What's air-conditioning?

Air conditioning is the process of removing heat/cold and moisture from the interior of an occupied space and often means equipment used for that process. A common air conditioner uses a mechanical system called a “heat pump” that allows for the transfer of heat between indoor and outdoor units, with the help of a gaseous refrigerant. An air conditioner draws heat from the indoor exchanger and releases it to the outdoor exchanger. When cooling, the compressor inside the outdoor unit liquefies the refrigerant to absorb heat. When heating, conversely, heated pressurized gas generated by the heat exchanger and compressor inside the outdoor unit is condensed to heat air in the room. These two cycles can be switched, allowing the system to provide both cooling and heating

History
The Evolution of Modern Air Conditioners
How an Air Conditioner Works
What Is Humidity Control?
Applications
Types of Air Conditioning Systems
Types of Air Conditioning Systems -Commercial Air Conditioning
Additional Equipment for Air Conditioning
Selecting an Air Conditioner That Best Fits Your Space
Controls
The Latest Air Conditioning Features That Increase the Quality of Life
Air Conditioners That Improve the Quality of Indoor Air
Air Conditioning That Is Genuinely Energy-Efficient and Green
Summary

Since prehistoric times, ice and water were used for cooling. Harvesting ice during winter and storing it for use in summer used to be a popular business across the globe. The capability of cooling things all year round that would not require ice producible only in winter had been what ancient people much long dreamed of.

The basic concept behind today's air conditioning can date back to ancient Egypt. Frescos painted the 25th century BC show that people back then fanning water seeping from fine pores of unglazed pots, cooling the water inside.

In 1758, Benjamin Franklin, an American politician, diplomat, writer, physicist and meteorologist, and John Hadley, a chemistry professor at Cambridge University, explored the principle of evaporation as a means to rapidly cool an object. Franklin and Hadley confirmed that 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.

In 1820, British scientist and inventor Michael Faraday discovered that compressing and liquefying ammonia could chill air.
In 1824, Sadi Carnot, a French military engineer and physicist, gave the first successful theory of the refrigeration cycle.
In 1834, Jacob Perkins, an American residing in England, invented the first mechanical vapor-compression refrigeration freezer. Perkins used ethyl ether, repeatedly compressed and expanded manually to produce a refrigeration state.
In 1842, American physician, scientist, and inventor John Gorrie used compressor technology to create ice, which he used to cool air for his patients in his hospital. Gorrie was granted a patent in 1851 for his ice-making machine.

In 1902, the first modern electric air conditioning unit was invented by Willis Carrier in Buffalo, New York. It was designed in response to an air quality problem experienced at a publishing company and was capable of controlling temperature and humidity. Carrier later founded Carrier Air Conditioning Company of America.

In 1906, engineer and contractor Stuart W. Cramer of Charlotte, North Carolina, was exploring ways to add moisture to the air in his textile mill. He combined moisture with ventilation to condition and change the air in factories, controlling the humidity to meet the required level in textile plants. Cramer is the one known for coining the term "air conditioning.”

The refrigerant circulates through the indoor and outdoor units of the air conditioner to carry heat, and cools or warms the indoor air. The first air conditioners and refrigerators in the early 20th century employed toxic or flammable gases, such as ammonia, methyl chloride, or propane, that could result in fatal accidents when they leaked.
Thomas Midgley, Jr created the first chlorofluorocarbon gas (CFC) in 1928.
Being chemically stable, non-flammable, and easily liquefied, fluorocarbons had been in use everywhere, as, e.g., refrigerants for air conditioners and refrigerators, foaming agents for heat-insulating materials, cleaning agents for precision parts, and aerosol propellants.
However, ozone depletion came up to the surface as a global issue in the 1970s. CFCs became the culprits mainly responsible for man-made chemical ozone depletion. The Vienna Convention for the Protection of the Ozone Layer signed in 1985 and the Montreal Protocol agreed in 1987 provided frameworks for international reductions in the production and trade of chlorofluorocarbons. These international frameworks encouraged the use of CFC alternatives, such as hydrochlorofluorocarbons (HCFCs) and hydrofluorocarbons (HFCs).
In the 1990s, HCFCs and HFCs were classified into a subset of a larger group of climate-changing greenhouse gases (GHGs). Then, the Kyoto Protocol agreed in 1997 set the broad outlines of emissions targets of GHGs.

