Here is information provided by Michael Plunkett of SmartRate:
BERS doesn’t do in floor heating/cooling systems as such.
The BCA requires a floor slab to have slab edge insulation provided (and possibly underfloor insulation as well) if the floor contains an underfloor heating/cooling system – Clause 184.108.40.206 (c)
This is added in BERS once zones etc. are drawn. The slide bar does not appear when choosing defaults for a job.
Add the desired R-Value by moving the slide bar.
You can only add it once and for the whole project – you cannot add to one zone and not another – limitation of the program.