Are ceiling fans good for saving energy?
Energy Efficiency Services Limited
Under the National Energy Efficient Fan Programme, EESL provides BEE 5 Star rated ceiling fans which are 30% more energy efficient than conventional fans. Fans will be sold for Rs. 1,150 per fan. EESL has distributed 6.2 lakh energy efficient fans under this scheme which will save 2.4 lakh kWh and Rs 8.2 lakh per day to the consumers. The price difference is Rs. 500 which is the primary reason for its low penetration, along with the lack of awareness. With the usage of these energy efficient fans it is estimated that consumer’s electricity bills will reduce by about Rs. 700-730 per year, and recover the extra cost in less than 2 years.
Energy Star
Energy Star qualified heat pumps, boilers, air conditioning systems, and furnaces are available. In addition, cooling and heating bills can be significantly lowered with air sealing and duct sealing. Air sealing reduces the outdoor air that penetrates a building, and duct sealing prevents attic or basement air from entering ducts and lessening the heating/cooling system’s efficiency. Energy Star qualified room air conditioners are at least 10% more energy efficient than the minimum U.S. federal government standards.
Ceiling fan
For cooling, the fan's direction of rotation should be set so that air is blown downward (Usually counter-clockwise from beneath), unless in rare case in which more breeze would be felt when blowing upward, such as when it's installed in hallway where blades would be so close to the walls. The blades should lead with the upturned side as they spin. The breeze created by a ceiling fan speeds the evaporation of perspiration on human skin, which makes the body's natural cooling mechanism much more efficient. Since the fan works directly on the body, rather than by changing the temperature of the air, during the summer it is a waste of electricity to leave a ceiling fan on when no one is in a room unless there's air conditioning, open windows, or anything that can heat up the room (such as oven) and fan is just to move air around.
Brushless DC electric motor
In addition to the brushless motor's higher efficiency, HVAC systems (especially those featuring variable-speed and/or load modulation) use brushless motors because the built-in microprocessor allows for programmability, control over airflow, and serial communication.
Some ceiling fan and portable fans are also featuring this motor. They advertise the motor being highly energy efficient and quieter than most fans.
Thermal destratification
Reducing thermal stratification can be accomplished by controlling the variables that are associated with increased stratification. Since many of the variables, including ceiling height, people and processes, solar gain, and outside weather conditions cannot be controlled, the most common technologies used are related to the building's HVAC (heating, ventilation, and air conditioning) system. One of the cheapest, most effective, and easiest to install technologies are destratification fans, including both axial destratification fans and HVLS (high-volume low-speed) fans.
High-volume low-speed fan
A high-volume low-speed (HVLS) fan is a type of mechanical fan greater than in diameter. HVLS fans are generally ceiling fans although some are pole mounted. HVLS fans move slowly and distribute large amounts of air at low rotational speed– hence the name "high volume, low speed."
Power supply unit (computer)
Various initiatives exist to improve the efficiency of computer power supplies. Climate Savers Computing Initiative promotes energy saving and reduction of greenhouse gas emissions by encouraging development and use of more efficient power supplies. 80 PLUS certifies a variety of efficiency levels for power supplies and encourages their use via financial incentives. Efficient power supplies also save money by wasting less power; as a result they use less electricity to power the same computer, and they emit less waste heat which results significant energy savings on central air conditioning in the summer. The gains of using an efficient power supply are more substantial in computers that use a lot of power.
Fan (machine)
In 1998, Walter K. Boyd invented the HVLS ceiling fan. A lifelong inventor, Boyd was charged with developing a system to cool dairy cattle. Dairy cattle, when overheated, decrease milk production. Using the laws of physics and airflow, Boyd developed a slow moving fan that incorporated 10 aluminum blades and was 8-feet diameter. Unlike traditional ceiling fans that move quickly, this large fan moved slowly. Due to its diameter size, the fan moved a large column of air down and out 360 degrees and continuously mixed fresh air with the stale air inside the barn. They are used in many industrial and agricultural settings, because of their energy efficiency. It also cooled the inside of the barn without causing the dairy cattle undue stress or kicking up dust.
Air conditioned clothing
One advantage of air-cooled clothing is that it requires much less energy to cool people down than to cool down their entire environment. For instance, an air cooled shirt uses 4,400 mAh of power for 8.5 hours on the fastest fan setting, while an average central air conditioning unit uses 3000 to 5000 watts of power. In some cases, the purpose of air-conditioning is not to cool down the objects in the room, but the people. Directly ventilating clothing is therefore far more efficient. A 2012 New York Times article reported that gases commonly used in air conditioning absorb some 2,100 times more infrared radiation per ton than carbon dioxide, and due partly to increasing use of air conditioning in the developing world (particularly in tropical areas like India, Malaysia, Indonesia, Brazil, and southern China), air conditioning is projected to contribute to some 27% of the overall greenhouse gas emissions by 2050. Although there are some ideas for room air conditioning units that do not significantly contribute to producing greenhouse gases, none of those options are yet on the market.
Dropped ceiling
In the event that the dropped ceiling is used as a plenum, low-voltage cables and wiring not installed inside conduit need to use a special low-smoke and low-toxicity wire insulation which will tend to char and stop burning on its own. This helps to protect building occupants so that they are not poisoned with toxic chemicals sucked through the ventilation system in the event of a fire, and helps to prevent fires from spreading inside the hidden plenum space. This special low-smoke cable is typically referred to as plenum cable or Low Smoke Zero Halogen (LSZH or LS0H) cable. While twisted pair cable for networking and telephone service is the most common form of plenum cable, coaxial cable also needs to be plenum-rated for safety.
Fan (machine)
Electric fans used for ventilation may be powered by solar panels instead of mains current. This is an attractive option because once the capital costs of the solar panel have been covered, the resulting electricity is free. In addition, electricity is always available when the sun is shining and the fan needs to run.
Fan coil unit
Speed control of the fan motors within a fan coil unit is partly used to control the heating and cooling output desired from the unit. Some manufacturers accomplish speed control by adjusting the taps on an AC transformer supplying the power to the fan motor. Typically this would require adjustment at the commissioning stage of the building construction process and is therefore set for life at a fixed speed. Other manufacturers provide custom-wound Permanent Split Capacitor (PSC) motors with speed taps in the windings, set to the desired speed levels for the fan coil unit design. A simple speed selector switch (Off-High-Medium-Low) is provided for the local room occupant to control the fan speed. Typically this speed selector switch is integral to the room thermostat, and is set manually or is controlled automatically by the digital room thermostat. Building Energy Management Systems can be used for automatic fan speed and temperature control. Fan motors are typically AC Shaded Pole or Permanent Split Capacitor. More recent developments include brushless DC designs with electronic commutation. Compared to units with asynchronous 3-speed motors, the fan coil units with brushless motors will reduce the power consumption up to 70%.
Air handler
Un-balanced fans wobble and vibrate. For home AC fans, this can be a major problem: air circulation is greatly reduced at the vents (as wobble is lost energy), efficiency is compromised, and noise is increased. Another major problem in fans that are not balanced is longevity of the bearings (attached to the fan and shaft) is compromised. This can cause failure to occur long before the bearings life expectancy.
