Energy Efficiency with Lighting

Lighting lets us see to carry out the daily tasks of life; it affects our comfort and mood, and it can provide safety and security. Lighting and lighting fixtures also play a major role in the interior decoration of our homes.

Our consumption of electricity related to lighting also affects our budgets, both at home and in our workplaces. The Department of Energy reports that we spend, on average, 5-10% of our electric bills on lighting in our homes. In some regions of the U.S. this amount can be as high as 25% where air-conditioning is a modest portion of the bill.

As a point of beginning, let's look at some basic concepts that will help us to better understand how these savings can be achieved.

Energy Efficiency with Lighting

Saving lighting energy requires either reducing electricity consumed by the light bulbs and light fixtures or reducing the length of time that the lights are on. This can be accomplished by:

• Reducing the amount of time that lights are on. This can be accomplished by using dimmers and other lighting controls, and educating family members to turn off unneeded lights.
• Lowering wattage, which involves replacing bulbs or entire fixtures with bulbs and fixtures that provide the same amount or greater amounts of light with but with reduced electricity usage. Today, this can be accomplished most easily by replacing inefficient incandescent bulbs with incandescent/halogen bulbs or compact fluorescent bulbs.

Making the appropriate lamp selection

A "lamp" is the term used in the lighting industry to describe what is most commonly called a light bulb. The key to lighting energy savings lies in the choice of lamp that we use.

There are three primary families of lamps, or bulbs:

• Incandescent
• Fluorescent
• High Intensity Discharge

Incandescent lamps have historically been the most frequently used in residential applications due to their low initial cost. Incandescent sources, however, are relatively inefficient in their conversion of electrical energy to visible light and can therefore add unnecessary electrical costs to our electric bills.

Fluorescent and High Intensity Discharge lamps have been used most often in commercial and industrial applications. Their initial cost is more than incandescent lamps, but they are much more energy-efficient and last significantly longer.

Due to major improvements over the last few years in the color rendering abilities of fluorescent lamps, and the availability of small fluorescent bulbs called "compact fluorescent lamps" or "CFL's", fluorescent lamps are now a very viable alternative to incandescent lamps for home lighting use. As an example, for the same amount of electrical energy, compact fluorescent bulbs produce 3-4 times more light than an incandescent bulb.

Incandescent Options

Incandescent lamps are the least expensive to buy but the most expensive to operate. Incandescent lamps also have the shortest lives of the common lighting types. They are also relatively inefficient compared with other lighting types.

The three most common types of incandescent lamps are

• standard incandescent
• tungsten halogen
• reflector lamps.

Standard incandescent
Known as the "A-type light bulb," these lamps are the most common yet the most inefficient light source available. Note that a larger wattage lamp or bulb may not be the most energy- or cost-effective option, depending on how much light is needed. "Long- life" bulbs, with thicker filaments, are a variation of these A-type bulbs. Although long-life bulbs last longer than their regular counterparts, they are less energy efficient. The best option to achieve energy-efficiency is to replace "A" lamps with compact fluorescent lamps, which will be discussed below.

Tungsten halogen
This newer type of incandescent lighting achieves better energy efficiency than the standard A-type bulb. These lamps are more expensive than standard incandescents but can have significant impact on achieving greater light output than standard incandescent lamps.

Reflector lamps and Parabolic Aluminized Reflector lamps

Reflector lamps (Type BR) are designed to spread light over specific areas and are used mostly in recessed downlight fixtures.

Parabolic aluminized reflectors (Type PAR) are an excellent replacement for the BR lamps. They have a specially designed reflector that is highly efficient in pushing light into the space.

Fluorescent

Fluorescent lighting is used mainly indoors both for general/ambient lighting and task lighting and is about 3 to 4 times as efficient as incandescent lighting. Fluorescent lamps last about 10 times longer than incandescents. To gain the most efficiency, you should install fluorescents in places where they will be on for several hours at a time.

You can also increase the energy savings for existing fluorescent lighting by replacing them with a more efficient model (providing a lower wattage but approximately the same light output), or by replacing the existing fixture with a more efficient model.

