Air conditioning in the context of Passive cooling

Waste heat is heat that is produced by a machine, or other process that uses energy, as a byproduct of doing work. All such processes give off some waste heat as a fundamental result of the laws of thermodynamics. Waste heat has lower utility (or in thermodynamics lexicon a lower exergy or higher entropy) than the original energy source. Sources of waste heat include all manner of human activities, natural systems, and all organisms, for example, incandescent light bulbs get hot, a refrigerator warms the room air, a building gets hot during peak hours, an internal combustion engine generates high-temperature exhaust gases, and electronic components get warm when in operation.

Instead of being "wasted" by release into the ambient environment, sometimes waste heat (or cold) can be used by another process (such as using hot engine coolant to heat a vehicle), or a portion of heat that would otherwise be wasted can be reused in the same process if make-up heat is added to the system (as with heat recovery ventilation in a building).

Background noise or ambient noise is any sound other than the sound being monitored (primary sound). Background noise is a form of noise pollution or interference. Background noise is an important concept in setting noise levels.

Background noises include environmental noises such as water waves, traffic noise, alarms, extraneous speech, bioacoustic noise from animals, and electrical noise from devices such as refrigerators, air conditioning, power supplies, and motors.

In thermodynamics, the thermal efficiency (${\displaystyle \eta _{\rm {th}}}$) is a dimensionless performance measure of a device that uses thermal energy, such as an internal combustion engine, steam turbine, steam engine, boiler, furnace, refrigerator, ACs etc.

For a heat engine, thermal efficiency is the ratio of the net work output to the heat input; in the case of a heat pump, thermal efficiency (known as the coefficient of performance or COP) is the ratio of net heat output (for heating), or the net heat removed (for cooling) to the energy input (external work). The efficiency of a heat engine is fractional as the output is always less than the input while the COP of a heat pump is more than 1. These values are further restricted by the Carnot theorem.

Refrigeration is any of various types of cooling of a space, substance, or system to lower or maintain its temperature below the ambient one (while the removed heat is rejected at a higher temperature). Refrigeration is an artificial, or human-made, cooling method.

Refrigeration refers to the process by which energy, in the form of heat, is removed from a low-temperature medium and transferred to a high-temperature medium. This work of energy transfer is traditionally driven by mechanical means (whether ice or electromechanical machines), but it can also be driven by heat, magnetism, electricity, laser, or other means. Refrigeration has many applications, including household refrigerators, industrial freezers, cryogenics, and air conditioning. Heat pumps may use the heat output of the refrigeration process, and also may be designed to be reversible, but are otherwise similar to air conditioning units.

Electric heating is a process in which electrical energy is converted directly to heat energy. Common applications include space heating, cooking, water heating and industrial processes. An electric heater is an electrical device that converts an electric current into heat. The heating element inside every electric heater is an electrical resistor, and works on the principle of Joule heating: an electric current passing through a resistor will convert that electrical energy into heat energy. Most modern electric heating devices use nichrome wire as the active element; the heating element, depicted on the right, uses nichrome wire supported by ceramic insulators.

Alternatively, a heat pump can achieve around 150% – 600% efficiency for heating, or COP 1.5 - 6.0 Coefficient of performance, because it uses electric power only for transferring existing thermal energy. The heat pump uses an electric motor to drive a reversed refrigeration cycle, that draws heat energy from an external source such as the ground or outside air (or the interior of a refrigerator) and directs that heat into the space to be warmed (in case of a fridge, the kitchen). This makes much better use of electric energy than direct electric heating, but requires much more expensive equipment, plus plumbing. Some heating systems can be operated in reverse for air conditioning so that the interior space is cooled and even hotter air or water is discharged outside or into the ground.

Hydrofluorocarbons (HFCs) are synthetic organic compounds that contain fluorine and hydrogen atoms, and are the most common type of organofluorine compounds. Most are gases at room temperature and pressure. They are frequently used in air conditioning and as refrigerants; R-134a (1,1,1,2-tetrafluoroethane) is one of the most commonly used HFC refrigerants. In order to aid the recovery of the stratospheric ozone layer, HFCs were adopted to replace the more potent chlorofluorocarbons (CFCs) such as R-12, which were phased out from use by the Montreal Protocol, and hydrochlorofluorocarbons (HCFCs) such as R-21 which are presently being phased out. HFCs are also used in insulating foams, aerosol propellants, as solvents and for fire protection.

HFCs may not harm the ozone layer as much as the compounds they replace, but they still contribute to global warming – with some like trifluoromethane (CHF₃ or R-23) having 11,700 times the warming potential of carbon dioxide. HFC atmospheric concentrations and contribution to anthropogenic greenhouse gas emissions are rapidly increasing – consumption rose from near zero in 1990 to 1.2 billion tons of carbon dioxide equivalent in 2010 – causing international concern about their radiative forcing.

