Company Logo

McDonald’s Garhoud – FAHU Control Optimization Test

Report prepared by: Tomasz Szeląg

Comparison of HVAC energy performance under EMS FAHU control vs. local FAHU control.

≈ 40% HVAC Energy Savings (measured) ≈ 36% Weather-normalized UAE – Garhoud
Executive Summary

The test demonstrates that activating FAHU control from the Energy Management System (EMS) – effectively limiting unnecessary fresh air operation – delivers a substantial reduction in HVAC electricity consumption compared to local FAHU control, while maintaining comfort conditions in the restaurant.

  • 1,937.6 kWh total HVAC energy saved per week in measured conditions.
  • ≈ 39.7% reduction in HVAC consumption vs. the week with local FAHU control.
  • After correcting for higher outdoor temperature during the reference week, normalized savings are still about 35.6% (≈ 1,628 kWh/week).
  • Indoor temperature remained stable at ~23 °C with EMS FAHU control.
  • CO₂ levels stayed low and within comfortable indoor air quality ranges.

The reference week with local FAHU control was on average ~2.5 °C hotter outside. This naturally increases cooling demand and explains part of the measured savings; even after normalization, EMS-based FAHU control delivers strong energy benefits.

Total HVAC Energy
Weekly consumption – EMS FAHU control vs. local control
Energy by System
FAHU and PACUs – weekly kWh
Indoor Air Quality
Average CO₂ levels – lobby and kitchen

Both control strategies remain within very comfortable CO₂ ranges. Theoretically, limiting FAHU operation under EMS control would tend to increase CO₂; the measured differences are small and within normal operational variation.

Temperature Conditions
Room vs. outside temperature

Indoor temperature remained stable at ~23 °C for both weeks, confirming that comfort was not compromised when FAHU was controlled by EMS. The reference week with local FAHU control experienced a higher average outdoor temperature (31.7 °C vs. 29.2 °C), which explains part of the measured savings. After applying a conservative weather adjustment, HVAC savings remain on the order of 35–36%.

Interpretation & Recommendation

Activating FAHU control from the EMS significantly reduces the constant fresh-air load compared to local FAHU control without EMS. This eliminates unnecessary FAHU runtime (≈ 1,730 kWh/week) and slightly reduces the energy demand of PACU1 and PACU2. PACU3 shows only a marginal increase, likely related to normal operational variability and load redistribution.

  • Energy: EMS-based FAHU control is the primary optimization lever at this site, delivering nearly 2 MWh/week of measured savings and still around 1.6 MWh/week after weather normalization.
  • Comfort: Indoor air quality and temperature indicators remain within comfortable limits; no deterioration is observed with EMS FAHU control.
  • Weather impact: The week with local FAHU control experienced ~2.5 °C higher outdoor temperature, naturally driving up cooling demand. Correcting for this effect still leaves a robust ≈ 35.6% HVAC energy reduction attributable to the control strategy itself.
  • Scalability: The results support extending EMS-based FAHU control to other restaurants with similar configuration, with ongoing monitoring of IAQ to confirm performance.