By Konrad Putzier

A number of big U.S. tech companies are moonlighting as part-time real-estate developers. China's Tencent Holdings Ltd. is trying its hand at urban planning.

In Shenzhen, the company wants to build a real-estate development on land the size of an area of Manhattan called Midtown West. The 21-million-square-foot development that will include corporate offices, a school, apartments, sports facilities, parks and retail space, according to the project's architect, NBBJ.

Construction is set to begin later this year. The project will be completed in three phases, with apartments, offices and a transit hub opening first, NBBJ said.

The project, dubbed Net City, is the latest ambitious real-estate project to be launched by tech companies. An affiliate of Google parent Alphabet Inc. planned to build a new neighborhood in Toronto before backing out last month amid the coronavirus pandemic. Meanwhile, Facebook has plans to build 20,000 housing units in California.

Tencent's project "tracks a broader trend of technology companies getting involved in the real-estate business," said Sarah Moser, an associate professor of geography at McGill University. In the past, plans for utopian cities were often conceived by authoritarian governments, she said, but they are increasingly taking shape in democratic countries, often with the involvement of the private sector.

Last year, Tencent tapped architecture firm NBBJ to come up with plans for the project, which will sit on 320 acres of government-owned land facing a bay. Jonathan Ward, a design partner at NBBJ, said the idea behind the project was to build a blueprint for a sustainable city of the future.

Net City will have few roads accessible by car to encourage residents to walk or use other modes of transportation. Some roads will be designed to make driving slower. Residents will also be able to reach the surrounding city via bike paths, ferries or the subway.

Its waterfront is being designed to withstand storm surges and rising sea levels, and properties are being conceived to maximize shade and minimize energy use. Building heights will be lower than in other developments, such as New York City's Hudson Yards, in part because lower buildings require less material and energy to build, Mr. Ward said. Rooftops will have solar cells and grass.

Many of the specifics remain unclear. While NBBJ is the master designer, Tencent has yet to tap architects to design the parcels within the project. NBBJ started design work earlier this year, and the goal is to complete the project in seven years, Mr. Ward said. NBBJ designed Tencent's current headquarters in Shenzhen, which opened in 2018. Tencent didn't respond to a request for an interview.

The coronavirus pandemic has led some to question whether dense cities will lose their appeal, but Mr. Ward said people would continue to be drawn to urban centers. "Seoul is twice as dense as New York City, and they had a tiny, tiny, tiny fraction of the deaths that New York City had," he said. "I think the city will be alive and well in the future."

For now, the economic crisis has thrown many big developments around the globe into turmoil. But Ms. Moser said the crisis could lead to a boom in master-planned cities, much like what happened after the 2008 financial crisis, as companies snap up cheap land and governments look for ways to boost their economies.

Building master-planned communities and even entire cities for millions of people is increasingly common in East Asia, said John Macomber, a senior lecturer of business administration at the Harvard Business School.

Land is often more easily available and permits often faster to get under the region's centralized governments compared with some Western countries, he said.

Meanwhile, rapid urbanization, and the congestion that comes with it, creates the need for new neighborhoods where people can work and live. "There's still half a billion people in the interior in China who would like to live in the cities where the wealth is created," he said.

Write to Konrad Putzier at konrad.putzier@wsj.com 



  Corrections & Amplifications


  This story was corrected July 31, 2020, to fix the misstated size of plans to build a real-estate development in Shenzhen, China. It is roughly the size of an area of Manhattan called Midtown West, not Midtown Manhattan.