Room Lighting/ General Lighting
Room Lighting/ General Lighting
Based on information provided by Joyce Matlack, A.S.I.D., Matlack-VanEvery Design, Inc., Santa Cruz, California
- Fluorescent lighting remains the preferred choice in orthodontic office lighting.
- Types of fluorescent fixtures include prismatic, parabolic, direct/indirect and cans.
- Natural light can provide an even, diffused light and a connection with the outdoor environment. In the orthodontic bay, natural lighting should come from the north to minimize glare.
- LED lighting is gaining in use. LEDs offer small size, efficiency and long life, and give off no heat.
General lighting is the overall lighting that illuminates the office. First of all, if you are planning your building from the ground up consider capturing as much natural light as possible. Work with what you have for remodels or tenant improvements in existing buildings to maximize the benefit of the natural light that is available.
Fluorescent lighting remains the preferred choice in office lighting, including orthodontic offices. Many new choices are available in fluorescents today to improve appearance and reduce glare. LED lighting is gaining in use as general lighting for commercial environments, and is now available in the many color temperatures (yellow vs. blue light) that have been the benefit of fluorescent options for many years.
A well-planned room lighting configuration will provide uniform lighting that supports the work environment and brings out the natural colors in people and objects. Signs of a poor lighting configuration are hot spots and dark areas; some workstations will have glare while others are lit insufficiently. Inadequate lighting may also make people’s skin tones look pale or yellow. Selecting the proper lighting fixtures and placing them appropriately is a professional job; at minimum, go to a local lighting showroom and ask for assistance. Ideally, your office designer or architect will assist you.
Fluorescent lights have been the standard of office lighting for their energy efficiency, economy and even distribution of light.
Fluorescent fixtures offer electronic ballasts that eliminate the humming and blinking often associated with fluorescent lights. Today’s fluorescent tubes are manufactured to last 20,000 hours, compared to 750 hours for an incandescent bulb. Fluorescents produce little or no heat, helping to save on air-conditioning costs.
Fluorescent tubes require less maintenance; however it remains important to replace bulbs at prescribed intervals. Bulbs should be replaced in groups, to help assure that bulbs of the same color temperature are used.
Fluorescent fixtures are available in many shapes and configurations. Following are the types most likely to be used in an orthodontic office.
Prismatic. A common fixture, the prismatic has a textured lens covering the fluorescent tubes. A major concern is the glare they cause, particularly on computer workstations.
Parabolic. Also common is the parabolic fixture which contains bulbs set above a set of diffuser plates. When you look up at the fixture, you see what appears to be an egg-crate shape. The plates act to reflect light from the tubes and spread it more uniformly, thus reducing hot spots and glare. Parabolic fixtures are available in square, rectangular or round shapes. The size of the parabolic cube determines the pattern of light fall below. A 2’ x 4’ parabolic fixture with 32 cells would be the fixture of choice in the orthodontic office. Parabolic fixtures are most often recessed in the ceiling.
Direct/Indirect. A newer type of fluorescent is the direct/indirect. It places diffusers above and below the bulb. This type of fixture should be used in all computer station locations and treatment areas to reduce glare on computer screens and eye strain.
Direct/indirect fixtures can be suspended from the ceiling, called a “pendant”, to create uniform lighting and a contemporary appearance. Direct/indirect fixtures also can be recessed into the ceiling.
Fluorescent Cans. This is a rounded, can-shaped fixture that is recessed into the ceiling. Its bulbs plug into the fixture from only one end, not both as in standard fluorescents. Bulbs have one or more tubes projecting from the socket. A can light with horizontal tube is preferred as the tube itself will be less visible.
Fluorescent Fixture Sizes. The standard fluorescent fixture size is 2 feet by 4 feet. However, 1 x 4 and 2 x 2 also are common sizes. Fluorescent fixtures may have one or as many as four bulbs.
The size of a fluorescent bulb is represented as T-4, T-5 or T-8, with the number representing the relative diameter of the bulb; a T-8 is one inch in diameter while a T-5 is 5/8-inch in diameter.
Your lighting designer will determine the appropriate mix of fixture sizes and number of bulbs per fixture to achieve general room lighting that is uniform and pleasing. The structure of your ceiling and the amount of space available above the ceiling also will influence fixture choices.
You can add to your office lighting with the use of windows or skylights for natural light. Natural light can provide an even, diffused light and provide a connection with the outdoor environment, such as a landscaped area or garden. However, adequate light should be available from other sources since natural light may not be available during all working hours in the winter, and will vary by weather conditions. Natural lighting in the orthodontic bay should come from the north to minimize glare. Solar tubes are another great way to capture and funnel natural light into your interior rooms. Also consider transom or clerestory windows above doors or cabinets to bring light from the rooms on exterior walls into halls and interior rooms.
LED Lighting for General Illumination
Size and Efficiency. LEDs measure from 3 to 8 mm long and can be used singly or as part of an array. The small size and low profile of LEDs allow them to be used in spaces that are too small for other light bulbs. In addition, because LEDs give off light in a specific direction, they are more efficient in application than incandescent and fluorescent bulbs, which waste energy by emitting light in all directions.
Long Life. The life of a high-power white LED is projected to be from 35,000 to 50,000 hours, compared to 750 to 2,000 hours for an incandescent bulb, 8,000 to 10,000 hours for a compact fluorescent and 20,000 to 30,000 hours for a linear fluorescent bulb. LED lifetimes are rated differently than conventional lights, which go out when the filament breaks. Typical lifetime is defined as the average number of hours until light falls to 70 percent of initial brightness, in lumens. LEDs typically just fade gradually.
Lower Temperatures. Conventional light bulbs waste most of their energy as heat. For example, an incandescent bulb gives off 90 percent of its energy as heat, while a compact fluorescent bulb wastes 80 percent as heat. LEDs remain cool. In addition, since they contain no glass components, they are not vulnerable to vibration or breakage like conventional bulbs. LEDs are thus better suited for use in areas like sports facilities and high-crime locations.
EnergyStar LEDs. Poorly designed LEDs may not be long-lasting or efficient. LEDs that are EnergyStar-qualified should provide stable light output over their projected lifetime. The light should be of excellent color, with a brightness at least as great as conventional light sources and efficiency at least as great as fluorescent lighting. The LEDs should also light up instantly when turned on, should not flicker when dimmed and should not consume any power when turned off.
(Above LED information courtesy of Lexa W. Lee from the National Geographic green living website)
Types of LED light fixtures for general illumination:
LED Can Light
Direct Indirect LED