Who does what
Four parties shape a district cooling connection. The developer or owner signs the connection or supply agreement and declares contracted capacity. The MEP consultant designs the ETS room and secondary system and submits drawings to the provider. The district cooling provider designs or approves the primary side, supplies or specifies heat exchangers, control valves and energy meters, and witnesses tests.
The MEP contractor installs the secondary pumps, piping, valves, controls and terminal units, coordinates the ETS room with civil works, and leads testing and commissioning on the building side. The main contractor provides the room, sleeves, trenches and lifting access on time. Most delays come from unclear boundaries between these parties.
Step 1: Capacity, agreement and design submission
The process typically starts with a load estimate and an application to the provider, followed by a connection agreement that fixes contracted capacity, supply and return temperatures, and penalty or incentive terms for return temperature. The consultant then submits ETS layout, schematics, secondary pump selection and control philosophy for provider approval.
Common reasons for provider comments include undersized ETS rooms, missing maintenance clearances around heat exchangers, no drain or ventilation in the room, three-way valves or bypasses on the secondary side, and control sequences that do not protect return temperature.
- Approved load calculation and diversity assumptions
- ETS room layout with clearances, drainage, ventilation and lifting route
- Secondary chilled-water schematic showing two-way valves only
- Pump selections with VFDs and control philosophy
- BMS interface points and metering arrangement
Step 2: The ETS room and heat exchangers
The ETS normally sits in the basement or ground floor close to where the primary pipes enter the plot. Plate heat exchangers are sized by the provider or to its specification, with an approach temperature that allows the building to receive secondary water close to the primary supply temperature. Space must allow plates to be opened and cleaned in place.
On the primary side the provider usually installs isolation valves, strainers, the energy meter and a control valve that throttles primary flow to maintain secondary supply temperature. The MEP contractor's scope generally starts at the secondary flanges. Sleeves through the basement wall must be waterproofed properly, because groundwater ingress around primary pipes is a recurring snag.
Step 3: The building's chilled-water network
Downstream of the ETS, the secondary system is a normal variable-flow chilled-water network: duty and standby pumps with VFDs, risers, branch piping, AHUs and FCUs with two-way control valves, and balancing or pressure-independent valves. Pipe insulation with continuous vapour barrier is essential in UAE ceiling voids to stop condensation.
Flushing and cleaning before connection is critical. Debris, welding slag and dirty water reaching the heat exchangers foul the plates and reduce capacity from day one. Providers often require evidence of flushing, chemical cleaning and water quality results before they open primary valves.
Step 4: Delta-T discipline
District cooling plants are designed around a specific temperature difference between supply and return. If buildings return water too cold, the plant must pump more water to deliver the same energy, and the building cannot draw its contracted capacity. This is called low delta-T syndrome, and many connection agreements include penalties for it.
The causes are well known: three-way valves and bypasses, oversized or poorly selected coils, dirty coils and filters, control valves hunting or stuck open, and wrong setpoints. Fixing them is far cheaper during design and shop drawings than after occupancy.
- Use two-way valves on all coils; avoid permanent bypasses
- Select coils for the design delta-T, not only for capacity
- Consider pressure-independent control valves on larger coils
- Trend secondary supply and return temperatures on the BMS
Step 5: Metering and billing
The provider's energy meter at the ETS measures flow and temperature difference to calculate the energy delivered to the building, which is the basis for consumption charges. Inside the building, landlords commonly install sub-meters (often called BTU meters) per apartment or tenant to recover costs.
Sub-meters need correct straight pipe runs, accessible locations, matched temperature sensors and a data connection to the billing system. Poorly installed sub-meters lead to disputes between owners, facility managers and tenants for years, so they deserve the same care as the main meter.
Step 6: Testing, commissioning and energising
Before chilled water is introduced, the secondary system is pressure tested, flushed, cleaned and filled with treated water. Pumps, VFDs and controls are tested, then the provider witnesses the ETS checks and opens the primary valves. The system is then balanced, and performance is demonstrated across load conditions, including return temperature.
Handover typically includes test certificates, flushing and water quality reports, balancing reports, as-built drawings, O&M manuals and the provider's acceptance. Duration depends mainly on provider scheduling, the readiness of the primary network to the plot, and how clean the secondary system is on the first attempt.
How Manolia delivers district cooling connections
Manolia Group has delivered district-cooled HVAC including six G+2 buildings at a Dubai Investments Park driving centre with an underground chilled-water network, and a complex of factories and headquarters served from one cooling station. Our 8-stage delivery process puts provider submissions, ETS coordination and flushing plans at the start, not at the end. Contact +971 54 569 3856 or info@manolia.co.
Frequently asked questions
What is an ETS in district cooling?
An energy transfer station is the plant room where the district cooling provider's primary chilled water passes through plate heat exchangers to cool the building's own secondary chilled water. It contains the heat exchangers, control valves, energy meter, secondary pumps and controls. It keeps the two water systems separate, so problems in one building do not contaminate the network.
Why does the provider care about return temperature?
A district cooling plant delivers energy as flow multiplied by temperature difference. If a building returns water too cold, the plant must move more water for the same cooling, which wastes pumping energy and limits plant capacity. Agreements therefore set a minimum return temperature and may apply penalties when buildings fail to meet it.
Can an existing building switch from chillers to district cooling?
Often yes, if a network is available near the plot and the provider has capacity. The work typically involves building an ETS, adapting the secondary pumps and controls, replacing three-way valves, and decommissioning the old chillers. It must be phased so the building keeps cooling during the changeover, sometimes with temporary chillers.
What delays district cooling connections most often?
The usual causes are late provider approval of drawings, an ETS room that is too small or lacks drainage and access, primary pipes not yet reaching the plot boundary, and a secondary system that fails flushing or water quality checks. Early coordination between consultant, contractor and provider avoids most of these.