Miscellaneous electric load
Encyclopedia
Miscellaneous electric loads (MELs) in buildings are electric loads resulting from electronic devices not responsible for space heating, cooling, water heating, or lighting. MELs are produced by hard-wired and “plug-in” electrical devices, including home entertainment centers
, kitchen electronics such as microwaves and toaster ovens, bath items such as hair dryers and electric hot tubs, and others such as security systems and ceiling fans. MELs are gaining greater importance as home electronics become more sophisticated and more widespread, and miscellaneous electric use can only be expected to rise.
s such as refrigerators, stoves, dryers, etc. Although each device may draw a small amount of power, the large and steadily increasing number of devices can use a significant portion of a home’s energy. In the United States, MELs comprise nearly one quarter of residential energy use, larger than either heating or cooling energy end-use. In low-energy house
s, this percentage increases dramatically, because MELs are often ignored while increasing whole-house efficiency
.
On average, home entertainment equipment, including televisions, audio equipment, and computers, make up about half of the total MELs in a United States home. About 13 percent of MELs come from devices in standby
mode.
appliances), modifying occupant behavior and managing standby power
. Still, MELs are a significant obstacle in creating zero-energy buildings. Heating, cooling and water heating
energy loads can be reduced by improvements to the building envelope
, HVAC
and water heating equipment, and air distribution system
. MELs are more elusive, however, because of their diversity. Many miscellaneous electric devices that can be found in a large fraction of houses are smaller—for example toasters, televisions and internet routers, while larger power draws, such as well pumps or waterbed heaters, are present in only a small fraction of houses. Such variety makes it hard to find a systematic method of reducing MELs. If MELs cannot be reduced, the only way to counter them is with larger (and thus more costly) solar
arrays or other electricity generation methods.
With recent advances in technology, energy feedback devices can be purchased for $100–$150. Feedback devices allow people to identify and reduce standby power
and as well as cut back on unnecessary power draws. In addition, occupants can see the effects of running pool pumps/heaters, supplemental space heaters, air conditioners, etc.
Energy feedback devices can further assist zero energy buildings, where it is desirable to align electric loads with photovoltaic panel output.
Entertainment center
A home entertainment center is a piece of furniture seen in many homes in North America, which houses major electronic items, such as a television set, a VCR and/or DVD player, stereo components , and cable or satellite television receivers...
, kitchen electronics such as microwaves and toaster ovens, bath items such as hair dryers and electric hot tubs, and others such as security systems and ceiling fans. MELs are gaining greater importance as home electronics become more sophisticated and more widespread, and miscellaneous electric use can only be expected to rise.
Description
Miscellaneous electric use includes a diverse collection of electronics, such as power adapters, pool pumps, computer equipment, televisions, door bells, phone/fax machines, and many, many others. MELs usually do not include major applianceMajor appliance
A major appliance, or domestic appliance, is usually defined as a large machine which accomplishes some routine housekeeping task, which includes purposes such as cooking, or food preservation, whether in a household, institutional, commercial or industrial setting...
s such as refrigerators, stoves, dryers, etc. Although each device may draw a small amount of power, the large and steadily increasing number of devices can use a significant portion of a home’s energy. In the United States, MELs comprise nearly one quarter of residential energy use, larger than either heating or cooling energy end-use. In low-energy house
Low-energy house
A low-energy house is any type of house that from design, technologies and building products uses less energy, from any source, than a traditional or average contemporary house...
s, this percentage increases dramatically, because MELs are often ignored while increasing whole-house efficiency
Efficient energy use
Efficient energy use, sometimes simply called energy efficiency, is the goal of efforts to reduce the amount of energy required to provide products and services. For example, insulating a home allows a building to use less heating and cooling energy to achieve and maintain a comfortable temperature...
.
On average, home entertainment equipment, including televisions, audio equipment, and computers, make up about half of the total MELs in a United States home. About 13 percent of MELs come from devices in standby
Standby power
Standby power, also called vampire power, vampire draw, phantom load, or leaking electricity , refers to the electric power consumed by electronic and electrical appliances while they are switched off Standby power, also called vampire power, vampire draw, phantom load, or leaking electricity...
mode.
Significance to zero-energy buildings
MELs can be lowered by using fewer electronic devices, choosing more efficient electronics (for example, Energy StarEnergy Star
Energy Star is an international standard for energy efficient consumer products originated in the United States of America. It was first created as a United States government program during the early 1990s, but Australia, Canada, Japan, New Zealand, Taiwan and the European Union have also adopted...
appliances), modifying occupant behavior and managing standby power
Standby power
Standby power, also called vampire power, vampire draw, phantom load, or leaking electricity , refers to the electric power consumed by electronic and electrical appliances while they are switched off Standby power, also called vampire power, vampire draw, phantom load, or leaking electricity...
. Still, MELs are a significant obstacle in creating zero-energy buildings. Heating, cooling and water heating
Water heating
Water heating is a thermodynamic process using an energy source to heat water above its initial temperature. Typical domestic uses of hot water are for cooking, cleaning, bathing, and space heating...
energy loads can be reduced by improvements to the building envelope
Building envelope
The building envelope is the physical separator between the interior and the exterior environments of a building. Another emerging term is "Building Enclosure". It serves as the outer shell to help maintain the indoor environment and facilitate its climate control...
, HVAC
HVAC
HVAC refers to technology of indoor or automotive environmental comfort. HVAC system design is a major subdiscipline of mechanical engineering, based on the principles of thermodynamics, fluid mechanics, and heat transfer...
and water heating equipment, and air distribution system
Duct (HVAC)
Ducts are used in heating, ventilation, and air conditioning to deliver and remove air. These needed airflows include, for example, supply air, return air, and exhaust air. Ducts also deliver, most commonly as part of the supply air, ventilation air...
. MELs are more elusive, however, because of their diversity. Many miscellaneous electric devices that can be found in a large fraction of houses are smaller—for example toasters, televisions and internet routers, while larger power draws, such as well pumps or waterbed heaters, are present in only a small fraction of houses. Such variety makes it hard to find a systematic method of reducing MELs. If MELs cannot be reduced, the only way to counter them is with larger (and thus more costly) solar
Solar cell
A solar cell is a solid state electrical device that converts the energy of light directly into electricity by the photovoltaic effect....
arrays or other electricity generation methods.
Energy feedback devices
One reason MELs are difficult to reduce is because the use of small electric devices are controlled directly by a building’s inhabitants. One way to reduce MELs is by the use of energy feedback devices which report real-time energy use to a house’s occupants. The use of these devices has been tested in numerous studies which suggest whole-house savings of 5%-15%.With recent advances in technology, energy feedback devices can be purchased for $100–$150. Feedback devices allow people to identify and reduce standby power
Standby power
Standby power, also called vampire power, vampire draw, phantom load, or leaking electricity , refers to the electric power consumed by electronic and electrical appliances while they are switched off Standby power, also called vampire power, vampire draw, phantom load, or leaking electricity...
and as well as cut back on unnecessary power draws. In addition, occupants can see the effects of running pool pumps/heaters, supplemental space heaters, air conditioners, etc.
Energy feedback devices can further assist zero energy buildings, where it is desirable to align electric loads with photovoltaic panel output.