Residents in Tengah are the first to trial the centralised cooling system in Singapore. Managed by SP Group, the system is a key feature of Tengah’s branding as a smart and eco-friendly town.

Tengah is the first HDB town to be planned with smart technologies in mind from the outset. For instance, residents’ homes will have additional power and data points to enable easier adoption of smart home devices.

Four out of eight BTO projects have been completed in the Plantation district. The first batch of residents collected the keys to their homes at the end of August 2023.

The other four Tengah districts – Garden, Park, Brickland and Forest Hill – are in the works.

The keys to 5,712 units, or about 82.8 per cent of the 6,900 booked units in the Plantation district and two projects in the Garden district, were collected by the end of July, HDB said.

As at July, about 8,000 households have opted for the cooling system.

While the technology behind the centralised cooling system is not new, it is typically used in commercial buildings. This is the first time it is used in public housing in Singapore. Here’s how it works.

This means that when one chiller plant is offline for maintenance, for instance, others in the cluster will take up the cooling load for residents, ensuring redundancy and efficiency.

SP Group said this cooling alternative offers up to 30 per cent savings in “life-cycle costs” – including those for maintenance – compared with conventional systems. Life-cycle cost savings are calculated based on a 20-year period.

Air-conditioning makes up nearly a quarter of electricity consumption for an average household in Singapore, according to data from the National Environment Agency. The authorities and experts say this is why alternative cooling solutions are key to creating sustainable towns in Singapore.

Air-conditioning alone accounts for about 24 per cent of an average household’s electricity consumption, more than the use of any other appliance.

Mr Kavickumar Muruganathan, who lectures part-time on energy, the environment and economics at the National University of Singapore, said conventional split-unit air-conditioners tend to be more energy-intensive and rely on refrigerants that contribute to ozone depletion and global warming.

“In comparison, cooling with chilled water through centralised systems tends to be more energy-efficient, which could result in lower utility bills,” he said.

But the roll-out of the new cooling system caused hiccups for some residents.

They include Mr Casper Tan, 32, who discovered water leaking from the cooling system’s trunking in his four-room flat in Plantation Grange in October 2023. The leak damaged some parts of a wall and a door frame.

“When I pressed on the door frame, water would spurt out,” said the group communications executive.

Others, such as Mr Muhammad Aqeel Kaskhy, faced issues with condensation.

The 33-year-old marine service coordinator, also a resident of Plantation Grange, noticed water droplets forming around the cooling system’s trunking in February. It was resolved after SP Group added extra layers of insulation around the pipes.

“I’m still facing condensation issues right outside my door, which drips water onto my shoes. I’m still waiting for this to be fixed,” said Mr Aqeel.

SP Group’s project director for Tengah, Mr S. Harsha, said residents like Mr Tan experienced leaks because of a particular workmanship issue: Workers over-tightened the T-joint, which is made of brass, that connects the water pipe from the living room to the bedrooms.

“The brass T-joint needed a little bit of space to account for expansion and contraction. You have chilled water running in when the air-con is switched on, and after you switch it off, the water in the system starts to warm up,” he said.

When over-tightened, the brass T-joint would be put through multiple cycles of expansion and contraction, which led to hairline cracks. If this is not rectified, the crack will become larger, leading to leaks.

T-joints are installed only in four-room and larger flats.

Mr Harsha said that since December 2023, flats have been fitted with T-joints made of a stronger and sturdier material – galvanised iron – that will not have the same issue when over-tightened.

As for the earlier batches of flats, more than 1,000 units were fitted with brass T-joints, and 6 per cent of these had sustained hairline cracks.

We want to make sure that this leakage problem is behind us and it’s completely arrested. We want to put this problem behind us and move forward.

Mr Harsha said the firm is working towards replacing every household’s brass T-joints and is contacting residents.

At present, almost 90 per cent of the more than 1,000 units have had their brass T-joints replaced with ones made of galvanised iron.

The system works by channelling chilled water to a flat through a supply pipe, allowing the fan coil units to pump out cold air. This process heats up the water, which is then ported back to the centralised chiller on the rooftop via a return pipe.

Mr Harsha said the condensation issues sometimes also occurred because residents “stress-tested” the system when their flats were empty.

Without a heat load in the house – from people living there or running electrical appliances – the chilled water in the pipes remained cold, leading to condensation issues on the return pipes.

