There was an article in BUILDING ENERGY SIMULATION, Vol 19, No 1, Spring 1998, called "Underground Surfaces How to Get a Better Underground Surface Heat Transfer Calculation in DOE-2.1E". It outlined the process for converting F- and C-factors into DOE2 inputs. That article's process required changing both the U-EFFECTIVE and a Ficticious R Material (Typically called UF/UWMat in eQUEST).

Does anyone know why they required changing both the U-EFFECTIVE and the Ficticious R (UF/UWMat)? We've run some parametrics and found the energy use difference between changing only U-EFFECTIVE versus changing both the U-EFFECTIVE and Ficticious R to be small.

-Eric

Eric,

You can find that article at:

http://simulationresearch.lbl.gov/dirun/1901.pdf (page 6) if you want to

look at it in more detail. In that on page 7, they state:

"The fictitious insulating layer is required to give the correct

effective resistance for the construction..." and also "The procedure

makes the approximation that the heat transfer through an underground

surface with no exposed perimeter, such as a basement floor, is zero."

The fictitious R is to more closely approximate the realistic conditions

of the earth contact.

JEREMY R. POLING, PE, LEED AP