Air-conditioning myths and facts

A/C use can affect fuel-consumption and CO2 emissions but not the ozone layer

Published: July 23, 2017, 5:50 PM
Updated: October 11, 2021, 10:06 AM

Woman enjoying air-conditioning

It's that time of year when the air-conditioning systems in our cars and trucks are getting a real workout. Given some of the rhetoric you may have heard about the impact of A/C use on the environment, you may be feeling some guilt about using it. So let’s take a look at what those effects really are and separate the myths from the facts.

Chances are the environmental impact of using A/C may be quite different from what you have been led to believe.

MYTH: Using your car’s air-conditioning causes depletion of the earth’s ozone layer.

FACT: Use of a properly functioning air-conditioning system plays no role in ozone depletion.

Car air-conditioning

Back in the 1970s, it was discovered that some man-made chemicals, including the refrigerant used in automobile air-conditioning systems (called Freon 12 or R12), were having a deleterious effect on the earth's ozone layer, which helps protect us from damaging ultraviolet-B (UVB) radiation from the sun.

At that time, it was common practice for refrigerant to be released into the atmosphere when A/C systems were being serviced, allowing it to migrate to the stratosphere where it contributed to ozone depletion.

In 1987, most of the world's industrialized nations signed onto the Montreal Protocol on Substances that Deplete the Ozone Layer, which resulted in eradication by the year 2000 of major ozone-depleting chemicals, including R12.

New regulations also mandated that R12 be recovered rather than released when A/C systems were serviced and that it be replaced, both in older vehicles being serviced and in new vehicles, with a new refrigerant called HFC 134a (R-134a), which was benign to the ozone layer. Subsequently, some manufacturers have replaced that refrigerant too but with another that is similarly benign.

During the initial transition from R12, some well-meaning but ill-informed environmental advocates urged people to stop using the air-conditioning in their cars and trucks to help protect the ozone layer. What they failed to understand is that as long as the refrigerant stays within the closed system of the vehicle, whatever it is, it can do no harm.

So, simply using a properly functioning air-conditioning system plays no role in ozone depletion.

MYTH : Using your car’s air conditioning contributes to Climate Change.

FACT 1: Using your car’s air-conditioning has no direct impact on climate change as long as the system is functioning properly and the refrigerant is contained.

Car air-conditioning

By the end of the 20th century, after the entire new vehicle fleet had adopted R-134a as its A/C refrigerant, environmental attention had refocused on global warming and climate change. And R-134a, although benign to the ozone layer, was found to be a global warming or greenhouse gas (GWG), with a relatively high global-warming index.

Given that all refrigerants must now be recaptured during system servicing and vehicle disposal, the amounts of the refrigerant released into the atmosphere are relatively low so its impact is quite small.

Nevertheless, the industry once again undertook to find a new refrigerant that is both ozone-friendly and has a low-impact on global warming.

That work zeroed in on a next-generation refrigerant, called R-1234yf, which satisfies those criteria and it has now been adopted by much of the industry. Some German manufacturers are taking a different route, actually adopting CO2 as a refrigerant..

Whatever refrigerant your vehicle uses, however, it has no direct impact on climate change as long as it stays within the closed system of a properly functioning air-conditioning system.

FACT 2: Using your car’s air-conditioning can have an indirect impact on climate by increasing fuel consumption, which in turn increases CO2 emissions.

Car air-conditioning

Using your air-conditioning requires some additional fuel use by the engine to power the refrigerant compressor when the system is on.

The amount of carbon-dioxide (CO2) produced in a vehicle's exhaust is proportional to the amount of fuel used and CO2 is also a global warming gas.

Just how much additional fuel the use of air-conditioning requires varies dramatically with such factors as the vehicle itself, driving speed, wind conditions and temperature.

Various studies suggest the range of that effect is typically between 1 and 10 percent, with the greatest increase in consumption in urban stop-and-go driving and the least effect at expressway speeds.

Rolling the windows down rather than using the air-conditioning also has a negative effect on fuel-consumption at higher speeds, because of the additional aerodynamic drag created so it may or may not be a worthwhile alternative.

Whether or not to use your air-conditioning, then, comes down to a choice between personal comfort and a modest increase in fuel-consumption and consequent CO2 production. The choice of yours.