Computer fan
Used to cool the heatsink of the graphics processing unit or the memory on graphics cards. These fans were not necessary on older cards because of their low power dissipation, but most modern graphics cards designed for 3D graphics and gaming need their own dedicated cooling fans. Some of the higher powered cards can produce more heat than the CPU (dissipating up to 289 watts), so effective cooling is especially important. Since 2010, graphics cards have been released with either axial fans, or a centrifugal fan commonly known as a blower, turbo or squirrel cage fan.
Computer fan
Standard axial case fans are 80, 92, 120, 140, 200 and 230 mm in width and length. As case fans are often the most readily visible form of cooling on a PC, decorative fans are widely available and may be lit with LEDs, made of UV-reactive plastic, and/or covered with decorative grilles. Decorative fans and accessories are popular with case modders. Air filters are often used over intake fans, to prevent dust from entering the case and clogging up the internal components. Heatsinks are especially vulnerable to being clogged up, as the insulating effect of the dust will rapidly degrade the heatsink's ability to dissipate heat.
Computer cooling
There is little agreement on the effectiveness of different fan placement configurations, and little in the way of systematic testing has been done. For a rectangular PC (ATX) case, a fan in the front with a fan in the rear and one in the top has been found to be a suitable configuration. However, AMD's (somewhat outdated) system cooling guidelines notes that "A front cooling fan does not seem to be essential. In fact, in some extreme situations, testing showed these fans to be recirculating hot air rather than introducing cool air." It may be that fans in the side panels could have a similar detrimental effect—possibly through disrupting the normal air flow through the case. However, this is unconfirmed and probably varies with the configuration.
Ceiling fan
The key components of a ceiling fan are the following:
HVAC
Demand controlled kitchen ventilation (DCKV) is a building controls approach of slowing down kitchen exhaust fans and subsequent supply air in response to the actual cooking loads in a commercial kitchen. Traditional commercial kitchen ventilation systems operate at 100% fan speed independent of the volume of cooking activity and DCKV technology changes that to provide significant fan energy and conditioned air savings. By deploying smart sensing technology, both the exhaust and supply fans can be controlled to capitalize on the Law of Affinity for motor energy savings, reduce makeup air heating and cooling energy, increasing safety and reducing ambient kitchen noise levels.
Ceiling fan
For heating, ceiling fans should usually be set to turn the opposite direction (usually clockwise; the blades should spin with the downward turned side leading) and on a low speed (or the lowest speed the fan is able to circulate the air down to the floor). Air naturally stratifies—that is, warmer air rises to the ceiling while cooler air sinks. Unfortunately, this means it is colder on or near the floor where human beings spend most of their time. A ceiling fan, with its direction of rotation set so that air is drawn upward, pulls up the colder air below, forcing the warmer air nearer the ceiling to move down to take its place, without blowing a stream of air directly at the occupants of the room. This action works to even out the temperature in the room, making it cooler nearer the ceiling, but warmer nearer the floor. Thus the thermostat in the area can be set a few degrees lower to save energy, while maintaining the same level of comfort. It is important to run the fan at a low speed (or a lowest speed the fan is able to circulate the air down to the floor) to minimize the wind chill effect described above. However if the ceiling is high enough, or the lowest speed downdraft would not create wind chill effect, it can be left on downdraft year around.
Ceiling protection switch
Ceiling protection switches are installed in secondary condensate drain pans in split system HVAC applications. The switch has a buoyant component that floats when the secondary condensate drain pan fills with water from the primary drain pan and shuts down the HVAC system to avoid overflowing. The ceiling protection switch is mainly used in applications where a piece of HVAC equipment is located in an attic or interior space where water damage is likely to occur. The switch does not guarantee the prevention of overflow, but may reduce the amount. Overflow water occurs when the condensate drain line becomes clogged restricting the flow of condensation from the interior to the exterior of the space. Overflow also occurs when an indoor HVAC coil becomes frozen, which when thaws creates excess water.
Chilled beam
The primary advantage of the chilled beam system is its lower operating cost. For example, because the temperature of cooled water is higher than the temperature of cooled air, but it delivers the same cooling ability, the costs of the cooled water system are lower. Because cooling and heating of air are no longer linked to the delivery of air, buildings also save money by being able to run fewer air circulation fans and at lower speeds. One estimate places the amount of air handled at 25 to 50 percent less using chilled beam systems. By being able to target the delivery of clean outdoor air where it is needed (rather than injecting it into the entire system and heating or cooling it), there is a reduced need to treat large amounts of outdoor air (also saving money). In one case, the Genomic Science Building at the University of North Carolina at Chapel Hill lowered its HVAC costs by 20 percent with an active chilled beam system. This is a typical energy cost savings. Chilled beam systems also have some advantages in that they are almost noiseless, require little maintenance, and are highly efficient. Traditional fan-driven HVAC systems create somewhat higher air velocities, which some people find uncomfortable. Chilled beam HVAC systems also require less ceiling space than forced-air HVAC systems, which can lead to lower building heights and higher ceilings. Since they do not require high forced air flows, chilled beam systems also require reduced air distribution duct networks (which also helps to lower cost).
High-volume low-speed fan
Commercial HVLS fans differ from residential ceiling fans with regard to diameter, rotational speed, and performance. While some fans use contemporary blades to move air, other methods are being used to make it more efficient such as using airfoils.
Exterior insulation finishing system
Research, conducted by the Oak Ridge National Laboratory and supported by the Department of Energy, has validated that EIFS are the "best performing cladding" in relation to thermal and moisture control when compared to brick, stucco, and cementitious fiberboard siding. In addition EIFS are in full compliance with modern building codes which emphasize energy conservation through the use of CI (continuous insulation) and a continuous air barrier. Both these components are built into today's EIFS products to provide maximum energy savings, reduced environmental impact over the life of the structure, and improved IAQ, Indoor Air Quality. Along with these functional advantages come virtually unlimited color, texture, and decorative choices to enhance curb appeal and enjoyment of almost any home or structure. 
EIFS before 2000 were barrier systems, meaning that the EIFS itself was the weather barrier. After 2000 the EIFS industry introduced the air/moisture barrier that resides behind the foam. In a study done by the Department Of Energy's Office of Science - Oak Ridge National Laboratory it was found that the best air/moisture barrier was a fluid barrier. The Oak Ridge National Laboratory, ATLANTA, Oct. 28, 2006 — EIFS "outperformed all other walls in terms of moisture while maintaining superior thermal performance." The National Institute of Standards and Technology (NIST) has evaluated the five life cycle stages of the environmental impact of EIFS alongside brick, aluminum, stucco, vinyl, and cedar. Depending on a variety of site and project specific conditions, EIFS have the potential to save money in construction costs and contribute toward energy efficient operations and environmental responsibility when correctly designed and executed.
Centrifugal fan
Centrifugal fans use the kinetic energy of the impellers to increase the volume of the air stream, which in turn moves them against the resistance caused by ducts, dampers and other components. Centrifugal fans displace air radially, changing the direction (typically by 90°) of the airflow. They are sturdy, quiet, reliable, and capable of operating over a wide range of conditions.
