Lighting and Phantom Loads
Lighting and Phantom Loads Offer Opportunities for Energy Savings
Bird's eye view
Non-appliance plug loads are easy targets for conservation
Lighting and plug loads other than appliances account for a significant percentage of residential energy use. Strategies to cut consumption include the use of compact fluorescent or LEDLight-emitting diode. Illumination technology that produces light by running electrical current through a semiconductor diode. LED lamps are much longer lasting and much more energy efficient than incandescent lamps; unlike fluorescent lamps, LED lamps do not contain mercury and can be readily dimmed. light bulbs, and tracking down and eliminating phantom electrical loads. A smart meter showing real-time electrical use can help.
Straight fluorescent bulbs are the most efficient
Lighting. The most efficient residential bulbs are linear fluorescent tubes, the same lamps seen in schools and commercial buildings. While most CFLs produce between 44 and 80 lumens per watt, T-5 and T-8 lamps (the newer straight fluorescent tubes with smaller diameters than the old-fashioned kind) produce between 98 and 105 lumens per watt. These lamps can easily be used in kitchens. When installed in coves, they can also be used to provide ambient light in living rooms and bedrooms.
At 11 to 25 lumens per watt, most LED (light-emitting diode) fixtures are slightly more efficient than incandescent bulbs (14 to 17 lumens per watt) but less efficient than CFLs.
Meters. There are two main types of meter that can provide feedback to homeowners. The least expensive option is a portable meter that measures how much current is flowing to any device that’s plugged into it. Kill-A-Watt and Watt-Minder are two brands. Such meters are helpful in figuring out how much electricity various devices use in standby mode — “off” but not really off — as well as under normal operation. Their main disadvantage is that they are unable to measure the current used by hard-wired appliances like water heaters.
A more expensive option is a whole-house electricity use meter with a display for the living room or kitchen. One well-known brand is The Energy Dectective (www.theenergydetective.com). To learn more about electricity meters, see "Smart Meters," below.
Good lighting takes planning
DaylightingUse of sunlight for daytime lighting needs. Daylighting strategies include solar orientation of windows as well as the use of skylights, clerestory windows, solar tubes, reflective surfaces, and interior glazing to allow light to move through a structure.. Window size and placement along with room layout directly affect the extent to which homeowners can substitute natural light for electric lights.
To take advantage of sunlight, it helps to consider the solar orientation of your home. Choosing the right windows or skylights and designing the house to put the light where you need it can create spaces that are inviting, practical and energy efficient. To get the most out of these decisions, don't forget that daylighting and passive solar heating often go hand in hand.
Task lighting. A good lighting design requires a great many well placed task lights, each individually switched. Good task lighting allows occupants to save energy by illuminating only a few areas at a time.
Power strips can shut down phantom loads
Phantom loads can be addressed by the use of power strips. A newer type of power strip dubbed the Smart Strip switches off other connected devices when a television, computer or other master device is turned off. Another solution is switched receptacles. The location of the receptacles and switches must be carefully planned if there is any hope that they will be used.
Switching to fluorescent bulbs
The 2009 version of the International Residential Code includes new lighting efficiency requirements. The code will require that 50% of the lamps in permanently installed fixtures to be CFLs or T-8 linear fluorescent lamps; either screw-base lamps or pin-base lamps will be acceptable.
ABOUT LIGHTING AND PHANTOM LOADS
Look for opportunities to cut consumption
Both lighting and non-appliance plug loads are easy targets for conservation. Lighting accounts for nearly 9% of residential energy consumption. Getting rid of incandescent bulbs, which produce mostly heat, and switching to compact fluorescents or light emitting diodes (LEDs) means instant savings.
Phantom loads represent the current that computers, telephones, entertainment systems and other devices draw even when they are turned off. For the most part, it's a waste.
The current that keeps these devices in standby mode so they power up quickly may seem like a trickle. But by sheer volume, these electronic gizmos use more power than many homeowners would guess.
It may not be obvious when a device is drawing power on the sly, but there are a couple of easy and effective ways to deal with the problem.
MORE ABOUT LIGHTING
The old bulbs produce more heat than light
Incandescent bulbs are incredibly effective — at generating heat, not light. Only a small portion of the energy they consume produces light. Most is turned into heat which we don't want in the first place.
