Existing Capacity Is Only One Assumption
Cooling is one of the largest energy demands in UAE buildings. According to the Abu Dhabi Department of Energy, air-conditioning accounts for approximately 60–70% of building electricity consumption, while AC systems are often oversized by 25–35%
At cooling plant level, the DoE’s 2026 Cooling Load Manual notes that oversized chiller plants can have up to twice the required cooling capacity.
This makes installed capacity an important question when ageing chillers reach renewal — but it is not the only one.
The future plant needs to respond to the actual cooling demand and load profile of the asset. How that demand changes across operating hours and seasons matters. So do required temperature levels, redundancy and resilience requirements, and the way total capacity is distributed across individual chillers.
A plant designed around several chillers of different or equal capacities can behave very differently at part load from another configuration with the same total installed capacity.
The investment decision should therefore not start by asking how many tonnes of cooling capacity need to be replaced.
It should start by understanding how the asset actually requires cooling to be delivered.
Challenge the Design Assumptions Before Comparing Chillers
Existing calculations, energy audits, engineering studies and vendor proposals can provide valuable evidence. But the assumptions behind them should be understood before they become the basis for capital commitment.
For a major renewal, relevant questions can include:
What is the actual peak and part-load profile? · How much capacity is genuinely required? · How should capacity be distributed across multiple chillers? · What redundancy is necessary? · Which chilled-water temperature levels are appropriate? · How will different configurations perform across actual operating conditions?
These questions are interconnected.
Reducing nominal capacity may lower CAPEX, but capacity alone does not determine the investment optimum. Chiller configuration, sequencing and part-load efficiency can materially affect annual electricity consumption and OPEX.
Likewise, changing system temperatures or operating strategies can affect not only chillers but pumps, heat exchangers and other connected infrastructure.
The objective is therefore not simply to minimise installed capacity.
It is to determine the technical configuration that creates the strongest investment case for the owner’s requirements.
The Investment Case Is CAPEX and Lifecycle Economics
The DoE estimates that proper AC sizing can reduce installed AC costs by up to 35%. For owners considering major cooling renewal, this demonstrates the potential capital consequence of unnecessary capacity.
But the lowest initial investment is not necessarily the strongest investment decision.
Cooling infrastructure operates for many years and under continuously changing loads. Alternative configurations should therefore be compared across both initial and long-term economics:
CAPEX · OPEX · Energy Performance · Lifecycle Economics · Operational Requirements · Resilience
A higher-efficiency configuration could require different initial capital but reduce operating expenditure over its lifecycle. Conversely, additional equipment or redundancy may be economically justified where operational resilience is critical.
This is why a chiller replacement should be evaluated as an investment case, not simply an equipment procurement.
From Replacement Solution to Investment Pathway
Once the underlying requirements and assumptions are understood, credible alternatives can be compared.
That may include a rightsized replacement plant, different combinations and sizes of chillers, demand reduction before replacement, changes to system configuration or, where appropriate, an alternative cooling-supply strategy.
The DoE Cooling Load Manual itself points to broader considerations including heat recovery, thermal energy storage, Cooling as a Service and future district-cooling interoperability.
The objective is not to introduce technology for its own sake.
It is to determine which Cooling Investment Pathway best meets the owner’s defined objectives across technical performance, CAPEX, OPEX, lifecycle economics and long-term asset requirements.
A major cooling plant may remain in operation for many years. Decisions made at renewal can therefore lock both technical assumptions and economic consequences into the asset for the next investment cycle.
Challenge the assumptions before selecting the replacement.
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Sources
Abu Dhabi Department of Energy, Cooling Load Manual for the Emirate of Abu Dhabi, May 2026.
Abu Dhabi Department of Energy / Abu Dhabi Media Office, Abu Dhabi Department of Energy launches Cooling Load Manual to enhance energy efficiency and sustainable building design, 3 July 2026.
