LEED Gold Certification for a Bangladesh Garment Factory Using BMS Energy Management

The factory's LEED certification pursuit was managed by a LEED Accredited Professional (AP) consultant engaged by the company's sustainability director. The LEED BD+C (Building Design and Construction) for New Construction credit framework requires documented energy performance improvements over a baseline, with Energy and Atmosphere (EA) credits representing the highest point value in the system. To achieve LEED Gold (60+ points out of 110), the factory needed to maximize its EA credit score — and the EA prerequisites and credits require metered, documented energy performance data, not estimated or modelled performance.

The factory's HVAC system — including air handling units for the production floors, precision cooling for the server and ERP equipment area, and split units for office areas — was the largest energy consumer in the building, representing approximately 68% of total electricity consumption. The HVAC's energy consumption in the first year of factory operation had been measured through the main utility meter at BDT 9.8 lakh per month — a figure the sustainability director knew was higher than necessary because the HVAC ran on fixed operational schedules regardless of production schedules, ambient conditions, or actual occupancy.

The specific HVAC inefficiency patterns identified by the LEED AP consultant's energy audit were threefold. First, all Air Handling Units ran at full speed from 07:00 to 21:00 regardless of production floor occupancy — during the 30-minute shift changeover periods when the production floor was transitioning between workers, AHUs continued at full capacity for an empty floor. Second, the factory's three chillers (each 120TR) operated in parallel even during the cooler November-February period when a single chiller would have provided adequate cooling at a fraction of the energy consumption of three units partially loaded. Third, the supply air temperature setpoint was fixed at 18°C year-round, providing over-cooling in cooler months and requiring heating to bring the air back to a comfortable delivery temperature — a thermodynamically inefficient practice known as simultaneous heating and cooling.

For LEED EA credit documentation, the factory needed to demonstrate these inefficiencies, quantify them, implement BMS-based control improvements, and then measure and document the resulting energy savings over a minimum monitoring period. The documentation requirement — not merely implementing improvements but metering and reporting them in LEED-compliant format — was the specific gap that the factory's facilities team could not fill with conventional manual monitoring.

SSAL designed and installed a Siemens Desigo CC BMS with 800 DDC control points covering the factory's complete HVAC infrastructure, with energy sub-metering and LEED-format reporting.

Siemens Desigo CC Building Management System: The Siemens Desigo CC platform was installed on a dedicated server in the factory's IT server room. Desigo CC is Siemens' flagship intelligent building management platform, providing HVAC control, energy management, and integrated reporting through a unified graphical interface. The system communicates to field controllers via BACnet/IP over the factory's existing fiber backbone network, which had been designed during the building's 2020 construction to reach all plant rooms and mechanical equipment areas.

DDC Field Controllers — 800 Points: Siemens PXC Series DDC (Direct Digital Control) controllers were installed at each AHU plant room and at the chiller plant room, providing direct digital control over all HVAC equipment. Control logic was programmed by SSAL's Desigo CC certified engineers, implementing the following optimizations:

Variable Air Volume (VAV) AHU Control: All 14 AHUs across the production floors were converted from constant air volume (CAV) fixed-speed operation to VAV control, with supply fan speed modulated by VFD (Variable Frequency Drive) output from the DDC controller based on duct static pressure and return air CO2 concentration. During production hours, AHU fan speeds range from 40-100% depending on actual occupancy and thermal load. During shift changeover periods (30-minute intervals), AHUs automatically reduce to 35% speed, recovering the wasted energy of full-speed operation for empty floors.

Chiller Sequencing: All three 120TR chillers were integrated into Desigo CC via their BACnet interfaces. The chiller sequencing algorithm starts one chiller and monitors its load percentage: if load exceeds 78%, the second chiller starts. If the first two chillers together exceed 75% load, the third starts. In the cooler November-February period, cooling loads typically require only one chiller — the other two remain off rather than running at partial load as previously. Cooling tower fan speed is modulated by VFD via DDC control, further reducing ancillary HVAC energy.

Supply Air Temperature Reset: Supply air temperature is reset dynamically based on outdoor ambient temperature. When outdoor temperature is below 30°C, supply air temperature is reset upward (to 22°C), reducing chiller energy required to cool the air and eliminating the simultaneous heating scenario. At maximum outdoor temperature (38-40°C in summer), the supply temperature is maintained at 18°C to deliver adequate cooling to the production floor.

Occupied/Unoccupied Scheduling: The factory's production schedule (06:00-22:00 production, 22:00-05:00 maintenance/cleaning) is encoded in the BMS scheduling module. During the maintenance period, all production floor AHUs run at 20% minimum ventilation (for air quality compliance), and chiller operations are reduced to a single unit at minimum load. Pre-conditioning starts at 05:30 to bring the production floor to setpoint before the 06:00 production start.

Energy Sub-Metering — LEED Compliance: 18 digital energy sub-meters (Siemens SENTRON PAC3200) were installed at key distribution boards: individual sub-meters for each AHU plant room (8 meters), each chiller (3 meters), cooling towers (1 meter), server room precision cooling (1 meter), office split units (2 meters), and production floor lighting (3 meters). All 18 meters communicate via Modbus TCP to Desigo CC, providing real-time energy consumption data by system and by zone.

LEED Energy Data Export: Desigo CC's LEED reporting module generates monthly LEED-format energy reports showing measured energy consumption by system, comparison against the pre-BMS baseline (established by a 3-month pre-installation sub-meter baseline measurement period), and percentage improvement by system category. These reports are formatted to align with LEED EA Credit 1 (Optimize Energy Performance) documentation requirements and were pre-reviewed by the LEED AP consultant before system go-live to confirm acceptance by the certifying body.