Bruno Travalja, 52, was kneeling to take a measurement on the 42nd floor of the Manhattan building when he stood up and felt "dizzy", say police reports.
His body was found between 52nd and 53rd streets in midtown on Thursday afternoon, according to local media.
Officials are investigating whether faulty equipment or any violated safety protocols were factors in the death.
It is thought the New Jersey architect fell from the former Flatotel, which construction crews are converting into condominiums and offices.
The NYPD and the city's Department of Buildings are investigating the incident.
Mr Travalja was the owner of Crown Architectural Systems, according to his Facebook page.
Cetra/Ruddy, the architectural firm of record on the project, did not immediately respond to a request for comment.

That is the view of the organisation representing micro breweries which says the thirst for craft beer in pubs and beyond shows no signs of drying up.
It comes as the number of traditional pubs have declined, with a pub closing every couple of days in Wales.
But the number of breweries has doubled in the past five years to 88.
"It's growing really rapidly," said Buster Grant, chairman of Drinks Wales, which represents independent brewers as well as cider and wine producers.
Welsh brewers are set to showcase their beers at two key events.
There is Cardiff Brew Fest this weekend and a three-day festival in London next month will feature 100 Welsh beers and ciders.
Mr Grant, managing director of Brecon Brewery, said: "There's a growth of craft beer in places like Cardiff where people like stronger, hoppier beers and more extreme flavours but also there's still growth in more traditional ales.
"In an age of austerity, people are not going out quite as much but when they do they're seeking out something different; they're a little bit more picky about where they go and are prepared to pay a little bit more."
He said Welsh brewers are taking their beers across the UK and looking abroad. At home, 20 small Welsh breweries now have their own pubs.
Four micro breweries -  Bragdy Nant, Bragdy Conwy, Purple Moose and Great Orme - got together to reopen one pub in Conwy three years ago and recently bought two more.
Bragdy Conwy employs nine people and has enjoyed 20% year-on-year growth, supplying supermarkets, bars, restaurants and pubs.
Owner and head brewer Gwynne Thomas said it was difficult to predict the industry's future.
"About 2008, during the financial crisis, I thought we'd reached saturation point but the last few years growth has accelerated.
"It's a relatively straightforward but there are people who are good at the technical side of brewing but haven't got the organisational side right. You have to be strong at both."
Q&A: Real ale? Craft beer? Confused?
The Campaign for Real Ale (Camra) included 14 new Welsh breweries in its annual beer guide last year.
This is set against a background of a pub closures, which is running at a net loss of about 10 a month in Wales.
Spokesman Neil Walker said the boom in people setting up their own micro breweries or finding work in the industry "can only be good news for the future of beer and pubs" .
An architect has fallen to his death from a New York City skyscraper after losing his footing while at work.
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If the number of independent brewers in Wales continues to rise, it could hit the 100 mark within the next year.