Centrifugal fan
Bearings are an important part of a fan. Sleeve-ring oil bearings are used extensively in fans. Some sleeve-ring bearings may be water-cooled. Water-cooled sleeve bearings are often used when the fan moves hot gases. Heat is conducted through the shaft and into the oil, which must be cooled to prevent overheating the bearing. Lower-speed fans have bearings in hard-to-reach spots, so they use grease-packed bearings.
Cellular shades
Windows and doors make up for approximately one-third of a home’s total thermal loss, according to the Natural Resources Defense Council. This applies to heat loss in winter, and entry of undesired heat in summer. When air inside the room comes in contact with windows, it is cooled or warmed. By convection this air then circulates around the room. Cell shapes in the blinds hold trapped air and create a barrier between the window surface and the room. Shades, however, provide only slight control of air infiltration.
Ceiling fan
Unlike air conditioners, fans only move air—they do not directly change its temperature. Therefore, ceiling fans that have a mechanism for reversing the direction in which the blades push air (most commonly an electrical switch on the unit's switch housing, motor housing, or lower canopy) can help in both heating and cooling.
Ceiling fan
An additional use of ceiling fans is coupling them with an air conditioning unit. Through-the-wall/through-the-window air conditioning units typically found in rented properties in North America usually have both the tasks of cooling the air inside the room and circulating it. Provided the ceiling fan is properly sized for the room in which it is operating, its efficiency of moving air far exceeds that of an air conditioning unit, therefore, for peak efficiency, the air conditioner should be set to a low fan setting and the ceiling fan should be used to circulate the air.
Radiant barrier
Radiant barriers are more effective in hot climates than in cooler/cold climates (especially when cooling air ducts are located in the attic). When the sun heats a roof, it's primarily the sun's radiant energy that makes the roof hot. Much of this heat travels by conduction through the roofing materials to the attic side of the roof. The hot roof material then radiates its gained heat energy onto the cooler attic surfaces, including the air ducts and the attic floor. A radiant barrier reduces the radiant heat transfer from the underside of the roof to the other surfaces in the attic. Some studies show that radiant barriers can reduce cooling costs 5% to 10% when used in a warm, sunny climate. The reduced heat gain may even allow for a smaller air conditioning system. In cool climates, however, it's usually more cost-effective to install more thermal insulation than to add a radiant barrier.
Heat recovery ventilation
Energy saving is one of the key issues for both fossil fuel consumption and protection of global environment.The rising cost of energy and the global warming underlined that developing of the improved energy systems is necessary to increase the energy efficiency while reducing greenhouse gas emissions. The most effective way to reduce energy demand is to use energy more efficiently. Therefore, waste heat recovery is becoming popular in recent years since it improves energy efficiency. About 26% of industrial energy is still wasted as hot gas or fluid in many countries. However, during last two decades there has been remarkable attention to recover waste heat from various industries and to optimize the units which are used to absorb heat from waste gases. Thus, these attempts enhance reducing of global warming as well as of energy demand.
Ceiling fan
Almost immediately he faced fierce competition due to the commercial success of the ceiling fan. He continued to make improvements to his invention and created a light kit fitted to the ceiling fan to combine both functions in one unit. By World War I most ceiling fans were made with four blades instead of the original two, which made fans quieter and allowed them to circulate more air. The early turn-of-the-century companies who successfully commercialized the sale of ceiling fans in the United States were the Hunter Brothers division of Robbins & Myers, Westinghouse Corporation and Emerson Electric.
Hashem Akbari
The UHI group in LBNL have monitored buildings in the California central valley with lightly colored, more reflective roofs and found that these buildings used up to 40% less energy for cooling than buildings with darker roofs. In a study funded by the U.S. Environmental Protection Agency, they carried out a detailed analysis of energy-saving potential of light-colored roofs in 11 U.S. metropolitan areas, with resulting estimated savings potential of about $175 million per year (1998 USD) for the 11 cities. Extrapolated national energy savings from air conditioning was estimated at $750 (1998 USD) million per year. The savings from shade trees and vegetation is also estimated at $1B per year. The impacts of savings in health and lost work time owing to a projected 12% O3 reduction are three times larger than that cited for air conditioning above. Heat island mitigation technologies apply all around the world in both developed and developing countries. They estimate that the potential energy savings and health benefits from a worldwide implementation of heat-island mitigation technologies can save over $10B per year. They are working with manufacturers of roofing and paving materials to develop ‘colored’ solar-reflective materials for the marketplace, including both dark and light-colored cool shingles with reflectivity of up to 60%.
Energy Conservation Program for Consumer Products
In order for consumers to better understand the different energy efficiencies and cost associated with appliance options, appliances must be labeled to give consumers this information. The appliances the must have this label are Ceiling Fans, Showerheads, Faucets, Water Closets, Urinals, Room Air Conditioners, Water Heaters (all types), Pool Heaters, Furnaces and Boilers, Clothes Washers, Freezers, Refrigerator-Freezers, Refrigerators, Heat Pumps, Central Air Conditioners, Dishwashers, and various types of lamps. The label must show the model number, the size, key features, and display largely a graph showing the annual operating cost in range with similar models, and the estimated yearly energy cost.
Air handler
Weights can be strategically placed to correct for a smooth spin (for a ceiling fan, trial and error placement typically resolves the problem). Home / central AC fans or other big fans are typically taken to shops, which have special balancers for more complicated balancing (trial and error can cause damage before the correct points are found). The fan motor itself does not typically vibrate.
Chilled beam
The chilled beam is distinguishable from the chilled ceiling. The chilled ceiling uses water flowing through pipes like a chilled beam does; however, the pipes in a chilled ceiling lie behind metal ceiling plates, and the heated or cooled plates are the cause of convection and not the pipe unit itself. Chilled beams are about 85 percent more effective at convection than chilled ceilings. The chilled ceiling must cover a relatively large ceiling area because it provides heating and cooling mainly by radiant, rather than convective, heat transfer.
Chilled beam
Active chilled beams are mounted in a suspended ceiling and then anchored to the overhead structure, because T-bar ceilings cannot support the typical operating weight of a chilled beam. They are generally wide, and require less than of overhead space. A typical wide chilled beam system generally weighs about per length of the beam. Chilled beams are generally installed so that the center of each beam is no more than from the center of the next beam. Some architects and end-users dislike the beams because they do not cover the entire ceiling so ducts, wiring, and other infrastructure can be seen. Some designers have installed one chilled beam system around the building perimeter (where temperature differences can be the greatest) and another in the interior of the building, to better control temperature throughout the structure. Higher system performance may be obtained by increasing the static pressure of the air in the building. The systems generally need little cleaning (vacuuming of dirt and dust from the fins every five years).
Radiant cooling
Radiant cooling panels are generally attached to ceilings, but can be attached to walls also. They are usually suspended from the ceiling, but can also be directly integrated with continuous dropped ceilings. Modular construction offers increased flexibility in terms of placement and integration with lighting or other electrical systems. Lower thermal mass compared to chilled slabs means they can’t easily take advantage of passive cooling from thermal storage, but controls in panels can more quickly adjust to changes in outdoor temperature. Chilled panels are also better suited to buildings with spaces that have a greater variance in cooling loads. Perforated panels also offer better acoustical dampening than chilled slabs. Ceiling panels are also very suitable for retrofits because they can be attached to any ceiling. Chilled ceiling panels can be more easily integrated with ventilation supplied from the ceiling. Panels tend to cost more per unit of surface area than chilled slabs.