Higher cooling capacity which increases heat transfer efficiency.

Consumes less energy, helping you to save on electricity costs.

Zero impact on the ozone layer, thus it’s friendlier to the environment.

As technologies advance, modern air conditioners continue to evolve. In this section, we walk you through how future air conditioners will connect to devices via the Internet and produce greater comfort with air for better quality of life.

HVAC stands for Heating, Ventilation, and Air Conditioning. It is environmental comfort technology that plays an essential part of residential structures such as single-family homes, apartment buildings, medium to large industrial and office buildings, and vehicles such as cars, trains, ships, and airplanes.
You might not need more than one air conditioner with a ventilator to cool or heat the living space of your house or apartment. For larger buildings, however, service designers and mechanical engineers design and specify HVAC systems appropriate to the analyzed requirements and limitations.

A smart home is a residence that uses network-connected devices to enable the remote monitoring and management of appliances and systems that use IoT (Internet of Things), artificial intelligence (AI) and/or sensing. It provides homeowners comfort, security, and safety by allowing them to control “smart appliances,” often by a smart home app on their smartphone or other network device. Smart appliances designed to deliver convenience and improve quality of life are now seen in:

Most of the latest air conditioners come with wireless LAN (WLAN) connection capability that offers users smartphone controls over the Internet.
For example, aside from being able to switch on the air conditioner remotely before arriving home, Panasonic’s home-use air conditioner, “Eolia”, developed in Japan, also scans the air quality using dust sensors, and then displays it on the app. It is installed with a cutting edge technology that foresees future impurities in the air based on the provided data and starts cleaning the air accordingly.

We have seen the history of air conditioning and the latest trends in what modern air conditioners offer. Yet, some may not be sure how air is heated or cooled. Let's walk you through quickly how an air conditioner works.

The underlying principle of evaporative cooling is the fact that water must have heat, known as the “heat of vaporization”, applied to it to change from a liquid to a vapor. For example, touching rubbing alcohol irritates your finger because it takes heat away from the skin as the alcohol evaporates. This represents the principle of evaporative cooling. Conversely, when a gas liquefies, it releases a lot of heat, which is how evaporative heating takes place.
Air conditioners work using these principles. A liquid called a “refrigerant” circulates through a closed piping system, repeatedly liquefying and evaporating to cool air. Reversing the refrigerant flow (reverse cycle) heats air.

Substances change state, i.e., solid, liquid, gas, usually when they are heated or cooled. That is called “changing states of matter”. Air conditioners leverage the changes in states of refrigerant to cool or heat room air. The refrigeration cycle continuously changes the states of a refrigerant circulating in a closed piping system.

1. Compressing
When the cooling process starts, the refrigerant at low temperature and pressure is compressed by the compressor. The temperature of the gas increases, whereby making the refrigerant gaseous at high temperature and pressure.

2. Condensing
The gaseous refrigerant is transferred to the condenser (heat changer), where heat is exchanged between the refrigerant and outdoor air. This releases the heat of the refrigerant into the outdoor air. Releasing the heat, the refrigerant changes its state to a medium-temperature and high-pressure liquid.

3. Expansion
The liquefied refrigerant moves to the expansion valve that decreases the pressure of the refrigerant. Depressurized refrigerant expands, dropping the temperature and changing its state into a liquid of low temperature and pressure.

4. Vaporization
The refrigerant turned into a low-temperature and low-pressure liquid at the expansion valve is transferred to the evaporator (heat exchanger), where heat is exchanged between the refrigerant and indoor air. The heat of the indoor air moves to the refrigerant and the air is cooled. The refrigerant picks up the heat from the air, changing its state into a low-temperature and low-pressure gas, and goes back to the compressor again.

