"Obviously, it's designed as a fundraiser ... because Lifewise needs to raise all of its money it needs to work in the homeless area itself ... as there is very limited government funding for this work.
"But we also have people who have worked on the frontline of homelessness and have been homeless that we have housed.
"They have volunteered to come back ... and share their experiences with participants of the Big Sleepout."
Mr McCarthy said they were hoping to raise more than last year's Big Sleepout, which collected $110,00 in donations.
"When I last checked we were up around the $105,000 mark."
Deputy Mayor Penny Hulse was one of the participants.
She said last night the entire experience was going to be an "eye-opener".
"I mean usually I finish work and go home to a warm house, have a glass of wine and unwind from the day. I get to have a nice meal and hop into a warm bed."
Mrs Hulse said she had worked with many community projects over the years, and was looking forward to "putting her money where her mouth is".
"Though I know it doesn't at all compare to living on the streets, I think it's an experience which will really bring the problem home."
AUT Vice-Chancellor Derek McCormack said he had been paying close attention to the weather forecast - which was predicting the temperature to drop to 10C. Strong southwest winds and showers throughout the night were also expected.
