Success Stories

Low Delta-T assessment for a building in Dubai

Observe how Ark Energy resolved the Delta-T issue present in a local building in Dubai

Background Story

The client owns a high-quality commercial and residential skyscraper located in DIFC, Dubai, UAE. It is characterized by a gross area of 300,871 m2 of mixed-use spaces, including 25 commercial stories, 48 residential stories, and a total conditioned area of 192,711 m2. The tower has the capacity and potential to integrate significant energy efficiency improvements through the deployment of technology and equipment upgrades, as well as detailed energy management.

Ark Energy was engaged to develop and execute a Delta-T rehabilitation project, energy retrofit project, and digitalization of energy management to reduce overall energy consumption, eliminate Delta-T surcharges, and digitize their O&M. The total energy cost for the tower between May 2018 and April 2019 was 19.4 million AED, detailed below by energy source. On average, the tower was paying 2.63 million AED annually in Delta-T surcharges.

Table 01

The Tower’s  consumption profile

Main Objective

The main objective of this project was to alleviate the Client from the Delta-T surcharges through the implementation of ideal low Delta-T Solutions and carry out a Detailed Engineering and Design, Procurement, Installation, and Commissioning activities for the said ideal low Delta-T solution.

Figure 01

The Tower’s monthly energy cost distribution during the period od 2018 to 2019, 000’AED


The Client was suffering from low Delta-T syndrome and paying up to 2.0m AED in surcharges. Delta-T surcharges were waivered twice by the district cooling operator, provided that the building is undergoing a proper Delta-T rehabilitation. A Delta-T study investigating the low figure and presenting possible solutions to rectify the issue, was conducted.

Ark Energy applied a structured six-step approach to get the most optimal solution for low Delta-T rehabilitation. As a first phase in the activity,  an  Engineering Analysis and Operational Review was conducted,  where the collected data were analyzed and reviewed to recommend mitigation measures for low Delta-T. From the analysis, the following steps were conducted as part of the methodology:

  1. Review of data collected from site surveys and discussions with operation and maintenance personnel
  2. Review of data collected from BMS and visual inspections which included DPT locations and setpoints, pump VFD readings, and heat exchanger temperature
  3. 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 where presented:

  1. The DPTs used on each pump are not in-line with VFD speeds shown in the BMS readings
  2. 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
  3. The major reasons of the imbalance in the system are oversized fan coil units, Air Handling Units, and oversized control valves
  4. The Index DPT location is not appropriate and should be relocated

In the second phase of the project an analysis was conducted to pinpoint the point sources of the Low-Delta T Syndrome. Ark Energy  carried out a detailed site measurement and testing to determine the main causes behind the Delta-T issues. From the systematic approach, 19 different causes for low Delta-T that have been assessed based on capital constraints and technical criteria

Table 02

A sample of the different possible causes for the Low-Delta T, with their severity presented

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


The results that were generated from the project include the following:

  1. 1.191,342 AED of annual savings
  2. 8% of annual energy savings

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