Fixing Rattling Noises in Cooling Systems

Fixing Rattling Noises in Cooling Systems

central heating unit

Identifying Causes of Rattling Noises in Cooling Systems


Cooling systems are integral to the efficient operation of various machines and appliances, from industrial setups to household refrigerators. However, one common issue that can plague these systems is the presence of rattling noises. These noises are not merely an annoyance; they often signal underlying problems that require prompt attention to prevent further damage or inefficiency. Identifying the causes of these rattling sounds is crucial for effective troubleshooting and repair.


One of the primary causes of rattling noises in cooling systems is loose components. Over time, the constant vibration and movement inherent in a cooling system can cause screws, bolts, or other fasteners to loosen. This results in parts shifting slightly out of place and creating noise as they move against each other or their housing. Postponing HVAC Repair can lead to reduced system efficiency and higher power bills HVAC repair to improve your home's ventilation and air quality. Regular maintenance checks can help ensure that all components remain securely fastened, thereby reducing this risk.


Another potential source of rattling is worn-out or damaged fan blades. Fans play a critical role in regulating temperature within cooling systems by circulating air efficiently. When fan blades become damaged-perhaps due to debris ingress or long-term wear-they may produce rattling sounds as they spin unevenly or wobble on their axis. Inspecting fan blades for signs of wear and replacing them if necessary can alleviate this problem.


Pipes and tubes within cooling systems can also be culprits behind rattling noises. As fluids circulate through these conduits, any instability or improper installation might cause them to vibrate excessively against surrounding structures. Ensuring that pipes are correctly secured with appropriate brackets or clamps will minimize movement and reduce noise production.


Additionally, the compressor-a vital component responsible for circulating refrigerant throughout the system-can be a source of rattling if it becomes faulty or starts malfunctioning. A failing compressor may exhibit irregular vibrations that translate into unsettling noises. Diagnosing a compressor issue often requires professional expertise because it involves handling refrigerants and intricate electrical components.


Finally, external factors should not be overlooked when identifying causes of rattling sounds in cooling systems. Environmental elements such as debris accumulation around outdoor units can lead to obstructions that interfere with normal operations, causing various parts to rattle as they struggle against these impediments.


In conclusion, while rattling noises in cooling systems might seem like minor nuisances at first glance, they often indicate deeper issues needing attention. By systematically examining each potential source-from loose components to external factors-technicians and users alike can effectively diagnose problems and implement solutions that restore peace and functionality to their systems. Regular maintenance coupled with keen observation remains key in preventing these disturbances from escalating into more significant concerns over time.

When tackling the issue of rattling noises in cooling systems, safety precautions before inspection and repair cannot be overstated. Rattling noises often indicate underlying issues that could range from minor to significant, and addressing them requires a careful approach. Ensuring safety not only protects the technician but also preserves the integrity of the cooling system.


First and foremost, it is essential to power down the entire cooling system before beginning any inspection or repair work. This precaution helps prevent electrical shocks or other accidents that could occur if the system were inadvertently activated during the process. Disconnecting the power source entirely ensures there is no risk of accidental engagement.


Wearing appropriate personal protective equipment (PPE) is another vital step. This includes safety goggles to protect eyes from debris or refrigerant leaks, gloves to shield hands from sharp components or chemicals, and possibly ear protection if noise levels are high during operation checks. The use of PPE acts as a physical barrier against potential hazards encountered during inspection and repair tasks.


Before delving into repairs, it is crucial to allow sufficient time for any residual energy in capacitors within the cooling system to dissipate completely. Capacitors can hold charge even when disconnected from their power sources, posing a risk of electric shock if handled too soon after powering down.




Fixing Rattling Noises in Cooling Systems - Cleanser

  1. heat pump
  2. Mobile
  3. gas

Additionally, ventilation should be prioritized when working with cooling systems. Many contain refrigerants that can be harmful if inhaled in concentrated amounts. Ensuring good airflow in the workspace minimizes exposure risks and contributes to a safer working environment.


Another important consideration is having a clear understanding of the system's schematics and operating procedures. Familiarity with these documents aids in identifying problem areas accurately without unnecessary tampering with parts that could lead to further issues or voiding warranties.


Lastly, maintaining an organized workspace helps mitigate risks associated with tripping hazards or misplaced tools that could cause injury or damage components of the cooling system during repairs.


In summary, thorough preparation and adherence to safety precautions are fundamental when dealing with rattling noises in cooling systems. These measures not only safeguard individuals performing inspections and repairs but also enhance efficiency by preventing additional complications that might arise from neglecting proper protocols. Safety remains at the forefront as we strive for effective resolution of any mechanical discord within our essential cooling systems.

Citations and other links

Inspecting External Components for Loose Parts

When it comes to the smooth operation of cooling systems, one of the most common nuisances that can arise is the presence of rattling noises. These unsettling sounds not only disrupt the peaceful ambiance but may also indicate underlying issues that require attention. One crucial aspect in addressing and fixing these rattling noises involves inspecting external components for loose parts.


Cooling systems, whether installed in residential settings or industrial environments, are complex assemblies comprising various external components such as fans, ducts, grills, and panels. Over time, through continuous operation or due to external factors like vibrations or impacts, these components can become loosened. When left unchecked, even a minor loose part has the potential to cause significant noise and lead to more severe damage.


The process of inspecting external components begins with a thorough visual examination. This step involves carefully observing each element of the cooling system while it operates. By doing so, you can identify any visible signs of looseness or misalignment that may be contributing to the rattling noise. Components like screws, bolts, and brackets should be scrutinized for any indications that they have been jarred out of their secure positions.


In addition to visual inspection, a tactile approach is also beneficial. Gently touching and wiggling parts such as fan blades or protective grills while the system is off can reveal any instability that might not be immediately apparent just by looking. Listen closely during this process; sometimes even subtle movements can produce telltale clinks or taps indicative of a problem area.


Once potential sources of looseness are identified, tightening them securely becomes imperative. Using appropriate tools like screwdrivers and wrenches ensures that each component is fastened according to its specifications without over-tightening which could cause additional stress on other parts.


Furthermore, periodically checking for wear and tear on rubber grommets or insulators is important because these small items play a critical role in damping vibrations between metal surfaces and preventing unnecessary noise.


Regular maintenance routines should incorporate these inspections as preventative measures against future occurrences of rattling noises in cooling systems. Consistent upkeep helps maintain optimal performance levels while extending equipment life expectancy-saving both time and money by avoiding costly repairs down the line.


In conclusion, inspecting external components for loose parts forms an essential part when addressing rattling noises within cooling systems efficiently. Through vigilant observation combined with routine maintenance practices aimed at securing all elements tightly into place; one can ensure quieter operations aligned with long-term reliability goals-a win-win situation benefiting both users' comfort level indoors alongside safeguarding valuable investments made towards effective climate control solutions!

Inspecting External Components for Loose Parts

Checking Internal Components: Fans, Blades, and Motors

When dealing with cooling systems, few issues are as frustrating and potentially alarming as the presence of rattling noises. These disturbances not only disrupt the tranquility of an environment but can also signal underlying problems that, if left unaddressed, might lead to larger mechanical failures. Understanding the internal components-specifically fans, blades, and motors-can be pivotal in diagnosing and fixing these unsettling sounds.


The fan is often the first component to inspect when addressing rattling noises. Fans play a crucial role in maintaining airflow within cooling systems, ensuring that heat is effectively dissipated from the unit. Over time, dust and debris can accumulate on fan blades, leading to imbalances that cause vibrations and rattles during operation. Regular cleaning can often remedy this issue. Additionally, checking for any physical damage or warping in the blades is essential; even slight deformities can disrupt balance and create noise.


Beyond cleanliness and damage, one must consider the security of the fan assembly itself. Loose screws or brackets can result in an unstable installation where vibrations are transferred to other parts of the unit, amplifying noise levels significantly. Ensuring all components are tightly secured helps maintain optimal performance and minimizes unnecessary sound.


While addressing fan-related issues might solve many rattling problems, one must not overlook the motor-the powerhouse driving the entire system. A motor's condition is critical because its performance directly affects how smoothly other components operate. Worn-out bearings within a motor can lead to friction-heavy movement which manifests audibly as rattling or grinding noises. In such cases, lubricating or replacing bearings may be necessary to restore quiet operation.


Furthermore, electrical imbalances within a motor could also contribute to irregular functioning that results in noise production. Ensuring proper voltage supply and inspecting wiring for wear or corrosion are prudent steps in maintaining overall system health.


In conclusion, fixing rattling noises in cooling systems involves a meticulous examination of internal components like fans, blades, and motors.

Fixing Rattling Noises in Cooling Systems - central heating unit

  1. central heating unit
  2. South Carolina
  3. Cleanser
Regular maintenance practices such as cleaning debris from fans and ensuring secure installations go hand-in-hand with more technical inspections like bearing checks within motors. By understanding each component's role in potential noise creation-and addressing issues promptly-one ensures not only quieter operations but also prolongs the lifespan of their cooling system while preventing minor inconveniences from snowballing into major repairs down the line.

Solutions for Securing or Replacing Faulty Parts

Fixing rattling noises in cooling systems can often feel like chasing an elusive gremlin that seems to evade detection just when you think you've pinpointed its source. Yet, addressing these disturbances is crucial not only for maintaining the efficiency of the system but also for preventing potential damage that could lead to more costly repairs. Understanding the root causes of these noises and implementing effective solutions can transform a frustrating problem into a manageable task.


Rattling noises in cooling systems are often symptomatic of underlying issues, typically originating from loose or faulty parts within the system's intricate network. These components work in concert to ensure optimal performance, but even a minor fault can disrupt harmony, leading to vibrations and noise. The first step towards resolving such issues is identifying the precise cause. This might involve a thorough inspection, where each component-from fans and compressors to ducts and mounts-is examined for wear and tear, loose fittings, or misalignment.


Once identified, securing or replacing faulty parts becomes imperative. For example, if the noise is traced back to a loose fan blade or mount, tightening screws and ensuring secure attachments can immediately resolve the issue. Conversely, if parts are damaged beyond repair-such as cracked fan blades or worn-out bearings-replacement becomes necessary. Investing in high-quality replacement parts not only resolves current issues but also enhances system longevity.


In some cases, rattling may stem from external factors such as debris caught within the system or insufficient lubrication of moving parts. Regular maintenance routines can preemptively address these concerns before they escalate into audible disturbances. Cleaning out accumulated debris and applying appropriate lubricants ensures smoother operation and reduces friction-induced vibrations.


Furthermore, upgrading certain elements of the cooling system can offer long-term solutions against rattling noises. Modern components designed with noise reduction technology minimize operational sound levels while maintaining efficiency. This proactive approach not only addresses existing issues but also contributes to creating a quieter environment.


Ultimately, fixing rattling noises in cooling systems requires a combination of detective work and practical solutions aimed at both securing existing components and replacing those that no longer function optimally. By approaching this challenge methodically-through inspection, maintenance, and strategic upgrades-homeowners and technicians alike can ensure their cooling systems operate smoothly without unwelcome auditory disruptions.

Fixing Rattling Noises in Cooling Systems - Cleanser

  1. Saraland
  2. Mississippi Gulf Coast
  3. Daphne
In doing so, they safeguard both their comfort and their investment in reliable climate control technology.

Preventative Maintenance Tips to Avoid Future Rattling

Preventative Maintenance Tips to Avoid Future Rattling: Fixing Rattling Noises in Cooling Systems


Rattling noises emanating from a cooling system can be both irritating and concerning, signaling potential underlying issues that require attention. Cooling systems are engineered to operate smoothly and quietly, ensuring optimal performance while maintaining the right temperature. When these systems begin to rattle, it's often a sign that something is amiss. Addressing these issues proactively through preventative maintenance can save time, money, and headaches down the line.


To start with, regular inspection of the cooling system is crucial. This involves checking for any loose components which could be causing vibrations or making contact where they shouldn't be. Fans and blades within the system are common culprits of rattling noises when they become loose or misaligned. Ensuring that all screws and fasteners are tightened properly can significantly reduce the likelihood of this issue.


Another important step in preventative maintenance is keeping the cooling unit clean and free from debris. Over time, dust and dirt can accumulate on various components such as fans or filters, potentially leading to imbalance or obstruction. Regular cleaning not only helps maintain efficiency but also minimizes unnecessary strain on parts that could lead to rattling.


Additionally, lubrication plays a vital role in maintaining a quiet cooling system. Moving parts like fan bearings need to be adequately lubricated to function smoothly. Without proper lubrication, these parts may experience increased friction and wear, leading to noise-producing vibrations.


It's also wise to check for wear and tear on belts within the system. Worn-out belts can cause vibration as they slip or move unevenly during operation. Replacing them before they fail ensures smooth operation and prevents noise from developing into more severe mechanical problems.


Lastly, consider investing in professional inspections periodically. While DIY checks are beneficial for routine upkeep, certified technicians have the expertise to spot subtle signs of trouble that might go unnoticed by untrained eyes. They can provide valuable insights into potential weak spots within your cooling system that could cause future rattling if left unchecked.


In conclusion, preventing rattling noises in cooling systems involves a combination of regular inspections, cleaning routines, proper lubrication practices, timely replacements of worn-out components, and professional assessments when needed. By implementing these preventative maintenance tips diligently, you ensure not only quieter operation but also extend the lifespan of your cooling system while avoiding costly repairs in the future. Remember: proactive care today saves you from reactive fixes tomorrow.

When to Call a Professional HVAC Technician

When the comforting hum of your cooling system transforms into a disturbing rattle, it can be both annoying and alarming. While some homeowners might feel inclined to tackle such issues themselves, understanding when to call a professional HVAC technician is crucial for both safety and efficiency. Rattling noises in cooling systems can indicate a range of problems, from minor inconveniences to serious mechanical failures. Recognizing the signs that require expert intervention ensures your system remains functional and avoids further damage.


Initially, it's essential to identify the source of the rattling noise. Sometimes, it can be as simple as loose screws or debris caught in the vents. These are issues that an observant homeowner might resolve with basic tools and little effort. However, if the noise persists despite these preliminary checks, it's time to consider reaching out to a professional.


One primary reason to call an HVAC technician is when the rattling noise suggests deeper mechanical issues. For instance, if parts within the compressor or motor have become dislodged or worn out, continuing to operate the system could result in severe damage or even complete failure. A trained technician can accurately diagnose these problems and provide solutions that prevent costly repairs down the line.


