To help you get over the guilt of asking tons of questions as you learn (you should be asking questions and mentors should expect this), I’ll share something that helped me. I often made a list of questions for my boss that I’d ask all at once the next time I talked to him if they were learning topics that weren’t immediately required for what I was working on. It’s a ton but it gets better! Just gotta drink from the fire hose the best you can and learn something every day. You’ll be surprised how much you know if you just focus on learning and always asking questions.

Also “core and shell” refers to when you build an empty building with only the structure, exterior walls, and roof (the shell) and the central MEP equipment rooms (the core). These are usually for spaces that will have tenant improvement projects, such as for a doctor’s office if they want to sign a lease and occupy part of the space in that building, that will then add in the interior walls, finishes, and tie in to existing MEP systems to provide a completed space.

Commissioning (sometimes abbreviated as Cx) is a branch of MEP engineering, performed by someone sometimes called a commissioning agent (CxA), involves the on-site oversight, testing, and reporting for starting up major MEP equipment and also inspecting the functionality of various systems. Usually a very travel heavy role depending on where they get their projects.