Tiernan is an Assistant Planner at CARLIN Planning and a Licentiate Member of the RTPI. He joined the company in 2022 as a Placement Student and has recently graduated from Ulster University with First Class Honours in MSci Planning, Regeneration, and Development. He is the recipient of RTPI Northern Ireland Student Project Prize and the EPLANI Planning and Property Development Prize for his research on resilient urban design in Belfast. In addition, Tiernan serves as a committee member for the RTPI Northern Ireland Young Planners (NIYP) Network.

Tiernan has gained valuable experience consulting on a diverse range of projects across Northern Ireland, the Republic of Ireland, and England, collaborating with both private and public sector partners. His expertise includes planning applications, feasibility studies, and public consultations.