An air conditioner is an appliance, system, or mechanism designed to extract heat from an area using a refrigeration cycle. System (from Latin systēma, in turn from Greek systēma is a set of interacting or interdependent Entities, real or abstract A mechanism is some technical aspect of a larger process or mechanical device or combination of parts designed to perform a particular function In construction, a complete system of heating, ventilation, and air conditioning is referred to as HVAC. HVAC (pronounced either "H-V-A-C" or occasionally " H-vak " is an Initialism or Acronym that stands for " Heating Its purpose, in the home or in the car, is to provide comfort during either hot or cold weather.
Contents |
History
Air conditioning applications
Air conditioning system basics and theories
Refrigeration cycle
In the refrigeration cycle, a heat pump transfers heat from a lower temperature heat source into a higher temperature heat sink. Thermodynamic heat pump and refrigeration cycles are the models for Heat pumps and Refrigerators. A heat pump is a machine or device that moves Heat from one location (the 'source' to another location (the 'sink' or 'heat sink' using work. Heat would naturally flow in the opposite direction. This is the most common type of air conditioning. A refrigerator works in much the same way, as it pumps the heat out of the interior into the room in which it stands.
This cycle takes advantage of the universal gas law PV = nRT, where P is pressure, V is volume, R is the universal gas constant, T is temperature, and n is the number of moles of gas (1 mole = 6. The ideal gas law is the Equation of state of a hypothetical Ideal gas, first stated by Benoît Paul Émile Clapeyron in 1834 Relationship with the Boltzmann constant The Boltzmann constant kB (often abbreviated k) may be used in place of the gas constant by working 022×1023 molecules).
The most common refrigeration cycle uses an electric motor to drive a compressor. A gas compressor is a mechanical device that increases the Pressure of a Gas by reducing its Volume. In an automobile, the compressor is driven by a belt over a pulley, the belt being driven by the engine's crankshaft (similar to the driving of the pulleys for the alternator, power steering, etc. A pulley (also called a sheave or block) is a Wheel with a groove between two Flanges around its Circumference The crankshaft, sometimes casually abbreviated to crank, is the part of an Engine which translates reciprocating Linear ). Whether in a car or the house, both use electric fan motors for air circulation. Since evaporation occurs when heat is absorbed, and condensation occurs when heat is released, air conditioners are designed to use a compressor to cause pressure changes between two compartments, and actively condense and pump a refrigerant around. Evaporation is the process by which Molecules in a Liquid state (e In Physics, heat, symbolized by Q, is Energy transferred from one body or system to another due to a difference in Temperature Condensation is the change of the physical state of aggregation (or simply state of matter from gaseous phase into liquid phase A refrigerant is pumped into the cooled compartment (the evaporator coil), where the low pressure and low temperature cause the refrigerant to evaporate into a vapor, taking heat with it. In the other compartment (the condenser), the refrigerant vapor is compressed and forced through another heat exchange coil, condensing into a liquid, rejecting the heat previously absorbed from the cooled space.
Humidity
Refrigeration air conditioning equipment usually reduces the humidity of the air processed by the system. Humidity is the amount of water vapor in the air In daily language the term "humidity" is normally taken to mean Relative humidity. The relatively cold (below the dewpoint) evaporator coil condenses water vapor from the processed air, (much like an ice cold drink will condense water on the outside of a glass), sending the water to a drain and removing water vapor from the cooled space and lowering the relative humidity. The dew point (sometimes spelled dewpoint) is the Temperature to which a given parcel of Air must be cooled at constant Barometric pressure, Since humans perspire to provide natural cooling by the evaporation of perspiration from the skin, drier air (up to a point) improves the comfort provided. Evaporation is the process by which Molecules in a Liquid state (e The comfort air conditioner is designed to create a 40% to 60% relative humidity in the occupied space. In food retailing establishments large open chiller cabinets act as highly effective air dehumidifying units.
Some air conditioning units dry the air without cooling it. They work like a normal air conditioner, except that a heat exchanger is placed between the intake and exhaust. A heat exchanger is a device built for efficient Heat transfer from one medium to another whether the media are separated by a solid wall so that they never mix or the media In combination with convection fans they achieve a similar level of comfort as an air cooler in humid tropical climates, but only consume about 1/3 of the electricity. A mechanical fan is an electrically powered device used to produce an airflow for the purpose of creature comfort (particularly in the heat ventilation, exhaust Evaporative coolers (also called swamp, desert, or air coolers) are devices that cool air through the simple Evaporation of water They are also preferred by those who find the draft created by air coolers uncomfortable.