Reflective surfaces (climate engineering)
Unlike other Energy Star-rated products, such as appliances, this rating system does not look at the entire roof assembly, but only the exterior surface. Consumers (i.e. building owners) may believe that the Energy Star label means their roof is energy-efficient; however, the testing is not as stringent as their appliance standard and does not include the additional components of a roof (i.e. roof structure, fire rated barriers, insulation, adhesives, fasteners, etc.). A disclaimer is posted on their website "Although there are inherent benefits in the use of reflective roofing, before selecting a roofing product based on expected energy savings consumers should explore the expected calculated results that can be found on the Department of Energy's "Roof Savings Calculator" website at www.roofcalc.com. Please remember the Energy Savings that can be achieved with reflective roofing is highly dependent on facility design, insulation used, climatic conditions, building location, and building envelope efficiency."
Reflective surfaces (climate engineering)
Specifically, what works in California’s Central Valley, such as cool roofs, does not necessarily provide the same benefits to other regions of the country, like Florida. Assessing consequences that extend beyond near surface temperatures, such as rainfall and energy demand, reveals important trade-offs that are often unaccounted for. Cool roofs have been found to be particularly effective for certain areas during summertime. However, during winter, these same urban adaptation strategies, when deployed in northerly locations, further cool the environment, and consequently require additional heating to maintain comfort levels. “The energy savings gained during the summer season, for some regions, is nearly entirely lost during the winter season,” Georgescu said. In Florida, and to a lesser extent southwestern states, there is a very different effect caused by cool roofs. “In Florida, our simulations indicate a significant reduction in precipitation," he said. "The deployment of cool roofs results in a 2 to 4 millimeter per day reduction in rainfall, a considerable amount (nearly 50 percent) that will have implications for water availability, reduced stream flow and negative consequences for ecosystems. For Florida, cool roofs may not be the optimal way to battle the urban heat island because of these unintended consequences.” Overall, the researchers suggest that judicious planning and design choices should be considered in trying to counteract rising temperatures caused by urban sprawl and greenhouse gases. They add that “urban-induced climate change depends on specific geographic factors that must be assessed when choosing optimal approaches, as opposed to one-size-fits-all solutions.”
Ceiling fan
The first rotary ceiling fans appeared in the early 1860s and 1870s in the United States. At that time, they were not powered by any form of electric motor. Instead, a stream of running water was used, in conjunction with a turbine, to drive a system of belts which would turn the blades of two-blade fan units. These systems could accommodate several fan units, and so became popular in stores, restaurants, and offices. Some of these systems survive today, and can be seen in parts of the southern United States where they originally proved useful.
Dedicated outdoor air system
Besides the advantages presented above, parallel radiant cooling panels offer other advantages as well, such as compact design, vertical shaft space area savings, and quick accommodation of dynamic controls. Energy savings in DOAS/radiant ceiling cooling panel system can by linked to: cooling coil load reduction, chiller energy reduction, pumping energy consumption and fan energy consumption reduction. In general, due to the total energy recovery and small supply air quantity of DOAS, the chiller energy consumption can be reduced significantly compared to the conventional VAV system. In a study of a pilot DOAS/radiant ceiling cooling panel system, hourly energy simulation predicts that the annual electrical energy consumption of the pilot DOAS/radiant panel cooling system is 42% less than that of the conventional VAV system with economizer control.
Economizer
Air-side economizers can reduce HVAC energy costs in cold and temperate climates while also potentially improving indoor air quality, but are most often not appropriate in hot and humid climates. With the appropriate controls, economizers can be used in climates which experience various weather systems. For information on how economizers and other controls can affect energy efficiency and indoor air quality in buildings, see the US Environmental Protection Agency report, "Energy Cost and IAQ Performance of Ventilation Systems and Controls Study."
Skyline Solar
The output of the PV system can be increased with improvements in cell efficiency, the use of trackers, concentration, and other more subtle engineering improvements. Tracking provides up to thirty percent more energy per peak Watt compared to fixed tilt (non-tracking) systems. Controlling the temperature of the cells in a CPV system is critical to high energy generation because higher cell temperatures reduce the output of the panel. Skyline Solar uses a combination of tracking, cooling fins, and reflectors to focus light on a single strip of silicon cells and maximize energy production.
Rooftop photovoltaic power station
A report released in June 2018 by the Consumer Energy Alliance (CEA) that analyzed U.S. solar incentives showed that a combination of federal, state and local incentives, along with the declining net cost of installing PV systems, has caused a greater usage of rooftop solar across the nation. According to "Daily Energy Insider", "In 2016, residential solar PV capacity grew 20 percent over the prior year, the report said. The average installed cost of residential solar, meanwhile, dropped 21 percent to $2.84 per watt-dc in the first quarter of 2017 versus first quarter 2015." In fact, in eight states the group studied, the total government incentives for installing a rooftop solar PV system actually exceeded the cost of doing so.
Electrostatic fluid accelerator
Potential advantages of EFA cooling devices include improvement on all these issues; EFA fans produce no vibration and have no parts to wear out. Their power consumption and airflow are controllable electronically, allowing them to be run in an optimal fashion to maximize cooling and efficiency. In particular, EFA fans can produce flow which is fairly laminar, and the velocity profile of the flow can be controlled to a much greater extent than conventional fans.
Control of the airflow may have the most important impact on cooling effectiveness. Electrostatically accelerated flows have been shown experimentally to alter the boundary layer along a fixed surface so that the heat transfer rate is increased, in some cases by more than twofold.
Computer fan
Fans may be mounted next to or onto a hard disk drive for cooling purposes. Hard drives can produce considerable heat over time, and are heat sensitive components that should not operate at excessive temperatures. In many situations, natural convective cooling suffices, but in some cases fans may be required. These may include -Fans are, less commonly, used for other purposes such as:Due to the low pressure, high volume air flows they create, most fans used in computers are of the axial flow type; centrifugal and crossflow fans type. Two important functional specifications are the airflow that can be moved, typically stated in cubic feet per minute (CFM), and static pressure. Given in decibels, the sound volume figure can be also very important for home and office computers; larger fans are generally quieter for the same CFM.
Ceiling
Ceilings have frequently been decorated with fresco painting, mosaic tiles and other surface treatments. While hard to execute (at least in place) a decorated ceiling has the advantage that it is largely protected from damage by fingers and dust. In the past, however, this was more than compensated for by the damage from smoke from candles or a fireplace. Many historic buildings have celebrated ceilings. Perhaps the most famous is the Sistine Chapel ceiling by Michelangelo.
