The new national children's hospital has been ordered to install an extensive sprinkler system.
The hospital had appealed against the condition imposed by Dublin City Council - but An Bord Pleanála has ruled that sprinklers must be fitted throughout the building.
The planning board said that "given the nature, height, scale, form and layout" of the hospital, it believes that a full sprinkler system would "limit the size of the fire; control fire spread; provide additional time to escape; limit fire damage; and be beneficial in terms of operational continuity."
An Bord Pleanála also imposed a new condition that if Christmas trees are to be installed in the atrium they must be artificial, fire retardant and a maximum height of 2.5 metres.
It removed two other conditions that the hospital had appealed against - but said if there were any design changes to the atrium a new fire safety certificate would be required.
The National Paediatric Hospital Development Board, which is overseeing the building of the new hospital, said in a statement: "The fire safety design measures that had been proposed by the NPHDB were both compliant with, and indeed exceeded, current fire safety regulations and healthcare design standards.
"However, [An Bord Pleanála] has ruled that additional measures - above and beyond what is set out in regulations and standards - would be beneficial, and the NPHDB will comply with its ruling."
It had also suggested that its proposed sprinkler system would "exceed the number that is set out within the fire safety regulation legislation".
It was revealed yesterday that the new hospital in the grounds of St James's Hospital campus will be named Phoenix Children’s Hospital Ireland.
The hospital is due to begin operating in 2022.
Additional reporting by Nicole Gernon