Energy Model Credibility

This question may be somewhat unusual because it isn’t about the energy modeling software per se. I’m wondering how does an energy model achieve enough credibility to base major design decisions on? As designers we agree that energy modeling is a legitimate and useful tool, but at the same time, there is no easy way to test a given model against its performance in real life.

For example in architecture school I worked hard to teach myself energy modeling with honeybee. I wanted to be able to use it as a tool when working as an architect and I achieved a good understanding of the software and concepts involved.

Fast forward to my current situation working for a small architecture firm. My boss wants to do energy modeling on one of our projects and I told him I could do it. The scope of what he wants to model seems well within my capabilities. However, I think he isn’t really confident in my ability and fair enough. In his shoes I’m not sure I would base HVAC sizing and other major design decisions on me and my mysterious(from his perspective) model.

So I guess what I’m wondering is how do I get to the point where I can use energy modeling as a design tool in my work? What are ways to convince those dependent on an energy model that it actually reflects performance of a building in reality?

My question is more philosophical than technical which I realize is not the norm for this forum, but I figured this is the most qualified community to answer it.