Crawl space vent
Modern crawl space thinking has reconsidered the usage of crawl space vents in the home. While crawl space vents do allow outside air to ventilate into the home, the ability of that air to dry out the crawl space is debatable. In areas with humid summers, during the summer months, the air vented into a crawl space will be humid, and as it enters the crawl space, which has been cooled naturally by the earth, the relative humidity of the air will rise. In those cases, crawl space vents can even increase the humidity level of a crawl space and lead to condensation on cool surfaces within, such as metal and wood. In the winter, crawl space vents should be shut off entirely, to keep out the cold winter air which can cool hot water pipes, furnaces, and water heaters stored within. During rainy weather, crawl space vents bring wet air into the crawl space, which will not dry the space effectively.
Helicoidal Skyscraper
The Helicoidal Skyscraper can be considered a sustainable building or an example of the green architecture concept due to several aspects of its design. As a tall building, for instance, it addresses the energy problem by minimising the quantities of materials needed for its construction. Also, its unique logarithmic spiral would have reacted to the wind with a vertical force that drives it upwards, taking with the air pollution - out from the streets below. It avoids the capability of most tall buildings to serve as obstructions that affect the atmospheric circulation and the dispersion of pollutants. There is an expectation of the so-called "chimney effect," which eliminates the creation of an unpleasant micro-climate and the accumulation of pollution in the lower strata of the urban atmosphere by increasing the conviction currents created by the thermal distribution of solar heat on the external surfaces of the tower.
Power station
In areas with restricted water use, a dry cooling tower or directly air-cooled radiators may be necessary, since the cost or environmental consequences of obtaining make-up water for evaporative cooling would be prohibitive. These coolers have lower efficiency and higher energy consumption to drive fans, compared to a typical wet, evaporative cooling tower.
BG Group Place
Glass fins that act as sunshades reduce the building's need for air-conditioning. The 10-foot ceilings (a foot higher than the modern standard) allow in more sunlight, cutting the need for electric lights.
Solar-powered fan
It is similar to the roof mounted solar fan, except that its installation is a little different. Most attic fans are installed on the roof surface, whereas gable fans are installed in the gables, inside the attic and behind an existing louvered gable vent as the name suggests. They are mostly installed in places like greenhouse, cabin, RV's garages or barns and other storage places where heat and moisture are usually present. These types of fans are generally installed behind intake grills to provide ventilation. Gable Solar Fans are usually installed high on the gable close to the ridge and are also coupled with soffit or roof vents for well-balanced intake and exhaust air avenues. The airflow depends upon the level of sunlight when there is more sunlight, the airflow will be more resulting in enhanced cooling. It is also capable of lowering the air conditioning costs by cooling the attic.
Energy conservation
Building technologies and smart meters can allow energy users, both commercial and residential, to visualize the impact their energy use can have in their workplace or homes. Advanced real-time energy metering can help people save energy by their actions.
In passive solar building design, windows, walls, and floors are made to collect, store, and distribute solar energy in the form of heat in the winter and reject solar heat in the summer. This is called passive solar design or climatic design because, unlike active solar heating systems, it does not involve the use of mechanical and electrical devices.
High-volume low-speed fan
Typical applications for HVLS fans fall into two classifications—industrial and commercial. In industrial applications, air conditioning is often cost prohibitive or impractical. Fans installed in spaces like warehouses, barns, hangars and distribution centers can prevent heat stress, increase worker comfort and the productivity of both workers and livestock. HVLS fans are also used in commercial spaces, where air conditioning is more common, but increased air movement from ceiling fans can cost-effectively augment occupant comfort or prevent stratification. Typical commercial applications include shopping malls, churches, office buildings, airport terminal buildings, fitness centers and schools.
Bank of America Tower (Manhattan)
Temperature control and the production of some of its energy are accomplished in an environmentally friendly manner for the tower. Insulated glazing reduces thermal loss, lowering energy consumption and increasing transparency. Carbon dioxide sensors signal increased fresh air ventilation when elevated levels of carbon dioxide are detected in the building. Conditioned air for the occupants is provided by multiple air column units located in the tenant space that deliver 50 °F air into a raised access floor plenum. This underfloor air system provides users with the ability to control their own space temperature as well as improving the ventilation effectiveness. When building churn occurs, workstation moves can be performed more easily with lower cost and less product waste. The cooling system produces and stores ice during off-peak hours, and allows the ice to melt to help cool the building during peak load, similar to the ice batteries in the 1995 Hotel New Otani Tokyo in Japan. Ice batteries have been used since absorption chillers first made ice commercially available 150 years ago, before the invention of the electric light bulb.
Fan (machine)
Between 1882 and 1886 Schuyler Wheeler invented a fan powered by electricity. It was commercially marketed by the American firm Crocker & Curtis electric motor company. In 1882, Philip Diehl developed the world's first electric ceiling fan. During this intense period of innovation, fans powered by alcohol, oil, or kerosene were common around the turn of the 20th century.
In 1909, KDK of Japan pioneered the invention of mass-produced electric fans for home use. In the 1920s, industrial advances allowed steel fans to be mass-produced in different shapes, bringing fan prices down and allowing more homeowners to afford them. In the 1930s, the first art deco fan (the "swan fan") was designed. By the 1940s, Crompton Greaves of India became the world's largest manufacturer of electric ceiling fans mainly for sale in India, Asia and the Middle East. By the 1950s, table and stand fans were manufactured in colors that were bright and eye catching.
Space heater
However the metal reflectors needed to be fairly heavy gauge, and if the size was reduced then the metal housing would get too hot to be safe. In the mid-20th century, the cheapest heaters were radiative, but with the heating wires stretched relatively closely across a larger thin metal reflector separated from a thin metal housing. A small fan blew just enough air between the housing and the reflector to cool them; the main output to the room was the radiative heat and not the heated air. Having the heating wires stretched across a larger area meant that fewer expensive ceramic insulators were needed, and the small fan was cheaper than a larger or heavier housing.
Khoo Teck Puat Hospital
"Fins" along the building's walls are designed to channel the prevailing north-east winds into the building. Wind tunnel tests conducted at the National University of Singapore found that the "fins" would enhance the air flow by 20 to 30%. Sunshades over the windows protect patients from the direct glare of sunlight. The shades also re-direct light towards the ceiling to enhance the brightness of the wards and save on the use of energy. Large fans in public areas are powered by solar panels on the roof. The air-conditioning system draws supply air from its internal courtyards, where the air is cooler, hence reducing the cooling loads.
Climate change mitigation
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. Installing LED lighting, fluorescent lighting, or natural skylight windows reduces the amount of energy required to attain the same level of illumination compared to using traditional incandescent light bulbs. Compact fluorescent lamps use only 33% of the energy and may last 6 to 10 times longer than incandescent lights. LED lamps use only about 10% of the energy an incandescent lamp requires.
Computer cooling
Fewer fans but strategically placed will improve the airflow internally within the PC and thus lower the overall internal case temperature in relation to ambient conditions. The use of larger fans also improves efficiency and lowers the amount of waste heat along with the amount of noise generated by the fans while in operation.