A heat pump air conditioner uses a four-way valve that reverses refrigerant flow to offer both cooling and heating for air-conditioned comfort all year round. This function is referred to as a “reverse cycle”. The term “reverse cycle air conditioner”, another name for a heat pump air conditioner, comes from the mechanism of the cycle.

An air conditioner compressor is a component in the system that raises the pressure of the vapor refrigerant to cause changes in the refrigerant temperatures. Most home use air conditioners have compressors inside their outdoor units.

Heat flows from hot to cold. A heat pump reverses that flow by extracting heat from one place and transfers it to another. Depending on whether the cooling or heating mode is selected, it pumps heat in and out using the heat cycle of compression, condensation, expansion, and evaporation.

A power inverter, or simply, inverter, is an electronic device or circuitry that changes direct current (DC) to alternating current (AC). Most domestic and commercial buildings are usually powered by AC. Standard voltages and frequencies vary by country. Changing frequency or voltage requires an inverter that converts AC to DC and, after needed changes in frequency and voltage, converts DC back to AC. Air conditioners with inverters run at controllable motor speeds—an efficient way for energy saving.

A water-cooled chiller system has a chiller that uses water as the refrigerant and can be found in many commercial and industrial applications. The water picks up heat inside the building, returns to the chiller, where it is cooled, then goes back to circulating through the building.

A cooling tower, often located on rooftops, is a heat rejection device that helps refrigerated air conditioning work effectively. Heat exchange taking place in the refrigeration unit increases the temperature of the cooling water. The cooling tower retains and exposes the water to air fanned into the tower to allow evaporation, which lowers the water temperature. Then, the water is passed back to the refrigerant unit and reused.

Free cooling is an economical method of using low external air temperatures in winter to assist in chilling water. The chilled water can be stored until summer and used in the cooling tower to release heat. When the ambient air temperature drops to a set temperature, a modulating valve allows the chilled water to by-pass an existing chiller and run through the free cooling system, which requires much less power to cool the water in the system.
In Europe, free cooling may refer to an outside air cooling system that uses external air inflows to cool air.

Decreased humidity leads to dry air, which causes mucous membrane in the throat to become less immune to flu pathogens and other infections. Too much humidity, on the other hand, causes discomfort. When the humidity of the air increases, it allows the growth of biological contaminants such as mold and mites. The American Society of Heating, Refrigerating and Air-Conditioning Engineers (ASHRAE) recommend that indoor relative humidity be maintained between 40-60%.

A lot of air conditioners serve as dehumidifiers. Air conditioning (cooling) is a function that prioritizes the lowering of room temperatures. So, when the cooling mode is selected on an air conditioner, it continues to cool air until it drops to a set temperature. Dehumidifiers are designed to lower the humidity level of a given space and run a weak cooling mode until the preset relative humidity is reached. Some dehumidifiers can dehumidify and reheat to produce a room environment with drier air without lowering temperatures.

Air conditioning is about creating desired air environments for occupants or objects inside. Air conditioning applications are broadly divided into comfort and process applications.

With comfort air conditioning, the focus is on people living, working, etc., in office buildings, medical facilities, schools, stores, or vehicles.

Packaged window unit (in-window) air conditioners or split system air conditioners are the popular choices for houses and low-rise apartment buildings. Split-system air conditioners come in two forms: single-split and multi-split (central) systems. A single-split system is usually composed of one indoor unit and one outdoor unit, while a multi-split system has two or more indoor units. The type of system, room size, and functions needed are typical elements to be considered in selecting an air conditioner.

