Nearly a quarter of all condos in some parts of downtown Vancouver area are empty or occupied only part of the year by non-residents, according to data from the 2011 census data.

In Coal Harbour, about one in four condos are "non-resident occupied", said Andy Yan, a senior researcher with BTAworks, the research division of Bing Thom Architects.

Yan has been trying to quantify the impact of foreign investment on real estate in Vancouver for years. But the data doesn't allow him to separate units occupied by foreigners from those sitting empty.

"We live in a globalized capital market and we need to adapt to that new realty and ensure that those that want to live here, can grow here."

Yan was speaking at a SFU Woodward's talk about "foreign investment in Vancouver real estate" on Wednesday night.

Experts say the city benefits from the property taxes paid by condo owners, whether they live here or not.

"They pay lots of money in taxes and use very few city services," said Tsur Somerville, an associate professor at the UBC Centre for Urban Economics and Real Estate.

But there is a downside to having so many vacant units.

"From a city revenue standpoint these units are wonderful. On the other hand, most of us don't want to live in a ghost town," Somerville added.

The high vacancy rate means less business for neighbourhood shops and and restaurants in Coal Harbour. While some local businesses struggle to stay afloat, others say they do well, even without year-round residents.

"They spend more money when they're here than some people who live here all the time would spend in a year," said Douglas Lloyd Somerville of Lloyd Bruce Home Collections, a high-end furniture store.

Nonetheless, Yan said some Vancouver neighbourhoods may appear to be very dense, but actually are not.

"Hopefully, this will be part of a larger discussion about housing affordability and economic and physical development" in Vancouver, he said in a statement.