[Equest-users] F-Factor

[Michael Daley]

Tom,

You've stumbled onto one of the items that needs to be updated in the next version of E-Quest.  The F-factor is not the same as the U-factor you've indicated on the attached document.  The way to correctly account for the heat loss through the slab perimeter is to correlate the F factor to an equivalent U value for input into the program.  Take a look at the 2009 ASHRAE fundamentals Chapter 18.30-32 equations 35, 41, and 42 for how to do this.  Inputting the F-factor directly for the U value could greatly skew the heat loss that occurs through the slab.

Sincerely,

Michael Daley, PE
Mechanical
HARGIS ENGINEERS
600 Stewart Street
Suite 1000
Seattle, WA 98101
www.hargis.biz<http://www.hargis.biz>

d | 206.436.0469 c | 206.914.5587
o | 206.448.3376  f | 206.448.4450
From: Eckwahl, Tom [mailto:TEckwahl at karpinskieng.com]
Sent: Friday, February 26, 2010 10:29 AM
To: equest-users at lists.onebuilding.org
Subject: [Equest-users] F-Factor

What is the consensus on where F Factor should be input?  I have been putting it under the underfloor material data (see attached).

Is this correct?

Thomas N. Eckwahl
Project Engineer, Mechanical
karpinski
ENGINEERING

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