Moreover, unfamiliarity with HVAC systems poses potential safety hazards. Attempting repairs without proper knowledge could lead to electrical shocks or other accidents. Professional technicians not only have specialized training but also possess tools designed for safely handling complex machinery.


Another critical factor is maintaining energy efficiency. A poorly functioning system often consumes more power than necessary, leading to inflated utility bills-a concern any homeowner wishes to avoid. An experienced technician can ensure all components are operating optimally, thus enhancing efficiency and reducing costs.


Lastly, engaging a professional provides peace of mind through preventive maintenance advice tailored specifically for your system's needs. Regular check-ups conducted by experts can prolong your cooling system's lifespan and stave off future complications.


In conclusion, while some rattling noises may initially appear manageable with DIY fixes, knowing when to call in a professional HVAC technician is vital for preserving both your cooling system's health and your own safety. By entrusting professionals with diagnosing and addressing significant concerns early on, you safeguard against unexpected breakdowns and ensure continued comfort throughout warmer months.

 

There are various types of air conditioners. Popular examples include: Window-mounted air conditioner (Suriname, 1955); Ceiling-mounted cassette air conditioner (China, 2023); Wall-mounted air conditioner (Japan, 2020); Ceiling-mounted console (Also called ceiling suspended) air conditioner (China, 2023); and portable air conditioner (Vatican City, 2018).

Air conditioning, often abbreviated as A/C (US) or air con (UK),[1] is the process of removing heat from an enclosed space to achieve a more comfortable interior temperature and in some cases also controlling the humidity of internal air. Air conditioning can be achieved using a mechanical 'air conditioner' or by other methods, including passive cooling and ventilative cooling.[2][3] Air conditioning is a member of a family of systems and techniques that provide heating, ventilation, and air conditioning (HVAC).[4] Heat pumps are similar in many ways to air conditioners, but use a reversing valve to allow them both to heat and to cool an enclosed space.[5]

Air conditioners, which typically use vapor-compression refrigeration, range in size from small units used in vehicles or single rooms to massive units that can cool large buildings.[6] Air source heat pumps, which can be used for heating as well as cooling, are becoming increasingly common in cooler climates.

Air conditioners can reduce mortality rates due to higher temperature.[7] According to the International Energy Agency (IEA) 1.6 billion air conditioning units were used globally in 2016.[8] The United Nations called for the technology to be made more sustainable to mitigate climate change and for the use of alternatives, like passive cooling, evaporative cooling, selective shading, windcatchers, and better thermal insulation.

History

[edit]

Air conditioning dates back to prehistory.[9] Double-walled living quarters, with a gap between the two walls to encourage air flow, were found in the ancient city of Hamoukar, in modern Syria.[10] Ancient Egyptian buildings also used a wide variety of passive air-conditioning techniques.[11] These became widespread from the Iberian Peninsula through North Africa, the Middle East, and Northern India.[12]

Passive techniques remained widespread until the 20th century when they fell out of fashion and were replaced by powered air conditioning. Using information from engineering studies of traditional buildings, passive techniques are being revived and modified for 21st-century architectural designs.[13][12]

An array of air conditioner condenser units outside a commercial office building

Air conditioners allow the building's indoor environment to remain relatively constant, largely independent of changes in external weather conditions and internal heat loads. They also enable deep plan buildings to be created and have allowed people to live comfortably in hotter parts of the world.[14]

Development

[edit]

Preceding discoveries

[edit]

In 1558, Giambattista della Porta described a method of chilling ice to temperatures far below its freezing point by mixing it with potassium nitrate (then called "nitre") in his popular science book Natural Magic.[15][16][17] In 1620, Cornelis Drebbel demonstrated "Turning Summer into Winter" for James I of England, chilling part of the Great Hall of Westminster Abbey with an apparatus of troughs and vats.[18] Drebbel's contemporary Francis Bacon, like della Porta a believer in science communication, may not have been present at the demonstration, but in a book published later the same year, he described it as "experiment of artificial freezing" and said that "Nitre (or rather its spirit) is very cold, and hence nitre or salt when added to snow or ice intensifies the cold of the latter, the nitre by adding to its cold, but the salt by supplying activity to the cold of the snow."[15]

In 1758, Benjamin Franklin and John Hadley, a chemistry professor at the University of Cambridge, conducted experiments applying the principle of evaporation as a means to cool an object rapidly. Franklin and Hadley confirmed that the evaporation of highly volatile liquids (such as alcohol and ether) could be used to drive down the temperature of an object past the freezing point of water. They experimented with the bulb of a mercury-in-glass thermometer as their object. They used a bellows to speed up the evaporation. They lowered the temperature of the thermometer bulb down to −14 °C (7 °F) while the ambient temperature was 18 °C (64 °F). Franklin noted that soon after they passed the freezing point of water 0 °C (32 °F), a thin film of ice formed on the surface of the thermometer's bulb and that the ice mass was about 6 mm (14 in) thick when they stopped the experiment upon reaching −14 °C (7 °F). Franklin concluded: "From this experiment, one may see the possibility of freezing a man to death on a warm summer's day."[19]

The 19th century included many developments in compression technology. In 1820, English scientist and inventor Michael Faraday discovered that compressing and liquefying ammonia could chill air when the liquefied ammonia was allowed to evaporate.[20] In 1842, Florida physician John Gorrie used compressor technology to create ice, which he used to cool air for his patients in his hospital in Apalachicola, Florida. He hoped to eventually use his ice-making machine to regulate the temperature of buildings.[20][21] He envisioned centralized air conditioning that could cool entire cities. Gorrie was granted a patent in 1851,[22] but following the death of his main backer, he was not able to realize his invention.[23] In 1851, James Harrison created the first mechanical ice-making machine in Geelong, Australia, and was granted a patent for an ether vapor-compression refrigeration system in 1855 that produced three tons of ice per day.[24] In 1860, Harrison established a second ice company. He later entered the debate over competing against the American advantage of ice-refrigerated beef sales to the United Kingdom.[24]

First devices

[edit]
Willis Carrier, who is credited with building the first modern electrical air conditioning unit

Electricity made the development of effective units possible. In 1901, American inventor Willis H. Carrier built what is considered the first modern electrical air conditioning unit.[25][26][27][28] In 1902, he installed his first air-conditioning system, in the Sackett-Wilhelms Lithographing & Publishing Company in Brooklyn, New York.[29] His invention controlled both the temperature and humidity, which helped maintain consistent paper dimensions and ink alignment at the printing plant. Later, together with six other employees, Carrier formed The Carrier Air Conditioning Company of America, a business that in 2020 employed 53,000 people and was valued at $18.6 billion.[30][31]

In 1906, Stuart W. Cramer of Charlotte, North Carolina, was exploring ways to add moisture to the air in his textile mill. Cramer coined the term "air conditioning" in a patent claim which he filed that year, where he suggested that air conditioning was analogous to "water conditioning", then a well-known process for making textiles easier to process.[32] He combined moisture with ventilation to "condition" and change the air in the factories; thus, controlling the humidity that is necessary in textile plants. Willis Carrier adopted the term and incorporated it into the name of his company.[33]

Domestic air conditioning soon took off. In 1914, the first domestic air conditioning was installed in Minneapolis in the home of Charles Gilbert Gates. It is, however, possible that the considerable device (c. 2.1 m × 1.8 m × 6.1 m; 7 ft × 6 ft × 20 ft) was never used, as the house remained uninhabited[20] (Gates had already died in October 1913.)

In 1931, H.H. Schultz and J.Q. Sherman developed what would become the most common type of individual room air conditioner: one designed to sit on a window ledge. The units went on sale in 1932 at US$10,000 to $50,000 (the equivalent of $200,000 to $1,200,000 in 2024.)[20] A year later, the first air conditioning systems for cars were offered for sale.[34] Chrysler Motors introduced the first practical semi-portable air conditioning unit in 1935,[35] and Packard became the first automobile manufacturer to offer an air conditioning unit in its cars in 1939.[36]

Further development

[edit]

Innovations in the latter half of the 20th century allowed more ubiquitous air conditioner use. In 1945, Robert Sherman of Lynn, Massachusetts, invented a portable, in-window air conditioner that cooled, heated, humidified, dehumidified, and filtered the air.[37] The first inverter air conditioners were released in 1980–1981.[38][39]

In 1954, Ned Cole, a 1939 architecture graduate from the University of Texas at Austin, developed the first experimental "suburb" with inbuilt air conditioning in each house. 22 homes were developed on a flat, treeless track in northwest Austin, Texas, and the community was christened the 'Austin Air-Conditioned Village.' The residents were subjected to a year-long study of the effects of air conditioning led by the nation’s premier air conditioning companies, builders, and social scientists. In addition, researchers from UT’s Health Service and Psychology Department studied the effects on the "artificially cooled humans." One of the more amusing discoveries was that each family reported being troubled with scorpions, the leading theory being that scorpions sought cool, shady places. Other reported changes in lifestyle were that mothers baked more, families ate heavier foods, and they were more apt to choose hot drinks.[40][41]

Air conditioner adoption tends to increase above around $10,000 annual household income in warmer areas.[42] Global GDP growth explains around 85% of increased air condition adoption by 2050, while the remaining 15% can be explained by climate change.[42]

As of 2016 an estimated 1.6 billion air conditioning units were used worldwide, with over half of them in China and USA, and a total cooling capacity of 11,675 gigawatts.[8][43] The International Energy Agency predicted in 2018 that the number of air conditioning units would grow to around 4 billion units by 2050 and that the total cooling capacity would grow to around 23,000 GW, with the biggest increases in India and China.[8] Between 1995 and 2004, the proportion of urban households in China with air conditioners increased from 8% to 70%.[44] As of 2015, nearly 100 million homes, or about 87% of US households, had air conditioning systems.[45] In 2019, it was estimated that 90% of new single-family homes constructed in the US included air conditioning (ranging from 99% in the South to 62% in the West).[46][47]

Operation

[edit]

Operating principles

[edit]
A simple stylized diagram of the refrigeration cycle: 1) condensing coil, 2) expansion valve, 3) evaporator coil, 4) compressor

Cooling in traditional air conditioner systems is accomplished using the vapor-compression cycle, which uses a refrigerant's forced circulation and phase change between gas and liquid to transfer heat.[48][49] The vapor-compression cycle can occur within a unitary, or packaged piece of equipment; or within a chiller that is connected to terminal cooling equipment (such as a fan coil unit in an air handler) on its evaporator side and heat rejection equipment such as a cooling tower on its condenser side. An air source heat pump shares many components with an air conditioning system, but includes a reversing valve, which allows the unit to be used to heat as well as cool a space.[50]

Air conditioning equipment will reduce the absolute humidity of the air processed by the system if the surface of the evaporator coil is significantly cooler than the dew point of the surrounding air. An air conditioner designed for an occupied space will typically achieve a 30% to 60% relative humidity in the occupied space.[51]

Most modern air-conditioning systems feature a dehumidification cycle during which the compressor runs. At the same time, the fan is slowed to reduce the evaporator temperature and condense more water. A dehumidifier uses the same refrigeration cycle but incorporates both the evaporator and the condenser into the same air path; the air first passes over the evaporator coil, where it is cooled[52] and dehumidified before passing over the condenser coil, where it is warmed again before it is released back into the room.[citation needed]

Free cooling can sometimes be selected when the external air is cooler than the internal air. Therefore, the compressor does not need to be used, resulting in high cooling efficiencies for these times. This may also be combined with seasonal thermal energy storage.[53]

Heating

[edit]

Some air conditioning systems can reverse the refrigeration cycle and act as an air source heat pump, thus heating instead of cooling the indoor environment. They are also commonly referred to as "reverse cycle air conditioners". The heat pump is significantly more energy-efficient than electric resistance heating, because it moves energy from air or groundwater to the heated space and the heat from purchased electrical energy. When the heat pump is in heating mode, the indoor evaporator coil switches roles and becomes the condenser coil, producing heat. The outdoor condenser unit also switches roles to serve as the evaporator and discharges cold air (colder than the ambient outdoor air).

Most air source heat pumps become less efficient in outdoor temperatures lower than 4 °C or 40 °F.[54] This is partly because ice forms on the outdoor unit's heat exchanger coil, which blocks air flow over the coil. To compensate for this, the heat pump system must temporarily switch back into the regular air conditioning mode to switch the outdoor evaporator coil back to the condenser coil, to heat up and defrost. Therefore, some heat pump systems will have electric resistance heating in the indoor air path that is activated only in this mode to compensate for the temporary indoor air cooling, which would otherwise be uncomfortable in the winter.

Newer models have improved cold-weather performance, with efficient heating capacity down to −14 °F (−26 °C).[55][54][56] However, there is always a chance that the humidity that condenses on the heat exchanger of the outdoor unit could freeze, even in models that have improved cold-weather performance, requiring a defrosting cycle to be performed.

The icing problem becomes much more severe with lower outdoor temperatures, so heat pumps are sometimes installed in tandem with a more conventional form of heating, such as an electrical heater, a natural gas, heating oil, or wood-burning fireplace or central heating, which is used instead of or in addition to the heat pump during harsher winter temperatures. In this case, the heat pump is used efficiently during milder temperatures, and the system is switched to the conventional heat source when the outdoor temperature is lower.

Performance

[edit]

The coefficient of performance (COP) of an air conditioning system is a ratio of useful heating or cooling provided to the work required.[57][58] Higher COPs equate to lower operating costs. The COP usually exceeds 1; however, the exact value is highly dependent on operating conditions, especially absolute temperature and relative temperature between sink and system, and is often graphed or averaged against expected conditions.[59] Air conditioner equipment power in the U.S. is often described in terms of "tons of refrigeration", with each approximately equal to the cooling power of one short ton (2,000 pounds (910 kg) of ice melting in a 24-hour period. The value is equal to 12,000 BTUIT per hour, or 3,517 watts.[60] Residential central air systems are usually from 1 to 5 tons (3.5 to 18 kW) in capacity.[citation needed]

The efficiency of air conditioners is often rated by the seasonal energy efficiency ratio (SEER), which is defined by the Air Conditioning, Heating and Refrigeration Institute in its 2008 standard AHRI 210/240, Performance Rating of Unitary Air-Conditioning and Air-Source Heat Pump Equipment.[61] A similar standard is the European seasonal energy efficiency ratio (ESEER).[citation needed]

Efficiency is strongly affected by the humidity of the air to be cooled. Dehumidifying the air before attempting to cool it can reduce subsequent cooling costs by as much as 90 percent. Thus, reducing dehumidifying costs can materially affect overall air conditioning costs.[62]

Control system

[edit]

Wireless remote control

[edit]
A wireless remote controller
The infrared transmitting LED on the remote
The infrared receiver on the air conditioner

This type of controller uses an infrared LED to relay commands from a remote control to the air conditioner. The output of the infrared LED (like that of any infrared remote) is invisible to the human eye because its wavelength is beyond the range of visible light (940 nm). This system is commonly used on mini-split air conditioners because it is simple and portable. Some window and ducted central air conditioners uses it as well.

