A security office built at the Department of Finance in Dublin cost more than €1.4 m (£1.2m).
Chairman of the Office of Public Works (OPW) John Conlon revealed the figure at the Oireachtas Finance Committee on Wednesday.
He emphasised that the pavilion's construction followed an "extensive" security review by An Garda Síochána (Irish police).
However Tánaiste (Deputy Irish PM) Micheál Martin described the spend as "ridiculous".
Martin said he was "shocked" when he first heard the cost of the project and said a "fundamental review" was needed.
'Significant costs'
Green Party TD Steven Matthews said that while the the shelter is "very attractive", it was "quite a significant, high cost project".
Speaking on Wednesday, Mr Conlon confirmed that the OPW constructed and finalised the project, which had a total cost of €1.429 million (£1.193 million).
"While it looks like, and is, a fairly significant cost, there are very significant mechanical, electrical and security system costs in that," he said.
"There was also a significant cost to provide a temporary structure while that building was taking place."
Mr Conlon added that there were also significant costs for underground works, ventilation, data, comunications, CCTV, a control centre, sub-structure works and re-routing of underground services.
"There is a huge security element to this project," he said.
Value for money
Speaking about the security shelter from New York, Taoiseach (Irish PM) Simon Harris stressed the importance of value for money.
"Of course, projects need to be carried out for security reasons from time to time," he said.
"Security is extraordinarily important, but also making sure that happens within in the context of value for money is an absolute imperative."
A report was also published on Wednesday morning on a controversial €336,000 (£283,149) covered bike shelter built in the grounds of the Irish parliament last year.
The report was written by Mr Conlon, who said that while the project's costs "can be explained", the overall cost "is completely not acceptable in the wider context of value for money and value for the taxpayer".
“It is an extraordinary cost for the provision of a covered bicycle parking facility and one which the OPW has to seriously reflect on," he added.
According to the report, the OPW told authorities in Leinster House three years ago that installing uncovered bicycle parking outside the Member's Restaurant would have been a cost-effective option.
This was not deemed acceptable following security advice, although the OPW felt that any operational changes needed in relation to security "were not insurmountable".
Mr Conlon said he has revised project approval thresholds downwards and will ensure members of the OPW Management Board will approve all works above €200,000 (£167,000).
He has also engaged an external auditor to advise how to ensure value for money for projects below €500,000 (£418,000).