The larger the building, the more complex the air conditioning system can be.
Air conditioning systems for high-rise housing are broadly classified into two types by how the heat source is distributed: central heating and distributed heating. A central heating system provides warmth to the whole interior of a building from one point (e.g., a machine room, where all heat sources such as a boiler and refrigeration unit are housed) to multiple rooms. In a distributed heating system, heat sources are located at multiple points from which air conditioning for rooms of a floor or zone is provided.

Medical center or educational institution buildings have spaces with different functions, therefore they require specific designs appropriate to the purpose of how they are used. For example, waiting rooms or offices require typical comfort air conditioning, while operating rooms or kitchens have to be designed to meet function-specific requirements.

Office buildings provide spaces for businesspersons, who can be warm weather persons or who prefer temperatures a little lower. Airflow directions should be made selectable for comfort air conditioning. In designing a system, direct exposure to drafts from an air conditioner should also be avoided.

Commercial buildings house varying businesses that require different capacities of air conditioning even when all tenants have the same area. If there is a restaurant in the building, ease of maintenance and an oil-trapping filter system should be considered in air conditioning design for its kitchen area. For commercial buildings, tenant-centric air conditioning with desirable indoor unit designs and outdoor unit layouts that offer comfort for customers is an additional requirement.

In addition to comfort, industrial air conditioning design may involve cooling equipment for machinery and tooling. Cooling the vast space of an industrial facility requires significantly large power output. That is why it is often recommended to use the convenience of spot coolers or fans to reduce the overall power consumption.

Buses, refrigerated vehicles, railways, aircraft, and ships—they all need air conditioning plans appropriate to the needs of what they carry. Public vehicles tend to get packed with many people, making it essential to be well ventilated in addition to controlling the temperature and humidity. For aircraft, cabin pressure must be maintained at a constant level, in order to create a safe and comfortable environment for passengers and crew flying at high altitudes.

Process applications aim to provide a suitable environment, e.g., internal heat and humidity loads, for a process being carried out, as well as for materials or machinery being used for it. Process applications include industrial environments; plants and farm growing areas; food cooking, processing, and storage areas; and environmental control of data centers.

A cleanroom is a facility that, as a part of specialized industrial production or scientific research, maintains extremely low levels of particulates, meeting specified cleanliness requirements and when necessary, controllable temperature and humidity levels.
Cleanroom air conditioning design involves the use of high-performance filters to keep airflow circulation and dust levels under thresholds.

Facilities for breeding laboratory animals need to be air-conditioned to special requirements in order to provide an environment for obtaining highly reliable data. Temperature and humidity must be carefully controlled to levels appropriate to animals being bred. Interior air must meet cleanliness requirements and be properly deodorized.

Air conditioning for data centers needs to suppress heat generation from computers and servers, and, at the same time, distribute conditioned air to suit the thermal comfort needs of humans. Capabilities for keeping moderate humidity level and saving energy must be also factored into the air condition planning.

Basic requirements for air conditioning systems in operating theaters include the regulation of temperature and humidity and the air comfort for patients and medical care practitioners. Operating rooms need to have a positive pressure relationship to adjacent areas, i.e., a pressure inside needs to be kept greater than the environment that surrounds the room.

The classification of home-use air conditioners include:

In a window air conditioner, all the components, namely the compressor, condenser, expansion valve or coil, evaporator, and cooling coil are enclosed in a single box package. This unit is fitted in, commonly, a windowsill, eliminating the need for ducting.

The split air conditioner is comprised of two parts -- the outdoor unit and the indoor unit -- and comes in single split or multi split configurations.

In a single split air conditioner, one outdoor unit runs the system to provide conditioned air from an indoor unit.

The outdoor unit of a multi split air conditioner runs more than one indoor unit. A popular choice for owners of newly built houses. Because it requires only one unit outdoor, a multi split system contributes to a sleek house appearance.

The following requirements should be taken into consideration.

Piping Routes
A multi split system needs piping to connect the outdoor unit and multiple indoor units. Dimensional constraints should be reviewed beforehand to ensure the installation of all piping.

Outdoor Unit Capacity
The total capacity of the indoor units has to be kept below the capacity of the outdoor unit.