The insulation on the return pipes was also thinner than that of the supply pipes. The return pipes have since been fitted with thicker insulation.

SP Group declined to reveal specific figures on water temperatures and insulation thickness, citing commercial sensitivities.

But it added: “Since the implementation of the additional insulation, and Daikin’s enhanced workmanship, we have noticed a significant drop in the reported number of condensation cases.”

Less than 2 per cent of the households with thicker pipe insulation and better workmanship reported issues. Most of these were minor condensation cases, SP Group said.

Mr Harsha said SP Group and Daikin would generally require about four months to install the system in a BTO project. But they were given less than half that time to do so for the initial batches of flats in 2023.

As a result, there might have been gaps in the insulation during installation that workers failed to spot, leading to condensation issues, he said.

Although Daikin had doubled the number of installers and stepped up efforts to train them, “the compressed timeline did take its toll; it was a snowball effect”, he added.

HDB had said previously the compressed timeline was because it prioritised handing over keys to home owners by the committed completion date, so they could move in as soon as possible.

The delays due to Covid-19 have eased, and Daikin has also doubled the number of people in its quality control team to conduct extra checks on the system, Mr Harsha noted.

On average, about 170 Daikin workers in Tengah are carrying out installation, maintenance and rectification works daily.

The condensation and leakage issues are unlikely to happen in projects that are completed from 2024, said Mr Harsha.

SP Group said in February that it had more than 9,000 subscribers to the cooling system, or seven out of every 10 Tengah flat owners. The number dropped to about 8,000 subscribers at the end of July.

In comparison, an archived webpage dated Nov 15, 2023, on the group’s myTengah website showed that there were 10,600 subscribers to the system.

Mr Harsha said the company has been reaching out to these residents. It has also been conducting monthly engagement sessions with residents since May to explain how the problems occurred and the steps taken to fix them.

Hong Kah North MP Amy Khor, whose constituency includes Tengah, said the number of complaints she received from residents has gone down significantly in recent months.

“Some of the issues that cropped up, especially for the first few precincts, could have been better addressed,” she added.

Vertical solar panels have been installed on the rooftops of two BTO projects in the Park district – Parc Clover @ Tengah and Parc Residences @ Tengah – the first time solar panels have been oriented in this fashion in an HDB development.

The vertical design allows the limited rooftop space to house water tanks and the centralised cooling system’s chillers, HDB said.

Solar energy will be used to fully power common services, such as lifts and lights in the block’s common areas, during the day.

The facade walls of a childcare centre in Parc Residences and a bin centre facade in Parc Clover have been fabricated using 3D concrete printing technology.

HDB said the curved forms and details of the printed architectural elements would not have been possible to achieve through the use of precast moulds.

If adopted on a larger scale, the technology also addresses potential labour shortages by reducing dependency on precast fabrication workers.

Across Tengah, 23,000 flats across 22 BTO projects have been launched so far, making up 75 per cent of the 30,000 public housing units planned for the town.

By the end of 2024, the first projects in the Park district are expected to be completed, and four pre-schools will open in the Plantation district, HDB said.

A community club will also be completed in 2024.

While the town is coming together, residents said they wish other concerns can also be addressed, including more transport options and better mobile coverage.

Marketing executive Tan Jing Rong, 31, said she avoids working from home as work calls may not get through due to the weak mobile phone signal.

“I am able to work from home a few days a week, but I can’t risk missing important work calls. Booking a Grab or private-hire car can also be tricky, as there may not be a signal in the carpark,” she added.

Dr Khor, who is also Senior Minister of State for Transport, and Sustainability and the Environment, said time is needed for amenities and facilities to be built up, especially as Tengah is a greenfield site, or a place that has not been previously built on.

She pointed to the recently opened neighbourhood town centre, Plantation Plaza, and the bus interchange, adding that residents can expect more shops to open as well as more bus services in the future.

“My grassroots and I have been doing regular house visits to provide as much support and assistance to residents as possible, and minimise any inconvenience for them,” she said.

That said, not all residents are complaining. Plantation Grange’s Mr Tan said he feels content living in Tengah even though he faced issues with his cooling system.

“I love taking walks as there’s a lot of greenery and it’s peaceful at night. Although there are other issues like bad cell reception and a lack of bus services at this point, these can be improved over time. I don’t regret choosing Tengah,” he said.