Refrigerants
"Freon" is a trade name for a family of haloalkane refrigerants manufactured by DuPont and other companies. A refrigerant is a compound used in a heat cycle that undergoes a Phase change from a Gas to a Liquid and back The haloalkanes (also known as halogenoalkanes or alkyl halides) are a group of Chemical compounds consisting of Alkanes such as Methane The haloalkanes (also known as halogenoalkanes or alkyl halides) are a group of Chemical compounds consisting of Alkanes such as Methane A refrigerant is a compound used in a heat cycle that undergoes a Phase change from a Gas to a Liquid and back E I du Pont de Nemours and Company (,) is an American chemical company that was founded in July 1802 as a Gunpowder mill by Eleuthère Irénée These refrigerants were commonly used due to their superior stability and safety properties. Unfortunately, evidence has accumulated that these chlorine bearing refrigerants reach the upper atmosphere when they escape. The chemistry is poorly understood but general consensus seems to be that CFCs break up in the stratosphere due to UV-radiation, releasing their chlorine atoms. The stratosphere is the second major layer of Earth's atmosphere, just above the Troposphere, and below the Mesosphere. Ultraviolet ( UV) light is Electromagnetic radiation with a Wavelength shorter than that of Visible light, but longer than X-rays These chlorine atoms act as catalysts in the breakdown of ozone, which does severe damage to the ozone layer that shields the Earth's surface from the strong UV radiation. Catalysis is the process in which the rate of a Chemical reaction is increased by means of a Chemical substance known as a catalyst The photochemical mechanisms that give rise to the ozone layer were worked out by the British physicist Sidney Chapman in 1930 The chlorine will remain active as a catalyst until and unless it binds with another particle forming a stable molecule. CFC refrigerants in common but receding usage include R-11 and R-12. Newer and more environmentally-safe refrigerants include HCFCs (R-22, used in most homes today) and HFCs (R-134a, used in most cars) have replaced most CFC use. The haloalkanes (also known as halogenoalkanes or alkyl halides) are a group of Chemical compounds consisting of Alkanes such as Methane Chlorodifluoromethane or difluoromonochloromethane is a Hydrochlorofluorocarbon (HCFC HCFCs in turn are being phased out under the Montreal Protocol and replaced by hydrofluorocarbons (HFCs), such as R-410A, which lack chlorine. For other similarly-named agreements see Montreal Convention (disambiguation. R-410A, sold under the trademarked names Puron, Genetron R410A, and AZ-20, is a near- azeotropic mixture of Difluoromethane (CH2F2 Chlorine (ˈklɔriːn from the Greek word 'χλωρóς' ( khlôros, meaning 'pale green' is the Chemical element with Atomic number 17 and
Types of air conditioner equipment
Window and through-wall units
Many traditional air conditioners in homes or other buildings are single rectangular units used to cool an apartment, a house or part of it, or part of a building. For an example, see the photos to the right. Hotels frequently use PTAC systems, which combine heating into the same unit. A packaged terminal air conditioner (often abbreviated PTAC) is a type of self-contained Air conditioning and heating system commonly found in hotels and Air conditioner units need to have access to the space they are cooling (the inside) and a heat sink; normally outside air is used to cool the condenser section. For this reason, single unit air conditioners are placed in windows or through openings in a wall made for the air conditioner; the latter type includes portable air conditioners. [1]
Window and through-wall units have vents on both the inside and outside, so inside air to be cooled can be blown in and out by a fan in the unit, and outside air can also be blown in and out by another fan to act as the heat sink. The controls are on the inside.
A large house or building may have several such units. Should virtually every room be cooled with its own air conditioning unit, most of the day, it would be less expensive to use central air conditioning, though that may not be physically possible.
