Hello.
In the building which I’m modeling there is an underground floor whose slab-on-grade floor can be considered as divided in three parts: one part (wellness) is heated with heated floor, another part is heated with another system (radiators) and to a lower temperature, and the third part (garage) is unheated. The second part is between the first one and the third one.
For the baseline model I have to consider table 5.5-4 of ASHRAE 90.1-2007, therefore for the part which is conditioned with radiators the F-value is equal to 1.264 (SI units) and for the part which is heated with heated floor it’s equal to 1.489, right?
In order to calculate the U-value
U-value = F-value*P/A
which perimeter P shall I consider? I mean, to calculate the U-value of the heated floor shall I consider in the perimeter P also the lengths of the sides which separate the part which is heated with the heated floor from the part which is heated with radiators? And to calculate the U-value of the part which is heated with radiators shall I consider in the perimeter both the lengths of the sides which separate it from the wellness and the lengths of the sides which separate it from the garage? Thank you for your attention.
Best Regards