The CEO of the Children's Hospital Group says the site at St James' is the best location for the facility.
The HSE yesterday approved the brief for the project in Dublin City Centre, with construction due to start in July of next year.
Critics of the site say it is too small and inaccessible to families living outside the capital, who comprise most of the patient body.
Children's Hospital Group CEO Eilish Hardiman told Newstalk's Breakfast refuted those claims, insisting the facilities available at St James's make it the ideal site:
The blueprint approved includes 384 in-patient beds, 14 operating theatres and 62 critical care beds.
The Health Minister James Reilly says the hospital can proceed to the planning phase once a design team is appointed.
Ms. Hardiman laid out a new timeline for the project, "There will be 7 months of planning to get it into An Bord Pleanála, which will happen in Spring of next year. It's expected to be a 6-month process, which means it comes out in Summer of 2015, and construction starts. We are still aiming to have the transfer of the services end of 2018."