Thanks to all who have tried to help. I found this for having Excel calculate an approximate enthalpy. I have it entered in a spread sheet. I have WD sending current indoor and outdoor temperature and humidity to my own website. The spreadsheet scraps the indoor and outdoor temp and humidity from the website and calculates the entropy.
Here is the article I found on the internet:
temperature and relative humidity.
By Engineer Joe, www.mrexcel.com
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July 29th, 2015
This isn't actually a question. I worked for a while to come up with a feasible formula working between 0 and 100