Transitioning from a traditional BMS to an IoT-based BMS reduces electricity usage in HVAC systems

TERI’s recent whitepaper recognises the HVAC energy-saving potential of IoT BMS, ranging between 13.4 percent and 24.9 percent. It delves into the energy-saving potential of utilising an Internet of Things (IoT)-based Building Management System (BMS) for HVAC systems in commercial buildings across different climatic zones in India.

The primary aim of this study was to evaluate and compare the energy-saving capabilities of HVAC systems managed by conventional BMS versus those controlled by IoT-based BMS. Through a comprehensive simulation exercise, the study explored the energy efficiencies enabled by the IoT-based BMS, including sensor networks to address thermal imbalances, indoor air quality management, optimisation of total fresh air intake, chilled water system optimisation, CO2 sensor deployment, and strategies leveraging temperature reversals in buildings.

HVAC energy savings in Indian commercial buildings

The findings reveal that transitioning from a traditional BMS to an IoT-based BMS can significantly reduce electricity usage for HVAC systems, with savings ranging between 13.4 percent to 24.9 percent. Moreover, the whitepaper highlights that implementing an IoT-BMS reduces energy consumption and enhances occupant health, comfort, and productivity.

IoT based BMS versus traditional BMS

This technical note investigates the energy-saving potential of using an Internet of Things (IoT)-based Building Management System (BMS) for HVAC systems in commercial buildings in different climatic zones in India. The study’s main objective was to compare the energy-saving potential of HVAC systems between conventional Building Management Systems (BMS) and IoT-based BMS. The study utilised a simulation exercise to assess the energy savings achieved through various factors enabled by IoT-based BMS, such as sensor networks for addressing thermal imbalances, indoor air quality requirements, total fresh air needs, chilled water optimisation, CO2 sensors, and strategies to capitalise on temperature reversals in the building.

Methodology

To identify the potential for energy efficiency in commercial buildings in India, sixteen commercial buildings of four different typologies, i.e., offices, health care, hospitality and retail, are studied using a simulation approach.

The energy models of all the buildings were developed using BEE-approved eQUEST simulation tools while following the guidelines of the Energy Conservation Building Code (ECBC) of 2017. The input parameters, such as the thermal transmittance of external wall, roof, and glazing system, Lighting Power Density (LPD), Equipment Power Density (EPD), and occupancy schedules, were based on the standards specified in the ECBC Code. The design parameters of the building’s HVAC system were used as per Indian HVAC industry norms.

 The energy models were simulated using eQUEST version 3.65 and DOE-2, which can dynamically simulate building energy demand for each hour throughout the year. Each energy model included a baseline model (Conventional BMS) and a design model (IoT-BMS), incorporating the advanced control strategies developed by 75F. Various centralised HVAC systems, primary-secondary pumps, VAV systems, cooling towers, and condenser pumps were considered to analyse larger buildings > 50,000 sq. ft. As Variable Refrigerant Flow (VRF) systems are a great option for compact spaces because of their adaptability and efficacy, refrigerant-based systems were considered for smaller buildings between 5,000 sq.ft. and 50,000 sq. ft.

While evaluating IoT-based BMS, the study tested these seven advanced control strategies of 75F: Outdoor Air Optimisation (OAO), OAO Interval Modulation, Smart Variable Air Volume, Dynamic Chilled Water Balancing, Dynamic AirBalancing, and Epidemic Mode.

Results: Commercial buildings

Compared to conventional BMS, IoT-BMS leads to a decrease in airflow requirements (CMF/sq. ft.) and an improvement in HVAC system performance (sq.ft./ton). This analysis shows significant savings from IoT-based BMS that uses applications such as Dynamic Chill Water Balancing, Outside Air Optimisation sequences and Smart VAV in large offices, particularly in Temperate zones. The study suggests that implementing the IoT-BMS solution in place of traditional BMS systems can significantly reduce electricity usage of HVAC systems, ranging from 13.4– 15.4 percent. After analysing various building typologies and climatic zones in India, the study revealed that over 50 percent of energy savings for centralised chillers stem from the chiller side. This includes fan energy savings, accounting for 6 to 19 percent of total HVAC energy savings, heat rejection energy savings ranging from 8 to 14 percent, and pump energy savings contributing 21 percent to 25 percent of overall HVAC savings.

Energy savings in HVAC for different climates

Composite -up to 13.40 percent, Warm and Humid up to 13.40 percent, Temperate -15.40 percent, and Hot & Dry 13.70 percent.

The percentage savings on EPI in buildings:

Composite climate -7 percent, Warm and Humid climate -up to 8.30 percent, Temperate climate -7.80 percent, and Hot & Dry climate -5.90 percent.

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