The Effects of AC Unit Refrigeration & Global Warming

Global Warming Potential of Refrigerants

• Global Warming Potential (GWP) measures the strength of certain substances as greenhouse gases and their potential for contributing to global warming. The GWP metric is indexed to CO2, with the GWP of CO2 equal to one. Many common refrigerants used in air conditioning units, such as chlorofluorocarbons (CFCs) and hydrofluorocarbons (HFCs), have astoundingly high GWPs, in some cases 1,000 times or more greater than CO2. These compounds can leak into the environment during installation, servicing and disposal of air conditioning equipment. Once in the environment, these chemicals make their way up into the atmosphere, where they accumulate and act as greenhouse gases, contributing to planetary warming by trapping solar radiation in the atmosphere in an energy-absorbing blanket.

Carbon Dioxide Emissions

• Refrigerants are not the only way that air conditioning units contribute to global warming. In fact, the energy used to operate them, if sourced from fossil fuels such as coal-fired electrical plants, is a much more significant source of greenhouse gas production. Even though the GWP of CO2 is much less than that of refrigerants, because it is emitted during the operation of air conditioning equipment, not just at discrete points in time, it is a significant source of greenhouse gases over the life of the equipment.

Energy Efficiency

• Because of their CO2 emissions, the efficiency of air conditioning units is a major factor in the amount of greenhouse gases they produce. Atmospheric damage from refrigerants is limited by design and law: Refrigerants are typically well contained within the unit, and regulations and safeguards restrict the amount of refrigerants released into the air. Conversely, CO2 is a byproduct of traditional methods of energy production and is released whenever energy is used. For this reason, high-efficiency units can significantly reduce greenhouse gas emissions.

Alternatives to Synthetic Refrigerants

• Even though they are contained, synthetic refrigerants still pose an environmental hazard. Luckily, they are not the only refrigerants available for air conditioning units. Early air conditioning units actually used naturally occurring CO2 as a refrigerant. Technical limitations that make CO2 difficult to work with as a refrigerant --- mainly that it requires high pressures --- led to the development of synthetics, including CFCs and HFCs. Current technologies make the use of CO2 again practical, particularly for small air conditioners. Even though CO2 is itself a greenhouse gas, its impact is insignificant compared with the impact of synthetic refrigerants and insignificant compared with the CO2 released during energy production.