Wired controller

[edit]
Several wired controllers (Indonesia, 2024)

A wired controller, also called a "wired thermostat," is a device that controls an air conditioner by switching heating or cooling on or off. It uses different sensors to measure temperatures and actuate control operations. Mechanical thermostats commonly use bimetallic strips, converting a temperature change into mechanical displacement, to actuate control of the air conditioner. Electronic thermostats, instead, use a thermistor or other semiconductor sensor, processing temperature change as electronic signals to control the air conditioner.

These controllers are usually used in hotel rooms because they are permanently installed into a wall and hard-wired directly into the air conditioner unit, eliminating the need for batteries.

Types

[edit]
 
Types Typical Capacity* Air supply Mounting Typical application
Mini-split small – large Direct Wall Residential
Window very small – small Direct Window Residential
Portable very small – small Direct / Ducted Floor Residential, remote areas
Ducted (individual) small – very large Ducted Ceiling Residential, commercial
Ducted (central) medium – very large Ducted Ceiling Residential, commercial
Ceiling suspended medium – large Direct Ceiling Commercial
Cassette medium – large Direct / Ducted Ceiling Commercial
Floor standing medium – large Direct / Ducted Floor Commercial
Packaged very large Direct / Ducted Floor Commercial
Packaged RTU (Rooftop Unit) very large Ducted Rooftop Commercial

* where the typical capacity is in kilowatt as follows:

  • very small: <1.5 kW
  • small: 1.5–3.5 kW
  • medium: 4.2–7.1 kW
  • large: 7.2–14 kW
  • very large: >14 kW

Mini-split and multi-split systems

[edit]
Evaporator, indoor unit, or terminal, side of a ductless split-type air conditioner

Ductless systems (often mini-split, though there are now ducted mini-split) typically supply conditioned and heated air to a single or a few rooms of a building, without ducts and in a decentralized manner.[63] Multi-zone or multi-split systems are a common application of ductless systems and allow up to eight rooms (zones or locations) to be conditioned independently from each other, each with its indoor unit and simultaneously from a single outdoor unit.

The first mini-split system was sold in 1961 by Toshiba in Japan, and the first wall-mounted mini-split air conditioner was sold in 1968 in Japan by Mitsubishi Electric, where small home sizes motivated their development. The Mitsubishi model was the first air conditioner with a cross-flow fan.[64][65][66] In 1969, the first mini-split air conditioner was sold in the US.[67] Multi-zone ductless systems were invented by Daikin in 1973, and variable refrigerant flow systems (which can be thought of as larger multi-split systems) were also invented by Daikin in 1982. Both were first sold in Japan.[68] Variable refrigerant flow systems when compared with central plant cooling from an air handler, eliminate the need for large cool air ducts, air handlers, and chillers; instead cool refrigerant is transported through much smaller pipes to the indoor units in the spaces to be conditioned, thus allowing for less space above dropped ceilings and a lower structural impact, while also allowing for more individual and independent temperature control of spaces. The outdoor and indoor units can be spread across the building.[69] Variable refrigerant flow indoor units can also be turned off individually in unused spaces.[citation needed] The lower start-up power of VRF's DC inverter compressors and their inherent DC power requirements also allow VRF solar-powered heat pumps to be run using DC-providing solar panels.

Ducted central systems

[edit]

Split-system central air conditioners consist of two heat exchangers, an outside unit (the condenser) from which heat is rejected to the environment and an internal heat exchanger (the evaporator, or Fan Coil Unit, FCU) with the piped refrigerant being circulated between the two. The FCU is then connected to the spaces to be cooled by ventilation ducts.[70] Floor standing air conditioners are similar to this type of air conditioner but sit within spaces that need cooling.

Central plant cooling

[edit]
Industrial air conditioners on top of the shopping mall Passage in Linz, Austria

Large central cooling plants may use intermediate coolant such as chilled water pumped into air handlers or fan coil units near or in the spaces to be cooled which then duct or deliver cold air into the spaces to be conditioned, rather than ducting cold air directly to these spaces from the plant, which is not done due to the low density and heat capacity of air, which would require impractically large ducts. The chilled water is cooled by chillers in the plant, which uses a refrigeration cycle to cool water, often transferring its heat to the atmosphere even in liquid-cooled chillers through the use of cooling towers. Chillers may be air- or liquid-cooled.[71][72]

Portable units

[edit]

A portable system has an indoor unit on wheels connected to an outdoor unit via flexible pipes, similar to a permanently fixed installed unit (such as a ductless split air conditioner).

Hose systems, which can be monoblock or air-to-air, are vented to the outside via air ducts. The monoblock type collects the water in a bucket or tray and stops when full. The air-to-air type re-evaporates the water, discharges it through the ducted hose, and can run continuously. Many but not all portable units draw indoor air and expel it outdoors through a single duct, negatively impacting their overall cooling efficiency.

Many portable air conditioners come with heat as well as a dehumidification function.[73]

Window unit and packaged terminal

[edit]
Through-the-wall PTAC units, University Motor Inn, Philadelphia

The packaged terminal air conditioner (PTAC), through-the-wall, and window air conditioners are similar. These units are installed on a window frame or on a wall opening. The unit usually has an internal partition separating its indoor and outdoor sides, which contain the unit's condenser and evaporator, respectively. PTAC systems may be adapted to provide heating in cold weather, either directly by using an electric strip, gas, or other heaters, or by reversing the refrigerant flow to heat the interior and draw heat from the exterior air, converting the air conditioner into a heat pump. They may be installed in a wall opening with the help of a special sleeve on the wall and a custom grill that is flush with the wall and window air conditioners can also be installed in a window, but without a custom grill.[74]

Packaged air conditioner

[edit]

Packaged air conditioners (also known as self-contained units)[75][76] are central systems that integrate into a single housing all the components of a split central system, and deliver air, possibly through ducts, to the spaces to be cooled. Depending on their construction they may be outdoors or indoors, on roofs (rooftop units),[77][78] draw the air to be conditioned from inside or outside a building and be water or air-cooled. Often, outdoor units are air-cooled while indoor units are liquid-cooled using a cooling tower.[70][79][80][81][82][83]

Types of compressors

[edit]
 
Compressor types Common applications Typical capacity Efficiency Durability Repairability
Reciprocating Refrigerator, Walk-in freezer, portable air conditioners small – large very low (small capacity)

medium (large capacity)

very low medium
Rotary vane Residential mini splits small low low easy
Scroll Commercial and central systems, VRF medium medium medium easy
Rotary screw Commercial chiller medium – large medium medium hard
Centrifugal Commercial chiller very large medium high hard
Maglev Centrifugal Commercial chiller very large high very high very hard

Reciprocating

[edit]

This compressor consists of a crankcase, crankshaft, piston rod, piston, piston ring, cylinder head and valves. [citation needed]

Scroll

[edit]

This compressor uses two interleaving scrolls to compress the refrigerant.[84] it consists of one fixed and one orbiting scrolls. This type of compressor is more efficient because it has 70 percent less moving parts than a reciprocating compressor. [citation needed]

Screw

[edit]

This compressor use two very closely meshing spiral rotors to compress the gas. The gas enters at the suction side and moves through the threads as the screws rotate. The meshing rotors force the gas through the compressor, and the gas exits at the end of the screws. The working area is the inter-lobe volume between the male and female rotors. It is larger at the intake end, and decreases along the length of the rotors until the exhaust port. This change in volume is the compression. [citation needed]

Capacity modulation technologies

[edit]

There are several ways to modulate the cooling capacity in refrigeration or air conditioning and heating systems. The most common in air conditioning are: on-off cycling, hot gas bypass, use or not of liquid injection, manifold configurations of multiple compressors, mechanical modulation (also called digital), and inverter technology. [citation needed]

Hot gas bypass

[edit]

Hot gas bypass involves injecting a quantity of gas from discharge to the suction side. The compressor will keep operating at the same speed, but due to the bypass, the refrigerant mass flow circulating with the system is reduced, and thus the cooling capacity. This naturally causes the compressor to run uselessly during the periods when the bypass is operating. The turn down capacity varies between 0 and 100%.[85]

Manifold configurations

[edit]

Several compressors can be installed in the system to provide the peak cooling capacity. Each compressor can run or not in order to stage the cooling capacity of the unit. The turn down capacity is either 0/33/66 or 100% for a trio configuration and either 0/50 or 100% for a tandem.[citation needed]

Mechanically modulated compressor

[edit]

This internal mechanical capacity modulation is based on periodic compression process with a control valve, the two scroll set move apart stopping the compression for a given time period. This method varies refrigerant flow by changing the average time of compression, but not the actual speed of the motor. Despite an excellent turndown ratio – from 10 to 100% of the cooling capacity, mechanically modulated scrolls have high energy consumption as the motor continuously runs.[citation needed]

Variable-speed compressor

[edit]

This system uses a variable-frequency drive (also called an Inverter) to control the speed of the compressor. The refrigerant flow rate is changed by the change in the speed of the compressor. The turn down ratio depends on the system configuration and manufacturer. It modulates from 15 or 25% up to 100% at full capacity with a single inverter from 12 to 100% with a hybrid tandem. This method is the most efficient way to modulate an air conditioner's capacity. It is up to 58% more efficient than a fixed speed system.[citation needed]

Impact

[edit]

Health effects

[edit]
Rooftop condenser unit fitted on top of an Osaka Municipal Subway 10 series subway carriage. Air conditioning has become increasingly prevalent on public transport vehicles as a form of climate control, and to ensure passenger comfort and drivers' occupational safety and health.

In hot weather, air conditioning can prevent heat stroke, dehydration due to excessive sweating, electrolyte imbalance, kidney failure, and other issues due to hyperthermia.[8][86] Heat waves are the most lethal type of weather phenomenon in the United States.[87][88] A 2020 study found that areas with lower use of air conditioning correlated with higher rates of heat-related mortality and hospitalizations.[89] The August 2003 France heatwave resulted in approximately 15,000 deaths, where 80% of the victims were over 75 years old. In response, the French government required all retirement homes to have at least one air-conditioned room at 25 °C (77 °F) per floor during heatwaves.[8]

Air conditioning (including filtration, humidification, cooling and disinfection) can be used to provide a clean, safe, hypoallergenic atmosphere in hospital operating rooms and other environments where proper atmosphere is critical to patient safety and well-being. It is sometimes recommended for home use by people with allergies, especially mold.[90][91] However, poorly maintained water cooling towers can promote the growth and spread of microorganisms such as Legionella pneumophila, the infectious agent responsible for Legionnaires' disease. As long as the cooling tower is kept clean (usually by means of a chlorine treatment), these health hazards can be avoided or reduced. The state of New York has codified requirements for registration, maintenance, and testing of cooling towers to protect against Legionella.[92]

Economic effects

[edit]

First designed to benefit targeted industries such as the press as well as large factories, the invention quickly spread to public agencies and administrations with studies with claims of increased productivity close to 24% in places equipped with air conditioning.[93]

Air conditioning caused various shifts in demography, notably that of the United States starting from the 1970s. In the US, the birth rate was lower in the spring than during other seasons until the 1970s but this difference then declined since then.[94] As of 2007, the Sun Belt contained 30% of the total US population while it was inhabited by 24% of Americans at the beginning of the 20th century.[95] Moreover, the summer mortality rate in the US, which had been higher in regions subject to a heat wave during the summer, also evened out.[7]

The spread of the use of air conditioning acts as a main driver for the growth of global demand of electricity.[96] According to a 2018 report from the International Energy Agency (IEA), it was revealed that the energy consumption for cooling in the United States, involving 328 million Americans, surpasses the combined energy consumption of 4.4 billion people in Africa, Latin America, the Middle East, and Asia (excluding China).[8] A 2020 survey found that an estimated 88% of all US households use AC, increasing to 93% when solely looking at homes built between 2010 and 2020.[97]

Environmental effects

[edit]
Air conditioner farm in the facade of a building in Singapore

Space cooling including air conditioning accounted globally for 2021 terawatt-hours of energy usage in 2016 with around 99% in the form of electricity, according to a 2018 report on air-conditioning efficiency by the International Energy Agency.[8] The report predicts an increase of electricity usage due to space cooling to around 6200 TWh by 2050,[8][98] and that with the progress currently seen, greenhouse gas emissions attributable to space cooling will double: 1,135 million tons (2016) to 2,070 million tons.[8] There is some push to increase the energy efficiency of air conditioners. United Nations Environment Programme (UNEP) and the IEA found that if air conditioners could be twice as effective as now, 460 billion tons of GHG could be cut over 40 years.[99] The UNEP and IEA also recommended legislation to decrease the use of hydrofluorocarbons, better building insulation, and more sustainable temperature-controlled food supply chains going forward.[99]

Refrigerants have also caused and continue to cause serious environmental issues, including ozone depletion and climate change, as several countries have not yet ratified the Kigali Amendment to reduce the consumption and production of hydrofluorocarbons.[100] CFCs and HCFCs refrigerants such as R-12 and R-22, respectively, used within air conditioners have caused damage to the ozone layer,[101] and hydrofluorocarbon refrigerants such as R-410A and R-404A, which were designed to replace CFCs and HCFCs, are instead exacerbating climate change.[102] Both issues happen due to the venting of refrigerant to the atmosphere, such as during repairs. HFO refrigerants, used in some if not most new equipment, solve both issues with an ozone damage potential (ODP) of zero and a much lower global warming potential (GWP) in the single or double digits vs. the three or four digits of hydrofluorocarbons.[103]

Hydrofluorocarbons would have raised global temperatures by around 0.3–0.5 °C (0.5–0.9 °F) by 2100 without the Kigali Amendment. With the Kigali Amendment, the increase of global temperatures by 2100 due to hydrofluorocarbons is predicted to be around 0.06 °C (0.1 °F).[104]

