Overview of Energy-Efficient Technologies

Most major-appliance manufacturers offer energy-efficient versions of their products, which are sometimes marked with a label to designate them as such. See the Standards, Rating and Labeling Technical Guide for more information on appliance labeling.

Clothes Dryers

Energy-efficient dryers use less energy than conventional models without sacrificing features or performance. They do this by deploying technologies such as moisture sensors that detect when clothes are dry and automatically shut the dryer off. Or they may incorporate low-heat settings, which use less energy in longer drying cycles.

Clothes Washers

Energy-efficient washers have greater tub capacities, which means fewer loads to clean the same amount of laundry. They can include technologies such as sensors to monitor incoming water levels and temperature; or repeated high-pressure spraying, instead of soaking clothes in a full tub of water. Front-loading clothes washers also use substantially less water than top-loading models. According to the U.S. Environmental Protection Agency (EPA), highly efficient clothes washers can use 25 percent less energy and 40 percent less water than regular washers.

Dehumidifiers

Energy-efficient dehumidifiers have more efficient refrigeration coils, compressors, and fans than conventional models, which means they remove the same amount of moisture but use 15 percent less energy.

Dishwashers

Efficient dishwasher technology includes a number of different features. Soil sensors, for instance, adjust the cycle to achieve minimum water and energy use by testing for dish dirtiness. Improved water filtration removes food soils from the wash water to allow efficient use of detergent and water. Finally, efficient jets use less energy to spray detergent and water over dishes when cleaning, and innovative dish rack designs maximize cleaning by strategically positioning dishes.

Refrigerators and Freezers

Efficient refrigerators and freezers used in residential, commercial, and industrial applications employ more effective insulation and higher efficiency compressors to save energy.

Vending Machines

Efficient vending machines incorporate more efficient fan motors, lighting systems, and compressors for refrigeration. Sometimes they include motion sensors which automatically switch to low-energy lighting and/or low-energy refrigeration mode during times of extended inactivity.

Electric and Electronic Equipment (Computers, Phones, TVs)

Owners can improve the efficiency of their electric and electronic appliances by using switch-mode power supplies (that convert electrical power efficiently), “smart” chargers (that communicate with batteries to ensure optimal charge), efficient backlighting settings, and low-power mode.

HVAC (Heating, Ventilation and Cooling Systems)

Heating and cooling (i.e., conditioning) the indoor environment ensures occupant comfort in many climates and can improve productivity. Ventilation systems can help improve indoor air quality and, when implemented correctly, can have positive health benefits for occupants. HVAC systems include a variety of technologies and can be used in residential, commercial, or industrial settings.

Air Conditioning

Air conditioning is the process of altering air temperature and humidity to distribute air and improve occupant comfort and indoor air quality. Air conditioners function in much the same way refrigerators do, by using energy to transfer heat from the interior of a building to the outside environment.

Boilers (gas or oil-fueled)

Boilers heat water or produce steam, which is circulated through a building to radiators or other terminal units in order to heat the building. A boiler’s efficiency is measured by annual fuel utilization efficiency (AFUE), which is the ratio of useful energy output to energy input expressed in percentage terms. Higher AFUE percentages indicate higher efficiency.

Furnaces (gas or oil-fueled)

Furnaces heat air and deliver it directly to interior spaces. The efficiency of a furnace in converting gas or oil into heating energy is reflected in its annual fuel-utilization-efficiency (AFUE) rating, which is expressed as a percentage. The higher the number, the more heat the furnace can produce from each unit of gas or oil.

Heat Pumps: Air Source and Ground Source

Heat pumps transport heat from outside to inside (in heating mode), or from inside to outside (in cooling mode). There are two major types of heat pumps: air source and ground source. Air source heat pumps usually use a separate outdoor compressor unit to move heat in and out of a residence or building. Ground source heat pumps (also called geothermal heat pumps) provide heating, cooling, and water heating by taking advantage of the Earth’s natural heat and stable temperatures. Ground source heat pumps use an underground piping system called a “loop” to move heat between deep wells in the ground and the inside of the building (in heating mode) or vice versa (in cooling mode).

Air Compression Systems

Energy efficiency opportunities for air compressors include comprehensive system evaluations, new compressors, refrigerated dryers, additional storage, enhanced controls, piping improvements, and leak repairs.

Chillers

There are two types of high-efficiency chillers for HVAC systems: air-cooled chillers and water-cooled chillers. A chiller’s efficiency is measured by the coefficient of performance (COP), which is the ratio of heating or cooling provided to electrical energy consumed. Higher COPs indicate greater efficiency.

Manufacturers may improve chiller efficiency through enhanced controls, enlarged and improved condenser sections, and high-efficiency compressors with variable-speed motor drives. Evaporative or swamp coolers, which are packaged units that cool the air by humidifying it and then evaporating the moisture, use significantly less energy than all-electric chillers. Cumulatively, they can reduce peak electricity demand.

Heat Recovery

During inefficient manufacturing processes, 20 to 50 percent of energy consumed ultimately may be lost via waste heat. The waste is contained in streams of hot exhaust gases or liquids, or occurs through conduction, convection, or radiation from hot equipment surfaces and from heated product streams. Recovery technologies capture the waste heat for reuse in other processes. An example of one of these technologies is an economizer, which comes in condensing and air source models. Economizers can be paired with other equipment to improve its efficiency. For example, a condensing economizer can be paired with a boiler to recover heat from fluid that is hot, but not hot enough to be used in the boiler itself.

Ventilation Fans

The efficiency of ventilation fans, typically integrated into central HVAC systems, may be enhanced by features such as humidity sensors and motion ensors.

Ceiling Fans

Improved motors and blade designs deliver greater efficiency than in conventional models of ceiling fans.

