[Bldg-sim] wetbulb formula

[Jeff Haberl]

Alec,



ASHRAE also has wetbulb formula in the spreadsheets that come with the ASHRAE RP865 final report, which are being incorporated into Standard 140.



Jeff



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Jeff S. Haberl, Ph.D.,P.E., FASHRAE..............jhaberl at tamu.edu

Professor............................................................Office Ph: 979-845-6507

Department of Architecture.............................Lab Ph:979-845-6065

Energy Systems Laboratory.............................FAX: 979-862-2457

Texas A&M University.....................................77843-3581

College Station, Texas, USA, 77843..................URL:www.esl.tamu.edu

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________________________________
From: bldg-sim-bounces at lists.onebuilding.org [bldg-sim-bounces at lists.onebuilding.org] on behalf of Alec Stevens [astevens at dmiinc.com]
Sent: Thursday, December 09, 2010 4:43 PM
To: bldg-sim at lists.onebuilding.org
Subject: [Bldg-sim] wetbulb formula

Hi,
Does anyone have an Excel-friendly equation they would be willing to share that can convert Tdb and RH into Twb?  We have metered data giving us Tdb, RH, and Tdp, but we need to know wetbulb.  We usually solve this problem with an Excel psychrometric add-in, but we need to distribute this spreadsheet to a client and cannot distribute the add-in at the same time.

We’ve tried a couple of multivariable regressions on the data, but because it is nonlinear, it is not proving to be that straightforward.  Next stop might be a two-way lookup table, but that is kind of cumbersome and was hoping to avoid it.

Any help much appreciated.

Sincerely,
Alec Stevens

DMI
35 Walnut Street, Wellesley, MA 02481
p: 781 431 1100 x11   f:781 431 1109
e: astevens at dmiinc.com