ENERPOS
- Ceiling fans 11%
Computer fan
While the power supply (PSU) contains a fan with few exceptions, it is not to be used for case ventilation. The hotter the PSU's intake air is, the hotter the PSU gets. As the PSU temperature rises, the conductivity of its internal components decrease. Decreased conductivity means that the PSU will convert more of the input electric energy into thermal energy (heat). This cycle of increasing temperature and decreased efficiency continues until the PSU either overheats, or its cooling fan is spinning fast enough to keep the PSU adequately supplied with comparatively cool air. The PSU is mainly bottom-mounted in modern PCs, having its own dedicated intake and exhaust vents, preferably with a dust filter in its intake vent.
Tile
Ceiling tiles also provide a barrier to the spread of smoke and fire. Breaking, displacing, or removing ceiling tiles enables hot gases and smoke from a fire to rise and accumulate above detectors and sprinklers. Doing so delays their activation, enabling fires to grow more rapidly.
Ventilation (architecture)
With the advent of practical steam power, fans could finally be used for ventilation. Reid installed four steam powered fans in the ceiling of St George's Hospital in Liverpool, so that the pressure produced by the fans would force the incoming air upward and through vents in the ceiling. Reid's pioneering work provides the basis for ventilation systems to this day. He was remembered as "Dr. Reid the ventilator" in the twenty-first century in discussions of energy efficiency, by Lord Wade of Chorlton.
Natural ventilation
While natural ventilation eliminates electrical energy consumed by fans, overall energy consumption of natural ventilation systems is often higher than that of modern mechanical ventilation systems featuring heat recovery. Typical modern mechanical ventilation systems use as little as 2000 J/m3 for fan operation, and in cold weather they can recover much more energy than this in the form of heat transferred from waste exhaust air to fresh supply air using recuperators.
Spray foam
The insulation at eaves level will leave your loft area comfortable for use and free from condensation. By installing the insulation at rafter level, it keeps the loft void warmer and prevents condensation build-up, which can otherwise occur when increasing insulation at ceiling level. The warmer, drier, cleaner roof space eliminates the risk of pipes and tanks freezing.
Popcorn ceiling
Since the mid-2000s, the popularity for textured popcorn ceilings has diminished significantly across North America. A movement towards more modern, clean lined design features has influenced home imporvement professionals to provide popcorn ceiling removal services. This feature has a multitude of benefits over the textured ceiling, such as its association with a high-end asthetic, it multiplies natural light throughout the space, it does not harbor dust and allergens (only to be re-introduced into the air), easier patching and touching up after a drywall repair, etc. The process can be difficult to execute for the average do-it-yourself home owner, as it requires skim-coating techniques often only mastered by experienced plasterers. Several coats should be adminstered to achieve a level smooth surface ready to be sealed and painted. The final cost is usually quite high, thus being less favorable to new construction builders, and sourced by homeowners looking to add value to their properties.
Air door
Air curtains consume electrical energy during their operation, but can be used for net energy savings by reducing the heat transfer (via mass transfer when air mixes across the threshold) between two spaces. However, a closed and well-sealed physical door is much more effective in reducing energy loss. Both technologies are often utilized in tandem; when the solid door is opened the air curtain turns on, minimizing air exchange between inside and outside.
Thermal destratification
Axial destratification fans are self-contained units that are installed in an array at the ceiling with the goal of blowing conditioned air in the ceiling down to the floor, where people live and work. Because axial fans are designed to blow air straight down at the floor, they can be used in ceiling and roof structures over 100 ft. tall. Because axial destratification fans can achieve destratification with low CFMs, it is imperative that the air leaving the nozzle achieve an air speed at the floor of between 0.2 and 0.5 m/s. The result of this level of air movement is the integration of conditioned air from the ceiling with air at the floor level. Failing to impact the floor will result in destratification of medial layers of air but not achieve destratification at the floor. Since the area around the thermostat will not be destratified in this instance, it is hypothesized that there will be little or no cost savings, as the thermostat will continue to overheat or overcool the room.
Computer fan
Fans may be controlled by sensors and circuits that reduce their speed when temperature is not high, leading to quieter operation, longer life, and lower power consumption than fixed-speed fans. Fan lifetimes are usually quoted under the assumption of running at maximum speed and at a fixed ambient temperature.
Air source heat pumps
All-electric heat pump systems have an electric furnace or electric resistance heat, or strip heat, which typically consists of rows of electric coils that heat up. A fan blows over the heated coils and circulates warm air throughout the home. This serves as an adequate heating source, but as temperatures go down, electricity costs rise. Electrical service outages pose the same threat as to central forced-air systems and pump-based boilers, but woodstoves and non-electric fireplace inserts can mitigate this risk. Some ASHPs can be coupled to solar panels as primary energy source, with a conventional electric grid as backup source.
Attic fan
A powered attic ventilator, or attic fan, is a ventilation fan which regulates the heat level of a building's attic by exhausting hot air. A thermostat is used to automatically turn the fan off and on, while sometimes a manual switch is used. An attic fan can be gable mounted or roof mounted. Additional vents are required to draw in fresh air as the hot air is exhausted. Attic fans are typically used in warmer months, when temperatures in an attic can exceed . A fan may be installed in an attic for the different purpose of cooling a whole house, venting hot air out via the attic; such fans are often called whole-house fans.
HVAC
Ceiling fans and table/floor fans circulate air within a room for the purpose of reducing the perceived temperature by increasing evaporation of perspiration on the skin of the occupants. Because hot air rises, ceiling fans may be used to keep a room warmer in the winter by circulating the warm stratified air from the ceiling to the floor.
Solar air conditioning
There are new non-compressor-based electrical air conditioning systems with a SEER above 20 coming on the market. New versions of phase-change indirect evaporative coolers use nothing but a fan and a supply of water to cool buildings without adding extra interior humidity (such as at McCarran Airport Las Vegas Nevada). In dry arid climates with relative humidity below 45% (about 40% of the continental U.S.) indirect evaporative coolers can achieve a SEER above 20, and up to SEER 40. A 100,000 BTU indirect evaporative cooler would only need enough photovoltaic power for the circulation fan (plus a water supply).
Ceiling fan
Another concern with installing a ceiling fan relates to the height of the blades relative to the floor. Building codes throughout the United States prohibit residential ceiling fans from being mounted with the blades closer than seven feet from the floor; this sometimes proves, however, to not be high enough. If a ceiling fan is turned on and a person fully extends his or her arms into the air, as sometimes happens during normal tasks such as stretching or changing bedsheets, it is possible for the blades to strike their hands, potentially causing injury. Also, if one is carrying a long and awkward object, one end may inadvertently enter the path of rotation of a ceiling fan's blades, which can cause damage to the fan. Building codes throughout the United States also prohibit industrial ceiling fans from being mounted with the blades closer than 10 feet from the floor for these reasons.
Attic fan
Because an attic fan is made of metal, and is also subject to lightning strikes if mounted on a roof, grounding is extremely important. On some attic fans, grounding is achieved through a screw mounted on the thermostat box of the attic fan. The grounding wire is attached to the box via the screw and thereby grounds the external metal components. Most modern attic fans have this as well as a grounding wire connected directly to the motor, thereby ensuring all parts are grounded.
Vent-Axia
Vent-Axia introduced the world’s first Safety Extra Low Voltage (SELV) fan in 1992. SELV was designed for the extra safety that is required in domestic bathrooms. Recently, the company has introduced a range of LoCarbon domestic fans, using DC motors which reduce energy consumption by up to 90%, when compared to variants using AC motors. In 2017, the company released their new Positive Input Ventilation (PIV) unit titled "PoziDry Pro".
