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Carrier Marks the 100th Anniversary of the Rational Psychrometric Formulae

Dec. 8, 2011

FARMINGTON, CONN. – Some consider it the gift that keeps on giving - whether it’s 2 or 102 degrees outside. Today marks the 100th anniversary of the Rational Psychrometric Formulae, the cornerstone of all fundamental calculations in the air conditioning industry, developed by inventor Dr. Willis Carrier, founder of Carrier, the world’s leader in high technology heating, air-conditioning and refrigeration solutions. Carrier is a part of UTC Climate, Controls & Security Systems, a unit of United Technologies Corp. (NYSE: UTX).

Less than a decade after inventing modern air conditioning in 1902, Carrier’s research and development efforts came together in the single most famous and enduring document ever prepared on air conditioning, the “Rationale Psychrometric Formulae.” Called the Magna Carta of Psychrometrics, the document helps determine the precise correlation between temperature and humidity to create a comfortable environment year-round.

Carrier presented the psychrometric formulae on December 8, 1911 at the annual meeting of the American Society of Mechanical Engineers and initiated the field of scientific air-conditioning design. His invitation to the meeting recognized air conditioning as a formal branch of engineering, and turned 35-year- old Carrier into an internationally recognized leader in the field.

"Dr. Carrier's development of the psychrometric formulae unlocked the potential of air conditioning for the world," said John Mandyck, chief sustainability officer, UTC Climate, Controls & Security Systems. "From his first installation that marked the birth of modern air conditioning, the psychrometric formulae enabled an entire global industry to flourish by meeting the comfort, productivity and health needs of people across the world.”

Carrier’s work continues to impact the next generation of engineers, who learn the formulae as part of their coursework. According to Charles Williamson, the Willis H. Carrier Professor at Cornell University's College of Engineering, Carrier’s work resulted in the acceptance of the “control of air” as a branch of the engineering, and paved the way for the countless engineers and inventors that followed him.

"Students of engineering today appreciate the tremendous work done by Willis Carrier. Without these early researchers, and the work they did with little or no equipment, we would not have the basis for the sophisticated systems for air conditioning we have today."

Revered in a countless ways around the globe, Carrier has earned special recognition at Cornell University, his alma mater.

"The Willis H. Carrier Endowed Professorship is a fitting and lasting tribute to the work of a pioneering inventor,” said Lance Collins, Dean of Cornell University's College of Engineering. “We are very pleased that the Carrier name will be associated with Cornell in perpetuity.  Endowed professorships support our most esteemed faculty members, so that they can continue to advance their fields of knowledge."

Willis Carrier wouldn’t have it any other way.

For more information on Carrier and his work, visit the history section on

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