I want to use Sobol SA with Sobol sampling to find the most influential parameters on the energy consumption of a pilot building. I have 40 input variables (building characteristics) that some have uniform and some normal distributions.
For Sobol sampling I know the total cost for the first order and total order estimation is N(k+2), how can I choose the sampling size (N)?
Is grouping actually helpful for 40 parameters?
So I also thought of first running a first order and second order SA and based on the results of second-order indices, I group my input variables. But I do not know if that is actually helpful cause my main intention is to simplify the simulation.