I am trying to figure out if I could grow cool weather vegetable (say lettuce) in hot but dry climate by using swamp cooler to lower the temp of shade house. I have downloaded daily temp and humidity from www.weatherunderground.com and a chart on the potential temp drop: The thing is that I have 3 years of data from weatherunderground on a spreadsheet, doing manual matching of data is laborious. Does anyone know the formula behind the above chart? I think that chart assumed the airflow is perfectly matched to the room size. Thanks for helping.