Every Day Is Special: November 26 – Happy Birthday, Willis Carrier

November 26 – Happy Birthday, Willis Carrier

Posted on November 26, 2016

When I typed “Carrier” into Google, the first thing that came up was Carrier Air Conditioning.

And that's all well and good, because today's birthday boy invented modern air conditioning!

Born in New York on this date in 1876, Willis Carrier grew up to be an engineer. He invented the first air conditioning unit in 1902 and started Carrier Corporation in 1915. Carrier advertises that it is still a world leader in HVAC (Heating, Ventilation, and Air Conditioning).

Of course, even before Carrier's invention, people had been cooling their homes and work places since prehistoric times, often using snow and ice – even storing ice for use during summer. Some people used shade or moist cloths or reeds hung in windows so that breezes would bring in cooler, moister air. Even ancient people used water circulating in pipes inside walls to cool particular rooms, and early civilizations utilized things such as wind towers and cisterns to cool the air. Ancient peoples also invented human- or animal-powered rotary fans to move air around.

But Carrier's air conditioning unit used electricity to do four important things:

control temperature
control humidity (how much moisture is in the air)
control air circulation, or movement, and ventilation
cleanse the air

Basically, Carrier's invention heated water in order to put more humidity into the air, and it cooled water in order to take humidity out of the air.

Carrier tied together the ideas of absolute humidity, relative humidity, and dew-point temperature in a document sometimes referred to as the most important document ever written on HVAC stuff.

Let's see what these three ideas mean:

Absolute humidity – a measure of the water vapor in air no matter what the temperature is, expressed in grams of water per cubic meter of air.

Relative humidity – a measure of water vapor in the air relative to the temperature of the air, expressed as a percentage of the total amount of water vapor that could be held by air at that temperature.

Warm air can hold a lot more water vapor than can cold air.

Relative humidity is important because it affects how we experience temperature. If the air is really moist and 90 degrees, we feel a LOT hotter and more uncomfortable than if the air is quite dry and 90 degrees.

Dew-point temperature – when relative humidity reaches 100%, the air is called “saturated” – which means it is holding as much water vapor as it can possibly hold at that temperature. Some water vapor is condensing (forming drops of liquid water) on solid surfaces or particles, but some drops of water are also evaporating and becoming water vapor...Because of this steady condensation and evaporation, the amount of water vapor stays the same.

But when the temperature drops a smidge (or a lot) below the dew-point temperature, the water vapor condenses at a higher rate than liquid water evaporates. And dew begins to form on leaves and blades of grass and cars and other objects. Or drops of water condense on particles of dirt or sand in the air, causing the formation of either fog or clouds, depending on how high the drops are located.