Alternatives to continual air conditioning include passive cooling, passive solar cooling, natural ventilation, operating shades to reduce solar gain, using trees, architectural shades, windows (and using window coatings) to reduce solar gain.[citation needed]

Social effects

[edit]

Socioeconomic groups with a household income below around $10,000 tend to have a low air conditioning adoption,[42] which worsens heat-related mortality.[7] The lack of cooling can be hazardous, as areas with lower use of air conditioning correlate with higher rates of heat-related mortality and hospitalizations.[89] Premature mortality in NYC is projected to grow between 47% and 95% in 30 years, with lower-income and vulnerable populations most at risk.[89] Studies on the correlation between heat-related mortality and hospitalizations and living in low socioeconomic locations can be traced in Phoenix, Arizona,[105] Hong Kong,[106] China,[106] Japan,[107] and Italy.[108][109] Additionally, costs concerning health care can act as another barrier, as the lack of private health insurance during a 2009 heat wave in Australia, was associated with heat-related hospitalization.[109]

Disparities in socioeconomic status and access to air conditioning are connected by some to institutionalized racism, which leads to the association of specific marginalized communities with lower economic status, poorer health, residing in hotter neighborhoods, engaging in physically demanding labor, and experiencing limited access to cooling technologies such as air conditioning.[109] A study overlooking Chicago, Illinois, Detroit, and Michigan found that black households were half as likely to have central air conditioning units when compared to their white counterparts.[110] Especially in cities, Redlining creates heat islands, increasing temperatures in certain parts of the city.[109] This is due to materials heat-absorbing building materials and pavements and lack of vegetation and shade coverage.[111] There have been initiatives that provide cooling solutions to low-income communities, such as public cooling spaces.[8][111]

Other techniques

[edit]

Buildings designed with passive air conditioning are generally less expensive to construct and maintain than buildings with conventional HVAC systems with lower energy demands.[112] While tens of air changes per hour, and cooling of tens of degrees, can be achieved with passive methods, site-specific microclimate must be taken into account, complicating building design.[12]

Many techniques can be used to increase comfort and reduce the temperature in buildings. These include evaporative cooling, selective shading, wind, thermal convection, and heat storage.[113]

Passive ventilation

[edit]
The ventilation system of a regular earthship
Dogtrot houses are designed to maximise natural ventilation.
A roof turbine ventilator, colloquially known as a 'Whirly Bird' is an application of wind driven ventilation.

Passive ventilation is the process of supplying air to and removing air from an indoor space without using mechanical systems. It refers to the flow of external air to an indoor space as a result of pressure differences arising from natural forces.

There are two types of natural ventilation occurring in buildings: wind driven ventilation and buoyancy-driven ventilation. Wind driven ventilation arises from the different pressures created by wind around a building or structure, and openings being formed on the perimeter which then permit flow through the building. Buoyancy-driven ventilation occurs as a result of the directional buoyancy force that results from temperature differences between the interior and exterior.[114]

Since the internal heat gains which create temperature differences between the interior and exterior are created by natural processes, including the heat from people, and wind effects are variable, naturally ventilated buildings are sometimes called "breathing buildings".

Passive cooling

[edit]
 
A traditional Iranian solar cooling design using a wind tower

Passive cooling is a building design approach that focuses on heat gain control and heat dissipation in a building in order to improve the indoor thermal comfort with low or no energy consumption.[115][116] This approach works either by preventing heat from entering the interior (heat gain prevention) or by removing heat from the building (natural cooling).[117]

Natural cooling utilizes on-site energy, available from the natural environment, combined with the architectural design of building components (e.g. building envelope), rather than mechanical systems to dissipate heat.[118] Therefore, natural cooling depends not only on the architectural design of the building but on how the site's natural resources are used as heat sinks (i.e. everything that absorbs or dissipates heat). Examples of on-site heat sinks are the upper atmosphere (night sky), the outdoor air (wind), and the earth/soil.

Passive cooling is an important tool for design of buildings for climate change adaptation – reducing dependency on energy-intensive air conditioning in warming environments.[119][120]
A pair of short windcatchers (malqaf) used in traditional architecture; wind is forced down on the windward side and leaves on the leeward side (cross-ventilation). In the absence of wind, the circulation can be driven with evaporative cooling in the inlet (which is also designed to catch dust). In the center, a shuksheika (roof lantern vent), used to shade the qa'a below while allowing hot air rise out of it (stack effect).[11]

Daytime radiative cooling

[edit]
Passive daytime radiative cooling (PDRC) surfaces are high in solar reflectance and heat emittance, cooling with zero energy use or pollution.[121]

Passive daytime radiative cooling (PDRC) surfaces reflect incoming solar radiation and heat back into outer space through the infrared window for cooling during the daytime. Daytime radiative cooling became possible with the ability to suppress solar heating using photonic structures, which emerged through a study by Raman et al. (2014).[122] PDRCs can come in a variety of forms, including paint coatings and films, that are designed to be high in solar reflectance and thermal emittance.[121][123]

PDRC applications on building roofs and envelopes have demonstrated significant decreases in energy consumption and costs.[123] In suburban single-family residential areas, PDRC application on roofs can potentially lower energy costs by 26% to 46%.[124] PDRCs are predicted to show a market size of ~$27 billion for indoor space cooling by 2025 and have undergone a surge in research and development since the 2010s.[125][126]

Fans

[edit]

Hand fans have existed since prehistory. Large human-powered fans built into buildings include the punkah.

The 2nd-century Chinese inventor Ding Huan of the Han dynasty invented a rotary fan for air conditioning, with seven wheels 3 m (10 ft) in diameter and manually powered by prisoners.[127]: 99, 151, 233  In 747, Emperor Xuanzong (r. 712–762) of the Tang dynasty (618–907) had the Cool Hall (Liang Dian 涼殿) built in the imperial palace, which the Tang Yulin describes as having water-powered fan wheels for air conditioning as well as rising jet streams of water from fountains. During the subsequent Song dynasty (960–1279), written sources mentioned the air conditioning rotary fan as even more widely used.[127]: 134, 151 

Thermal buffering

[edit]

In areas that are cold at night or in winter, heat storage is used. Heat may be stored in earth or masonry; air is drawn past the masonry to heat or cool it.[13]

In areas that are below freezing at night in winter, snow and ice can be collected and stored in ice houses for later use in cooling.[13] This technique is over 3,700 years old in the Middle East.[128] Harvesting outdoor ice during winter and transporting and storing for use in summer was practiced by wealthy Europeans in the early 1600s,[15] and became popular in Europe and the Americas towards the end of the 1600s.[129] This practice was replaced by mechanical compression-cycle icemakers.

Evaporative cooling

[edit]
An evaporative cooler

In dry, hot climates, the evaporative cooling effect may be used by placing water at the air intake, such that the draft draws air over water and then into the house. For this reason, it is sometimes said that the fountain, in the architecture of hot, arid climates, is like the fireplace in the architecture of cold climates.[11] Evaporative cooling also makes the air more humid, which can be beneficial in a dry desert climate.[130]

Evaporative coolers tend to feel as if they are not working during times of high humidity, when there is not much dry air with which the coolers can work to make the air as cool as possible for dwelling occupants. Unlike other types of air conditioners, evaporative coolers rely on the outside air to be channeled through cooler pads that cool the air before it reaches the inside of a house through its air duct system; this cooled outside air must be allowed to push the warmer air within the house out through an exhaust opening such as an open door or window.[131]

See also

[edit]