Evaporative coolers
In very dry climates, evaporative coolers (or "swamp coolers") are popular for improving comfort during hot weather. Evaporative coolers (also called swamp, desert, or air coolers) are devices that cool air through the simple Evaporation of water The weather is a set of all the phenomena occurring in a given Atmosphere at a given Time. This type of cooler is the dominant cooler used in Iran which has the largest number of units of any country in the world, hence some referring to them as Persian coolers[2]. For a topic outline on this subject see List of basic Iran topics. An evaporative cooler is a device that draws outside air through a wet pad, such as a large sponge soaked with water. The sensible heat of the incoming air, as measured by a dry bulb thermometer, is reduced. Sensible heat is Potential energy in the form of thermal energy or Heat. The dry-bulb temperature is the Temperature of Air measured by a Thermometer freely exposed to the air but shielded from Radiation and Moisture The total heat (sensible heat plus latent heat) of the entering air is unchanged. Sensible heat is Potential energy in the form of thermal energy or Heat. In Thermochemistry, latent heat is the amount of Energy in the form of Heat released or absorbed by a substance during a change of phase Some of the sensible heat of the entering air is converted to latent heat by the evaporation of water in the wet cooler pads. If the entering air is dry enough, the results can be quite comfortable. These coolers cost less and are mechanically simple to understand and maintain.
An early type of cooler, using ice for a further effect, was patented by John Gorrie of Apalachicola, Florida in 1842. John Gorrie, ( October 3, 1802 &ndash June 29, 1855) physician scientist inventor and humanitarian is considered the father of He used the device to cool the patients in his malaria hospital. Malaria is a vector -borne Infectious disease caused by Protozoan Parasites It is widespread in tropical and subtropical regions including
There is a related, more complex process called absorptive refrigeration which uses heat to produce cooling. The absorption refrigerator is a Refrigerator that utilizes a heat source (e In one instance, a three-stage absorptive cooler first dehumidifies the air with a spray of salt-water or brine. The absorption refrigerator is a Refrigerator that utilizes a heat source (e Brine (lat saltus) is Water saturated or nearly saturated with Salt (NaCl The brine osmotically absorbs water vapor from the air. Osmosis is the Diffusion of a solvent (frequently water through a semi-permeable membrane, from a solution of low solute concentration (high water potential The second stage sprays water in the air, cooling the air by evaporation. Finally, to control the humidity, the air passes through another brine spray. The brine is reconcentrated by distillation. The system is used in some hospitals because, with filtering, a sufficiently hot regenerative distillation removes airborne organisms.
Absorptive chillers
Some buildings use gas turbines to generate electricity. The absorption refrigerator is a Refrigerator that utilizes a heat source (e The exhausts of these are hot enough to drive an absorptive chiller that produces cold water. The absorption refrigerator is a Refrigerator that utilizes a heat source (e The cold water is then run through radiators in air ducts for hydronic cooling. The dual use of the energy, both to generate electricity and cooling, makes this technology attractive when regional utility and fuel prices are right. Producing heat, power, and cooling in one system is known as trigeneration. Trigeneration or trigen is the simultaneous production of mechanical power (often converted to electricity heat and cooling from a single heat source such as Fuel
Central air conditioning
Central air conditioning, commonly referred to as central air (US) or air-con (UK), is an air conditioning system which uses ducts to distribute cooled and/or dehumidified air to more than one room, or uses pipes to distribute chilled water to heat exchangers in more than one room, and which is not plugged into a standard electrical outlet.
With a typical split system, the condenser and compressor are located in an outdoor unit; the evaporator is mounted in the air handling unit (which is often a forced air furnace). A gas compressor is a mechanical device that increases the Pressure of a Gas by reducing its Volume. Within a Downstream processing system several stages are used to further isolate and purify the desired product With a package system, all components are located in a single outdoor unit that may be located on the ground or roof.
Central air conditioning performs like a regular air conditioner but has several added benefits:
- When the air handling unit turns on, room air is drawn in from various parts of the building through return-air ducts. This air is pulled through a filter where airborne particles such as dust and lint are removed. An air filter is a device which removes solid Particulates such as Dust, Pollen, Mold, and bacteria from Air. Dust is a general name for minute Solid particles with Diameters less than 500 micrometers. Sophisticated filters may remove microscopic pollutants as well. Pollution is the introduction of contaminants into an environment that causes instability disorder harm or discomfort to the physical systems or living organisms they are in The filtered air is routed to air supply ductwork that carries it back to rooms. Whenever the air conditioner is running, this cycle repeats continually.
