. But if you want your lighting to do more than just light up a room, you’ll probably need the services of a lighting designer.
But if you do experience problems you think are being caused by too much or too little lighting, see your doctor for advice.