[EnergyPlus_Support] Constructions, Layer Thickness/Total Thickness

[Linda Lawrie <linda@xxxxxxxxxx>]

Maximum number of layers is 10, is there a limit of total thickness?
DOE-2.1E has a limit of 3 or 4 ft.

The Energy+.IDD has a 3m limit on the thickness of each material in a
construction.  Theoretically, you could increase or reduce this
limit. The true limit is the numerical precision of the CTF calculation
which is more of a mass and thickness limit.  But in EnergyPlus the
CTF calculation is not necessarily calculated at the heat balance time
step.  It can be longer to maintain numerical stability and is done
automatically by the CTF calculation module.  For example, the slab
on grade floors at a 15 minute time step was found to be unstable and a
procedure was developed to let the more capacitive elements update their
time histories at their natural frequency.  This is explained in
detail in the Engineering Manual and papers that are referenced
there.  What this does is make larger, more capacitive building
elements feasible in a short time step simulation without allowing them
to be numerically unstable.

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