- Because the central air conditioning unit is located outside the home, it offers a lower level of noise indoors than a free-standing air conditioning unit.
Thermostats
Thermostats control the operation of HVAC systems, turning on the heating or cooling systems to bring the building to the set temperature. A thermostat is a device for regulating the Temperature of a System so that the system's temperature is maintained near a desired setpoint A thermostat is a device for regulating the Temperature of a System so that the system's temperature is maintained near a desired setpoint Typically the heating and cooling systems have separate control systems (even though they may share a thermostat) so that the temperature is only controlled "one-way". A thermostat is a device for regulating the Temperature of a System so that the system's temperature is maintained near a desired setpoint That is, in winter, a building that is too hot will not be cooled by the thermostat. Thermostats may also be incorporated into facility energy management systems in which the power utility customer may control the overall energy expenditure. A public utility (usually just utility) is an organization that maintains the Infrastructure for a public service (often also providing a service using In addition, a growing number of power utilities have made available a device which, when professionally installed, will control or limit the power to an HVAC system during peak use times in order to avoid necessitating the use of rolling blackouts. A rolling blackout, also referred to as load shedding, is an intentionally-engineered electrical Power outage. The customer is given a credit of some sort in exchange, so it is often to the advantage of the consumer to buy the most efficient thermostat possible.
Equipment capacity
Air conditioner equipment power in the U.S. is often described in terms of "tons of refrigeration". The United States of America —commonly referred to as the A "ton of refrigeration" is defined as the cooling power of one short ton (2000 pounds or 907 kilograms) of ice melting in a 24-hour period. The short ton ( S/T) is a unit of mass equal to 2000 lb (around 907 The pound or pound-mass (abbreviation lb, lbm, or sometimes in the United States #) is a unit of Mass Ice is a Solid phase, usually crystalline, of a Non-metalic substance that is liquid or gas at Room temperature, such as Ammonia This is equal to 12,000 BTU per hour, or 3517 watts (http://physics.nist.gov/Pubs/SP811/appenB9.html). The hour (symbol h) is a unit of Time. It is not an SI unit but is accepted for use with the SI The watt (symbol W) is the SI derived unit of power, equal to one Joule of energy per Second. Residential "central air" systems are usually from 1 to 5 tons (3 to 20 kW) in capacity. An air conditioner is an Appliance, System, or mechanism designed to extract Heat from an area via a Refrigeration cycle
The use of electric/compressive air conditioning puts a major demand on the nation's electrical power grid in warm weather, when most units are operating under heavy load. Electric power transmission, a process in the delivery of Electricity to consumers is the bulk transfer of electrical power In the aftermath of the 2003 North America blackout locals were asked to keep their air conditioning off. The Northeast Blackout of 2003 was a massive widespread Power outage that occurred throughout parts of the Northeastern and Midwestern United States During peak demand, additional power plants must often be brought online, usually natural gas fired plants because of their rapid startup. A power station (also referred to as generating station, power plant or powerhouse) is an industrial facility for the generation of Natural gas is a Gaseous Fossil fuel consisting primarily of Methane but including significant quantities of Ethane, Propane, A 1995 study of various utility studies of residential air conditioning concluded that the average air conditioner wasted 40% of the input energy. Year 1995 ( MCMXCV) was a Common year starting on Sunday. Events of 1995 This energy is lost in the form of heat, which must be pumped out. There is a huge opportunity to reduce the need for new power plants and to conserve energy.