References

[edit]
  1. ^ "Air Con". Cambridge Dictionary. Archived from the original on May 3, 2022. Retrieved January 6, 2023.
  2. ^ Dissertation Abstracts International: The humanities and social sciences. A. University Microfilms. 2005. p. 3600.
  3. ^ 1993 ASHRAE Handbook: Fundamentals. ASHRAE. 1993. ISBN 978-0-910110-97-6.
  4. ^ Enteria, Napoleon; Sawachi, Takao; Saito, Kiyoshi (January 31, 2023). Variable Refrigerant Flow Systems: Advances and Applications of VRF. Springer Nature. p. 46. ISBN 978-981-19-6833-4.
  5. ^ Agencies, United States Congress House Committee on Appropriations Subcommittee on Dept of the Interior and Related (1988). Department of the Interior and Related Agencies Appropriations for 1989: Testimony of public witnesses, energy programs, Institute of Museum Services, National Endowment for the Arts, National Endowment for the Humanities. U.S. Government Printing Office. p. 629.
  6. ^ "Earth Tubes: Providing the freshest possible air to your building". Earth Rangers Centre for Sustainable Technology Showcase. Archived from the original on January 28, 2021. Retrieved May 12, 2021.
  7. ^ a b c Barreca, Alan; Clay, Karen; Deschenes, Olivier; Greenstone, Michael; Shapiro, Joseph S. (February 2016). "Adapting to Climate Change: The Remarkable Decline in the US Temperature-Mortality Relationship over the Twentieth Century". Journal of Political Economy. 124 (1): 105–159. doi:10.1086/684582.
  8. ^ a b c d e f g h i j International Energy Agency (May 15, 2018). The Future of Cooling - Opportunities for energy-efficient air conditioning (PDF) (Report). Archived (PDF) from the original on June 26, 2024. Retrieved July 1, 2024.
  9. ^ Laub, Julian M. (1963). Air Conditioning & Heating Practice. Holt, Rinehart and Winston. p. 367. ISBN 978-0-03-011225-6.
  10. ^ "Air-conditioning found at 'oldest city in the world'". The Independent. June 24, 2000. Archived from the original on December 8, 2023. Retrieved December 9, 2023.
  11. ^ a b c Mohamed, Mady A.A. (January 2010). Lehmann, S.; Waer, H.A.; Al-Qawasmi, J. (eds.). Traditional Ways of Dealing with Climate in Egypt. The Seventh International Conference of Sustainable Architecture and Urban Development (SAUD 2010). Amman, Jordan: The Center for the Study of Architecture in Arab Region (CSAAR Press). pp. 247–266. Archived from the original on May 13, 2021. Retrieved May 12, 2021.
  12. ^ a b c Ford, Brian (September 2001). "Passive downdraught evaporative cooling: principles and practice". Architectural Research Quarterly. 5 (3): 271–280. doi:10.1017/S1359135501001312.
  13. ^ a b c Attia, Shady; Herde, André de (June 22–24, 2009). Designing the Malqaf for Summer Cooling in Low-Rise Housing, an Experimental Study. 26th Conference on Passive and Low Energy Architecture (PLEA2009). Quebec City. Archived from the original on May 13, 2021. Retrieved May 12, 2021 – via ResearchGate.
  14. ^ "Heating, Ventilation and Air-Conditioning Systems, Part of Indoor Air Quality Design Tools for Schools". US EPA. October 17, 2014. Archived from the original on July 5, 2022. Retrieved July 5, 2022.
  15. ^ a b c Shachtman, Tom (1999). "Winter in Summer". Absolute zero and the conquest of cold. Boston: Houghton Mifflin Harcourt. ISBN 978-0395938881. OCLC 421754998. Archived from the original on May 13, 2021. Retrieved May 12, 2021.
  16. ^ Porta, Giambattista Della (1584). Magiae naturalis (PDF). London. LCCN 09023451. Archived (PDF) from the original on May 13, 2021. Retrieved May 12, 2021. In our method I shall observe what our ancestors have said; then I shall show by my own experience, whether they be true or false
  17. ^ Beck, Leonard D. (October 1974). "Things Magical in the collections of the Rare Book and Special Collections Division" (PDF). Library of Congress Quarterly Journal. 31: 208–234. Archived (PDF) from the original on March 24, 2021. Retrieved May 12, 2021.
  18. ^ Laszlo, Pierre (2001). Salt: Grain of Life. Columbia University Press. p. 117. ISBN 978-0231121989. OCLC 785781471. Cornelius Drebbel air conditioning.
  19. ^ Franklin, Benjamin (June 17, 1758). "The Montgomery Family: An historical and photographic perspective". Letter to John Lining. Archived from the original on February 25, 2021. Retrieved May 12, 2021.
  20. ^ a b c d Green, Amanda (January 1, 2015). "The Cool History of the Air Conditioner". Popular Mechanics. Archived from the original on April 10, 2021. Retrieved May 12, 2021.
  21. ^ "John Gorrie". Encyclopædia Britannica. September 29, 2020. Archived from the original on March 13, 2021. Retrieved May 12, 2021.
  22. ^ Gorrie, John "Improved process for the artificial production of ice" U.S. Patent no. 8080 (Issued: May 6, 1851).
  23. ^ Wright, E. Lynne (2009). It Happened in Florida: Remarkable Events That Shaped History. Rowman & Littlefield. pp. 13–. ISBN 978-0762761692.
  24. ^ a b Bruce-Wallace, L. G. (1966). "Harrison, James (1816–1893)". Australian Dictionary of Biography. Vol. 1. Canberra: National Centre of Biography, Australian National University. ISBN 978-0-522-84459-7. ISSN 1833-7538. OCLC 70677943. Retrieved May 12, 2021.
  25. ^ Palermo, Elizabeth (May 1, 2014). "Who Invented Air Conditioning?". livescience.com. Archived from the original on January 16, 2021. Retrieved May 12, 2021.
  26. ^ Varrasi, John (June 6, 2011). "Global Cooling: The History of Air Conditioning". American Society of Mechanical Engineers. Archived from the original on March 8, 2021. Retrieved May 12, 2021.
  27. ^ Simha, R. V. (February 2012). "Willis H Carrier". Resonance. 17 (2): 117–138. doi:10.1007/s12045-012-0014-y. ISSN 0971-8044. S2CID 116582893.
  28. ^ Gulledge III, Charles; Knight, Dennis (February 11, 2016). "Heating, Ventilating, Air-Conditioning, And Refrigerating Engineering". National Institute of Building Sciences. Archived from the original on April 20, 2021. Retrieved May 12, 2021. Though he did not actually invent air-conditioning nor did he take the first documented scientific approach to applying it, Willis Carrier is credited with integrating the scientific method, engineering, and business of this developing technology and creating the industry we know today as air-conditioning.
  29. ^ "Willis Carrier – 1876–1902". Carrier Global. Archived from the original on February 27, 2021. Retrieved May 12, 2021.
  30. ^ "Carrier Reports First Quarter 2020 Earnings". Carrier Global (Press release). May 8, 2020. Archived from the original on January 24, 2021. Retrieved May 12, 2021.
  31. ^ "Carrier Becomes Independent, Publicly Traded Company, Begins Trading on New York Stock Exchange". Carrier Global (Press release). April 3, 2020. Archived from the original on February 25, 2021. Retrieved May 12, 2021.
  32. ^ Cramer, Stuart W. "Humidifying and air conditioning apparatus" U.S. Patent no. 852,823 (filed: April 18, 1906; issued: May 7, 1907).
    • See also: Cramer, Stuart W. (1906) "Recent development in air conditioning" in: Proceedings of the Tenth Annual Convention of the American Cotton Manufacturers Association Held at Asheville, North Carolina May 16–17, 1906. Charlotte, North Carolina, USA: Queen City Publishing Co. pp. 182-211.
  33. ^ US patent US808897A, Carrier, Willis H., "Apparatus for treating air", published January 2, 1906, issued January 2, 1906 and Buffalo Forge Company "No. 808,897 Patented Jan. 2, 1906: H. W. Carrier: Apparatus for Treating Air" (PDF). Archived (PDF) from the original on December 5, 2019. Retrieved May 12, 2021.
  34. ^ "First Air-Conditioned Auto". Popular Science. Vol. 123, no. 5. November 1933. p. 30. ISSN 0161-7370. Archived from the original on April 26, 2021. Retrieved May 12, 2021.
  35. ^ "Room-size air conditioner fits under window sill". Popular Mechanics. Vol. 63, no. 6. June 1935. p. 885. ISSN 0032-4558. Archived from the original on November 22, 2016. Retrieved May 12, 2021.
  36. ^ "Michigan Fast Facts and Trivia". 50states.com. Archived from the original on June 18, 2017. Retrieved May 12, 2021.
  37. ^ US patent US2433960A, Sherman, Robert S., "Air conditioning apparatus", published January 6, 1948, issued January 6, 1948 
  38. ^ "IEEE milestones (39) Inverter Air Conditioners, 1980–1981" (PDF). March 2021. Archived (PDF) from the original on January 21, 2024. Retrieved February 9, 2024.
  39. ^ "Inverter Air Conditioners, 1980–1981 IEEE Milestone Celebration Ceremony" (PDF). March 16, 2021. Archived (PDF) from the original on January 21, 2024. Retrieved February 9, 2024.
  40. ^ Seale, Avrel (August 7, 2023). "Texas alumnus and his alma mater central to air-conditioned homes". UT News. Retrieved November 13, 2024.
  41. ^ "Air Conditioned Village". Atlas Obscura. Retrieved November 13, 2024.
  42. ^ a b c Davis, Lucas; Gertler, Paul; Jarvis, Stephen; Wolfram, Catherine (July 2021). "Air conditioning and global inequality". Global Environmental Change. 69: 102299. Bibcode:2021GEC....6902299D. doi:10.1016/j.gloenvcha.2021.102299.
  43. ^ Pierre-Louis, Kendra (May 15, 2018). "The World Wants Air-Conditioning. That Could Warm the World". The New York Times. Archived from the original on February 16, 2021. Retrieved May 12, 2021.
  44. ^ Carroll, Rory (October 26, 2015). "How America became addicted to air conditioning". The Guardian. Los Angeles. Archived from the original on March 13, 2021. Retrieved May 12, 2021.
  45. ^ Lester, Paul (July 20, 2015). "History of Air Conditioning". United States Department of Energy. Archived from the original on June 5, 2020. Retrieved May 12, 2021.
  46. ^ Cornish, Cheryl; Cooper, Stephen; Jenkins, Salima. Characteristics of New Housing (Report). United States Census Bureau. Archived from the original on April 11, 2021. Retrieved May 12, 2021.
  47. ^ "Central Air Conditioning Buying Guide". Consumer Reports. March 3, 2021. Archived from the original on May 9, 2021. Retrieved May 12, 2021.
  48. ^ Petchers, Neil (2003). Combined Heating, Cooling & Power Handbook: Technologies & Applications : an Integrated Approach to Energy Resource Optimization. The Fairmont Press. p. 737. ISBN 978-0-88173-433-1.
  49. ^ Krarti, Moncef (December 1, 2020). Energy Audit of Building Systems: An Engineering Approach, Third Edition. CRC Press. p. 370. ISBN 978-1-000-25967-4.
  50. ^ "What is a Reversing Valve". Samsung India. Archived from the original on February 22, 2019. Retrieved May 12, 2021.
  51. ^ "Humidity and Comfort" (PDF). DriSteem. Archived from the original (PDF) on May 16, 2018. Retrieved May 12, 2021.
  52. ^ Perryman, Oliver (April 19, 2021). "Dehumidifier vs Air Conditioning". Dehumidifier Critic. Archived from the original on May 13, 2021. Retrieved May 12, 2021.
  53. ^ Snijders, Aart L. (July 30, 2008). "Aquifer Thermal Energy Storage (ATES) Technology Development and Major Applications in Europe" (PDF). Toronto and Region Conservation Authority. Arnhem: IFTech International. Archived (PDF) from the original on March 8, 2021. Retrieved May 12, 2021.
  54. ^ a b "Cold Climate Air Source Heat Pump" (PDF). Minnesota Department of Commerce, Division of Energy Resources. Archived (PDF) from the original on January 2, 2022. Retrieved March 29, 2022.
  55. ^ "Even in Frigid Temperatures, Air-Source Heat Pumps Keep Homes Warm From Alaska Coast to U.S. Mass Market". nrel.gov. Archived from the original on April 10, 2022. Retrieved March 29, 2022.
  56. ^ "Heat Pumps: A Practical Solution for Cold Climates". RMI. December 10, 2020. Archived from the original on March 31, 2022. Retrieved March 28, 2022.
  57. ^ "TEM Instruction Sheet" (PDF). TE Technology. March 14, 2012. Archived from the original (PDF) on January 24, 2013. Retrieved May 12, 2021.
  58. ^ "Coefficient of Performance (COP) heat pumps". Grundfos. November 18, 2020. Archived from the original on May 3, 2021. Retrieved May 12, 2021.
  59. ^ "Unpotted HP-199-1.4-0.8 at a hot-side temperature of 25 °C" (PDF). TE Technology. Archived from the original (PDF) on January 7, 2009. Retrieved February 9, 2024.
  60. ^ Newell, David B.; Tiesinga, Eite, eds. (August 2019). The International System of Units (SI) (PDF). National Institute of Standards and Technology. doi:10.6028/NIST.SP.330-2019. Archived (PDF) from the original on April 22, 2021. Retrieved May 13, 2021.
  61. ^ ANSI/AHRI 210/240-2008: 2008 Standard for Performance Rating of Unitary Air-Conditioning & Air-Source Heat Pump Equipment (PDF). Air Conditioning, Heating and Refrigeration Institute. 2012. Archived from the original on March 29, 2018. Retrieved May 13, 2021.
  62. ^ Baraniuk, Chris. "Cutting-Edge Technology Could Massively Reduce the Amount of Energy Used for Air Conditioning". Wired. ISSN 1059-1028. Retrieved July 18, 2024.
  63. ^ "M-Series Contractor Guide" (PDF). Mitsubishipro.com. p. 19. Archived (PDF) from the original on March 18, 2021. Retrieved May 12, 2021.
  64. ^ "エアコンの歴史とヒミツ | 調べよう家電と省エネ | キッズ版 省エネ家電 de スマートライフ(一般財団法人 家電製品協会) 学ぼう!スマートライフ". shouene-kaden.net. Archived from the original on September 7, 2022. Retrieved January 21, 2024.
  65. ^ "Air conditioner | History". Toshiba Carrier. April 2016. Archived from the original on March 9, 2021. Retrieved May 12, 2021.
  66. ^ "1920s–1970s | History". Mitsubishi Electric. Archived from the original on March 8, 2021. Retrieved May 12, 2021.
  67. ^ Wagner, Gerry (November 30, 2021). "The Duct Free Zone: History of the Mini Split". HPAC Magazine. Retrieved February 9, 2024.
  68. ^ "History of Daikin Innovation". Daikin. Archived from the original on June 5, 2020. Retrieved May 12, 2021.
  69. ^ Feit, Justin (December 20, 2017). "The Emergence of VRF as a Viable HVAC Option". buildings.com. Archived from the original on December 3, 2020. Retrieved May 12, 2021.
  70. ^ a b "Central Air Conditioning". United States Department of Energy. Archived from the original on January 30, 2021. Retrieved May 12, 2021.
  71. ^ Kreith, Frank; Wang, Shan K.; Norton, Paul (April 20, 2018). Air Conditioning and Refrigeration Engineering. CRC Press. ISBN 978-1-351-46783-4.
  72. ^ Wang, Shan K. (November 7, 2000). Handbook of Air Conditioning and Refrigeration. McGraw-Hill Education. ISBN 978-0-07-068167-5.