Calvin D. MacCracken
MacCracken is best known for his work in energy storage and ice rinks. He developed the IceBank® energy storage system, a form of thermal energy storage used to cool buildings by making ice at night when electricity rates are less expensive. IceBank® energy storage functions like a battery for a building's air-conditioning system. IceBank® saves dramatically on the cost to cool buildings by reducing a building's on-peak use of electricity. The IceBank ice battery system uses standard cooling equipment plus an energy storage tank to shift all or a portion of a building's cooling needs to off-peak, nighttime hours. During off-peak hours, ice is made and stored inside IceBank energy storage tanks. The stored ice is then used to cool the building the next day. IceBank® offers a critical service to grid, since air-conditioning is the main culprit behind spikes in peak electrical demand. This on-peak reduction decreases the need to build new power plants or turn on expensive “peaker” power plants. Over 1GW of IceBank energy storage is used in over 4,000 installations in 60 countries for commercial buildings, schools, government buildings, hospitals, hotels and retail.
Efficient energy use
A deep energy retrofit is a whole-building analysis and construction process that uses to achieve much larger energy savings than conventional energy retrofits. Deep energy retrofits can be applied to both residential and non-residential (“commercial”) buildings. A deep energy retrofit typically results in energy savings of 30 percent or more, perhaps spread over several years, and may significantly improve the building value. The Empire State Building has undergone a deep energy retrofit process that was completed in 2013. The project team, consisting of representatives from Johnson Controls, Rocky Mountain Institute, Clinton Climate Initiative, and Jones Lang LaSalle will have achieved an annual energy use reduction of 38% and $4.4 million. For example, the 6,500 windows were remanufactured onsite into superwindows which block heat but pass light. Air conditioning operating costs on hot days were reduced and this saved $17 million of the project's capital cost immediately, partly funding other retrofitting. Receiving a gold Leadership in Energy and Environmental Design (LEED) rating in September 2011, the Empire State Building is the tallest LEED certified building in the United States.
The Indianapolis City-County Building recently underwent a deep energy retrofit process, which has achieved an annual energy reduction of 46% and $750,000 annual energy saving.
Radiant barrier
According to a 2010 study by the Building Envelope Research Program of the Oak Ridge National Laboratory, homes with air-conditioning duct work in the attic in the hottest climate zones, such as in the US Deep South, could benefit the most from radiant barrier interventions, with annual utility bill savings up to $150, whereas homes in milder climates, e.g., Baltimore, could see savings about half those of their southern neighbors. On the other hand, if there are no ducts or air handlers in the attic, the annual savings could be even much less, from about $12 in Miami to $5 in Baltimore. Nevertheless, a radiant barrier may still help to improve comfort and to reduce the peak air-conditioning load.
Skyscraper
Skyscrapers have considerable mass, which means that they must be built on a sturdier foundation than would be required for shorter, lighter buildings. Building materials must also be lifted to the top of a skyscraper during construction, requiring more energy than would be necessary at lower heights. Furthermore, a skyscraper consumes a lot of electricity because potable and non-potable water has to be pumped to the highest occupied floors, skyscrapers are usually designed to be mechanically ventilated, elevators are generally used instead of stairs, and natural lighting cannot be utilized in rooms far from the windows and the windowless spaces such as elevators, bathrooms and stairwells.
Reflective surfaces (climate engineering)
According to the US DOE’s "Guidelines for Selecting Cool Roofs":
“Cool roofs must be considered in the context of your surroundings. It is relatively easy to specify a cool roof and predict energy savings, but some thinking ahead can prevent other headaches. Ask this question before installing a cool roof: Where will the reflected sunlight go?
A bright, reflective roof could reflect light and heat into the higher windows of taller neighboring buildings. In sunny conditions, this could cause uncomfortable glare and unwanted heat for you or your neighbors. Excess heat caused by reflections increases air conditioning energy use, negating some of the energy saving benefits of the cool roof.”
Fan death
Air movement will increase sweat evaporation, which cools the body. But in extreme heat – when the blown air is warmer than the body's temperature – it will increase the heat stress placed on the body, potentially speeding the onset of heat exhaustion and other detrimental conditions. The American Environmental Protection Agency (EPA) discourages people from using fans in closed rooms without ventilation when the heat index is above . The EPA does, however, approve of using a fan if a window is open and it is cooler outside, or when the heat index in a closed room is lower.
Ceiling fan
The electrically powered ceiling fan was invented in 1882 by Philip Diehl. He had engineered the electric motor used in the first electrically powered Singer sewing machines, and in 1882 he adapted that motor for use in a ceiling-mounted fan. Each fan had its own self-contained motor unit, with no need for belt drive.
Energy conservation in the United States
As furnace efficiency gets higher, appropriate matching of equipment size to distribution system capacity and building load becomes more critical to optimizing equipment ability to maximize efficient operation. Installing much lower output high-efficiency replacement equipment offers opportunity for comfort and savings gains, but improving the building envelope through air sealing and adding more insulation, advanced windows, etc., should be explored concurrently or before replacement equipment design stage. The passive house approach produces superinsulated buildings that approach zero net energy consumption. Improving the building envelope can also be cheaper than replacing a furnace or air conditioner.
Centrifugal fan
Backward-curved fans are much more energy efficient than radial blade fans and so, for high power applications may be a suitable alternative to the lower cost radial bladed fan.
Thermal destratification
An experiment in a room with a 21 ft. ceiling yielded a savings of 23.5% with the use of axial destratification fans.
Ventilative cooling
Ventilative cooling is the use of natural or mechanical ventilation to cool indoor spaces. The use of outside air reduces the cooling load and the energy consumption of these systems, while maintaining high quality indoor conditions. Ventilative cooling strategies are applied in a wide range of buildings and may even be critical to realize renovated or new high efficient buildings and zero-energy buildings (ZEBs) . Ventilation is present in buildings mainly for air quality reasons. It can be used additionally to remove both excess heat gains, as well as increase the velocity of the air and thereby widen the thermal comfort range. Ventilative cooling is assessed by long-term evaluation indices .Ventilative cooling is dependent on the availability of appropriate external conditions and on the thermal physical characteristics of the building.
Computer fan
Used to aerate the case of the computer. The components inside the case cannot dissipate heat efficiently if the surrounding air is too hot. Case fans move air through the case, usually drawing cooler outside air in through the front or bottom (where it may also be drawn over the internal hard drive racks) and expelling it through the top or rear. Some ATX tower cases have one or more vents and mounting points in the left side panel where one or more fans may be installed to blow cool air directly onto the motherboard components and expansions cards, which are ones of the largest heat sources.
Solar air conditioning
Earth cooling tubes are not cost effective in hot humid tropical environments where the ambient Earth temperature approaches human temperature comfort zone. A solar chimney or photovoltaic-powered fan can be used to exhaust undesired heat and draw in cooler, dehumidified air that has passed by ambient Earth temperature surfaces. Control of humidity and condensation are important design issues.
