Friday's announcement of an additional 600 affordable housing units to B.C.'s stock has people once again addressing the costs of homelessness in the province.

There are thousands of homeless living in B.C.'s Lower Mainland, caught in the cycle because of mental illness and addiction. But this existence is expensive.

"In the back of our minds we know that it costs us but until you actually do the math, you don't have a real understanding of what it costs," says Lesley Tannen of the Downtown Surrey Business Improvement Association.

For the first time, we're getting a look at how much homeless people actually costs various levels of government.

The association compiled data on one homeless person over a year. The organization would not reveal who that person is, but CTV News has learned that it is Sue, a woman who has spent the last 13 years living on the streets of Surrey.

"It was horrible, just horrible," she says. "Everything's been horrible."

Sue says every night she spent on the street she was afraid.

"I'd stay awake and walk and walk. Walk. Keep walking."

You might be shocked at what Sue -- one single homeless person -- can cost taxpayers.

In 2007, Sue spent 63 days in hospital and 196 days in shelter. Police were called to deal with her more than 340 times, mostly because of mental illness issues. She was also on probation, spent time in a pre-trial centre and received income assistance.

That brings the grand total for one year for Sue to a staggering $171,000. According to the province, the average costs of services for a person living on the streets is around $56,000.

"That's a huge cost to the community of doing nothing," says Tannen.

In six years, someone like Sue would cost the system more than a million dollars.

The Surrey Business Association believes by putting someone like Sue in stable housing with a support worker could drop the cost to $17,000 -- a 90 per cent decrease.

"From a business perspective, that's a no-brainer," says Peter Fedos, an advocate working for Highland House. "Doing something makes economic sense."

Fedos says social housing is always more cost effective than doing nothing.

"There are costs. Leaving them on the streets means you'll pay later and you'll pay heavily."

For now, Sue is now in supportive housing. She might not recognize the financial benefit, but she knows that it's a safe place.

With a report from CTV British Columbia's Michele Brunoro