A short-sighted approach to planning would eventually materially harm Dunedin’s attraction as a destination, Southern Heritage Trust chairwoman Jo Galer warned.
"Allowing the irreplaceable loss of built heritage shows very little understanding of Dunedin’s intrinsic and now nationally famous heritage values," she said.
"The more heritage buildings we replace with ordinary builds, the less desirable Dunedin becomes."
Intensification of housing in New Zealand cities has followed more relaxed planning regulations, brought in to make housing more affordable.
Terramark resource management planner Darryl Sycamore said the more permissive provisions in Dunedin’s district plan flowed out of central government directives.
Mr Sycamore said inquiries about infill development were hot about a year ago, but the property market had since cooled.
Otago Property Investors’ Association president Kathryn Seque-Roche said some old houses were in poor condition and should be knocked down.
"It’s not feasible to save some. Others should be saved. It’s case by case," Mrs Seque-Roche said.
They sometimes also prevented land from being used efficiently, she said.
"Obviously, we don’t have enough housing stock," Mrs Seque-Roche said.
"We need more."
There needed to be a balance between heritage and healthy, modern homes, she said.
One recent planning decision was in George St, in a heritage precinct.
Permission has been granted for a "character-contributing" building there to be demolished and replaced by a development comprising nine apartments.
The developers had wanted to invest in the existing dwelling, but it turned out defects would have been expensive to remediate and the most viable option was demolition and redevelopment.
A development in Manor Pl is also attracting attention.
An eight-bedroom, two-storey dwelling is being retained, but units are being built north and south of it, adding up to 19 "habitable rooms" in all.
Dunedin City Council urban designer Peter Christos advised the positive contribution of the historical house would be diluted, but not lost.
He was satisfied the exterior cladding would be sympathetic with the surrounding environment.
Ms Galer said the heritage trust was bitterly disappointed about both the George St and Manor Pl heritage losses.
The loss of the house in George St, in the block between St David St and Union St West, would diminish the amenity value of what remained, she said.
Ms Galer said the "once-grand" Manor Pl property was being suffocated.
Its stunning frontage was now blocked by a dominating new build, she said.
The trust had been contacted by street residents wondering how the development had been permitted, she said.
"These grand old houses have historic architectural and social values that communities treasure, and they cannot simply be replaced with an archway or bay window tacked on to a new build, as if this will be acceptable," Ms Galer said.
"This harms our reputation as a heritage city, because slowly and insidiously, the real McCoy is being removed without thought for the future and our economic wellbeing.
"Once a critical mass of these character-contributing buildings is lost, Dunedin’s key point of difference will be gone and lamented.
"As a city that wants to prosper and highlight our assets, we must stand up against this."