In an automobile the A/C system will use around 5 hp (4 kW) of the engine's power. In Physics, power (symbol P) is the rate at which work is performed or energy is transmitted or the amount of energy required or expended for
Seasonal Energy Efficiency Rating (SEER)
For residential homes, some countries set minimum requirements for energy efficiency. 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 the United States, the efficiency of air conditioners is often (but not always) rated by the Seasonal Energy Efficiency Ratio (SEER). The higher the SEER rating, the more energy efficient is the air conditioner. The SEER rating is the BTU of cooling output during its normal annual usage divided by the total electric energy input in watt-hours (W·h) during the same period. The watt (symbol W) is the SI derived unit of power, equal to one Joule of energy per Second. [3]
- SEER = BTU ÷ W·h
For example, a 5000 BTU/h air-conditioning unit, with a SEER of 10, operating for a total of 1000 hours during an annual cooling season (i. e. , 8 hours per day for 125 days) would provide an annual total cooling output of:
- 5000 BTU/h × 1000 h = 5,000,000 BTU
which, for a SEER of 10, would be an annual electrical energy usage of:
- 5,000,000 BTU ÷ 10 = 500,000 W·h
and that is equivalent to an average power usage during the cooling season of:
- 500,000 W·h ÷ 1000 h = 500 W
SEER is related to the coefficient of performance (COP) commonly used in thermodynamics and also to the Energy Efficiency Ratio (EER). The coefficient of performance, or COP (sometimes CP of a Heat pump is the ratio of the change in Heat at the "output" (the heat reservoir of interest In Physics, thermodynamics (from the Greek θερμη therme meaning " Heat " and δυναμις dynamis meaning " 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]] The EER is the efficiency rating for the equipment at a particular pair of external and internal temperatures, while SEER is calculated over a whole range of external temperatures (i. e. , the temperature distribution for the geographical location of the SEER test). SEER is unusual in that it is composed of an Imperial unit divided by a metric unit. Imperial units or the Imperial system is a collection of units first defined in the British Weights and Measures Act of 1824 The COP is a ratio with the same metric units of energy (joules) in both the numerator and denominator. They cancel out leaving a dimensionless quantity. In Dimensional analysis, a dimensionless quantity (or more precisely a quantity with the dimensions of 1) is a Quantity without any Physical units Formulas for the approximate conversion between SEER and EER or COP are available from the Pacific Gas and Electric company in California:[4]
- (1) SEER = EER ÷ 0. 9
- (2) SEER = COP x 3. 792
- (3) EER = COP x 3. 413
From equation (2) above, a SEER of 13 is equivalent to a COP of 3. 43, which means that 3. 43 units of heat energy are pumped per unit of work energy.
Today, it is rare to see systems rated below SEER 9 in the United States, since older units are being replaced with higher efficiency units. The United States now requires that residential systems manufactured in 2006 have a minimum SEER rating of 13 (although window-box systems are exempt from this law, so their SEER is still around 10). [5] Substantial energy savings can be obtained from more efficient systems. For example by upgrading from SEER 9 to SEER 13, the power consumption is reduced by 30% (equal to 1 - 9/13). It is claimed that this can result in an energy savings valued at up to $US 300 per year (depending on the usage rate and the cost of electricity). In many cases, the lifetime energy savings are likely to surpass the higher initial cost of a high-efficiency unit.
As an example, the annual cost of electric power consumed by a 72,000 BTU/h air conditioning unit operating for 1000 hours per year with a SEER rating of 10 and a power cost of $0. 08 per kilowatt-hour (kW·h) may be calculated as follows:
- unit size, BTU/h × hours per year, h × power cost, $/kW·h ÷ (SEER, BTU/W·h × 1000 W/kW)
- (72,000 BTU/h) × (1000 h) × ($0. 08/kW·h) ÷ [(10 BTU/W·h) × (1000 W/kW)] = $576. 00 annual cost
Air conditioner sizes are often given as "tons" of cooling. Units of mass There are three similar units of Mass called the ton: Long ton (simply ton in countries such as the United Multiplying the tons of cooling by 12,000 converts it to BTU/h.
A common misconception is that the SEER rating system also applies to heating systems. However, SEER ratings only apply to air conditioning.
Air conditioners (for cooling) and heat pumps (for heating) both work similarly in that heat is transferred or "pumped" from a cooler "heat-source" to a warmer "heat-sink". A heat pump is a machine or device that moves Heat from one location (the 'source' to another location (the 'sink' or 'heat sink' using work. A heat sink (or heatsink) is an environment or object that absorbs and dissipates heat from another object using Thermal contact (either direct or radiant Air conditioners and heat pumps usually operate most effectively at temperatures around 50 to 55 °F (10−13 °C). Fahrenheit is a temperature scale named after Daniel Gabriel Fahrenheit (1686–1736 a German Physicist who proposed it in 1724 A 'balance point' is reached when the heat source temperature falls below about 40 °F (4 °C), and the system is not able to pull any more heat from the heat-source. Fahrenheit is a temperature scale named after Daniel Gabriel Fahrenheit (1686–1736 a German Physicist who proposed it in 1724 (This point varies from heat pump to heat pump). Similarly, when the heat-sink temperature rises to about 120 °F (49 °C), the system will operate less effectively, and will not be able to 'push' out any more heat. Fahrenheit is a temperature scale named after Daniel Gabriel Fahrenheit (1686–1736 a German Physicist who proposed it in 1724 Ground-source (geothermal) heat pumps do not have this problem of reaching a balance point because they use the ground as a heat source/heat sink and the ground's thermal inertia prevents it from becoming too cold or too warm when moving heat from or to it. The ground's temperature does not vary nearly as much over a year as the air above it does.
