[Bldg-sim] eQuest: Slab on Grade Ueff Calculation (Underground Wall)

Brett Fero bfero at robsonwoese.com
Tue Mar 25 08:24:03 PDT 2008


I am modeling a slab-on-grade floor using the methods described under the
help for the U-EFF.  This is the described in the Volume 3: Topics/ Envelope
Components / Underground Wall eQuest 3.61e help files.  A sample calculation
is presented for the 100 ft x 50 ft slab-on-grade floor.  The sample input
is given as follows;

LAY-SLAB-1 = LAYERS
     MATERIAL           = ("Soil 12in","Conc HW 140lb 4in (CC03)")
     INSIDE-FILM-RES    = 0.77 ..

CON-SLAB-1 = CONSTRUCTION
     TYPE               = LAYERS
     LAYERS             = LAY-SLAB-1 ..

SLAB-1 = UNDERGROUND-FLOOR
     HEIGHT             = 50
     WIDTH              = 100
     TILT               = 180
     PERIM-EXPOSED      = 300
     PERIM-CONDCUT      = 0.50
     CONSTRUCTION       = CON-SLAB-1 ..

eQuest 3.61e does not appear to accept the PERIM-CONDUCT and PERIM-EXPOSED
keywords as input.  Instead it uses the keyword U-EFF.

In Vol 23, No.6 of the Building Energy Simulation User News for DOE2.1E,
slab-on-grade calculations were presented using the following;

Reff = A/(F2 x Pexp) where Reff = Reffective, A = area of slab (ft), F2 =
perimeter conduction factor, and Pexp = exposed perimeter length (ft).

So, is U-EFF required in eQuest 3.61e calculated as U-EFF = 1/Reff = (F2 x
Pexp)/Area using F2 factors from Table 9?

Or, is there a way that I should be entering PERIM-EXPOSED and PERIM-CONDUCT
for each floor?

Thanks in advance for any help clearing this up for me.

 

Brett Fero, P.E., LEED AP

RobsonWoese, Inc.

5824 Widewaters Parkway

East Syracuse, NY 13057

 

 

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