Efficient energy use
A building's location and surroundings play a key role in regulating its temperature and illumination. For example, trees, landscaping, and hills can provide shade and block wind. In cooler climates, designing northern hemisphere buildings with south facing windows and southern hemisphere buildings with north facing windows increases the amount of sun (ultimately heat energy) entering the building, minimizing energy use, by maximizing passive solar heating. Tight building design, including energy-efficient windows, well-sealed doors, and additional thermal insulation of walls, basement slabs, and foundations can reduce heat loss by 25 to 50 percent.
Thermal destratification
Because of their size, HVLS fans are normally installed in new construction, rather than retrofits, as the roof structure may have to be redesigned to accommodate the increased weight and size. It's not uncommon to require the relocation of lights, due to strobing as large fan blades pass under them, and sprinkler systems, which typically require unobstructed access to the floor to meet fire code. When used in the summer to encourage evaporative cooling, HVLS fans are run forward, blowing air at the floor. When used for destratification in the winter, the fans are run in reverse, blowing air towards ceiling which then circulates around the room. The height at which HVLS fans can be effective is limited compared to axial destratification fans.
Roof garden
A study at the National Research Council of Canada showed the differences between roofs with gardens and roofs without gardens against temperature. The study shows temperature effects on different layers of each roof at different times of the day. Roof gardens are obviously very beneficial in reducing the effects of temperature against roofs without gardens. “If widely adopted, rooftop gardens could reduce the urban heat island, which would decrease smog episodes, problems associated with heat stress and further lower energy consumption.”
Air conditioning
Advantages of the ductless system include smaller size and flexibility for zoning or heating and cooling individual rooms. The inside wall space required is significantly reduced. Also, the compressor and heat exchanger can be located farther away from the inside space, rather than merely on the other side of the same unit as in a PTAC or window air conditioner. Flexible exterior hoses lead from the outside unit to the interior one(s); these are often enclosed with metal to look like common drainpipes from the roof. In addition, ductless systems offer higher efficiency, reaching above 30 SEER.
Federal roofing tax credit for energy efficiency
The 2009 roofing tax credit is part of a twofold plan rolled out by the US federal government. The first and most relevant of goals was intended to stimulate the economy by motivating Americans to replace their roofs with more energy efficient roofs, thereby creating jobs by increasing the demand for labor in the roofing, manufacturing, and construction industries. The other goal of the 2009 federal roofing tax credit was to reduce carbon emissions to the environment by requiring consumers to install Energy Star products on their homes in order to receive the tax credit; the installation of energy star roofing products in homes would reduce the consumption of electricity needed to maintain the desired temperature within the residence.
Woodside Plaza
The tower is noted for its efforts towards efficient energy use. For instance, the building's air conditioning plant utilises variable-speed fans to consume less energy when extra cooling is unnecessary, and the floors are divided into several air conditioning zones. Internal lighting dims when natural ambient light is brighter, and the heat load of the building is reduced through the use of "low emissivity" glass on the building's facade. The building also implements water-saving measures through the installation in early 2008 of waterless urinals, saving an estimated of water each year.
Fan (machine)
Window and central air conditioning in the 1960s caused many companies to discontinue production of fans. But in the mid 1970s, with an increasing awareness of the cost of electricity and the amount of energy used to heat and cool homes, turn-of-the-century styled ceiling fans became immensely popular again as both decorative and energy efficient units.
Federal roofing tax credit for energy efficiency
It is an advisable idea to utilize materials that will reduce the heat of a homeowner's residence to reduce their energy consumption and their impact on the environment. But not all consumers will derive the same benefit from the use of a reflective heat-reducing roofs in reducing energy consumption.
Dedicated outdoor air system
Compared to other sensible cooling systems, radiant ceiling cooling panels are the best parallel system choice for use with the DOAS. Because the DOAS only accommodates the space ventilation and latent loads, it provides an opportunity to reduce the required floor-to-floor height by reducing the size of the duct system and the required fan power. There are numerous advantages of a radiant ceiling cooling system coupled with a DOAS. The general evaluation section in 2008 ASHRAE Handbook gives a brief description as follows:
Reflective surfaces (climate engineering)
In October 2013, the United States Department of Energy ranked Cool Roofs as a 53 out of 100 (0 to 100 weighted average) for a cost effective energy strategy. "Climate issues can affect cool roof performance. Cool roofs are more beneficial in warmer climates and may cause energy consumption for heating applications to rise in colder climates. Cool roofs have a lower impact the more insulation is used. The Secretary of Energy directed all U.S. Department of Energy (DOE) offices to install cool roofs, when life-cycle cost effectiveness is demonstrated, when constructing new roofs, or when replacing old roofs at DOE facilities. Other Federal agencies were also encouraged to do the same."
General Electric GE9X
The GE9X should increase fuel efficiency by 10% over the GE90. Its 61:1 overall pressure ratio should help provide a 5% lower thrust specific fuel consumption (TSFC) than the XWB-97 with maintenance costs comparable to the GE90-115B The initial thrust of will be followed by derated variants.
GE invested more than $2 billion for its development, its nacelle is wide.
Most efficiency increase comes from the better propulsion efficiency of the higher-bypass-ratio fan. The bypass ratio is planned for 10:1. The fan diameter is . It has only 16 blades, whereas the GE90 has 22 and the GEnx has 18. This makes the engine lighter, and allows the low pressure (LP) fan and booster to spin faster to better match its speed with the LP turbine. The fan blades feature steel leading edges and glass-fibre trailing edges to better absorb bird impacts with more flexibility than carbon fiber. Fourth generation carbon fiber composite materials, comprising the bulk of the fan blades, make them lighter, thinner, stronger, and more efficient. Using a composite fan case will also reduce weight.
The high pressure (HP) compressor is up to 2% more efficient. As the GE90 fan left little room to improve the bypass ratio, GE looked for additional efficiency by upping the overall pressure ratio from 40 to 60, focusing on boosting the high-pressure core's ratio from 19:1 to 27:1 by using 11 compressor stages instead of 9 or 10, and a third-generation, twin-annular pre-swirl (TAPS) combustor instead of the previous dual annular combustor. Able to endure hotter temperatures, ceramic matrix composites (CMC) are used in two combustor liners, two nozzles, and the shroud up from the CFM International LEAP stage 2 turbine shroud. CMCs are not used for the first-stage turbine blades, which have to endure extreme heat and centrifugal forces. These are improvements planned for the next iteration of engine technology.
The first-stage HP turbine shroud, the first- and second-stage HP turbine nozzles and the inner and outer combustor linings are made from CMCs, only static components, operating hotter than nickel alloys with some cooling. CMCs have twice the strength and one-third the weight of metal. The compressor is designed with 3D aerodynamics and its first five stages are blisks, combined bladed-disk. The combustor is lean burning for greater efficiency and 30% NOx margin to CAEP/8. The compressor and high pressure turbine are made from powdered metal. The low-pressure turbine airfoils made of titanium aluminide (TiAl) are stronger, lighter, and more durable than nickel-based parts. 3D printing is used to manufacture parts that would otherwise be impossible to make using traditional manufacturing processes. CMCs need 20% less cooling.