Insulation
Insulation reduces the required power of the air conditioning system. The term thermal insulation can refer to materials used to reduce the rate of Heat transfer, or the methods and processes used to reduce heat transfer Thick walls, reflective roofing material, curtains, and trees next to buildings also cut down on system and energy requirements.
Home air conditioning systems around the world
Domestic air conditioning is most prevalent and ubiquitous in developed Asian nations such as Japan, Taiwan, South Korea, Singapore and Hong Kong, especially in the latter two due to most of the population living in small high-rise flats. For a topic outline on this subject see List of basic Japan topics. Taiwan ( Taiwanese: Tâi-oân/Tāi-oân (historically 大灣/台員/大員/台圓/大圓/台窩灣 is an Island in East Asia. South Korea, officially the Republic of Korea and often referred to as Korea ( Korean: 대한민국 tɛː Singapore Hong Kong ( officially the Hong Kong Special Administrative Region, is a territory located on China 's south coast on the Pearl River Delta, and borders In this area, with soaring summer temperatures and a high standard of living, air conditioning is considered a necessity and not a luxury. Japanese-made domestic air conditioners are usually window or split types, the latter being more modern and expensive. It is also increasing in popularity with the rising standard of living in tropical Asian nations such as Thailand India, Malaysia and the Philippines. The Kingdom of Thailand (ˈtaɪlænd ราชอาณาจักรไทย, râːtɕʰa-ʔaːnaːtɕɑ̀k-tʰɑj India, officially the Republic of India (भारत गणराज्य inc-Latn Bhārat Gaṇarājya; see also other Indian languages) is a country For the biogeographical region see Malesia Malaysia (məˈleɪʒə or /məˈleɪziə/ is a country that consists of thirteen states and The Philippines ( Filipino: Pilipinas, officially known as the Republic of the Philippines (fil ''Republika ng Pilipinas'' RP In Indonesia, an air-conditioning set is a must in every homes due to the high temperature. The Republic of Indonesia ( (Republik Indonesia is a Country in Southeast Asia.
In the United States, home air conditioning is more prevalent in the South and on the East Coast, in most parts of which it has reached the ubiquity it enjoys in East Asia. Central air systems are most common in the United States, and are virtually standard in all new dwellings in most states.
In Europe, home air conditioning is generally less common in part due to higher energy costs and more moderate summer temperatures. Some European countries like Switzerland even forbid installation without permission, motivating that these devices use lots of energy and are environmentally unfriendly. Southern European countries, such as Greece, on the other hand, have seen a wide proliferation of home air-conditioning units in the past few years[1]. The lack of air conditioning in homes, in residential care homes and in medical facilities was identified as a contributing factor to the estimated 35,000 deaths left in the wake of the 2003 heat wave. Country-by-country France In France, 14802 people&mdashmostly elderly&mdashdied from heat according to the country's largest funeral service
Health implications
Air conditioning has no greater influence on health than heating—that is to say, very little—although poorly maintained air-conditioning systems (especially large, centralized systems) can occasionally promote the growth and spread of microorganisms, such as Legionella pneumophila, the infectious agent responsible for Legionnaire's disease, or thermophilic actinomycetes. Legionella pneumophila is a thin pleomorphic, Flagellated Gram-negative bacterium of the genus Legionella. Legionellosis is an Infectious disease caused by Bacteria belonging to the Genus Legionella. Actinobacteria or actinomycetes are a group of Gram-positive bacteria with high G+C ratio. [6] Conversely, air conditioning (including filtration, humidification, cooling, disinfection, etc. ) can be used to provide a clean, safe, hypoallergenic atmosphere in hospital operating rooms and other environments where an appropriate atmosphere is critical to patient safety and well-being. Hypoallergenic is a term coined by advertisers (based on the Greek prefix Hypo meaning "below normal" or "slightly" and first used in a cosmetics Air conditioning can have a positive effect on sufferers of allergies and asthma. Allergy is a disorder of the Immune system often also referred to as Atopy. Asthma is a chronic Condition involving the Respiratory system in which the airways occasionally constrict become inflamed, and are [7]
In serious heat waves, air conditioning can save the lives of the elderly. A heat wave is a prolonged period of excessively hot Weather, which may be accompanied by high Humidity. Some local authorities even set up public cooling centers for the benefit of those without air conditioning at home. A cooling center is a temporary air-conditioned Public space set up by local authorities to deal with the health effects of a Heat wave.