Compact fluorescent
Compact fluorescent lamps (CFLs) are the most significant lighting advance developed for homes in recent years. They combine the efficiency of fluorescent lighting with the convenience and popularity of incandescent fixtures.

CFLs can replace incandescents that are roughly three to four times their wattage, saving up to 75% of the initial lighting energy. Although CFLs cost from 10 to 15 times more than comparable incandescent bulbs, they also last 10 to 15 times as long. This energy savings and superior longevity make compact fluorescent lamps an excellent choice for residential use.

As previously discussed, CFLs are one of the best energy efficiency investments available. When introduced in the early- to mid-1980s, CFLs were bulky, heavy, and too big for many incandescent fixtures. However, newer models with lighter electronic ballasts are only slightly larger than the incandescent lamps they replace. The new CFLs also produce a better color for the home.

CFLs come in integral and modular designs. Integral CFLs have a ballast and a lamp in a single disposable unit. Modular designs feature a separate ballast that serves about five lamp replacements before it wears out.

High-Intensity Discharge

High-intensity discharge (HID) lamps provide the highest effectiveness and longest service life of any lighting type. They are commonly used for outdoor and street lighting, but have very limited applications in homes. Their residential use is limited to outdoor lighting for driveways, backyards, etc.

Replacing Lamps and Fixtures

"Relamping" means substituting one light bulb for another to save energy. You can decide to make illumination higher or lower when relamping. But be sure that the new bulbŐs light output fits the tasks performed in the space and conforms to the fixture's specifications.

Matching replacement bulbs to existing fixtures and ballasts can be challenging, especially with older fixtures. Buying new fixtures made for new lamps produces superior energy savings, reliability, and longevity compared with relamping.

Energy-Efficiency with Lighting Controls

Lighting controls are devices for turning lights on and off or for dimming them. The most useful controls for increasing lighting energy-efficiency in a home are dimmers, photocells, and occupancy sensors.

• Dimmers reduce the wattage and output of incandescent and fluorescent lamps and significantly increase the service life of incandescent lamps. Dimming fluorescents requires special dimming ballasts and fixtures, but does not reduce their efficiency.
• Photocells turn lights on and off in response to natural light levels. Photocells switch outdoor lights on at dusk and off at dawn, for example.
• Occupancy sensors activate lights when a person is in the area and then turn off the lights after the person has left. They are popular for areas such as closets and recreation rooms.

Energy-Efficiency with Ceiling Fans

Although ceiling fans cannot contribute directly to savings on lighting energy costs, but they can contribute significantly to savings on electrical costs associated with space heating and cooling. Household electrical costs associated with space heating and cooling are in the range of 35-45%. Using a ceiling fan can help to cool our homes in summer, and helps to more efficiently distribute heated air in winter.

Although it's difficult to place an exact savings amount related to the use of ceiling fans, it's an established fact that ceiling fans can help to reduce electrical costs by creating greater efficiency in how we heat and cool our home environments. Especially in summer, it's often more comfortable to turn off the air-conditioner at night, and use a ceiling fan at low speed in the bedroom.

Appoint a Household Energy Monitor

To educate your family members on the importance of energy conservation, appoint a Household Energy Monitor to turn off lights, set the thermostat, and to keep the windows/doors closed if the air conditioning or heater is on. Rotate the position so that all family members share in the responsibility. For the energy and money your family saves, have a family outing while knowing that your family is contributing to energy conservation.

Lighting and Electricity Concepts

Wattage, Lumens and Efficacy

Wattage is a measurement of the electrical energy used by an electrical device, such as a light bulb, but it is not a measurement of the amount of light being produced. The measurement of light output from a lamp is the lumen. All light bulbs have a lumen rating, and it is the relationship between the lumens being produced and the wattage being consumed that can provide us valuable information about the energy-efficiency of a light bulb.

Efficacy

The relationship between lumens and wattage is called efficacy. This is the ratio of light output from a lamp to the electric power it consumes and is measured in lumens per watt (LPW).

Incandescent lamps have an efficacy range from 15 lpw to slightly over 20 lpw. Fluorescent lamps have an efficacy range from 60 lpw to almost 100 lpw. As you can see from these numbers, the choice of light bulb can have a significant impact on electrical energy consumption.