Air conditioners have played a significant role in maintaining comfortable indoor temperatures worldwide. Indeed, the very definition of home comfort largely involves the use of air conditioning systems. However, the environmental impact of air conditioners has been the subject of increasing concern for several people, particularly regarding the emission of harmful gases.
Do air conditioners emit harmful gases? What exactly goes on in the air conditioning process? Is my family safe with using air conditioning units? How about the environment? How can I make my air conditioner more risk-free?
We hear you and we’d love to walk you through to find the answers.
Do Air Conditioners Emit Harmful Gases or Fumes?
NO. Air conditioners that are well-maintained and working properly DO NOT emit harmful gases. The cooling process of an air conditioner involves circulating the refrigerant, a liquid-gas chemical compound that absorbs heat from the air. The AC does not release any amount of refrigerant in normal operations because it is contained within the closed-loop system of air conditioning.
The only way refrigerant may leak is because of the erosion of the metal after many years of use. Regular annual maintenance including a thorough check for coolant leaks by a qualified HVAC professional can prevent a refrigerant leak from happening. Through the services of a certified technician, you will be able to detect minor issues early, repair the damages, and administer solutions before safety can be compromised.
How Does An Air Conditioner Work?
Before we can confidently answer the question, “Does an air conditioner emit poisonous gases?”, we need to understand how the conventional AC works.
In layman’s terms, the air conditioner removes the heat and aims to reduce excess humidity from your home’s air. Contrary to what people may have thought, the AC does not put cold air into the room. Rather, it takes the same air and processes it by removing the heat and moisture from it, then blows it back into your space.
That in itself is proof that air conditioners, in their efficient state, cannot be emitting harmful gases. The cold air you feel is not some new air from a different source produced by the AC but the existing air, only conditioned or cooled.
You may ask, “What about the refrigerant? Aren’t most air conditioners use this chemical substance to lower the temperature? Does the AC release it in the air while running and harm the health of your family?”
Let’s take a closer look at this peculiar but remarkable compound.
What is the Role of the Refrigerant in the Air Conditioning Process?
Refrigerant is an essential component in a home air conditioning system, responsible for cooling the air within the living space. The primary role of the refrigerant is to extract heat from the indoor air and expel it outdoors, thereby creating a comfortable indoor environment.
In a standard home air conditioning system, the refrigerant continually cycles through various phase changes (shifting between liquid and gas states) as it circulates within the system. Importantly, the refrigerant remains contained within the closed-loop system so air conditioners do not emit any gases during operation. This prevents exposure of any amount of refrigerant to the inhabitants of the home.
How Air Conditioners Make Use of Refrigerants
Here’s a simplified outline of the process of how the refrigerant is used in a cooling cycle of an air conditioning system:
1. The refrigerant begins as a low-pressure, low-temperature liquid inside the AC evaporator coil, which is situated indoors. Warm air from inside the home is blown over the evaporator coil, causing the refrigerant to absorb heat from the air and vaporize into a low-pressure gas. This exchange takes place within the confines of the coil, ensuring no direct contact with the home’s occupants.
2. The gaseous refrigerant, now holding the absorbed heat from the air, is compressed and transported to the outdoor condenser unit. This compression increases both the temperature and pressure of the refrigerant gas.
3. The high-pressure, high-temperature refrigerant gas then moves through the condenser coil, located outside the home. As the outdoor air passes over the condenser coil, the heat carried by the refrigerant is released into the external environment, causing the refrigerant to condense back into a high-pressure liquid. This exchange also occurs within the coil, keeping the refrigerant contained.
4. The high-pressure liquid refrigerant flows through an expansion valve or metering device, which reduces its pressure and temperature. This cooled, low-pressure liquid refrigerant re-enters the evaporator coil, restarting the cycle of cooling the air.
This continuous process of heat absorption and release enables air conditioning units to maintain a comfortable temperature within the home. The refrigerant, typically a type of hydrofluorocarbon (HFC), remains contained within the closed-loop system, preventing any exposure to the residents. HFCs have a lower environmental impact compared to older refrigerants like chlorofluorocarbons (CFCs) or hydrochlorofluorocarbons (HCFCs).
Is AC Refrigerant a Harmful Gas?
It is safe to say that all chemicals, whether organic or man-made, pose at least some degree of risk. Air conditioner refrigerants are no exception.
According to the United States Environmental Protection Agency or EPA, the hazards involving refrigerants may be categorized into the following:
- Toxicity. Acute toxicity may occur during a one-time or short-term exposure but in high concentrations. This may happen when a person accidentally opens a compressor or a gasket with refrigerant stuck inside it. Chronic toxicity, on the other hand, happens mostly to HVAC technicians who have recurring or sustained exposures to refrigerants.
- Flammability. Some types of refrigerants are flammable and others are not. Flammable refrigerants include R32 (difluoromethane and carbon difluoride), R290, R600a, and R717 (ammonia) refrigerant. Non-flammable refrigerants are R134a, R410A, R407C, R1233zd, R513A.
- Asphyxiation. Limited exposure to refrigerant can be mildly dangerous if you do not have the proper equipment. But purposely inhaling the cooling compound to abuse it or to get high will cause difficulty in breathing, fluid buildup in your lungs, organ failure, and even death.