Thermal comfort is the condition of mind that expresses subjective satisfaction with the thermal environment. The human body can be viewed as a heat engine where food is the input energy. The human body will release excess heat into the environment, so the body can continue to operate. The heat transfer is proportional to temperature difference. In cold environments, the body loses more heat to the environment and in hot environments the body does not release enough heat. Both the hot and cold scenarios lead to discomfort. Maintaining this standard of thermal comfort for occupants of buildings or other enclosures is one of the important goals of HVAC (heating, ventilation, and air conditioning) design engineers.

Thermal neutrality is maintained when the heat generated by human metabolism is allowed to dissipate, thus maintaining thermal equilibrium with the surroundings. The main factors that influence thermal neutrality are those that determine heat gain and loss, namely metabolic rate, clothing insulation, air temperature, mean radiant temperature, air speed and relative humidity. Psychological parameters, such as individual expectations, and physiological parameters also affect thermal neutrality. Neutral temperature is the temperature that can lead to thermal neutrality and it may vary greatly between individuals and depending on factors such as activity level, clothing, and humidity. People are highly sensitive to even small differences in environmental temperature. At 24 °C (75.2 °F), a difference of 0.38 °C (0.684 °F) can be detected between the temperature of two rooms.

A dehumidifier is an air conditioning device which reduces and maintains the level of humidity in the air. This is done usually for health or thermal comfort reasons or to eliminate musty odor and to prevent the growth of mildew by extracting water from the air. It can be used for household, commercial, or industrial applications. Large dehumidifiers are used in commercial buildings such as indoor ice rinks and swimming pools, as well as manufacturing plants or storage warehouses. Typical air conditioning systems combine dehumidification with cooling, by operating cooling coils below the dewpoint and draining away the water that condenses.

Dehumidifiers extract water from air that passes through the unit. There are two common types of dehumidifiers: condensate dehumidifiers and desiccant dehumidifiers, and there are also other emerging designs.

The Sun Belt is a region of the United States generally considered stretching across the Southeast and Southwest. Another rough definition of the region is the area south of the Parallel 36°30′ north. Several climates can be found in the region—desert/semi-desert (Eastern California, Nevada, Arizona, New Mexico, Utah, and West Texas), Mediterranean (California), humid subtropical (Alabama, Mississippi, Louisiana, Florida, Georgia, South Carolina, North Carolina, Arkansas,Tennessee and Texas), and tropical (South Florida).

The Sun Belt has seen substantial population growth post-World War II from an influx of people seeking a warm and sunny climate, a surge in retiring baby boomers, and growing economic opportunities. The advent of air conditioning created more comfortable summer conditions and allowed more manufacturing and industry to locate in the Sun Belt. Since much of the construction in the Sun Belt is new or recent, housing styles and design are often modern and open. Recreational opportunities in the Sun Belt are often not tied strictly to one season, and many tourist and resort cities in the region support a tourist industry all year.

Phoenix (/ˈfiːnɪks/ FEE-niks) is the capital and most populous city of the U.S. state of Arizona. With over 1.6 million residents at the 2020 census, Phoenix is the fifth-most populous city in the United States and the most populous state capital. The Phoenix metropolitan area, with an estimated 5.19 million residents, is the tenth-most populous metropolitan area in the U.S. and the most populous in the Southwest. Phoenix is the county seat of Maricopa County in the Salt River Valley and Arizona Sun Corridor and, with an area of 517.9 square miles (1,341 km), is the largest city by area in Arizona and 11th-largest city by area in the United States.

Phoenix was settled in 1867 as an agricultural community near the confluence of the Salt and Gila Rivers and was incorporated as a city in 1881. It became the capital of Arizona Territory in 1889. Its canal system led to a thriving farming community with the original settlers' crops, such as alfalfa, cotton, citrus, and hay, remaining important parts of the local economy for decades. Cotton, cattle, citrus, climate, and copper were known locally as the "Five C's" anchoring Phoenix's economy. These remained the driving forces of the city until after World War II, when high-tech companies began to move into the valley and air conditioning made Phoenix's hot summers more bearable.

A thermostat is a regulating device component which senses the temperature of a physical system and performs actions so that the system's temperature is maintained near a desired setpoint.

Thermostats are used in any device or system that heats or cools to a setpoint temperature. Examples include building heating, central heating, air conditioners, HVAC systems, water heaters, as well as kitchen equipment including ovens and refrigerators and medical and scientific incubators. In scientific literature, these devices are often broadly classified as thermostatically controlled loads (TCLs). Thermostatically controlled loads comprise roughly 50% of the overall electricity demand in the United States.

A heat exchanger is a system used to transfer heat between a source and a working fluid. Heat exchangers are used in both cooling and heating processes. The fluids may be separated by a solid wall to prevent mixing or they may be in direct contact. They are widely used in space heating, refrigeration, air conditioning, power stations, chemical plants, petrochemical plants, petroleum refineries, natural-gas processing, and sewage treatment. The classic example of a heat exchanger is found in an internal combustion engine in which a circulating fluid known as engine coolant flows through radiator coils and air flows past the coils, which cools the coolant and heats the incoming air. Another example is the heat sink, which is a passive heat exchanger that transfers the heat generated by an electronic or a mechanical device to a fluid medium, often air or a liquid coolant.