Water Heating

Water heaters are often categorized by the type of fuel that powers them (electric, natural gas, or solar) and by whether they heat a storage tank or provide heated water on demand (also known as “tankless” systems).

Electric Storage Water Heaters

Also known as heat pump water heaters (HPWH), electric storage water heaters use a highly efficient heat pump to transfer heat from the surrounding air to an enclosed tank. During periods of high hot water demand, HPWHs automatically switch to standard electric resistance heat. These heaters also come with selectable operating modes, such as efficiency/economy, to maximize energy efficiency; and a vacation or timer option to place the unit in “sleep” mode.

Natural Gas Water Heater, Gas Storage

In high-efficiency gas storage water heaters, a glass-lined steel tank is heated by a burner located at the bottom of the tank. Efficient models simply have better insulation, heat traps, and more efficient burners. Very high efficiency models use a secondary heat exchanger that extracts more heat from the combustion gas, cooling it to the point where there is condensation—hence, these types of heaters are called “gas condensing.”

Natural Gas Water Heater, Whole Home Gas Tankless

Whole-home gas tankless water heaters save energy by heating water only when needed and thereby eliminating energy lost during standby operation. When a hot water tap is turned on, cold water is drawn into the water heater. A flow sensor activates the gas burner, which warms the heat exchanger. Incoming cold water encircles the heat exchanger and leaves the heater at its set-point temperature. Combustion gases safely exit through a dedicated, sealed vent system. More efficient gas tankless water heaters use secondary heat exchangers to extract more heat from the combustion gas, cooling it to the point where there is condensation—hence these types of heaters are called “gas condensing.”

Solar Water Heater

Solar water heaters come in a wide variety of designs, all of which include an energy collector and a storage tank. They use the sun’s thermal energy to heat water and are typically described according to the type of collector and the circulation system.

Motors and Pumps (including industrial, agricultural and commercial examples)

Motors and pumps represent a substantial opportunity for energy efficiency improvements. The International Energy Agency estimates that electric motors (including those that drive pumps) account for 69 percent of electricity use in the industrial sector, 38 percent in the commercial sector, 22 percent in the residential sector, and 39 percent in the transportation and agriculture sectors combined.

Variable-Speed and High-Efficiency Motors

A variable-speed drive (VSD) is a type of adjustable-speed drive used in electro-mechanical drive systems. Its purpose is to control motor speed and torque by varying motor input frequency and voltage. VSDs are a relatively new technology that has not yet been widely implemented. Installing a VSD makes it feasible to closely correlate demand on the motor with the effort expended by the motor and, therefore, results in significant energy savings.

Controls

Automated control technology enables building managers and owners to reduce the need for lighting, heating, or cooling during low-occupancy hours of operation.

Lighting: Occupancy Sensors and Timers

An occupancy sensor is a lighting control device that detects occupancy and turns the lights on or off automatically, using infrared, ultrasonic, or microwave technology. Timers are set to turn off lights or other equipment (such as fans) after a specified period of time.

Lighting: Dimming controls

Dimmers are devices used to lower the brightness of a light. Modern dimmers are built from semiconductors and are highly efficient since they dissipate far less power than the older, variable resistor-type dimmers.

HVAC: Programmable Thermostats

A programmable thermostat is designed to adjust the temperature according to a series of programmed settings that take effect at different times of the day. Heating and cooling losses from a building become greater as the difference in temperature between the interior and exterior increases. A programmable thermostat reduces these losses by allowing the temperature difference to narrow at times when it would not be objectionable to occupants or detrimental to processes.

HVAC: Building Automation Systems

A building automation system can reduce energy consumption and operating costs by centralizing automated control of the heating, ventilation, air conditioning, lighting and other systems.

Process Equipment: Automatic Scheduling

Process controls determine how long equipment is required to operate, turning it on and off as needed.

Smart Meters

A smart meter is an electronic device that records the consumption of electric energy in intervals of an hour or less and communicates that information to the utility for monitoring and billing. Smart meters enable communication between the meter and the central system. These types of meters may also communicate with “smart” equipment, depending on device design as well as intermediary communication between the meter and other equipment, such as a Wi-Fi network or a power line carrier network. Smart meters permit greater control than traditional meters over the quantity of energy consumed and the times of use.

Since smart meters allow consumers to monitor their electricity consumption rates in real time, they can be paired with other behavioral incentives (i.e., price signals during peak-consumption hours) to positively reinforce energy conservation. The American Council for an Energy-Efficient Economy (ACEEE) reported in 2012 that across nine pilot studies involving real-time energy consumption feedback using smart meters, the average savings was 3.8 percent.

Sector-Specific Technologies

Transportation: Vehicles

Several jurisdictions around the world have put regulations into place to improve the average fuel economy of vehicles. One example is the Corporate Average Fuel Economy (CAFÉ) standards in the United States. Improvements in fuel economy are measured using miles per gallon (mpg) for this particular standard. Technological improvements that manufacturers have introduced include higher efficiency drivetrains and improved aerodynamics.

Transportation: Low-Rolling Tires

Fuel-efficient low-rolling tires use tread design and new materials to minimize the amount of gasoline required to move the vehicle.

Agricultural: Water Distribution Systems (Drip Irrigation)

Drip irrigation, also known as trickle irrigation, is a method that saves water and fertilizer by allowing water to drip slowly to the roots of plants, either onto the soil surface or directly onto the root zone, through a network of valves, pipes, tubing, and emitters. Drip irrigation is more efficient than sprinklers or flood irrigation because a much higher proportion of the water delivered to the plants is absorbed by the soil. Drip irrigation saves energy by reducing the quantity of water that needs to be supplied and pumped.