An AtoW heat pump traps heat from the air to warm the refrigerant. Like a split system air conditioner, the AtoW system is comprised of an indoor unit and outdoor unit. Heated water is stored in a tank inside the indoor unit and used for showering, drinking, interior air heating or floor heating.
The technology uses heat in the air and has been drawing attention in Europe, where environmental concerns are prompting people to move from conventional combustion boilers to systems that are less impactful on the environment.
Aquarea J Generation is a feature-packed air-to-water heat pump system mainly for Europe market representing Panasonic's latest technologies.

Cooling/heating capacity is where commercial/industry air conditioning systems significantly differ from residential air conditioners. Commercial/industry air conditioning systems are roughly classified, by their capacity, into those for medium-size offices or stores and those for buildings and large facilities.
Indoor units come in a variety of types to meet varying requirements that are defined by space volume and applications.

Single-Split Packaged Air Conditioners
In a single split air conditioner, one outdoor unit runs the system that provides conditioned air from an indoor unit.

Multi-Split Packaged Air Conditioners
In a multi split air conditioner, one outdoor unit runs more than one indoor unit, making it a popular choice for owners of stores and stand-alone offices.

Packaged Terminal Air Conditioners
A packaged terminal air conditioner (PTAC) is a ductless, self-contained through-the-wall heating and cooling system commonly found in hotels, housing facilities, and apartment buildings. With indoor evaporation units and outdoor condensation units connected through walls, PTACs are installable in a smaller area and provide individual air conditioning.

VRF/Mini VRF
In a variable refrigerant flow (VRF) system, one outdoor unit runs more than one indoor unit. VRFs are typically installed in medium to large buildings bigger than stores or stand-alone offices for which multi-split packaged air conditioners are the popular choice. Being operated at varying speeds, VRF units adjust to the needed rate allowing for substantial energy savings. Those that come with compact outdoor units designed for small to mid-size buildings are called mini VRFs.

Gas Heat Pump (GHP) Air Conditioning System
A gas heat pump (GHP) air conditioning system has a gas engine-powered compressor inside the outdoor unit and a heat pump to heat or cool air in living spaces.

Chiller
A chiller is a machine that removes heat from a liquid via a vapor-compression or absorption refrigeration cycle. This liquid called refrigerant is circulated through a heat exchanger to cool equipment. Chillers are in use for industrial machines and laboratory instruments, to continually maintain optimum temperatures. Commercial buildings and factories also use chillers for air conditioning.

Air Handling Unit (AHU)
An air handling unit (AHU) is a device used to regulate and circulate air as part of a heating, ventilating, and air-conditioning system. It uses cold/hot water or steam to regulate the temperatures and humidity of the air that flows into living spaces.

Central Air Conditioning
In a central air conditioning system, a heat source device installed in the building heats the water circulating in the system. The water flows to and from an AHU to provide conditioned air. That is in contrast to individual air conditioning systems that have heat sources for each floor and area.

Indoor units of commercial/industrial air conditioners come in various types, depending on room geometries and applications.

Indoor units of a ducted air conditioner are installed in the ceiling space. The air inlet or outlet grilles are the only parts visible on the ceiling surface.

The indoor unit is wall-mounted and entirely exposed.

The indoor unit of a built-in cassette air conditioner is installed in the ceiling space. The ceiling panel is the only part exposed and visible on the ceiling surface. The unit and ducts, being in the ceiling, are less visible and out of the way.

The indoor unit is mounted on the ceiling surface and exposed.

Being placed on the floor reduces time required for installation.

Below are apparatuses that help air conditioners provide better room air

An air purifier or air cleaner is a device which removes contaminants, e.g., dust, pollens, house dust, from the air in a room to improve the quality of indoor air.

An air conditioner provides cool/hot airflow but does not ventilate. Using fan ventilation, together with an air conditioner, ensures fresh air intake all the time.