Fujitsu Limited (富士通株式会社, Fujitsū kabushiki gaisha) is a Japanese multinational information and communications technology equipment and services corporation, established in 1935 and headquartered in Kawasaki, Kanagawa. It is the world's sixth-largest IT services provider by annual revenue, and it is the largest in Japan as of 2021.

Fujitsu's hardware offerings mainly consist of personal and enterprise computing products, including x86, SPARC, and mainframe-compatible server products. The corporation and its subsidiaries also offer diverse products and services in data storage, telecommunications, advanced microelectronics, and air conditioning. It has approximately 124,000 employees supporting customers in over 50 countries and regions.

Ferruccio Lamborghini Cavaliere di Gran Croce OMRI (/ˌlæmbərˈɡiːni/ LAM-bər-GHEE-nee; Italian: [ferˈruttʃo lamborˈɡiːni]; 28 April 1916 – 20 February 1993) was an Italian automobile designer, soldier, inventor, mechanic, engineer, winemaker, industrialist, and businessman who created Lamborghini Trattori in 1948 and the Automobili Lamborghini in 1963, a maker of high-end sports cars in Sant'Agata Bolognese.

Born to grape farmers in Renazzo, from the comune (municipality) of Cento, in the Emilia-Romagna region, his mechanical know-how led him to enter the business of tractor manufacturing in 1948, when he founded Lamborghini Trattori, which quickly became an important manufacturer of agricultural equipment in the midst of Italy's post-WWII economic boom. In 1959, he opened an oil burner factory, Lamborghini Bruciatori, which later entered the business of producing air conditioning equipment.

Thermodynamic heat pump cycles or refrigeration cycles are the conceptual and mathematical models for heat pump, air conditioning and refrigeration systems. A heat pump is a mechanical system that transmits heat from one location (the "source") at a certain temperature to another location (the "sink" or "heat sink") at a higher temperature. Thus a heat pump may be thought of as a "heater" if the objective is to warm the heat sink (as when warming the inside of a home on a cold day), or a "refrigerator" or "cooler" if the objective is to cool the heat source (as in the normal operation of a freezer). The operating principles in both cases are the same; energy is used to move heat from a colder place to a warmer place.

A damper is a valve or plate that stops or regulates the flow of air inside a duct, chimney, VAV box, air handler, or other air-handling equipment. A damper may be used to cut off central air conditioning (heating or cooling) to an unused room, or to regulate it for room-by-room temperature and climate control - for example, in the case of Volume Control Dampers. Its operation can be manual or automatic. Manual dampers are turned by a handle on the outside of a duct. Automatic dampers are used to regulate airflow constantly and are operated by electric or pneumatic motors, in turn controlled by a thermostat or building automation system. Automatic or motorized dampers may also be controlled by a solenoid, and the degree of air-flow calibrated, perhaps according to signals from the thermostat going to the actuator of the damper in order to modulate the flow of air-conditioned air in order to effect climate control.

In a chimney flue, a damper closes off the flue to keep the weather and animals (e.g. birds) out and warm or cool air in. This is usually done in the summer, but also may be done in the winter between uses. In some cases, the damper may also be partly closed to help control the rate of combustion. The damper may be accessible only by reaching up into the fireplace by hand or with a woodpoker, or sometimes by a lever or knob that sticks down or out. On a wood-burning stove or similar device, it is usually a handle on the vent duct as in an air conditioning system. Forgetting to open a damper before beginning a fire can cause serious smoke damage to the interior of a home, if not a house fire.

In systems involving heat transfer, a condenser is a heat exchanger used to condense a gaseous substance into a liquid state through cooling. In doing so, the latent heat is released by the substance and transferred to the surrounding environment. Condensers are used for efficient heat rejection in many industrial systems. Condensers can be made according to numerous designs and come in many sizes ranging from rather small (hand-held) to very large (industrial-scale units used in plant processes). For example, a refrigerator uses a condenser to get rid of heat extracted from the interior of the unit to the outside air.

Condensers are used in air conditioning, industrial chemical processes such as distillation, steam power plants, and other heat-exchange systems. The use of cooling water or surrounding air as the coolant is common in many condensers.

A cabin cruiser is a type of power boat that provides accommodation for its crew and passengers inside the structure of the craft.

A cabin cruiser usually ranges in size from 7.6 to 13.7 m (25 to 45 ft) in length, with larger pleasure craft usually considered yachts. Many cabin cruisers can be recovered and towed with a trailer and thus easily stored on land, which reduces maintenance and expense. These craft are generally equipped with a head (toilet), a galley, and at least one berth. Most cabin cruisers usually have a small dining area and some have an aft cabin (a cabin to the rear of the cockpit, with a double bed). Some cabin cruisers are equipped with heating, air conditioning, and power generators. Most also have water heaters and shore power electric systems.