[Equest-users] Slab on Grade Insulation
Steven Savich, LEED AP
ssavich at systemswestengineers.com
Fri Sep 5 13:24:38 PDT 2014
DOE2.2 is set up to use a perimeter input method to explicitly model perimeter heat loss, but I don't believe eQuest has had this implemented yet, so it still uses the U-effective method for underground surfaces. For some background reading, the 2002 Winkelman paper on heat transfer through underground surfaces has a method for calculating the U-effective or for calculating the U value of the "insulating layer" in a DOE2.2 underground surface construction.
From: Equest-users [mailto:equest-users-bounces at lists.onebuilding.org] On Behalf Of Nathan Miller
Sent: Friday, September 05, 2014 1:12 PM
To: Campion Mark; equest-users at lists.onebuilding.org
Subject: Re: [Equest-users] Slab on Grade Insulation
In the past I've done a custom calculation for SOG assemblies. Essentially I look up the appropriate F-factor for the slab condition, multiply by the perimeter to get F*P heat loss in BTUH/Hr/° F . Then I back calculated appropriate U-values for each floor section so that the UA calculation comes out to the same heat loss. I concentrated the heat loss in the perimeter zones, since the SOG F factors are based on the principle that most of the heat loss occurs at the perimeter of the slab.
Attached is an example. In this case I had portions that were heated SOG, unheated SOG, and some exposed slab-edge (not at grade), so it was pretty complex to makes sure assigned U-values for each assembly worked out to match what the F- and U-factor parameters should be. Hopefully the color coding helps you sort through it.
Nathan Miller, PE, LEED AP BD+C
Mechanical Engineer/Senior Energy Analyst
D 206-788-4577 | O 206-285-7100
From: Equest-users [mailto:equest-users-bounces at lists.onebuilding.org] On Behalf Of Campion Mark
Sent: Friday, September 05, 2014 3:52 PM
To: equest-users at lists.onebuilding.org<mailto:equest-users at lists.onebuilding.org>
Subject: [Equest-users] Slab on Grade Insulation
In eQUEST, when I select insulation under a slab for a basement, the Construction El1 UFLyrs(B.W1.U2) doesn't seem to recognize the default horizontal R-10 insulation; for 2 or 4 foot selections. In other words, the Construction layers do not change from an un-insulated slab in a basement......4 inch HW Concrete slab, 12 inch damp light soil, and a "dummy" value showing an R-Value of 100. Any tips or explanations are appreciated.
Policy & Technical Services
mark.campion at state.or.us<mailto:mark.campion at state.or.us>
BUILDING CODES DIVISION
1535 Edgewater Street NW
PO Box 14470
Salem, Oregon 97309-0404
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