Using a fan together with air conditioning boosts the cooling effect without unnecessarily lowering temperature. Fans are also useful to effectively deliver cool air to stuffy spaces.

It takes time to warm the entire room with an air conditioner in wintertime. Fan heaters increase the heating efficiency of air conditioning in use.

The air conditioning capacity is the first element to be factored in when choosing the correct commercial air conditioning system for your business.
To determine the capacity required, you may also need to take into account other factors; for example, is the room facing south or does it have large windows.
Pick one that best fits the size and requirements of the rooms, provides comfort, and saves power.

Advances in communication technologies allow more air conditioning systems to be network connected. Let us walk you through some examples of what recent air conditioners offer.

The latest air conditioners come with wireless LAN (WLAN) connection capability that offers users smartphone controls over the Internet. You can turn on your air conditioner while you are away which enables you to come home to a comfortable temperature.

Most air conditioners come with remote controls. They offer features like large display LED, ease-of-use, quick press buttons, and more.

A virtual personal assistant (also referred to as intelligent virtual assistant) is a software agent that can provide answers and perform tasks or services for an individual based on commands or questions. Dialogues with the end-user leverage natural language processing technologies. Artificial intelligence and voice recognition technologies embedded in the unit enable voice control on air conditioners and other digital devices.

A building management system (BMS) is a computer-based control system installed in buildings that mechanically and electronically controls and monitors the building systems such as access control, security systems, fire systems, lighting, elevators, and air conditioning.

Cloud computing is a form of computing use, typically, the on-demand availability of computer system resources, especially data storage and computing power, without direct active management by the user. It delivers services through network-connected computers (servers) to users’ personal computers or smartphones. Today, smart cloud services are rapidly being developed one after another to bring transformation in modern air conditioning.
One example is Panasonic's AC Smart Cloud. It remotely monitors the power consumption levels, capacities, efficiency performances of multiple air conditioning devices in different locations via cloud computing systems. Users have quick and easy access to the data from their tablets or personal computers to ensure sound operations of the devices, and they are ready 24/7 to respond in the event of a malfunction.

Bluetooth is a short-range wireless communication technology that allows devices and apparatuses to transmit data or voice wirelessly over a short distance. The technology is the same one that allows you to listen to music being streamed on your smartphone through wireless earphones.
Some recent lighting products and air conditioners equipped with Bluetooth technologies, capable of linking with smartphone apps, are receiving much attention in the market.

Zigbee is a wireless network specification for high-level communication protocols for proximity (i.e., personal area) wireless ad hoc network. The technology defined by the Zigbee specification offers limited transfer distance and speed in exchange for being less expensive and to running on lower power.
Devices supporting Zigbee provide remote controlled home automation for air conditioners, lightings, TVs, screens, curtains and other items.

BACnet is a communications protocol for building automation and control (BAC) networks. The BACnet protocol provides mechanisms for computerized building automation devices to exchange and monitor information, regardless of the building service they perform according to manufacturer’s specifications for air conditioning, electricity, or fire extinguishing systems.

Modbus is a serial communications protocol originally published by Modicon (now Schneider Electric) for use with its programmable logic controllers (PLCs). It has become a de facto standard communication protocol and is now a commonly available means of connecting building management systems (BMS), boilers, manufacturing machinery, and other industrial electronic devices.

Air conditioners are busy delivering comfort around the year, in particular, during summer and winter. So, be a savvy consumer and know what they offer. Let's have a look at the latest features available on Panasonic air conditioners.

An air conditioner fan circulates the cooled or heated air in the room. The speed and coverage of the fan affect the cooling/heating efficiency. Air conditioners with variable fan speeds and wide coverage lower/raise the room temperature quickly.

Typical operating modes include:

Auto:Automatically selects and changes modes to keep the room temperature at the specified level.
Cool:Discharges indoor heat to lower the room temperature.
Heat:Transfers outdoor heat to indoors to warm the room air.
DryDehumidifies the room air. Also cools the room air, but not as effectively as the cool mode.
Fan OnlyFlows air into the room to deliver a cool breeze with no heating or cooling.
Eco:Runs the air conditioner while limiting the power consumption.

