If you manage a commercial building in the UAE and you have not had a formal BMS commissioning review in the last three years, there is a strong chance your HVAC system is operating well below design intent. Industry benchmarking data from the Gulf region consistently shows that the average commercial chilled-water plant runs at 68–74% of its original design efficiency within 36 months of handover. This is not a fault of the equipment — it is a fault of the commissioning and maintenance process.
Problem One: Setpoint Drift
Every BMS is commissioned with a set of control sequences and setpoints that reflect the design conditions at the time of handover. Those conditions change. Occupancy patterns shift, building use evolves, and tenant fit-outs alter the internal heat load. But the setpoints rarely follow.
The most common manifestation is supply air temperature setpoint drift: a value that was set at 14 degC on a design basis creeps up to 16 or 17 degC through incremental operator adjustments in response to comfort complaints. A 2 degC rise in chilled water supply temperature can increase chiller COP by 4–6%, but if the drift is uncontrolled and unmonitored, the same system may be simultaneously overcooling unoccupied zones, destroying that gain and then some.
The fix is systematic: pull the BMS trend logs for supply air temperature, return air temperature, and zone demand across a representative 30-day period. Plot the deviation from design setpoints. In most systems we audit, at least one AHU is operating with a setpoint that has not been touched since the first year of operation. Reset it, trend it, and review quarterly.
Problem Two: Sequencing Failure
Multi-chiller plants are designed with a lead-lag sequencing strategy: one chiller carries the load at part-load conditions, additional chillers stage on as demand increases. This is the most efficient way to run a chilled-water plant, because centrifugal chillers achieve their best COP at 70–80% load rather than at full load.
Sequencing failure typically occurs when a plant has been through a controls upgrade, a chiller replacement, or a service visit where an engineer has manually staged chillers to clear a fault and not restored the automatic sequence. When that happens, two or three chillers run simultaneously at low load, each operating at a fraction of their peak efficiency. We have found buildings in Dubai where all three chillers were running at 30% load simultaneously on a cool November night — a condition that consumed nearly double the energy of the correct single-chiller strategy.
The diagnostic is straightforward. Review the BMS event log for manual overrides. Check whether the automatic lead-lag sequence is active. If it has been in manual mode for more than 24 hours, investigate why and restore automatic operation.
Problem Three: Fouled Coils and Blocked Filters
This is the least glamorous problem but statistically the most common cause of efficiency loss in the UAE market. The combination of construction dust, desert particulate, and high humidity creates ideal conditions for filter loading and coil fouling. A filter at 80% loading increases fan static pressure, reducing airflow and increasing fan energy consumption by up to 25%. A fouled chilled-water coil increases the approach temperature, requiring the chiller to work harder to maintain the same leaving-water condition.
Establishing a scheduled filter replacement interval tied to actual differential pressure measurement rather than a fixed calendar interval is consistently the highest-ROI maintenance action we recommend to new clients. The cost of a filter change is trivial; the energy saving over twelve months typically pays back the annual maintenance budget several times over.
What a BMS Audit Looks Like
A comprehensive efficiency audit from Prysmedge takes two to three days for a typical commercial floor plate of 2,000–5,000 square metres. We extract 90 days of trend data, analyse control sequences against the original design intent documentation, perform a physical walkthrough to check damper positions and sensor calibration, and produce a ranked action list with projected energy and cost savings for each item.
In every audit we have conducted in the UAE market, the total projected annual energy saving has exceeded the audit fee by a factor of at least eight. The payback period on remediation works has never exceeded 14 months.
If your building is more than two years old and has not been through this process, contact us. The data from your own BMS will tell you exactly what is happening — you just need someone to look at it properly.