- Physical hazards. Because refrigerants are used to cool the indoor air, it has a low boiling point. When it comes to direct contact with the skin, it can cause skin irritation or even frostbite. Some complained about sight impairment after mishandling the refrigerant.
Understanding Refrigerants
Since refrigerants come in many forms and categories, how will you know which type of refrigerant suits your home and is safer for usage? Read on to gain insight into common refrigerants in air conditioners and their environmental impact.
Common Refrigerants in Air Conditioners
Refrigerants are the cooling agents in air-conditioning units that help absorb heat and release it outside. Some of the most prevalent refrigerants include:
- Chlorofluorocarbons (CFCs)
- Hydrochlorofluorocarbons (HCFCs)
- Hydrofluorocarbons (HFCs)
- Natural refrigerants like ammonia and carbon dioxide
CFCs, such as Freon, were once popular refrigerants due to their effectiveness and low cost. They consist of chlorine, fluorine, and carbon. However, they have been largely phased out due to their contribution to ozone depletion.
HCFCs, which contain hydrogen in addition to other elements found in CFCs, were introduced as a temporary alternative to CFCs. Although they were less damaging to the ozone layer, they still contributed to greenhouse gas emissions.
HFCs emerged as a more environmentally friendly alternative to CFCs and HCFCs. They don’t contain chlorine, which makes them less harmful to the ozone layer. However, their high global warming potential still raises concerns.
Natural refrigerants, such as ammonia and carbon dioxide, are gaining popularity as they have minimal impact on the environment compared to their synthetic counterparts.
Environmental Impact of Refrigerants
Air conditioner refrigerants can have both direct and indirect impacts on the environment. Direct impact occurs when they are emitted into the atmosphere, while indirect impact results from the energy consumption of the air conditioning system.
| Refrigerant | Ozone Depletion Potential (ODP) | Global Warming Potential (GWP) |
| CFCs | High | High |
| HCFCs | Low-Medium | Medium |
| HFCs | None | High |
| Natural Refrigerants | None | Low |
Do Air Conditioners Contribute to Global Warming?
CFCs and HCFCs were highly detrimental to the ozone layer due to their chlorine content. When released, chlorine reacts with ozone molecules, leading to a decrease in the ozone concentration. This results in increased ultraviolet radiation reaching the Earth’s surface, posing risks to human health and ecosystems.
While HFCs have no ozone depletion potential, their high global warming potential remains an issue. Compared to carbon dioxide, some HFCs can trap thousands of times more heat in the atmosphere, contributing to climate change.
Natural refrigerants, such as ammonia and carbon dioxide, present a more environmentally friendly solution. With little to no ozone depletion potential and low global warming potential, they are increasingly being adopted in air conditioning systems to minimize the environmental impact.
Environment-Friendly Refrigerant Alternatives
In recent years, there has been a growing interest in developing safe and environmentally friendly alternatives to traditional refrigerants like hydrofluorocarbons (HFCs), chlorofluorocarbons (CFCs), and hydrochlorofluorocarbons (HCFCs), which contribute to global warming and ozone depletion. Some promising alternatives include:
1. Hydrofluoroolefins (HFOs): Because of the concern that air conditioners emit greenhouse gases in the form of hydrofluorocarbons, hence the innovation of HFOs. HFOs are a new class of AC refrigerants with low global warming potential (GWP) and zero ozone depletion potential (ODP). They have similar performance characteristics to HFCs but break down more quickly in the atmosphere, resulting in a lower climate impact. An example of an HFO refrigerant is R-1234yf, which is being used in some automotive air conditioning units.
2. Natural Refrigerants: Much older versions of refrigerants are found to contain potent greenhouse gases known as hydrofluorocarbons. This problem called for the shifting of attention to more organic compounds. These substances occur naturally in the environment and have minimal impact on the climate and ozone layer. Examples of natural refrigerants include
a. Carbon Dioxide (CO2 or R-744): CO2 is an eco-friendly refrigerant with a GWP of 1 and an ODP of 0. It has been used in various applications, such as commercial refrigeration, heat pumps, and air conditioning systems. CO2 systems typically operate at higher pressures than traditional AC refrigerants, which can present some design challenges.
b. Ammonia (NH3 or R-717): Ammonia has been used as a refrigerant for over a century, particularly in large-scale industrial refrigeration systems. It has a GWP of 0 and an ODP of 0 but is toxic and flammable at high concentrations, requiring careful handling and system design.
c. Hydrocarbons (HCs): Propane (R-290) and isobutane (R-600a) are examples of hydrocarbons used as AC refrigerants. They have low GWP and zero ODP but are flammable, necessitating safety precautions in system design and maintenance.
3. Water (R-718): Water can be used as a refrigerant in absorption chillers and adsorption chillers, which use heat to generate cooling. These systems are less energy-efficient than conventional vapor-compression units but can be advantageous in situations where waste heat or low-cost heat sources are available.
4. Air (R-729): Air can be used as a refrigerant in air cycle refrigeration systems, which are commonly employed in aircraft air conditioning. These AC units have low efficiency compared to vapor-compression systems but do not require any additional refrigerant.
As research continues, more environmentally friendly and safe alternatives to traditional refrigerants may become available. Each alternative has its own set of advantages and limitations, and the choice of AC refrigerant will depend on the specific application and system design requirements.