Owners of old apartments in the capital city of Hanoi have found themselves sitting on increasingly valuable pieces of real estate.

Le Hoang Nam, the owner of a unit in a Giang Vo apartment block, wanted to sell his third-floor apartment to buy a new one but decided against it when he found out that the apartment block would soon be upgraded.

“Last year, I intended to sell my apartment for 850 million VND (47,000 USD) but someone offered to buy it for 2 billion VND (112,000 USD),” Nam said.

Nam is one among thousands of old apartment owners who suddenly became dong billionaires when the city of Hanoi announced plans to renovate and rebuild all of them through the year 2015.

The city’s decision has warmed up the local real estate market, turning old apartments into goldmines. Investors are trying to snap them up because they believe they can earn big returns once the buildings are renovated.

Demand for older apartments has risen by about 40 percent, according to a report from the Hanoi Golden Land Joint Stock Co.

“The demand is increasing day-by-day, even with prices up 25 percent,” said Hanoi Golden Land director Doan Xuan Hai, “ Infrastructure of these old buildings is stable, and they often come near schools, markets and hospitals.”

Tran Trong Hieu, investment director of the International Investment and Urban Development Joint Stock Co, dismissed the idea that infrastructure was a factor in the rising value of these units.

“When they renovate the old buildings, they can’t improve all of the surrounding infrastructure systems,” said Hieu. “These systems were built a long time ago. They can meet the demands of small buildings, but if the buildings are expanded the infrastructure systems may break down.”/.