The classification of Housing Board towns into mature and non-mature estates based on the availability of land, instead of the age of existing flats, is a sound metric that is commonly used in urban planning, said analysts.
It also gives buyers a sense of the pricing and amenities expected, they added.
In a Build-To-Order (BTO) sales exercise that ended on Tuesday, Hougang and Jurong East - both with HDB flats close to 30 years old - were classified as non-mature estates.
ERA Realty head of research and consultancy Nicholas Mak said it is more useful to use availability of land as the metric from a policy and land planning perspective as the age of existing flats can be a "moving target".
"How do we judge the age of a town when some parts may be older and more built-up than another part? Do we use the average age of the blocks in the whole town?" he said.
"Hougang may be seen as an old town in terms of age, but in terms of land that can be redeveloped for future housing, it may not yet hit the threshold for a mature town," he said, citing the area around Defu industrial estate as an example.
"The classification is an additional tool to derive information when making policies, such as directing more young couples to certain towns to balance out an ageing population."
In 2017, the Ministry of National Development (MND) said the availability of land in each town is used in the mature and non-mature classification, without giving more details. "Non-mature towns refer to those where there is more land available for public housing development, whereas mature towns are usually those with limited land for public housing development," said MND.
During BTO and Sale of Balance Flats exercises, the estate classifications of the flats on offer are stated in the sales brochures, added MND.
Mature towns include Queenstown, Clementi, Ang Mo Kio and Pasir Ris, while non-mature towns include Yishun, Bukit Panjang, Sembawang and Sengkang.
Prices of BTO and resale flats are generally higher in mature estates than those in non-mature estates.
In the recently concluded BTO sales exercise, prices start from $382,000 for a three-room flat and $540,000 for a four-room flat in Queenstown. In comparison, prices start from $199,000 for a three-room flat and $324,000 for a four-room flat in one of the two BTO projects in Hougang.
National University of Singapore real estate adjunct associate professor Steven Choo said the mature and non-mature classification of HDB towns and estates has its place and should remain.
It is useful to help buyers form a mental map of various neighbourhoods, a sense of value and pricing expectations of a town, said Dr Choo, a veteran urban planner.
"If a town is listed as non-mature, there's a certain expectation on the flat pricing and the type of amenities in the area," he said.
"Of course, much will depend on the location - whether it's a five-minute walk or a feeder-bus ride to the nearest MRT station, shopping mall or school - but it helps buyers to form a topline impression."
He said the housing market here typically relies heavily on conventions phased out long ago, like the two-digit postal district codes which were replaced in 1979.
For instance, District 9 refers to the Orchard and River Valley area, while District 10 comprises Bukit Timah, Holland Road and Tanglin.
"We don't use those district codes in addresses anymore, but yet when you say District 9 or 10, you can immediately gauge the market standing of that area."
Agreeing, ERA's Mr Mak said: "It's better to have the classification than not have it because people need some kind of differentiation to make informed decisions.
"If we do away with the classification, it wouldn't be long before people start asking why this area is more expensive than the other one because there's no benchmark for comparison."
