Hi @obuchely. If you're referring to the OpenStudioApplication (or App), then you're correct: one cannot edit ground temperatures or activate Kiva using the App. @Jamie Sullivan is rightly pointing to superior solutions, but there are (rare) circumstances where even Kiva won't be of much help (unless this has changed recently). In such cases, you may need to fallback on resetting ground temperatures by hand. To ~safely reset ground temperatures, there's a simple hack described here.
There is a step-by-step Measure approach to deploying Kiva using the App, described here - should work for most cases.
Of course if you're familiar with the OpenStudio SDK (or API), then you can script your own solution based on a handful of classes (e.g. here and here). Here's a very straightforward example, in Ruby and in Python.
This depends. How are you modelling the ground? You basically never want to be directly connecting the floor to the "Ground" - you want to be using one of the ground/slab foundation models like GroundDomain or Kiva.
How do you implement ground/slab foundation models like Ground Domain or Kiva in openstudio?