Ageing Mall cuts emissions with green cooling technology

To modernise an ageing Mall’s HVAC system, Benchmark MEP Engineering Consultant implemented advanced green cooling technologies, reducing Green house gas (GHG) emissions and energy consumption. The retrofit integrated smart BMS, IoT sensors, and eco-friendly chillers to improve efficiency, sustainability, and occupant comfort.

The design of a shopping mall with retail outlets requires careful planning to optimise cooling efficiency. The traditional cooling system in older malls relies on high-capacity water-cooled chillers and cooling towers due to high electrical and equipment loads and heavy occupancy.

Project

To optimise cooling efficiency in a mall while meeting sustainability goals and implementing new cooling systems in an old mall by Benchmark MEP Engineering Consultant (BMEC).

The old cooling system in the mall

The chilled water capacity was 3,000 TR (Tons of Refrigeration), supported by three working water-cooled chillers of 1,000 TR each and one on standby. Cooling was done and maintained through three working cooling towers of 1,250 TR each, along with one standby unit.

The Building Management System (BMS) was a conventional system with limited Smart monitoring. This design led to higher energy consumption, resulting in increased operational costs and greenhouse gas (GHG) emissions.

Methodology

This study examines a mall with a built-up area of 498,000 square feet feet, comprising common spaces, retail shops, a food court, anchor stores, and three multiplex theatres.
The cooling system in the mall accommodated multiple floors, including basement, ground, lower ground, First, and Second Floors, ensuring safety, good air quality and comfort for visitors while reducing energy consumption, where newer cooling technologies were implemented.

Design aspects

The cooling system’s design in the mall prioritised energy efficiency, ECBC compliance, occupancy-based planning, double-glazed glass, and precise temperature zoning to meet Green Building norms, aligning with Mumbai’s climate requirements.

New cooling system for the mall

The following parameters were considered to satisfy Green Building norms.

• Light Power Density (LPD) was aligned with Energy Conservation Building Code (ECBC) standards.
• Occupancy density was based on relevant data and client experience, with retail spaces planned at 6.4 square meters per person and restaurants at 1.4 square meters per person.
• Given Mumbai’s tropical wet and dry climate, precise cooling solutions were needed. Glass optimisation involved using double-glazed glass for enhanced insulation along with the wall-to-window ratio.
• Temperature control was planned within the mall. The retail stores, restaurants, and anchor stores maintained 24°C, while common corridors were maintained at 25°C.

New cooling technology implemented

The advanced cooling system ensures energy efficiency, sustainability, and precise control through innovative technologies, supporting green building goals. The new technologies helped reduce operational costs, improving indoor air quality and comfort.

High-efficiency water-cooled chillers with eco-friendly refrigerants have been used, along with an enhanced fresh air intake increased by 30 percent in compliance with ASHRAE standards. Variable Frequency Drives (VFD) have been installed on all Air Handling Units (AHU) for zonal control, and Smart AHUS is equipped with EC fans.

HVAC energy metering has been introduced for real-time monitoring, and a high-side system with 65 percent diversity helps reduce energy wastage. The HVAC system motors feature a high energy efficiency factor, while PIBCV (Pressure Indicated Balancing Valves) have replaced conventional balancing valves to improve control.

• Smart technologies & IoT integration

Smart technologies and IoT integration play a crucial role in system performance. Iot-enabled sensors (HTO) are used for temperature and humidity monitoring, while IoT CPM-70 multifunction power meters enable precision energy tracking.  Predictive sensor integration supports smart HVAC maintenance, and a Smart Building Management System (BMS) ensures seamless automation.

• Sustainability improvement

Sustainable features include heat recovery wheels, CO sensors, automatic chiller cleaning, MERV 13 filters, and online monitoring for key HVAC parameters to maintain efficiency and air quality.

Sustainability-enhanced heat recovery wheels assist in pre-cooling fresh air. Carbon monoxide sensors were installed in the basement parking areas to monitor air quality, while automatic chiller tube cleaning technologies help maintain long-term efficiency.

MERV 13 filters are used for pre-filtration, and online monitoring tracks parameters such as IKW/TR, chilled and condenser in/out temperature, and condenser approach.

• Safety and Fire Protection Measures

Safety and fire protection measures have been implemented. Computational Fluid Dynamics (CFD) analysis was conducted to optimise basement ventilation, and smoke exhaust systems were installed in common areas.

The HVAC system is integrated with the fire alarm control panel for enhanced safety.

Challenges included selecting the right vendors based on quality rather than the lowest bid (L1), choosing a competent facility management team skilled in Smart technology, addressing the lack of trained manpower in operations and maintenance, and ensuring seamless integration of cooling, fire safety, and energy efficiency systems.

Results and outcomes

The newly designed cooling system has significantly improved efficiency. The new chilled water capacity is 1,800 TR, supported by two working water-cooled chillers of 950 TR each and one standby unit. Two cooling towers Capacity As 1400 TR each are operational, with one on standby. Further, an advanced Smart BMS has been integrated with IoT.

Energy reduction & cost savings

Under the previous design, energy consumption ranged between 130–140 kWh/sqm/annum, whereas the new design achieves 224–240 kWh/sqm/annum. This shift resulted in lower capital and operational expenditures while maintaining comfort levels and contributed significantly to greenhouse gas emission reductions, supporting the Net Zero Mission.

Conclusion

Innovations in smart HVAC, predictive maintenance, IoT integration, and Sustainable cooling strategies pave the way for GHG reduction in commercial spaces. As malls and retail spaces evolve, cooling technologies must be optimised for energy efficiency, thermal comfort, indoor air quality, and fire safety while aiming for net-zero emissions.

Standards & References:

• National Building Code of India (NBC) 2016
• Energy Conservation Building Code (ECBC 2017 Update)
• ASHRAE Handbook & Standards (ASHRAE 62.1-2022, ASHRAE 52.2-2022)
• SMACNA Standards for Duct Construction
• BIS Codes for air filtration systems
• National Fire Protection – NFPA
• National Electric Code – NEC