Detects the presence of a human body in an area and directs cool or warm wind in that direction. Increases air conditioning efficiency and helps reduce power consumption.
ECONAVI, a full spectrum of Panasonic's latest technologies, includes sensor analysis on how the room occupant feels the temperature (i.e., hot or cold), sunlight changes, furniture/room layout, to deliver personalized air conditioning.

Modern air conditioners have sophisticated air filtering capability to remove dust, mould, and bacteria that could be harmful to human health.
Many air conditioners clean the inside of units autonomously and suppress dust pile-up or mould growth. These functions keep air conditioner filters clean around the clock, reducing power loss, thus, efficiently reducing your electricity bills.

Night mode in an air conditioner commonly refers to a low power mode in which auto-temperature control and wind flow saving are activated for comfort when the user is sleeping. Once turned on, you can sleep peacefully with no worries about your room becoming too chilly or warm.

Because of convection where cold air moves down, and warm air rises, air circulates efficiently when louver slats on the front of air conditioners are turned upward during cooling and downward when heating. Most models have angle adjustment controls for louver slats on their remote controllers. Sideway angle adjustment helps deliver cool/warm air to a particular spot in the room.

Delayed restart prevents restart right after an air conditioner is turned off to protect the compressor.

As the awareness of global warming grows, demand response, a cap on the power consumption of an electric utility customer to avoid peaks in demand for power and maintain balance with the supply, is becoming a popular choice for power consumption control across the globe. Australia has national standards for Demand Response (AS/NZS 4755 series) on DREDs. This system has been implemented nationwide by electricity distributors. Voluntary rationing for air conditioners and other electrical appliances is encouraged by way of price incentives.

When an air conditioner is run under low outdoor temperatures and high humidity, frost may form on its outdoor unit. Over time, an accumulation of ice can form on the cooling element (evaporator coil). Eventually, this can block the circulation of the cold air. This is why defrosting is required. Auto-defrost regularly defrosts the evaporator by melting the frost and discharges the resulting water out of the indoor unit.

The average adult inhales and exhales about as much as 18 kg of air a day. That suggests the quality of air matters for everyone's health and comfort.
In recent years some social and health issues have been attributed to pollutants invisible to the naked eyes, e.g., pollens, PM2.5, house dust. Let's see what air conditioning can offer by improving the quality of indoor air.

Pollens such as Japanese cedar and Japanese cypress pollens are allergens that trigger allergic rhinitis, conjunctivitis, and/or asthma.
Particulate matter (PM) 2.5 is defined as the fraction of particles in the air, with an aerodynamic diameter smaller than 2.5 µm that can cause health hazards. Panasonic air conditioners with high-performance filters, e.g., dense HEPA filter, are effective at removing PM2.5.

In recent years, some cities in Northern China and South Asia have had very high levels of particulate matter concentrations, raising health concerns among neighboring countries. The particle size is small enough to penetrate deep inside human lungs, and studies show exposure to high concentrations of PM2.5 can increase the risk of respiratory and cardiovascular diseases including asthma and bronchitis.

Particles on the order of 10 μm or less are called PM10 (or coarse particulate matter). The sources are soot, yellow sand, coarse particulates and exhaust gases from various industrial processes, as well as volatile components from petroleum in the atmosphere. Like PM2.5, direct inhalation of PM10 causes respiratory diseases.
Carbon monoxide is produced from the partial oxidation of carbon-containing compounds, such as when operating gas or fuel run equipment that uses combustion for heating. It is a colorless, odorless, flammable gas and is toxic to animals that use hemoglobin as an oxygen carrier. Exposure to a high level of carbon monoxide may result in seizure, coma, and fatality.
Sulfur dioxide is a toxic gas produced as a by-product of the burning (oxidization) of fossil fuels, e.g., coal, crude oil, that are contaminated with sulfur compounds. Iron ore and copper ore also contain sulfur, therefore, iron or copper refining produces sulfur dioxide. Exposure to a high level of sulfur dioxide could result in fatality.
Nitrogen dioxide typically arises via the atmospheric oxidation of nitric oxide (NO) which comes from high-temperature combustion of fuels. High concentrations of the gaseous form of nitrogen dioxide cause distress, including irritation of the throat, bronchitis or pneumonia. Human-caused sources of nitrogen dioxide vary. Internal combustion engines, industrial processes, thermal power plants, domestic heaters or stoves that burn fossil fuels all produce nitrogen dioxide.

