Air-Conditioning and Refrigeration Institute members recently rang the closing bell at the NYSE.

Executives from member companies of the Air-Conditioning and Refrigeration Institute celebrated the production of 130 million central air conditioners by ringing the closing bell at the New York Stock Exchange.

ARI estimates up to 70 million central air conditioners and heat pumps, plus millions of commercial ac and refrigeration units are currently in service. Some 83% of housing units have air conditioning, about half of them central systems. Shipments of central ac and heat pumps are running 5% ahead of last year's 6.3 million total.

ARI said the efficiency of electric residential central ac has increased by nearly 50% over the past 25 years, and that chillers for commercial buildings are more than 40% more efficient.