Properly maintained air-conditioning systems do not directly cause or promote illness, despite superstitions that air-conditioning is unconditionally dangerous to one's health. However, they may indirectly lead to air pollution if the electricity required to power them is produced from fossil fuels. Air pollution is the human introduction into the atmosphere of Chemicals Particulate matter, or Biological materials that cause harm or discomfort Fossil fuels or mineral fuels are fossil source Fuels that is Hydrocarbons found within the top layer of the Earth’s crust.
References
- ^ Melonyce McAfee, "Coolin' the Gang: Which portable air conditioner works best?", Salon magazine, August 7, 2007
- ^ History of Air Conditioning Source: Jones Jr. , Malcolm. "Air Conditioning". Newsweek. Winter 1997 v130 n24-A p42(2). Retrieved 1 January 2007. New Year See also New Year The Ancient Romans began their consular year on January 1st since 153 BC
- ^ Definition of SEER (scroll down to "Seasonal energy efficiency ratio")
- ^ SEER conversion formulas from Pacific Gas and Electric
- ^ Minimum SEER ratings required in the US
- ^ Sick building syndrome
- ^ Home Control of Asthma & Allergies
See also
- Air filter
- Dehumidifier
- Energy
- Energy conservation
- Heat pump
- Heating
- HVAC
- Hydronics
- Noise mitigation
- Renewable energy
- Refrigeration
- Trigeneration
- Whole house fan
External links
- How Air Conditioners Work. An air filter is a device which removes solid Particulates such as Dust, Pollen, Mold, and bacteria from Air. A dehumidifier is a Household appliance that reduces the level of Humidity in air usually for health reasons as humid air can cause Mold and In Physics and other Sciences energy (from the Greek grc ἐνέργεια - Energeia, "activity operation" from grc ἐνεργός Energy conservation is the practice of decreasing the quantity of energy used A heat pump is a machine or device that moves Heat from one location (the 'source' to another location (the 'sink' or 'heat sink' using work. HVAC (pronounced either "H-V-A-C" or occasionally " H-vak " is an Initialism or Acronym that stands for " Heating Hydronics is the name for the use of Water as the heat-transfer medium in heating and cooling systems Some of the oldest and most common examples Noise mitigation is a set of strategies to reduce Noise pollution. Renewable energy is Energy generated from Natural resources mdashsuch as Sunlight, Wind, Rain, tides and geothermal Refrigeration is the process of removing Heat from an enclosed space or from a substance and moving it to a place where it is unobjectionable Trigeneration or trigen is the simultaneous production of mechanical power (often converted to electricity heat and cooling from a single heat source such as Fuel A whole-house fan is a type of fan installed in a building's ceiling designed to suck hot air out of the building
Energy efficiency
- Consumer Guide to Home Energy Savings - Central Air Conditioners from the American Council for an Energy Efficient Economy (ACEEE)
- Energy Efficiency Program Database from the ACEEE
- Space heating and cooling from the U. S. Department of Energy's Energy Efficiency and Renewable Energy
- UK Enhanced Capital Allowance Scheme (ECA), a UK Government scheme to provide tax rebates for companies who use products which are ECA approved.
- International Energy Agency - Energy Conservation In Buildings And Community Systems
- Top-Rated Energy-Efficient Central Air Conditioners
Dictionary
air conditioner
-noun
- A machine that is used to control temperature and humidity in an enclosed space.
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