How Humidity Influences Air Conditioning

woman turning on AC with a remoteOne of the signs you are ready for air conditioning replacement is that it no longer cools and dehumidifies. Cooling alone is simple – snow and ice have been used for cooling since ancient times. The ancient Egyptians and tribal peoples of the Mideast and on our continent had strategies for keeping dwellings relatively cool. 

Early Mechanical Cooling

It was in 1851 (that’s right, before the Civil War) that a patent was issued to John Gorrie of New Orleans for an “Improved Process for the Artificial Production of Ice.” For decades, the ice produced by Gorrie’s process was used for industrial cooling and refrigeration. But a need arose that called for new innovation. A printer in Brooklyn, NY, was having a problem with humidity control in the printing process. Willis Carrier was called to work on the project.

A Device for Treating Air

In response to the printer’s problems Willis Carrier set out to invent a machine that would cool and clean the air, and control humidity. He began work in 1902 and in 1906 received patent No. 808897 for an “Apparatus for Treating Air.” This was the first modern air conditioner that was able to cool and dehumidify at the same time. Over the next half-century, the air conditioner evolved to what we know today – compact and affordable enough to provide comfort to homes worldwide.

What Does Humidity Have to do with Comfort?

Comfort is determined by a combination of many factors, such as activity, clothing, metabolism, radiant heat, and air movement to name a few. All of these are considered when designing a new air conditioner for your home. But the most important two are temperature and humidity. We must control and correctly balance these to provide effective comfort conditioning.

Consider How our Bodies are Designed

Our bodies are cooled through perspiration. Heat is carried away through the process of evaporation into the surrounding air. That is why we feel the humidity when we step outside on a steamy Jupiter, Florida, summer afternoon. When the humidity in the surrounding air is high, our body’s personal cooling system – perspiration – does not operate effectively. 

It is the same inside our homes. Most people are comfortable at between 73 and 78 oF and between 50 and 55 % relative humidity. Because comfort preferences vary widely, those figures will also vary. However, there is no summer comfort when the air is not cool and dry enough to allow our bodies to lose excess heat. 

What is Humidity Relative?

Warm air holds more moisture than cool air, thus the humidity percent is relative and depends on temperature. Think of the air like a sponge. A dry sponge contains 0 % of the water it can hold, while a totally soaked sponge is at 100 % capacity. Similarly, air at 50 % relative humidity has room to hold more moisture. Air at between 20 and 30 % relative humidity absorbs too well and causes dry and cracked skin. At relative humidity above 60 %, the air has lost much of its ability to absorb more moisture and people begin to feel uncomfortable.

Losing Humidity Control

Moisture will condense on a cold glass, but not a warm one. This same process is used to dehumidify your home as the cooling coil extracts water from the air, sending it to a drain outside. If your air conditioner has lost 10 % of its refrigerant charge (a fraction of a pound of refrigerant), it will not dehumidify as well. The air conditioner will cool, but you need to set it at a lower temperature to be comfortable. You get less comfort and spend more money on increased utility bills. 

The best way to maintain proper dehumidification and overall operation of your air conditioner is by a Comfort Club membership. A trained professional will come to your home twice a year to check refrigerant and all the other many factors necessary for effective and efficient cooling. 

The Ultra Smart Thermostat for Humidity Control

The most advanced home comfort systems can precisely control the balance of temperature and humidity. The Lennox iComfort Ultra Smart Thermostat in my home is programmed for a “feels like” temperature of 76 oF and will control the compressor and fan to maintain the comfort I personally desire. 

Ask our Comfort Specialist about an ultra-smart thermostat and a high-efficiency system when you need air conditioning replacement. It is the best investment you can make in-home comfort conditioning.