Moving the plant/manufacturing area?
As an engineer, sometimes (usually) it falls upon me to put clear, concise specs onto my boss's wishing and handwaving. Sounds like this may be the case for you.
Start with the golden rule of navigation: wherever you go, there you are. Find out how much space you currently have and what it's used for, and then see where the squeeze is the tightest. This should give you and idea of the square footage you need. Same is true for power requirements, etc.
try these words in a search engine: facilities planning design