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Boasting a cooling capacity nearing 30,000 refrigeration-tons, ENGIE South East Asia's (ENGIE) District Cooling System (DCS) at Punggol Digital District (PDD) represents an advancement in cooling infrastructure. The DCS will streamline operations and enhance energy efficiency within the smart and sustainable district.
Designed, built and operated by ENGIE, the DCS functions on a straightforward yet sophisticated principle: An underground central plant distributes chilled water via an intricate network of pipes, transfer stations, and secondary networks within the district’s buildings. The performance of this closed-loop circulation of chilled water is enhanced through energy storage systems, further balancing the production and consumption of energy. The entire cooling process is monitored from a centralised control room, ensuring optimal operational efficiency and performance
Pipes galore: The DCS plant at Punggol Digital District.
For a mixed-use development like PDD, the DCS is a sustainable solution that offers several benefits. "We save on energy, we save on equipment, and we save on space,” explains Gavin Shen, the Chief Operating Officer at ENGIE.
Firstly, the DCS eliminates the need for individual buildings to maintain their own cooling facilities. In doing so, the system can reduce carbon emissions by an estimated 3,700 tons per year and achieve up to 30% reduction in energy consumption compared to standard commercial buildings.
Furthermore, individual building owners and businesses get to enjoy mutualised or reduced cost savings, whether in the form of plant room or electricity grid expenses. And by going underground, the DCS also frees up roof-top space conventionally occupied by cooling systems, thus facilitating the creation of green pockets and allowing for more renewable energy initiatives, such as the installation of roof-top solar panels within the 50-hectare district.
Designed for a greener tomorrow
Besides utilising best-in-class equipment for better efficiency, the DCS’s multifaceted approach to savings is achieved through what Shen describes as “thoughtful system design.” “It was important that we got the design of the DCS right. It’s not just about getting the chilled water from point A to B. It’s about bringing it from point A to B with the least amount of energy,” he adds.
Thanks to the expertise of its engineers, ENGIE was able to plan and route the pipes to ensure optimised water flow. The pipes were positioned in a unique 45-degree slant, as opposed to the usual 90-degree horizontal or vertical configurations. This helped to reduce the fractional loss of the pumping system, thereby eliminating the need for additional pumps to boost the pressure for delivering the chilled water.
“With the PDD DCS, secondary pumps are not required, unlike other typical DCS,” Shen notes. “When you reduce the pumping requirements, it results in a reduction of the number of equipment as well. All these allowed us to lower the system’s energy consumption.”
The PDD DCS also offered opportunities for ENGIE to explore methods for greater efficiency — including its build. “Traditionally, the pipes are welded together. Instead of this conventional method, we used a mechanical coupling system that operated like brackets to connect the pipes,” explains Dr Lu Lu, its Project Director. “This approach eliminated a significant amount of welding work, as well as the associated fire risks and toxic gas emissions. We succeeded in improving our project schedule, with installation time reduced by almost 80%.”
An overview of Punggol Digital District's DCS. Infographic: courtesy of ENGIE.
Cooling a district the smart way
The DCS contributes to PDD’s vision of not just being a sustainable mixed-use district, but a smart one. It will interface with and exchange real-time status monitoring and control functionality with JTC’s Open Digital Platform (ODP) where monitoring and machine learning of building usage patterns can be carried out.
Developed by JTC and GovTech, the ODP is an open standard multi-protocol middleware designed to address the issue of integrating proprietary systems and applications into a unified platform. It functions as a plug-and-play digital infrastructure for new services, creating possibilities for collaboration with smart business operators.
“We are primed for the ‘living lab’ concept. The DCS is not just a static system. In some ways, it’s alive. It ‘breathes’. We need to know a lot more insights beyond what we have, and there’s synergy with the ODP in this regard,” Shen says.
To mitigate any potential issues early, ENGIE is also introducing its integrated Smart Operation and Maintenance (O&M) tool aimed at improving the monitoring and maintenance of assets. "We've taken a more proactive approach, shifting from static maintenance to what we call performance-based maintenance. We constantly monitor the equipment's condition, and when its performance deviates, we trigger the maintenance,” he says.
A collective effort in district cooling
The team encountered a unique challenge with the PDD DCS – how to effectively cool a vast business park comprising office towers, a university, a shopping mall, and community spaces. This necessitated close collaboration with various stakeholders to seamlessly integrate the DCS with each building in the district. Dr Lu adds: “Besides the building’s function, we had to consider the specific building services, such as fire and plumbing systems. With these limitations in mind, we had to customise the DCS design to suit all the buildings.”
ENGIE also took demand into account when designing the DCS, and the system is primed for future expansion, ensuring the system's efficiency and sustainability as its capacity increases. "As PDD opens progressively, the buildings become operational at different times. We plan not only for the current capacity, but also for the different phases. In the DCS's plant room, provisions are in place for us to add capacity. The varied load profiles will enhance our operational insights for developing more efficient chiller capabilities," Dr Lu explains.
To further drive innovation in cooling solutions, ENGIE and the Singapore Institute of Technology (SIT) have signed a Memorandum of Understanding to develop a district cooling centre of excellence. The collaboration focuses on joint applied research, knowledge exchange projects, and work attachment opportunities. With the university situated within PDD, the DCS will serve as a real-world learning environment for students, fostering skill development in data-driven optimisation, DCS decarbonisation, and predictive maintenance.
A glimpse into the future of sustainable urban infrastructure
The PDD DCS stands as a testament to ENGIE’s commitment to supporting the cooling needs of Singapore’s next-generation business parks, as well as JTC’s sustainable development goals. With its approach to efficiency, integration with digital platforms, and smart operation and maintenance, the DCS opens the door to possibilities in future advancements.
Watch: Learn all about Punggol Digital District's sustainable features: