This video shows how to take an architectural model that is built for rendering purposes in SketchUp, and simplify it down to the essentials required for analysis.
For an explanation of why you are simplifying the model, see this article: Simplicity vs. Complexity -- Modeling for Energy & Daylighting Analysis in Sefaira. I highly recommend that those who are new to building performance simulation or energy modeling read this article, but the short of it is: an architectural model is typically outfitted with every detail of the building’s design with the goal of producing realistic orthographics and renderings. An energy model, however, only needs a few pieces of geometry to represent the building's performance.