Compact fluorescent lamps (CFLs) use less power to produce the same amount of light as an incandescent, so lower wattage CFLs can be used as replacements. For example, a 75-watt incandescent bulb produces up to 1,100 lumens, the same as a CFL drawing between 18 watts and 25 watts. CFLs that work with dimmers also are available.
Substantial energy savings. Switching from incandescents to CFLs is the single most cost-effective way to save residential energy, reducing power consumption for lighting by 75%.
As a bonus, the bulbs will last much longer. A compact fluorescent costs about six times as much as a conventional bulb but can last up to 10,000 hours (compared to 1,500 hours for the average incandescent). The government says each CFL saves about $30 in energy over its lifetime.
LEDLight-emitting diode. Illumination technology that produces light by running electrical current through a semiconductor diode. LED lamps are much longer lasting and much more energy efficient than incandescent lamps; unlike fluorescent lamps, LED lamps do not contain mercury and can be readily dimmed. Fixtures. Most light-emitting diode fixtures produce less usable light per watt that CFLs. In fact, the U.S. Department of Energy found that many of them don't produce as many lumens as manufacturers claim.
Most LED fixtures produce 11 to 25 lumens per watt, which is much less efficient than CFLs, which produce 48 to 80 lumens per watt. (Incandescent bulbs produce between 14 and 17 lumens per watt).
The most efficient LED fixture is probably the LR6 downlight from Cree, with a reported efficiency of 60 lumens per watt. LED manufacturers continue to improve their products, and many researchers predict that LED lamps will eventually outperform CFLs.
Costs are higher. LEDs are expensive, up to $90 per bulb. But they should last between 30,000 and 50,000 hours, the equivalent of 10 years when used for eight hours a day. LEDs are more vibration-resistant than either incandescents or CFLs, and the light they emit is much whiter.
Another bonus: Unlike compact fluorescents, LEDs contain no mercury.
Switches are important, too. Switches that sense when a room is unoccupied, dimmers and pressure-sensitive switches on closet doors also can help trim energy costs.
More information. For a thorough discussion of lighting design and bulb selection, see Martin’s 10 Rules of Lighting.
MORE ABOUT PHANTOM LOADS
Standby mode is quick but inefficient
Many televisions, VCRs, computers, stereo receivers, and other electronic devices use electricity even when they appear to be off. They're actually in standby mode so they can come to life without a long warm-up.
That's convenient, to be sure. But the U.S. Department of Energy estimates that 75% of the electricity used to power residential electronic devices is consumed while they are turned “off.” (However, a recent California field study concluded that the percentage is 39%, significantly lower than the DOEUnited States Department of Energy. estimate.) In an average household, phantom loads amount to about 450 kWh of power per year. Nationally, television sets alone waste $730 million a year.
Fighting back. Reducing phantom loads isn't a function of home design. It's entirely up to the people who live there. A good place to start is by buying Energy StarLabeling system sponsored by the Environmental Protection Agency and the US Department of Energy for labeling the most energy-efficient products on the market; applies to a wide range of products, from computers and office equipment to refrigerators and air conditioners. rated appliances and electronic devices, which use less electricity than standard models.
Beyond that, a few basic strategies can help:
Power strips. Plug televisions, computers and monitors into power strips and turn the strip off when the devices won't be used for more than a couple of hours. Equipment that doesn’t go through a power strip should be unplugged.
The Energy Department says the small surge of electricity a computer uses as it’s restarted is less than what the device would use by being left on for long periods. Turning a computer off and on has no practical effect on its service life.
Smart strips. A smart strip is similar to a power strip. The primary device (for example, a computer) is plugged into the control outlet on the smart strip, and peripheral electronics (printer, scanner, modem, etc.) are plugged into the switched outlets.
The smart strip monitors the current drawn on the control outlet. When the computer is turned off and current drops to a standby level, the power to all outlets is cut, turning off the peripheral machines as well.
Common applications for a smart strip are computer stations, television and accessory electronics (cable box, DVD, speakers, etc.).
Switched outlet. For charging stations, stereos, and entertainment centers, a switched outlet is a cleaner, more accessible alternative to power strips. It’s also convenient, because the switch can be across the room from the outlet.
