--- title: Carrier's Rational Psychrometric Formulae - the Basis for Air Conditioning and Spot Cooling description: Carrier celebrates the 100 Anniversary of the Rational Psychrometric Fomulae -- the cornerstone of air conditioning and spot cooling. --- Want to see us in action? Head over to our video gallery to see what we can do! [![View Video Gallery](https://no-cache.hubspot.com/cta/default/73348/6e0cd64c-ce93-4ae2-a3f8-e8fce9436848.png)](https://cta-redirect.hubspot.com/cta/redirect/73348/6e0cd64c-ce93-4ae2-a3f8-e8fce9436848) ![](https://cdn2.hubspot.net/hubfs/6162256/Icons/close.svg) [** 540.635.5011](tel:540.635.5011) [![footer_logo](https://www.airpacinc.com/hs-fs/hubfs/Airpac%20_2018/Images/footer_logo.png?width=186&name=footer_logo.png "footer_logo")](https://info.airpacinc.com/homepage) # Carrier's Rational Psychrometric Formulae - the Basis for Air Conditioning and Spot Cooling Posted by: [Tina Behnke](https://www.airpacinc.com/blog/author/tina-behnke) on Dec 8, 2011 *Rational Psychrometric Formulae*??  Say what?!  You may not be able to say it or even know what it is but the *Rational Psychrometric Formulae*, the cornerstone of all calculations in the air conditioning industry, impacts your comfort each day.  Deemed the Magna Carta of Psychrometrics, this document helps determine the precise correlation between temperature and humidity to create a comfortable environment year-round. **[Dr. Willis Carrier](http://inventors.about.com/library/weekly/aa081797.htm)**, inventor and founder of Carrier, had his flash of genius while waiting for a train on a foggy night, believe it or not!  And on December 8, 1911 he presented his Rational Psychrometric Formulae to the **[American Society of Mechanical Engineers](http://www.asme.org/)** at the annual meeting.  "Dr. Carrier's development unlocked the potential of air conditioning for the world," said John Mandyck, chief sustainability officer for UTC Carrier.  Carrier's inventions pioneered the design and manufacture of refrigeration machines to cool large spaces. By increasing industrial production in the summer months, air conditioning revolutionized American life. The introduction of residential air conditioning in the 1920s helped start the great migration to the Sunbelt that created an entire industry.  (Information courtesy of **[Wikipedia](http://en.wikipedia.org/wiki/Willis_Carrier)**.) I can't begin to tell you how these formulae were derived but am thankful to the "Father of Cool," actually we could call him the "Dr. of Cool," Dr. Willis Carrier, for his innovation and genius. You can check out an **[abstract from Carrier's Rational Pshchrometric Formulae](http://en.wikisource.org/wiki/Rational_Psychrometric_Formulae)** paper if you're into that sort of thing. Who knew modern day **[spot cooling](https://www.airpacinc.com/portable-applications/)** had such deep roots?  We can thank the good Dr. Carrier!  **Happy Anniversary -- 100 is sure something to celebrate!**  I think I'll treat myself to a yummy cupcake today.  I can always find a good reason to indulge my cupcake addiction!  Why not join me?  Tags: [HVAC Industry](https://www.airpacinc.com/blog/tag/hvac-industry), [Air Conditioning](https://www.airpacinc.com/blog/tag/air-conditioning), [Spot Cooling](https://www.airpacinc.com/blog/tag/spot-cooling) ##### Social Media - [** ](https://www.facebook.com/sharer/sharer.php?u=https://www.airpacinc.com/blog/bid/72236/carrier-s-rational-psychrometric-formulae-the-basis-for-air-conditioning-and-spot-cooling&title=Carrier's%20Rational%20Psychrometric%20Formulae%20-%20the%20Basis%20for%20Air%20Conditioning%20and%20Spot%20Cooling&picture=&description=Carrier%20celebrates%20the%20100%20Anniversary%20of%20the%20Rational%20Psychrometric%20Fomulae%20--%20the%20cornerstone%20of%20air%20conditioning%20and%20spot%20cooling.) - [**](https://twitter.com/intent/tweet?source=https://www.airpacinc.com/blog/bid/72236/carrier-s-rational-psychrometric-formulae-the-basis-for-air-conditioning-and-spot-cooling&text=Carrier's%20Rational%20Psychrometric%20Formulae%20-%20the%20Basis%20for%20Air%20Conditioning%20and%20Spot%20Cooling%20-%20https://www.airpacinc.com/blog/bid/72236/carrier-s-rational-psychrometric-formulae-the-basis-for-air-conditioning-and-spot-cooling) - [**](http://www.linkedin.com/shareArticle?mini=true&url=https://www.airpacinc.com/blog/bid/72236/carrier-s-rational-psychrometric-formulae-the-basis-for-air-conditioning-and-spot-cooling&title=Carrier's%20Rational%20Psychrometric%20Formulae%20-%20the%20Basis%20for%20Air%20Conditioning%20and%20Spot%20Cooling&summary=Carrier%20celebrates%20the%20100%20Anniversary%20of%20the%20Rational%20Psychrometric%20Fomulae%20--%20the%20cornerstone%20of%20air%20conditioning%20and%20spot%20cooling.) - [**](mailto:?subject=Carrier's%20Rational%20Psychrometric%20Formulae%20-%20the%20Basis%20for%20Air%20Conditioning%20and%20Spot%20Cooling&body=Carrier's%20Rational%20Psychrometric%20Formulae%20-%20the%20Basis%20for%20Air%20Conditioning%20and%20Spot%20Cooling%20https://www.airpacinc.com/blog/bid/72236/carrier-s-rational-psychrometric-formulae-the-basis-for-air-conditioning-and-spot-cooling) [Previous](https://www.airpacinc.com/blog/bid/72044/2012-hvac-industry-outlook-optimistic-ditto-for-spot-coolers) [Next](https://www.airpacinc.com/blog/bid/73702/electric-construction-heaters-keep-winter-projects-on-schedule) [![footer_logo.png](https://www.airpacinc.com/hs-fs/hubfs/Airpac%20_2018/Images/footer_logo.png?width=186&name=footer_logo.png "footer_logo.png")](https://info.airpacinc.com/homepage) AirPac is your solution for portable, temporary, and emergency heating and cooling for special events, commercial spaces, and industrial processes. 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