And while Belfast city centre chiefs said they were “happy” with the public’s response, some businesses said they had hoped for a larger turnout in customers.
Economist John Simpson said Northern Ireland loses around £2m a day in tourist spending when the shops are shut.
Shops opened at noon and closed at 4.30pm during Orangefest yesterday.
Mr Irvine said he was “happy” with the turnout and the number of retailers that opened.
“There are substantially more shops open than we had last year,” he said.
“We were probably operating on 50% of retailers open last year. I think we are operating on 80% today, so the retailers are certainly coming on board with it.
“I was doing a walk-around survey and the restaurants appear to be doing very well and were reasonably full.
Mr Irvine added: “I have to say I’m happy. There are a fair few people about, it is not busy, busy, but this is a three to five-year process, that’s the issue. We are only in year two.
“If you were to ask me at the start would we be 80% of shops open by year two, I probably wouldn’t have guessed us doing so well.
“If you take it over three to five years, I am happy with this.”
Among the retailers who opened was Dennis Troughan, owner of Belfast Coffee Company Ltd, on Royal Avenue.
He said it was “worthwhile” opening, but had hoped for a higher footfall of customers.
“I thought it would have been busier, but I suppose the catch is while they are watching the parade, they are not buying,” he said.
Mr Troughan added: “But there was a big number of people very positive about saying it was great to see the shop or business open.”
And among those who travelled into the city centre was Carmel Maguire (52), from north Belfast, with her daughter Ashley (26).
“Many of the smaller businesses weren’t open but I went into Victoria Square for a look. It was good to see the main shops open.
“I suppose there isn’t that many people about, but the atmosphere is good and it makes it easier to shop.”
Tourism Minister Arlene Foster said she wants every shop in Belfast city centre to be open on the Twelfth next year.
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