Did you read about the F-Factor calculations? (ignore
what I said about the Ground Heat transfer as it is a different
subject)
At 05:27 PM 2/14/2011, James wrote:
Here is the warning message
received when using the F-factor calculation.
** Warning ** BuildingSurface:Detailed="DC77DB",
underground Floor Area = 401.88
** ~~~ ** ..which does not match its
construction area.
This occurs for every slab on
grade.
Constructions - Modeling Underground Walls and
Ground Floors Defined with C and F Factors for Building Energy Code
Compliance Building energy code and standards like ASHRAE 90.1, 90.2 and
California Title 24 require the underground wall constructions and
slabs-on-grade or underground floors not to exceed certain maximum values
of C-factor and F-factor, which do not specify detailed layer-by-layer
materials for the constructions.
A simplified approach is introduced to create equivalent constructions
and model the ground heat transfer through underground walls and ground
floors for the building energy code compliance calculations. The approach
is to create constructions based on the user defined C or F factor with
two layers: one concrete layer (0.15 m thick) with thermal mass, and one
fictitious insulation layer with no thermal mass. Three new objects were
created for such purpose: Construction:CfactorUndergroundWall,
Construction:FfactorGroundFloor, and
Site:GroundTemperature:FCfactorMethod. Details of the approach are
described in the Engineering Reference document. The wall and floor
construction objects are described in this section; the ground
temperature object is described with the other ground temperature
objects.
start reading there (page 155 of IO Ref, pdf page 186) and change your
input accordingly.
You can also search on "F-Factor" in the
documentation.