Power-down or sleep-mode setting. Computers with an Energy Star rating drop to a sleep mode that uses 15 watts or less of power, 70% less than a computer without this feature, and then to a sort of deep sleep mode where power consumption is 8 watts.
Screen-savers do not mean the computer is using any less energy.
Watch those transformers. Transformers that convert AC line power to DC power for telephones, clocks and some electronic devices — so-called “wall cubes” — are particularly wasteful, although efforts are underway to improve their efficiency. Wall cubes should be unplugged when not in use.
ABOUT SMART METERS
A reminder to conserve energy
A whole-house electricity meter with an indoor display gives real-time feedback on power consumption. Smart meters make it easier to take advantage of lower off-peak electricity rates, and they serve as a reminder to conserve power.
Affordable plug-in watt meters can track individual electrical outlets, handy for tracking down phantom loads.
Paying attention pays off. Several studies have shown that a real-time meter with a display in the kitchen or living room can help homeowners save money. In one study by a Canadian utility, average electricity use dropped 6.5% after such meters were installed.
Off-peak rates help. Some utilities offer lower off-peak rates which encourage customers to time power-intensive household chores (for example, washing clothes or dishes) to coincide with periods of lower electricity demand. Such load-shifting flattens out sharp spikes in consumption and reduces the need to build new power plants.
Most North American utilities foresee the day when time-of-use rate structures become standard in the residential market. If that day comes, electricity used on hot summer afternoons will cost much more than electricity used between 10 p.m. and 6 a.m.
New meters on the horizon. A variety of new smart electricity meters, not all of which include indoor displays, are under development to help utilities implement time-of-use billing.
The latest devices track consumption and can transmit data directly to the utility. Customers may also have access to the information, allowing them to make decisions about when to use an electrical appliance or device and when to wait.
Alerted to spiking demands, utilities can ask customers to limit the use of electrical devices.
MORE ABOUT COMPACT FLUORESCENTS
Are compact fluorescents dangerous?
Environmental disadvantages. The major drawback with CFLs is that they contain small amounts of mercury. Each bulb contains about 4 mg. of mercury, about the amount that would cover the tip of a ballpoint pen. Standard 4-ft. fluorescent tubes contain 10 times that much. Neon lights have 25 times as much, and a standard residential wall-mounted thermostat contains 750 times as much.
Mercury has long been identified as highly toxic. In humans, it can harm the brain, heart, kidneys, lungs, and immune system. According to the Environmental Protection Agency (EPA), “High levels of methyl-mercury in the bloodstream of unborn babies and young children may harm the developing nervous system, making the child less able to think and learn.” Ironically, mercury is an ingredient in scores of consumer products, including cosmetics (eyeliner, mascara, and skin creams), children’s sneakers, thermostats, and fluorescent lights.
Mercury is a naturally occurring element that is found in many rocks. One of those rocks is coal. When coal is burned, mercury is released into the air. As it turns out, coal-fired electricity plants are the single-biggest source of airborne mercury in the United States (40%), followed by industrial boilers (10%), hazardous-waste burning (5%), and chlorine production (5%).
Mercury in the air eventually settles into water or onto land, where it can be washed into lakes and rivers. There, microorganisms convert it to methylmercury, the most-common form of mercury exposure in humans. Mercury concentration builds up in fish, shellfish, and animals that eat fish, including people.
According to the EPA, the mercury emissions attributable to a 13-watt CFL amount to 1.6 mg., compared with 5.8 mg. for a 60-watt incandescent. Moreover, some manufacturers have been able to reduce mercury content to 1.4 mg. per CFL.
Don't cycle CFLs frequently. CFLs won’t last as long as advertised if they are turned on and off frequently or exposed to heat, as they would in a recessed light fixture.
Unless they’re marked as such, they can’t be used with a dimmer.
No matter which bulbs are chosen, heavy lamp shades, dark grilles, or thick frosted globes all reduce the levels of light that escape from a fixture. Simple fixtures with minimal impediments between the bulb and the room will provide the most usable light.
- Krysta Doerfler / Fine Homebuilding
- Daniel Morrison / Fine Homebuilding
- Dan Thornton / Fine Homebuilding