Gas air conditioning systems are usually more expensive to buy and install than electric air conditioning systems but have lower operating costs. Determining whether a gas system is more cost-effective than an electrical system requires a life cycle cost analysis specific to a given project and site.
Gas air conditioning systems have up to twice the lifespan of similar electric-powered systems and have lower maintenance costs because they have fewer moving parts. Most systems suitable for residential use are absorption systems that use ammonia as the refrigerant. The system uses natural gas heating to boil ammonia out of water, condensing it in an outdoor coil. The system then evaporates the ammonia at low pressure to cool water, which circulates through a piping system in the area to be cooled. The cycle repeats as the ammonia is absorbed back into the water, and the solution returns to the heating unit.
Gas air conditioning systems use 30 to 50 percent less energy than comparable electric-powered systems, and ammonia is a more environmentally friendly refrigerant than those commonly used in electric-powered systems. Whether a gas air conditioning system is less expensive to run than an electric-powered system depends on the prices of natural gas and electricity in a given area.