As mentioned above, air pollutants human eyes can't see are everywhere. Revitalize your air with Panasonic air conditioning. A full spectrum of technologies delivers filtered air for your health, traps and reduces many types of pollutants and allergens like pollens and particulate matters.

Common air conditioning refrigerants, such as CFCs and HCFCs, contribute to ozone depletion and climate change. Governments mandate the collection of CFCs/HCFCs upon repair or disposal of air conditioners to prevent refrigerant leakage.
Large power-consuming air conditioners contribute to global warming, since air conditioning units run on electricity that relies primarily on fossil fuels to generate power.

Air conditioning requires a lot of electricity. In Europe, the use of renewable energies is on the rise, but China and other Asian countries lag behind. These nations still rely much on thermal power generation, namely, large quantities of oil and coal are combusted. The carbon dioxide emissions from burning fossil fuels for power generation represent the most prominent source of greenhouse gas, causing global warming.
Selecting energy-efficient air conditioning for residential, commercial, and industrial applications helps protect environments on a global scale.

Refrigerant circulates through the indoor and outdoor units of an air conditioner to carry heat. Fluorocarbons, especially chlorofluorocarbons (CFCs), were commonly used refrigerants for decades, but they are being phased out because of their ozone depletion effects that came up to the forefront as a global issue in the 1970s. The Vienna Convention for the Protection of the Ozone Layer signed in 1985 and the Montreal Protocol agreed in 1987 provided frameworks for international reductions in the production and trade of chlorofluorocarbons. These international frameworks encouraged the use of CFCs alternatives, such as hydrochlorofluorocarbons (HCFCs) and Hydrofluorocarbons (HFCs).
In the 1990s, HCFCs and HFCs were classified into a subset of a larger group of climate-changing greenhouse gases (GHGs). Then, the Kyoto Protocol agreed on in 1997 set the broad outlines of emissions targets of GHGs.
Difluoromethane, or R-32, used as a refrigerant has low global warming potential (GWP), therefore, is the preferred substitute today for CFCs and HCFCs. Research on refrigerants that are less impactful than R32 are underway around the world.

The energy efficiency ratio (EER) of an air conditioning device is the ratio of hourly output cooling energy (in BTU) to hourly input electrical energy (in watts) at a given operating point. A higher EER means the air conditioning system is more efficient.

The coefficient of performance or COP (sometimes CoP) of an air conditioning system is the ratio of useful heating or cooling in proportion to the work required, representing the system's energy consumption efficiency.
The output heat comes from both the heat source and 1 kWh of input energy.

The seasonal energy efficiency ratio (SEER) is the efficiency of an air conditioner during a given period (up to 12 months). Like EER, a higher SEER rating means the air conditioning system is more efficient.

The SEER rating of a unit is the cooling output during a typical cooling season (12 months max) divided by the total electric energy consumption during the same period.

Air conditioning is now a vital part of our life. People get cool in summer and warm in the winter with air conditioners.
Air conditioning products pursue more convenience and energy saving at the same time as Internet connectivity and AI technologies evolve. Challenges remain in the use of CFCs/HCFCs, and society’s need for more energy-efficient products.
Protecting the global environment and bringing comfort and health to people’s lives are currently vital missions for air conditioner manufacturers.