  73. ^ Hleborodova, Veronika (August 14, 2018). "Portable Vs Split System Air Conditioning | Pros & Cons". Canstar Blue. Archived from the original on March 9, 2021. Retrieved May 12, 2021.
  74. ^ Kamins, Toni L. (July 15, 2013). "Through-the-Wall Versus PTAC Air Conditioners: A Guide for New Yorkers". Brick Underground. Archived from the original on January 15, 2021. Retrieved May 12, 2021.
  75. ^ "Self-Contained Air Conditioning Systems". Daikin Applied Americas. 2015. Archived from the original on October 30, 2020. Retrieved May 12, 2021.
  76. ^ "LSWU/LSWD Vertical Water-Cooled Self-Contained Unit Engineering Guide" (PDF). Johnson Controls. April 6, 2018. Archived (PDF) from the original on May 13, 2021. Retrieved May 12, 2021.
  77. ^ "Packaged Rooftop Unit" (PDF). Carrier Global. 2016. Archived (PDF) from the original on May 13, 2021. Retrieved May 12, 2021.
  78. ^ "Packaged Rooftop Air Conditioners" (PDF). Trane Technologies. November 2006. Archived (PDF) from the original on May 13, 2021. Retrieved May 12, 2021.
  79. ^ "What is Packaged Air Conditioner? Types of Packged Air Condtioners". Bright Hub Engineering. January 13, 2010. Archived from the original on February 22, 2018. Retrieved May 12, 2021.
  80. ^ Evans, Paul (November 11, 2018). "RTU Rooftop Units explained". The Engineering Mindset. Archived from the original on January 15, 2021. Retrieved May 12, 2021.
  81. ^ "water-cooled – Johnson Supply". studylib.net. 2000. Archived from the original on May 13, 2021. Retrieved May 12, 2021.
  82. ^ "Water Cooled Packaged Air Conditioners" (PDF). Japan: Daikin. May 2, 2003. Archived (PDF) from the original on June 19, 2018. Retrieved May 12, 2021.
  83. ^ "Water Cooled Packaged Unit" (PDF). Daikin. Archived (PDF) from the original on May 13, 2021. Retrieved May 12, 2021.
  84. ^ Lun, Y. H. Venus; Tung, S. L. Dennis (November 13, 2019). Heat Pumps for Sustainable Heating and Cooling. Springer Nature. p. 25. ISBN 978-3-030-31387-6.
  85. ^ Ghanbariannaeeni, Ali; Ghazanfarihashemi, Ghazalehsadat (June 2012). "Bypass Method For Recip Compressor Capacity Control". Pipeline and Gas Journal. 239 (6). Archived from the original on August 12, 2014. Retrieved February 9, 2024.
  86. ^ "Heat Stroke (Hyperthermia)". Harvard Health. January 2, 2019. Archived from the original on January 29, 2021. Retrieved May 13, 2021.
  87. ^ "Weather Related Fatality and Injury Statistics". National Weather Service. 2021. Archived from the original on August 24, 2022. Retrieved August 24, 2022.
  88. ^ "Extreme Weather: A Guide to Surviving Flash Floods, Tornadoes, Hurricanes, Heat Waves, Snowstorms Tsunamis and Other Natural Disasters". Reference Reviews. 26 (8): 41. October 19, 2012. doi:10.1108/09504121211278322. ISSN 0950-4125. Archived from the original on January 21, 2024. Retrieved December 9, 2023.
  89. ^ a b c Gamarro, Harold; Ortiz, Luis; González, Jorge E. (August 1, 2020). "Adapting to Extreme Heat: Social, Atmospheric, and Infrastructure Impacts of Air-Conditioning in Megacities—The Case of New York City". Journal of Engineering for Sustainable Buildings and Cities. 1 (3). doi:10.1115/1.4048175. ISSN 2642-6641. S2CID 222121944.
  90. ^ Spiegelman, Jay; Friedman, Herman; Blumstein, George I. (September 1, 1963). "The effects of central air conditioning on pollen, mold, and bacterial concentrations". Journal of Allergy. 34 (5): 426–431. doi:10.1016/0021-8707(63)90007-8. ISSN 0021-8707. PMID 14066385.
  91. ^ Portnoy, Jay M.; Jara, David (February 1, 2015). "Mold allergy revisited". Annals of Allergy, Asthma & Immunology. 114 (2): 83–89. doi:10.1016/j.anai.2014.10.004. ISSN 1081-1206. PMID 25624128.
  92. ^ "Subpart 4-1 – Cooling Towers". New York Codes, Rules and Regulations. June 7, 2016. Archived from the original on May 13, 2021. Retrieved May 13, 2021.
  93. ^ Nordhaus, William D. (February 10, 2010). "Geography and macroeconomics: New data and new findings". Proceedings of the National Academy of Sciences. 103 (10): 3510–3517. doi:10.1073/pnas.0509842103. ISSN 0027-8424. PMC 1363683. PMID 16473945.
  94. ^ Barreca, Alan; Deschenes, Olivier; Guldi, Melanie (2018). "Maybe next month? Temperature shocks and dynamic adjustments in birth rates". Demography. 55 (4): 1269–1293. doi:10.1007/s13524-018-0690-7. PMC 7457515. PMID 29968058.
  95. ^ Glaeser, Edward L.; Tobio, Kristina (January 2008). "The Rise of the Sunbelt". Southern Economic Journal. 74 (3): 609–643. doi:10.1002/j.2325-8012.2008.tb00856.x.
  96. ^ Sherman, Peter; Lin, Haiyang; McElroy, Michael (2018). "Projected global demand for air conditioning associated with extreme heat and implications for electricity grids in poorer countries". Energy and Buildings. 268: 112198. doi:10.1016/j.enbuild.2022.112198. ISSN 0378-7788. S2CID 248979815.
  97. ^ Air Filters Used in Air Conditioning and General Ventilation Part 1: Methods of Test for Atmospheric Dust Spot Efficiency and Synthetic Dust Weight Arrestance (Withdrawn Standard). British Standards Institution. March 29, 1985. BS 6540-1:1985.
  98. ^ Mutschler, Robin; Rüdisüli, Martin; Heer, Philipp; Eggimann, Sven (April 15, 2021). "Benchmarking cooling and heating energy demands considering climate change, population growth and cooling device uptake". Applied Energy. 288: 116636. Bibcode:2021ApEn..28816636M. doi:10.1016/j.apenergy.2021.116636. ISSN 0306-2619.
  99. ^ a b "Climate-friendly cooling could cut years of Greenhouse Gas Emissions and save US$ trillions: UN". Climate Change and Law Collection. doi:10.1163/9789004322714_cclc_2020-0252-0973.
  100. ^ Gerretsen, Isabelle (December 8, 2020). "How your fridge is heating up the planet". BBC Future. Archived from the original on May 10, 2021. Retrieved May 13, 2021.
  101. ^ Encyclopedia of Energy: Ph-S. Elsevier. 2004. ISBN 978-0121764821.
  102. ^ Corberan, J.M. (2016). "New trends and developments in ground-source heat pumps". Advances in Ground-Source Heat Pump Systems. pp. 359–385. doi:10.1016/B978-0-08-100311-4.00013-3. ISBN 978-0-08-100311-4.
  103. ^ Roselli, Carlo; Sasso, Maurizio (2021). Geothermal Energy Utilization and Technologies 2020. MDPI. ISBN 978-3036507040.
  104. ^ "Cooling Emissions and Policy Synthesis Report: Benefits of cooling efficiency and the Kigali Amendment, United Nations Environment Programme - International Energy Agency, 2020" (PDF).
  105. ^ Harlan, Sharon L.; Declet-Barreto, Juan H.; Stefanov, William L.; Petitti, Diana B. (February 2013). "Neighborhood Effects on Heat Deaths: Social and Environmental Predictors of Vulnerability in Maricopa County, Arizona". Environmental Health Perspectives. 121 (2): 197–204. Bibcode:2013EnvHP.121..197H. doi:10.1289/ehp.1104625. ISSN 0091-6765. PMC 3569676. PMID 23164621.
  106. ^ a b Chan, Emily Ying Yang; Goggins, William B; Kim, Jacqueline Jakyoung; Griffiths, Sian M (April 2012). "A study of intracity variation of temperature-related mortality and socioeconomic status among the Chinese population in Hong Kong". Journal of Epidemiology and Community Health. 66 (4): 322–327. doi:10.1136/jech.2008.085167. ISSN 0143-005X. PMC 3292716. PMID 20974839.
  107. ^ Ng, Chris Fook Sheng; Ueda, Kayo; Takeuchi, Ayano; Nitta, Hiroshi; Konishi, Shoko; Bagrowicz, Rinako; Watanabe, Chiho; Takami, Akinori (2014). "Sociogeographic Variation in the Effects of Heat and Cold on Daily Mortality in Japan". Journal of Epidemiology. 24 (1): 15–24. doi:10.2188/jea.JE20130051. PMC 3872520. PMID 24317342.
  108. ^ Stafoggia, Massimo; Forastiere, Francesco; Agostini, Daniele; Biggeri, Annibale; Bisanti, Luigi; Cadum, Ennio; Caranci, Nicola; de'Donato, Francesca; De Lisio, Sara; De Maria, Moreno; Michelozzi, Paola; Miglio, Rossella; Pandolfi, Paolo; Picciotto, Sally; Rognoni, Magda (2006). "Vulnerability to Heat-Related Mortality: A Multicity, Population-Based, Case-Crossover Analysis". Epidemiology. 17 (3): 315–323. doi:10.1097/01.ede.0000208477.36665.34. ISSN 1044-3983. JSTOR 20486220. PMID 16570026. S2CID 20283342.
  109. ^ a b c d Gronlund, Carina J. (September 2014). "Racial and Socioeconomic Disparities in Heat-Related Health Effects and Their Mechanisms: a Review". Current Epidemiology Reports. 1 (3): 165–173. doi:10.1007/s40471-014-0014-4. PMC 4264980. PMID 25512891.
  110. ^ O'Neill, M. S. (May 11, 2005). "Disparities by Race in Heat-Related Mortality in Four US Cities: The Role of Air Conditioning Prevalence". Journal of Urban Health: Bulletin of the New York Academy of Medicine. 82 (2): 191–197. doi:10.1093/jurban/jti043. PMC 3456567. PMID 15888640.
  111. ^ a b Sampson, Natalie R.; Gronlund, Carina J.; Buxton, Miatta A.; Catalano, Linda; White-Newsome, Jalonne L.; Conlon, Kathryn C.; O’Neill, Marie S.; McCormick, Sabrina; Parker, Edith A. (April 1, 2013). "Staying cool in a changing climate: Reaching vulnerable populations during heat events". Global Environmental Change. 23 (2): 475–484. Bibcode:2013GEC....23..475S. doi:10.1016/j.gloenvcha.2012.12.011. ISSN 0959-3780. PMC 5784212. PMID 29375195.
  112. ^ Niktash, Amirreza; Huynh, B. Phuoc (July 2–4, 2014). Simulation and Analysis of Ventilation Flow Through a Room Caused by a Two-sided Windcatcher Using a LES Method (PDF). World Congress on Engineering. Lecture Notes in Engineering and Computer Science. Vol. 2. London. eISSN 2078-0966. ISBN 978-9881925350. ISSN 2078-0958. Archived (PDF) from the original on April 26, 2018. Retrieved May 13, 2021.
  113. ^ Zhang, Chen; Kazanci, Ongun Berk; Levinson, Ronnen; Heiselberg, Per; Olesen, Bjarne W.; Chiesa, Giacomo; Sodagar, Behzad; Ai, Zhengtao; Selkowitz, Stephen; Zinzi, Michele; Mahdavi, Ardeshir (November 15, 2021). "Resilient cooling strategies – A critical review and qualitative assessment". Energy and Buildings. 251: 111312. Bibcode:2021EneBu.25111312Z. doi:10.1016/j.enbuild.2021.111312. hdl:2117/363031. ISSN 0378-7788.
  114. ^ Linden, P. F. (1999). "The Fluid Mechanics of Natural Ventilation". Annual Review of Fluid Mechanics. 31: 201–238. Bibcode:1999AnRFM..31..201L. doi:10.1146/annurev.fluid.31.1.201.
  115. ^ Santamouris, M.; Asimakoupolos, D. (1996). Passive cooling of buildings (1st ed.). London: James & James (Science Publishers) Ltd. ISBN 978-1-873936-47-4.
  116. ^ Leo Samuel, D.G.; Shiva Nagendra, S.M.; Maiya, M.P. (August 2013). "Passive alternatives to mechanical air conditioning of building: A review". Building and Environment. 66: 54–64. Bibcode:2013BuEnv..66...54S. doi:10.1016/j.buildenv.2013.04.016.
  117. ^ M.j, Limb (January 1, 1998). "BIB 08: An Annotated Bibliography: Passive Cooling Technology for Office Buildings in Hot Dry and Temperate Climates".
  118. ^ Niles, Philip; Kenneth, Haggard (1980). Passive Solar Handbook. California Energy Resources Conservation. ASIN B001UYRTMM.
  119. ^ "Cooling: The hidden threat for climate change and sustainable goals". phys.org. Retrieved September 18, 2021.
  120. ^ Ford, Brian (September 2001). "Passive downdraught evaporative cooling: principles and practice". Arq: Architectural Research Quarterly. 5 (3): 271–280. doi:10.1017/S1359135501001312. ISSN 1474-0516. S2CID 110209529.
  121. ^ a b Chen, Meijie; Pang, Dan; Chen, Xingyu; Yan, Hongjie; Yang, Yuan (2022). "Passive daytime radiative cooling: Fundamentals, material designs, and applications". EcoMat. 4. doi:10.1002/eom2.12153. S2CID 240331557. Passive daytime radiative cooling (PDRC) dissipates terrestrial heat to the extremely cold outer space without using any energy input or producing pollution. It has the potential to simultaneously alleviate the two major problems of energy crisis and global warming.
  122. ^ Raman, Aaswath P.; Anoma, Marc Abou; Zhu, Linxiao; Rephaeli, Eden; Fan, Shanhui (November 2014). "Passive radiative cooling below ambient air temperature under direct sunlight". Nature. 515 (7528): 540–544. Bibcode:2014Natur.515..540R. doi:10.1038/nature13883. PMID 25428501.
  123. ^ a b Bijarniya, Jay Prakash; Sarkar, Jahar; Maiti, Pralay (November 2020). "Review on passive daytime radiative cooling: Fundamentals, recent researches, challenges and opportunities". Renewable and Sustainable Energy Reviews. 133: 110263. Bibcode:2020RSERv.13310263B. doi:10.1016/j.rser.2020.110263. S2CID 224874019.
  124. ^ Mokhtari, Reza; Ulpiani, Giulia; Ghasempour, Roghayeh (July 2022). "The Cooling Station: Combining hydronic radiant cooling and daytime radiative cooling for urban shelters". Applied Thermal Engineering. 211: 118493. Bibcode:2022AppTE.21118493M. doi:10.1016/j.applthermaleng.2022.118493.
  125. ^ Yang, Yuan; Zhang, Yifan (July 2020). "Passive daytime radiative cooling: Principle, application, and economic analysis". MRS Energy & Sustainability. 7 (1). doi:10.1557/mre.2020.18.
  126. ^ Miranda, Nicole D.; Renaldi, Renaldi; Khosla, Radhika; McCulloch, Malcolm D. (October 2021). "Bibliometric analysis and landscape of actors in passive cooling research". Renewable and Sustainable Energy Reviews. 149: 111406. Bibcode:2021RSERv.14911406M. doi:10.1016/j.rser.2021.111406.
  127. ^ a b Needham, Joseph; Wang, Ling (1991). Science and Civilisation in China, Volume 4: Physics and Physical Technology, Part 2, Mechanical Engineering. Cambridge University Press. ISBN 978-0521058032. OCLC 468144152.
  128. ^ Dalley, Stephanie (2002). Mari and Karana: Two Old Babylonian Cities (2nd ed.). Piscataway, New Jersey: Gorgias Press. p. 91. ISBN 978-1931956024. OCLC 961899663. Archived from the original on January 29, 2021. Retrieved May 13, 2021.
  129. ^ Nagengast, Bernard (February 1999). "Comfort from a Block of Ice: A History of Comfort Cooling Using Ice" (PDF). ASHRAE Journal. 41 (2): 49. ISSN 0001-2491. Archived (PDF) from the original on May 13, 2021. Retrieved May 13, 2021.
  130. ^ Bahadori, Mehdi N. (February 1978). "Passive Cooling Systems in Iranian Architecture". Scientific American. 238 (2): 144–154. Bibcode:1978SciAm.238b.144B. doi:10.1038/SCIENTIFICAMERICAN0278-144.
  131. ^ Smith, Shane (2000). Greenhouse Gardener's Companion: Growing Food and Flowers in Your Greenhouse Or Sunspace. Illustrated by Marjorie C. Leggitt (illustrated, revised ed.). Golden, Colorado: Fulcrum Publishing. p. 62. ISBN 978-1555914509. OCLC 905564174. Archived from the original on May 13, 2021. Retrieved August 25, 2020.
[edit]

