Developers are stuck in a time warp of single-use projects and the corny architecture of yesteryear. And most of them refuse to budge.

They say it's too risky to change, despite local successes and a groundbreaking UK study that shows mixed-use developments give "significantly" better returns.

Developers such as Summercon have made billions covering vast tracts of our cities with unspectacular cluster units and flats, to the apparent pleasure of their buyers but to the despair of city planners and urbanists.

Now Summercon has bought the property in Fourways that belonged to Mary Slack, sister of De Beers chairman Nicky Oppenheimer, as well as two adjoining sites. The site assembly totals 30 ha and is in the heart of one of SA's fastest-growing urban areas.

The combination of sites is ideal for a landmark mixed-use development, which has been government's main urban policy for eight years and is a concept embraced throughout the world. Planners see it as vital for healthy cities.

Summercon executive Peter Blanckenberg says a mixed-use development is precisely what the controversial company is going to create on the site. Summercon is creating a "precinct", he says, "a bit like Melrose Arch".

But Summercon has instructed its architects, Gapp, to divide the property into three separate precincts of car showrooms and shops, offices and its usual residential units behind high walls. There will be no street parking.

Real mixed use generally includes flats, lofts and studios above offices; interconnected shops and restaurants; a boutique hotel or two; and street parking and street life. But this is out of the question, says Blanckenberg.

"It's a great idea and we explored it," he says. "But it's unproven and too risky. We don't know who will buy an office building with residential units above it, so we're sticking to what we know." People want security and you can't provide it properly when you mix, he argues.

Summercon is not the only diehard. Most developers avoid building the kind of mixed-use "compact cities" envisaged by the Development Facilitation Act and Gauteng's spatial development framework. Against growing evidence of success around the world, SA commercial developers refuse to add residential components and residential developers avoid commercial components. Yet planners say the mix is essential to ensure effective public transport, sustainable municipal services and a healthy social life.

Officials approved Johannesburg's Illovo Boulevard complex in the late 1990s on condition that a residential component be included. But only offices were built.

One office developer in Illovo Boulevard initially refused to allow a residential development to spring up next door on the grounds that the residents - in homes costing R1m-plus - would hang their washing on their balconies and upset his tenants. But now developers are rushing to build residential units there because of market demand.

Montagu Property Group marketing director Kent Gush, a seller of new residential developments, backs Blanckenberg. "If we were asked to market a project on Summercon's site that combined coffee shops and restaurants with lofts, studios and apartments, we would tell the developer to drop it in favour of the classical residential scheme. It's simple: we know it will sell."

Blanckenberg and Gush are wrong, argues mixed-use developer Mvelaphanda Properties. Research by British property services company FPDSavills also shows that mixed-use developments have given investors better returns than single-use developments over three, five and 10 years in Britain.

More important, mixed-use developments dominated by residential components perform even better than ones with a balance between the two. And those whose offices have more than one use do best of all.

FPDSavills concedes that initial rentals in mixed developments may have been lower than in single-use developments because of the perceived risk. But subsequent increases in rental indicate strong demand.

"Summercon's site is ideal for a mixed-use development," says Mvelaprop executive director Geoff Chait. "It would sell at a premium of at least 20% over what they plan."

Buyers flocked to Cape-based Mvelaprop's Victoria Junction, which was built in a derelict area near Cape Town's Waterfront eight years ago, and, more recently, to Tyger Falls in the northern suburbs. Most of Victoria Junction's first 110 units sold off-plan within a week in 1995. Tyger Falls, which consists of 27 office, retail, leisure and residential buildings around a lake, sold in eight months to developers, most of whom resold not long afterwards, says Chait.

"Buyers love mixed use because it remains alive 24 hours a day," says Chait. "This gives it a self-nurturing security that is safer than the best technology and the highest walls."

The Summercon development could be spectacular, particularly if it were linked more closely with Fourways Crossing next door. But Summercon rejects criticism of its intentions.

"We have pioneered urban densification and will continue to do so," says Blanckenberg.

He adds that Summercon developments do support the concept of the compact city. These are as socially productive as mixed-use developments.

"We at Summercon agree that integrated development has its place in SA - Cape Town's V&A Waterfront springs to mind - and that the concept will spread," says Blanckenberg. "The major factor hindering it is still crime."

Blanckenberg says Chait's claim that mixed use is more secure than single use is "at present, unfortunately, wishful thinking".

Melrose Arch's architects, Osmond Lange, back Chait. "A mixed-use environment, open 24 hours a day, seven days a week, offers enhanced security," says partner John Dovey. "The eyes of owners, tenants and investors who own' the environment, plus a response team, are often more effective at reducing crime. How effective are security guards sitting at the gates of residential enclaves anyway?"

Dovey points out that South Africans love to visit and walk about the safe mixed-use cities of the world. "Who wants to walk around a walled residential suburb?"

So why do developers stick as doggedly to what they know as Summercon does?

"Because it's easier and quicker," says Dovey. "Single-use separatist developments are easy to plan, finance and sell. True mixed-use developments involve a great deal of effort. But it's worth it. The end product is socially more enriching, more robust and sustainable." Profitable, too, adds Chait.

Unfortunately, FPDSavills' research indicates that most developers will not be persuaded. "Any breakthrough is unlikely to be led by investor demand and more likely to occur through policy pressures and planning."

Financial Mail