Given the high cost of running air conditioners, was kicking around the idea of being able to automatically determine when is the right time to use a desert cooler (aka evaporative cooler or swamp cooler) vs an air conditioner. Can across some papers on Humidex / Heat Index which could be used to determine the same, therefore decided to implement a Humidex Calculator using Arduino.
First some theory about Humidex :-
The humidex is an index number used to describe how hot the weather feels to the average person, by combining the effect of heat and humidity. The humidex is a unit-less number based on the dew point, but it is equivalent to dry temperature in degrees Celsius. For example, if the temperature is 30 °C (86 °F), and the calculated humidex is 40, then it indicates the humid heat feels approximately like a dry temperature of 40 °C (104 °F).
According to the Meteorological Service of Canada, a humidex of at least 30 causes “some discomfort”, at least 40 causes “great discomfort” and above 45 is “dangerous”.