 

A Nest Labs thermostat

Smart thermostats are Wi-Fi thermostats that can be used with home automation and are responsible for controlling a home's heating, ventilation, and air conditioning. They perform similar functions as a programmable thermostat as they allow the user to control the temperature of their home throughout the day using a schedule, but also contain additional features, such as Wi-Fi connectivity,[1][2] that improve upon the issues with programming.

Like other Wi-Fi thermostats, they are connected to the Internet via a Wi-Fi network. They allow users to adjust heating settings from other internet-connected devices, such as a laptop or smartphones. This allows users to control the thermostat remotely. This ease of use is essential for ensuring energy savings: studies have shown that households with programmable thermostats actually have higher energy consumption than those with simple thermostats because residents program them incorrectly or disable them completely.[3][4]

Smart thermostats also record internal/external temperatures, the time the HVAC system has been running and can notify the user if the system's air filter needs to be replaced. This information is typically displayed later on an internet-connected device such as a smartphone.

Manual vs. programmable vs. smart thermostats

[edit]

Manual thermostats

[edit]
Honeywell Manual Thermostat

Manual thermostats (also known as analog thermostats) are the oldest and simplest type of thermostats. These thermostats are set to one temperature and do not change until the user manually adjusts the temperature.[5]

Programmable thermostats

[edit]

Programmable thermostats, first introduced over 100 years ago,[6] are a type of thermostat that allows the user to set a schedule for different temperatures at different times. Most programmable thermostats also have a hold feature which suspends the schedule and effectively turns the thermostat into a manual thermostat.[5] The idea of the scheduling feature is that users will set a warmer or cooler temperature when the home is unoccupied to save energy and money. Due to this assumed energy savings, some building codes and government programs began requiring the use of programmable thermostats.[7] Due to the way people use these devices, most programmable thermostats result in more energy use than the basic manual thermostat.[8]

Issues with programmable thermostats

[edit]

One of the main objectives of smart thermostats is to reduce the issues involved with using traditional programmable thermostats. In order to understand how smart thermostats take on this task, it is important to understand the issues regarding programmable thermostats and how they affect energy consumption. Between 2008-2009, Florida Power & Light (FPL) provided 400 homeowners with programmable thermostats and monitored their heating and cooling patterns. Out of the 400 participants, 56% of users used the programming feature while the remaining participants did not program the thermostat and left it on "hold". It was determined that the users who used the programming feature actually consumed 12% more energy than the non-programmers. This consumption increase resulted from higher overnight duty cycles associated with lower thermostat setpoints (i.e. lower temperature setting), due to confusion with setting the schedule. This study reveals that programmable thermostats will not necessarily save energy. The smart thermostat attempts to combat this issue by taking the user out of the picture and relying on sensors and computers to save energy.[8]

Another study conducted on the issue determined that the biggest problem for programmable thermostats was the human using it. The technology inside a programmable thermostat is no doubt one of the most important factors in determining whether or not the thermostat will be successful in saving energy. But an equally important factor is the human who is using the thermostat. Unfortunately, many people who own programmable thermostats do not know how to use the thermostat or are not using all of the features that are offered. One study conducted a number of interviews, surveys, and observations to determine that the vast majority of programmable thermostat owners are not using the thermostats for their intended purpose. An online survey showed that 89% of respondents do not use the schedule feature on their programmable thermostat. Other results from the interviews and surveys show that a large number of people have misconceptions about heating/cooling and the use of programmable thermostats. One misconception is people believing that heating all of the time is more efficient than scheduling the heat to turn off. Another misconception noted in the study is that turning down the thermostat does not substantially reduce energy consumption. These misconceptions reaffirm the idea that the programmable thermostat itself could have all of the necessary tools, but if the user does not use them or uses them incorrectly, then these thermostats will fail at saving energy.[7]

As a result of these studies and others like them, energy star suspended its labelling of programmable thermostats in December 2009. It became the goal of smart thermostats to address these issues by taking the human out of the picture and creating a thermostat that uses smart computing to truly reduce energy usage and cost.[7][8]

Smart thermostats

[edit]

Smart thermostats are similar to programmable thermostats in the sense that they have a scheduling feature that allows users to set different temperatures for different times of the day. In addition to this feature, smart thermostats implement other technologies to reduce the amount of human error involved with using programmable thermostats. Smart thermostats incorporate the use of sensors that determine whether or not the home is occupied and can suspend heating or cooling until the occupant returns. Additionally, smart thermostats utilize Wi-Fi connectivity to give the user access to the thermostat at all times. These additional technologies have proven to make smart thermostats successful in saving users energy and money.[5]

History

[edit]

Development of the smart thermostat began in 2007 with the creation of the ecobee thermostat. The founder of ecobee, Stuart Lombard, wanted to save energy and reduce his family's carbon footprint. After realizing that heating and cooling made up most of his home's energy usage,[9] Lombard purchased a programmable thermostat in an attempt to reduce total energy usage. Lombard quickly discovered that the programmable thermostat was difficult to use and unreliable. Following difficulties with the programmable thermostat, he set out to create a smart thermostat that saved energy and was easy to use. With that goal, the ecobee company was created in attempt to offer users a thermostat that could truly save energy by fixing the issues with programmable thermostats.[10]

Following the ecobee, EnergyHub released its version of a smart thermostat in 2009 with the creation of the EnergyHub Dashboard. The co-founder of EnergyHub, Seth Frader-Thompson, got the idea for the Dashboard from his Prius. The Prius had screens on the dashboard that displayed the car's gas mileage in real time. Thompson felt that a house should have something that does the same. With that goal in mind, Thompson created a thermostat that could communicate with a home's furnace and appliances to determine the energy usage and efficiency and how much it was costing. The thermostat also had the capability to turn off appliances or raise and lower the temperature to save energy and cost. Ultimately, the goal of this thermostat was to display energy usage to users and to save energy and money.[11]

Nest Labs company logo. Creators of the Nest Learning Thermostat.

In 2011, Nest Labs developed the Nest Learning Thermostat. The Nest Thermostat attempted to reduce home energy consumption by addressing the problems with programmable thermostats through the use of better technology. This new technology included the implementation of sensors, algorithms, machine learning, and cloud computing. These technologies learn the behaviors and preferences of the occupants, and adjust the temperature up or down to make the occupant comfortable when they are home and to save energy when they are away. Additionally, the Nest Thermostat connects to the home Wi-Fi. This allows users to change the temperature, adjust the schedule, and check energy usage from a smartphone or laptop. All of these features were part of Nest's goal to create an easy to use thermostat that saves users energy and money.[12]

Technology

[edit]

Programmable schedule and auto schedule

[edit]

The programmable schedule feature on the smart thermostat is similar to that on standard programmable thermostats. Users are given the option to program a custom schedule to reduce energy usage when they are away from the home. Studies have shown, though, that manually creating a schedule may lead to more energy usage than just keeping the thermostat at a set temperature.[8] To avoid this problem, smart thermostats also provide an auto schedule feature. This feature requires the use of algorithms and pattern recognition to create a schedule that results in occupant comfort and energy savings. Upon creating a schedule, the thermostat will continue monitoring occupant behavior to make changes to the auto schedule. By taking the human error out of the scheduling, smart thermostats can create smart schedules that actually save energy.[13]

Sensor

[edit]
The Nest Web Portal allows users to remotely change the temperature, create a schedule, and view past energy usage.

In an attempt to mitigate the issues with human error involved with programmable thermostats, the smart thermostat utilizes a sensor that can determine occupancy patterns to automatically change the temperature based on occupant patterns and behaviors. The Nest Learning Thermostat in particular uses passive infrared (PIR) motion sensors inside the unit to sense occupancy in the vicinity of the thermostat. This sensor informs the thermostat whether or not the home is occupied. In the case that the home is not occupied, the thermostat can suspend heating/cooling until the sensor is reactivated by an occupant. This sensor is also used to determine the occupancy patterns to create the auto schedule. A grille member is placed in front of the sensor to visually conceal and protect the PIR motion sensor inside the thermostat. The grille also helps to make the thermostat visually pleasing.[2] While this sensor technology is important for conserving energy, it is not without flaws. One of the major issues is that the sensor must be activated by someone walking in front of or near the thermostat. It is possible that an occupant could be at home and not pass in front of the sensor. In this case, the thermostat would shut off the heating/cooling and decrease human comfort.[14]

Wi-Fi connection

[edit]

A major feature of Wi-Fi thermostats (such as smart thermostats) is their ability to connect to the internet. These thermostats are designed with a Wi-Fi module that allows the thermostat to connect to the user's home or office network and interface with a web portal or smartphone application, allowing users to control the thermostat remotely.[15] The Wi-Fi feature also has the ability to send reports on energy usage and HVAC system performance via the web portal, informing the user on their energy efficiency and how it compares to other smart thermostat users. It also may alert users when a problem arises with their HVAC system or when it is time for equipment maintenance. The thermostat also may use the Wi-Fi connection to display current weather conditions and the weather forecast.[1]

Another feature offered by some smart thermostats through the internet connection is geofencing. A geofence is a perimeter boundary created around the location of a smartphone or other device, based on GPS signals. The benefit of having a smart thermostat with geofencing capabilities is that it uses a users smartphone location to determine whether the home is occupied. Instead of using a schedule or sensor to determine occupancy, the smart thermostat can rely on the location of the geofence to tell the HVAC system whether it needs to be on or off.[16] Since most people carry their phones with them, geofencing can be an accurate way to determine occupancy patterns.[13]

Learning thermostats

[edit]
The Ecobee 4 thermostat

Some smart thermostats, such as the Nest thermostat, can learn when the house is likely to be occupied, and when it is likely to be empty. This allows automatic pre-heating or pre-cooling so the temperature is comfortable when a resident arrives. If the residents or lifestyles change, these smart thermostats will gradually adjust the schedule, maintaining energy savings and comfort.

Motion detectors can determine if someone is home. One smart thermostat that uses motion detectors is the Ecobee4.[17]

A wireless network can be used to sense when someone is out of range, thus determining if they're in or nearby their home. This geofencing technique is used by the Honeywell T6 Smart Thermostat.

Connected thermostats

[edit]

A Connected thermostat is one that can be controlled through an internet connection, but will not provide analytic information. In recent years Wi-Fi thermostats have risen in popularity, they combine the technology of thermometers and Wi-Fi. So now you can have a thermometer in your home that is displayed on your phone that uses Wi-Fi technology. This technology is being developed right now so it will be available for thermostats in machinery and cars. Google is involved in this push towards technology since it acquired a Wi-Fi temperature company called Nest.[18] The market of smart thermostats is expected to reach around 3.5 Billion USD by the end of the year 2022.[citation needed]

Zoned systems

[edit]

Rather than controlling the temperature of the whole house, zoned systems can control individual rooms. This can increase energy savings, for example by heating or cooling only a Home-office and not the bedrooms and other areas that are empty during the day.

Studies

[edit]

Internal studies

[edit]

To show that their thermostats save energy and money, numerous smart thermostat producers have conducted models and studies to confirm their savings claims. One popular way that smart thermostat producers calculate energy usage is through energy modeling. In these models, the smart thermostat is compared to a thermostat set at a constant temperature, and savings are calculated. Using this method, ecobee calculated energy savings by correlating how long heating and cooling equipment run to local weather conditions. Energy savings were calculated relative to a constant temperature of 22 °C (72 °F). Upon conducting this model, ecobee determined a 23% savings on heating and cooling costs for those who switch to their smart thermostat.[19] Using a similar modeling method, Nest claimed a 20% energy savings for homeowners who install a Nest Learning Thermostat.[20]

To determine energy savings using actual data instead of energy models, in February 2015, Nest conducted a national study of Nest customers in 41 states who had enrolled in Nest's MyEnergy service. In May 2013, Nest acquired MyEnergy, a company that tracks and analyzes utility usage of people enrolled in the program. Upon acquiring MyEnergy, Nest was able to use the historical data to determine the energy savings of those who installed the Nest Learning Thermostat. This study looked at energy usage before and after the installation of a Nest Learning Thermostat and used a weather normalization procedure to prevent unusually cold or warm weather from skewing the data. The study had a sample size of 735 homes for gas usage analysis and 624 homes for electrical analysis. All of these homes were enrolled in the MyEnergy program and had sufficient energy data before and after the installation of a Nest Learning Thermostat. After observing the energy usage for one year, Nest determined that there was an average gas savings of 10% and a cooling savings of 17.5%. The savings varied from house to house depending on how occupants set their thermostat before the installation of a Nest thermostat, along with differences in occupancy patterns, house characteristics, and weather.[20]

Gas and Electric Savings Results[20]
Fuel Sample Size Pre-Nest Total Energy Use Pre-Nest HVAC Total Energy Savings % of HVAC
Natural Gas (therms/yr) 735 774 584 56 ±12 9.6 ±2.1%
Electricity (kWh/yr) 624 12,355 3,351 585 ±97 17.5 ±2.9%

While the results from the MyEnergy study are significantly lower than those from energy modeling, both show a savings in energy usage by switching to a smart thermostat.[19][20]

Third-party studies

[edit]

Since the release of smart thermostats, a number of third party studies have been conducted to determine if smart thermostats actually save energy and how they compare to manual and programmable thermostats with regards to savings. One study conducted an experiment in which 300 standard programmable thermostats were placed in homes and 300 Nest smart thermostats were placed in other homes. It is important to note that the homeowners involved in this study received proper training on how to properly use all of the thermostat functions. This effectively eliminated the issues regarding human error with programmable thermostats. All homes were located within one region of Indiana and had previously undergone home energy assessment. After 1 year of observation, the study concluded that Nest users reduced their heating gas consumption by 12.5% while users of a standard programmable thermostat reduced consumption by 5%. Additionally, it was concluded that Nest and standard programmable thermostat users reduced their cooling electric consumption by 13.9% and 13.1%, respectively. The major factors that allowed Nest to reduce consumption more than other thermostats was its ability to further reduce human error and set more efficient temperatures. The Nest thermostat used sensors and Wi-Fi connectivity to adjust the temperature on its own and provide more savings. This study helps to suggest that smart thermostats are in fact successful in reducing energy consumption.[21]

Gas Savings as a Percentage of Heating Gas Usage[21]
Thermostat Pre Heating

Usage (Therms)

Savings

(Therms)

Savings

(%)

Range of

Savings (Therms)

Range of

Savings (%)

Nest 548 69 12.5% 60 to 77 11 to 14%
Programmable 602 30 5% 22 to 38 4 to 6%
Electric Savings as a Percentage of Cooling Electricity Usage[21]
Thermostat Pre Usage

(kWh)

Savings

(kWh)

Savings

(%)

Range of

Savings (kWh)

Range of

Savings (%)

Nest 3,080 429 13.9% 270 to 589 9 to 19%
Programmable 2,537 332 13.1% 181 to 483 7 to 19%

A similar study conducted in 2012 with the ecobee thermostat also concluded that smart thermostats are capable of saving energy. The goal of this pilot program was to determine the gas and electric savings of smart thermostats. This study provided 86 households with 123 ecobee thermostats and monitored the homes for 12 months. The study included 69 houses from Massachusetts and 17 from Rhode Island. The participants either had manual or programmable thermostats before the study was conducted. Gas and electric billing data were provided for 12 months before the study was conducted to use as a baseline. After the 12 months of observation, the study concluded that ecobee thermostats led to an average electricity savings of 16% and an average gas savings of 10%. The gas savings for manual thermostat replacements (10% per thermostat) was found to be larger than for programmable thermostat replacements (8% per thermostat). The difference in electricity savings between homes whose prior equipment was a manual thermostat or programmable thermostat was found to be minimal.[1]

Gas Billing Analysis Savings Summary[1]
Previous

Thermostat

Number of

Participants

Pre Usage

(Therms)

Savings

(Therms)

Savings

(%)

Range of

Savings (Therms)

Range of

Savings (%)

Manual

Thermostat

23 890 87 10% 60 to 113 7 to 13%
Programmable

Thermostat

44 842 66 8% 43 to 88 5 to 10%
Electric Savings Analysis Savings Summary[1]
Previous

Thermostat

Number of

Participants

Pre Usage

(kWh)

Savings

(kWh)

Savings

(%)

Manual and

Programmable

Thermostat

12 640 113 16%

Although these studies report differing amounts of savings compared to the internal studies conducted by Nest and ecobee, both of these studies show that smart thermostats have the potential to save energy. This suggests that the technologies added to fix the issues with programmable thermostats have been successful.[1][21]

Study discrepancies

[edit]

Although most studies show that smart thermostats show an energy savings, the amount of savings varies. A large discrepancy is seen between energy modeling savings and the savings found using actual data. The energy modeling compares the smart thermostat to a constant set point temperature of 72 °F, but an online survey conducted by Nest showed that most users have a set point temperature that is 10% more efficient.[20] Therefore, the savings predicted by the energy modeling are going to be higher than real savings.

