The CDM 2015 dutyholder responsible for managing health and safety risk during the pre-construction design phase. The Principal Designer is a statutory role under the UK's CDM Regulations, responsible for planning, managing, and monitoring health and safety during the pre-construction design phase - coordinating how designers eliminate or reduce risk before it ever reaches site. It's a legal duty distinct from being the lead architect or BIM Manager, though on smaller projects the same person sometimes holds more than one of those roles.