Question-and-Answer Resource for the Building Energy Modeling Community
 | 1 | initial version |
CondFD model is especially challenging with regard to changing constructions on the fly. CondFD allocates all kinds of data for the internal nodes into variable length arrays. There is no practical way to reallocate these arrays move the thermal history over to allow a change between constructions with a different number of nodes. That is why this error trap is there and it is documented in the EMS applicaton guide.
The easiest thing to do is to switch from CondFD to CTF.
If you really must use CondFD, then you might experiment with the input field called Space Discretization Constant in the HeatBalanceSettings:ConductionFiniteDifference object to see if there is a setting where both constructions come out with the same number of nodes. You can also drive the number of nodes by breaking up the input for material layers in the construction, for example in WALLS_HIGHCOND, split the insulation into two separate thinner layers and it might change to 5 nodes.