There are other factors that cause discrepancies even between studies that all look at actual data. Most studies compare total energy consumption of a house from year to year to determine energy savings, as opposed to looking at just the energy that is used for heating and cooling. Due to this, there could be other factors that change the energy consumption of a house, and it might be incorrect to state that the thermostat is responsible for all energy savings in a house. For example, it is possible that other new energy efficient practices/appliances are partially responsible for the savings in addition to the thermostat.[20]

Another discrepancy to consider is the population of people involved in the study. Some studies, such as the MyEnergy study, involve people who signed up for an energy analysis program.[20] These people are likely to be more energy conscious and efficient and have better heating and cooling practices. This greater interest in energy efficiency may lead to lower energy savings by switching to a smart thermostat. The most energy-conscious customers are the ones more likely to have had efficient thermostat settings, therefore, the savings that they receive from the smart thermostat may not be as great.[1]

The weather will also have an impact on the results of a study. Having very high temperatures in the summer and very cold temperatures in the winter will lead to more cooling and heating in those months, requiring more energy. When comparing year to year data, if one year had extreme temperatures, while the following year had moderate temperatures, the savings may look drastic. In reality though, the savings are not from the thermostat, but rather from the change in weather. Studies will try to mitigate this problem through weather normalization procedures.[20]

Broader Impact

[edit]

While smart thermostats have the potential to save energy consumption, they can create unintended consequences on the broader electrical grid. Smart thermostats tend to operate similarly across a population and can create load synchronization. This load synchronization can create much higher peaks and more rapid changes in heating demand. Particularly in the winter, this heating demand is shifted earlier in the morning, when solar electricity is unavailable, making it more difficult to supply electric heating sources like heat pumps with renewable energy.[22]

Improvements

[edit]

Motion sensors

[edit]

One issue with using a smart thermostat is the unreliability of the motion sensor. One of the main features of the smart thermostat is the ability to change the temperature when the sensor in the thermostat does not sense an occupant. The only sensor that is used though is the sensor in the thermostat. This means that if the home is occupied but no one walks passed the thermostat, the thermostat will think that the home is unoccupied and will change the temperature, potentially leading to occupant discomfort.

One study attempted to address this issue by adding more sensors throughout the house. Instead of using just one sensor in the thermostat, this team experimented with placing motion sensors and door sensors throughout the house to gain better understanding of the occupant's sleeping and occupancy patterns. These sensors communicated with each other and used an algorithm to quickly determine whether the occupants were active, sleeping, or away. The system used historical data to estimate when occupants would be returning and would begin "preheating" the home before they arrived. Additionally, the system would drift further from the set point when it was certain that no one was home. The study compared a standard ("reactive") smart thermostat and the multiple sensor system to a manual thermostat. The study concluded that a reactive smart thermostat with just on sensor saves, on average, 6.8% of energy consumption, while the multiple sensor system saved an average of 28% of energy consumption. This study again shows that, on average, smart thermostats achieve their goal of saving energy. It also shows that smart thermostats are not as well developed as they could be, and the addition of more sensors could result in better performance and energy savings.[14]

User interface

[edit]

One of the issues with programmable thermostats that smart thermostats try to fix is the confusing user interface. Many owners of programmable thermostats found the controls and directions to be too confusing and opted out of using the scheduling feature completely. Others who used the feature used it incorrectly, due to the confusing directions, and saw an increase in energy usage.[7] Developers of smart thermostats have attempted to fix this issue by creating simple to use thermostats and providing proper direction. While this is an improvement on programmable thermostats, studies have shown that users desire more intense training from the installer of the thermostat on how to use the technical features. Additionally, many smart thermostats use a web portal where users can adjust the thermostat settings and look at their energy usage history. Again, studies have shown that users want this feature to be improved. Some complain that the web portal is not user friendly and they desire more training on how to use the web features during installation.[1]

Internet security

[edit]

Researchers from the University of Central Florida conducted an experiment to show that hackers could use the Nest thermostat as an entry point into one's home. Upon being connected to the internet, the hackers could use the thermostat to control local network traffic from a remote location. The hacker could also use the thermostat to act as a spy and would know whether or not the home is occupied. The research showed that in order for a hacker to gain access to the thermostat, they would have to gain physical access to the device and upload the malicious firmware via a USB port. This drastically decreases the chances that this type of attack will occur, but it is still possible if a used thermostat is purchased with the firmware already uploaded. The problem that allows this type of attack is with the hardware in the thermostat. Therefore, Nest cannot repair this issue with a simple software update, but rather it would need to build a new thermostat that can prevent this type of attack.[15][23]

Sustainability

[edit]
Residential Energy Consumption Survey conducted by the U.S. Energy Information Administration shows residential electricity consumption by category.

Climate change

[edit]

According to the 2015 Residential Energy Consumption Survey conducted by the U.S. Energy Information Administration, home heating and cooling account for the highest percentage of residential electrical energy consumption. Air conditioning accounts for 17% of electrical usage while space heating accounts for 15%.[9] The Residential Energy Consumption Survey from 2009 looked at energy consumption from all energy types (natural gas and electricity). This survey determined that space heating accounted for 42% of all residential energy consumption, while air conditioning accounted for 6%.[24] This energy usage needed to heat and cool homes is directly linked to climate change, as the energy provided for heating and cooling often comes from the burning of fossil fuels, leading to the release of greenhouse gas emissions. With an added focus on combating climate change and global warming, nations from around the world have begun to take on this issue by limiting greenhouse gas emissions and preventing the rise in global temperature through agreements such as The Paris Agreement.[25] Any steps taken to reduce residential energy consumption will help to achieve those goals.

Smart thermostats could be a solution to reducing energy consumption, as numerous studies have shown that these thermostats do in fact reduce home energy consumption.[1][19][20][21] Additionally, the technology within smart thermostats has proven to provide optimal occupant comfort, while still reducing energy consumption.[20] In addition to providing comfort, these technologies take the human out of the picture. Many sustainable devices rely heavily on how the user uses them. By relying on technology instead of human actions, smart thermostats reduce the amount of human error often experienced with other sustainable devices, such as the programmable thermostat. These factors suggest that installing a smart thermostat is one easy step than many people can take to reduce energy usage and greenhouse gas emissions, ultimately leading to a more sustainable future.

Programs

[edit]

Many housing corporations and smart thermostat developers realize the potential of smart thermostats to save energy, and have developed programs to advance sustainability through smarter technology. Ecobee promotes a sustainable future through its "A Better Tomorrow" program, in which the company donates time, data, and technology to ensure a brighter future.[26] As part of this program, in January 2018, ecobee donated 776 ecobee thermostats to the Toronto Community Housing Corporation (TCHC) to help the city of Toronto advance their climate change action plan. This donation helps to improve the TCHC's goal of providing healthy, safe, and sustainable homes for the people of Toronto.[27]

Another popular way that utility companies promote switching to a smart thermostat is through monetary incentives. The San Diego Gas & Electric company currently runs a program that offers participants a $50 e-gift card after switching to a smart thermostat.[28] The Wisconsin Focus on Energy program partners with utility companies across Wisconsin to offer a $75 check to those who purchase a qualifying smart thermostat.[29] Austin Energy, a utility company providing electricity to the city of Austin, Texas, offers a $25 rebate for each eligible smart thermostat that is purchased and installed.[30] Pacific Gas and Electric Company (PG&E) offers smart thermostat rebates in California for residential and multifamily customers.[31][32] Many other companies across the United States offer similar programs to incentive smart thermostats and more sustainable heating and cooling.[33][34]

Upon installing a smart thermostat, there are additional programs that continue to promote sustainability and reduced energy consumption. The Nest Rush Hour Rewards program partners with utility companies across the United States to incentivize customers to set a higher or lower temperature during peak demand periods. Energy rush hours occur when everyone in a particular area turns on their heating or cooling at the same time, such as during a heat wave. This extra demand may require utility companies to run additional power plants, leading to more cost and carbon emissions. To avoid this, the Rush Hour Rewards program incentivizes customers to set a more efficient temperature that will reduce the amount of energy needed to be produced by the utility.[35]

As more programs like these are created, smart thermostats will play an increasingly important role in reducing residential energy consumption. This reduction will lead to fewer greenhouse gas emissions, helping to create a more sustainable future.

See also

[edit]

References

[edit]
  1. ^ a b c d e f g h i Miller, Alexi, et al. Wi-Fi Programmable Controllable Thermostat Pilot Program Evaluation. The Cadmus Group, Sept. 2012, ma-eeac.org/wordpress/wp-content/uploads/Wi-Fi-Programmable-Controllable-Thermostat-Pilot-Program-Evaluation_Part-of-the-Massachusetts-2011-Residential-Retrofit-Low-Income-Program-Area-Study.pdf.
  2. ^ a b Huppi, Brian (19 Nov 2010). "System and method for integrating sensors in thermostats".
  3. ^ Environmental Protection Agency. Summary of Research Findings From the Programmable Thermostat Market. Washington, DC: Office of Headquarters, 2004
  4. ^ H Sachs. Programmable Thermostats. ACEEE, 2004
  5. ^ a b c "Manual vs Programmable vs Smart Thermostats | Which Is Best for You?". Service Champions. 2018-05-18. Retrieved 2018-12-06.
  6. ^ "The Honeywell Temperature Regulator".
  7. ^ a b c d Meier, Alan (2010). "How People Actually Use Thermostats". ACEEE. cite journal: Cite journal requires |journal= (help)[permanent dead link]
  8. ^ a b c d Lopes, Joseph. "FPL Residential Thermostat Load Control Pilot Project Evaluation" (PDF). ACEEE. cite journal: Cite journal requires |journal= (help)
  9. ^ a b "EIA's residential energy survey now includes estimates for more than 20 new end uses - Today in Energy - U.S. Energy Information Administration (EIA)". www.eia.gov. Retrieved 2018-12-07.
  10. ^ "About ecobee | ecobee | Smart Home Technology". www.ecobee.com. Retrieved 2018-12-06.
  11. ^ "The 50 Best Inventions of 2009 - TIME". Time. 2009-11-12. ISSN 0040-781X. Retrieved 2018-12-06.
  12. ^ "Nest Labs Introduces World's First Learning Thermostat". Nest. 25 Oct 2011.
  13. ^ a b Nest. "Support". Nest. Retrieved 2018-12-07.
  14. ^ a b Lu, Jiakang; Sookoor, Tamim; Srinivasan, Vijay; Gao, Ge; Holben, Brian; Stankovic, John; Field, Eric; Whitehouse, Kamin (2010). "The smart thermostat". Proceedings of the 8th ACM Conference on Embedded Networked Sensor Systems - Sen Sys '10. p. 211. doi:10.1145/1869983.1870005. ISBN 978-1-4503-0344-6. S2CID 207183167.
  15. ^ a b Hernandez, Grant; Arias, Orlando; Buentello, Daniel; Jin, Yier (2014). "Smart Nest Thermostat A Smart Spy in Your Home" (PDF). Blackhat. S2CID 14493263.
  16. ^ "Should You Get a Thermostat with Geofencing Technology?". General Heating & Air Conditioning. 2014-07-21. Retrieved 2018-12-07.
  17. ^ "Does the ecobee4 also have a built-in motion sensor?". ecobee Support. Retrieved 2018-09-21.
  18. ^ Whitney, Lance (February 12, 2014), "Google closes $3.2 billion purchase of Nest", CNET
  19. ^ a b c "Saving money with ecobee smart Wi-Fi thermostats | ecobee | Smart Home Technology". www.ecobee.com. Retrieved 2018-12-07.
  20. ^ a b c d e f g h i j "Energy Savings from the Nest Learning Thermostat: Energy Bill Analysis Results". Nest Labs, Inc., Feb. 2015, nest.com/-downloads/press/documents/energy-savings-white-paper.pdf.
  21. ^ a b c d e Asrish, Carlyn. Evaluation of the 2013–2014 Programmable and Smart Thermostat Program . The Cadmus Group, 9 Jan. 2015, www.cadmusgroup.com/wp-content/uploads/2015/06/Cadmus_Vectren_Nest_Report_Jan2015.pdf?submissionGuid=c8eda45b-2759-4a31-90e3-d2ecdb9001de.
  22. ^ Lee, Zachary (2022). "Unintended consequences of smart thermostats in the transition to electrified heating". Applied Energy. 322: 119384. doi:10.1016/j.apenergy.2022.119384. S2CID 249809288.
  23. ^ Tilley, Aaron. "How Hackers Could Use A Nest Thermostat As An Entry Point Into Your Home". Forbes. Retrieved 2018-12-07.
  24. ^ "Energy Use in Homes - Energy Explained, Your Guide To Understanding Energy - Energy Information Administration". www.eia.gov. Retrieved 2018-12-07.
  25. ^ "The Paris Agreement | UNFCCC". unfccc.int. Retrieved 2018-12-07.
  26. ^ "Social Impact | ecobee | Smart Home Technology". www.ecobee.com. Retrieved 2018-12-07.
  27. ^ "CNW | ecobee donates over 700 thermostats to Toronto Community Housing to improve sustainability and resident comfort". www.newswire.ca. Retrieved 2018-12-07.
  28. ^ "Smart Thermostat Incentives | San Diego Gas & Electric". www.sdge.com. Retrieved 2018-12-10.
  29. ^ "Smart Thermostats | Focus on Energy". www.focusonenergy.com. Retrieved 2018-12-10.
  30. ^ "Power Partner Thermostats". savings.austinenergy.com. 2013-04-24. Retrieved 2018-12-10.
  31. ^ "Smart thermostat rebate". www.pge.com. Retrieved 2021-09-29.
  32. ^ "Energy management for property managers". www.pge.com. Retrieved 2021-09-29.
  33. ^ "Smart Thermostat Rebate Program | The City of Naperville". www.naperville.il.us. Retrieved 2018-12-10.
  34. ^ "Energy Efficiency Programs | Entergy Mississippi, Inc". www.entergy-mississippi.com. Retrieved 2018-12-10.
  35. ^ Nest. "Support". Nest. Retrieved 2018-12-10.

Frequently Asked Questions

Rattling noises in cooling systems can be caused by loose or damaged components, such as fan blades, motor mounts, or ductwork. Debris trapped inside the system and worn-out bearings can also contribute to these sounds.
To identify the source of a rattling noise, start by turning off the system and inspecting visible components for any signs of looseness or damage. Listen closely when the system is running to pinpoint where the sound originates—whether it’s from the indoor unit, outdoor unit, or ductwork.
First, ensure all screws and bolts on accessible components like panels and fan blades are tightened. Check for debris inside units and remove if present. If problems persist, inspect for worn parts that may need replacing or consider consulting a professional technician.
Call a professional if you cannot locate or fix the issue after basic troubleshooting, if there are potential safety hazards (e.g., electrical issues), or if specialized tools/knowledge is required to access internal components safely.