The opening of Te Rangi Hiroa College on Castle St, which houses 127 students, and the expansion of other colleges had more than offset a ''minuscule'' increase in student numbers at the University of Otago, Ms Nidd said.
This comes after it was announced numbers at Otago rose by 0.1% on last year, or a total of 13 students,, following three years of decline.
Although landlords would be happy student numbers were no longer falling, such a small change had little effect.
''We've only got a minuscule increase in student numbers, so until we get a [large] rise in student numbers there is always going to be some left over [flats].''
She did not believe the number of empty flats had changed significantly compared with last year.
The extra spaces at residential halls had possibly resulted in a small increase, she said.
''It's bound to have an effect, because every person that's going into a hall of residence or a university property, is somebody who is not going to a privately owned property.''
Otago Property Investors Association president Wendy Bowman agreed the new residential college places had made it tougher.
It would become even tighter for landlords if new student hostels - such as the proposed joint Ngai Tahu and Otago Polytechnic investment - were built, she said.