Luis,
There may be some helpful resources for you on the web. I searched at www.google.com for "psychrometric labview" (without the quotes) and found several hits, mostly from companies (and universities) that had used LabVIEW in their psychrometric applications. You may want to see if any of these links prove to be helpful.
Good luck with your application, and have a pleasant weekend.
Sincerely,
Darren N.