Background StoryThe client owns a premium commercial and residential skyscraper located in DIFC, Dubai, UAE, spanning a gross area of 300,871 m². The tower consists of 25 commercial floors and 48 residential floors, with a total conditioned area of 192,711 m². Given its scale and energy-intensive operations, the tower had significant potential for energy efficiency improvements through technology upgrades, equipment retrofits, and advanced energy management strategies.
To optimize energy performance, the client engaged Ark Energy to implement a Delta-T rehabilitation project, an energy retrofit initiative, and a digitalized energy management system. The objective was to reduce overall energy consumption, eliminate Delta-T surcharges, and digitalize operations and maintenance (O&M) processes. Between May 2018 and April 2019, the tower’s total energy costs amounted to 19.4 million AED, with an annual Delta-T surcharge of 2.63 million AED.
Table 1
The Tower’s consumption profile
| Client's Tower | Total Concentrated Load | Conditioned Floor Area | Average Delta-T | Annual Delta-T Surcharges |
| RT | m2 | oC | AED |
| Value | 6,070 | 192,711 | 3.0 | 2,633,300 |
Source: Ark Energy Analysis
Figure 01
The Tower’s monthly energy cost distribution during the period od 2018 to 2019, 000’AED 
Source: Ark Energy Analysis
Main ObjectiveThe primary goal of the project was to eliminate Delta-T surcharges by implementing an optimized low Delta-T solution and executing a detailed engineering design, procurement, installation, and commissioning process.ApproachThe tower was experiencing low Delta-T syndrome, leading to surcharges of up to 2.0 million AED annually. The district cooling operator had waived these surcharges on two occasions, under the condition that the building undergo a proper Delta-T rehabilitation program. To address this, Ark Energy conducted a comprehensive Delta-T study to investigate the issue and identify practical solutions for mitigation.
To develop the most effective solution for Delta-T rehabilitation, Ark Energy followed a structured six-step methodology. The first phase involved conducting a detailed engineering analysis and operational review, during which collected data was analyzed to formulate corrective measures: - Review of data collected from site surveys and discussions with operation and maintenance personnel
- Review of data collected from BMS and visual inspections which included DPT locations and setpoints, pump VFD readings, and heat exchanger temperature
- Hydraulic calculations using the performance curve of the pumps to simulate the impact of over pumping and chilled water system imbalance on low Delta-T
From the works done, the following findings were presented:
- The DPTs used on each pump are not in-line with VFD speeds shown in the BMS readings
- The equipment placed on floors nearby to the pump sets are receiving high flow and the farthest ones are receiving low flow compared to their load and quantities
- The major reasons of the imbalance in the system are oversized fan coil units, Air Handling Units, and oversized control valves
- The Index DPT location is not appropriate and should be relocated
In the second phase, a systematic root cause analysis was carried out to pinpoint the primary sources of the low Delta-T issue. This included a detailed site investigation, measurement, and testing process. Through this structured approach, Ark Energy identified 19 key factors contributing to low Delta-T, which were then assessed based on technical feasibility and capital constraints to determine the most viable mitigation strategies.
Table 2
A sample of the different possible causes for the Low-Delta T, with their severity presented| Total Concentrated Load | Contribution to Low Delta-T Syndrome |
| Faulty valves/ actuators | High |
| Poor chilled water condition | Medium |
| Faulty actuators | High |
| Faulty thermostats | Low |
| Unbalanced CHW network | Medium |
| Pump control | Medium |
| Plant chilled water mixing | Medium |
| AHU supply air temperature below setpoint | High |
Source: Ark Energy Analysis
Ark Energy carried out a Detailed Engineering and Design, Procurement, Installation, and Commissioning activities for six (6) Delta-T solutions
The Delta-T solutions presented, in mix with other ECMS provided, resulted in the Client to aim to reduce their energy consumption by 10.7% with a payback period of 2.2 years
Table 03
The following solutions presented in the analysis| ECM # | Delta-T Solution |
| DT 1.3 | HEX Maintenance |
| DT 2.1 | Smart PICVs |
| DT 2.2 | PICV-Based CHW Pump Control |
| DT 2.3 | BMS Recommissioning |
| DT 2.4 | BTU Meter Recommissioning |
| DT 3.2 | BMS/ECMS Alarm Implementation |
Source: Ark Energy Analysis
Results
The results that were generated from the project include the following:
- 1,191,342 AED of annual savings
- 8% of annual energy savings