Method and system to optimize energy consumption in a zone with a multi-air handling unit (AHU) setup
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Solution Overview
Problem
Conventional HVAC systems in large buildings with multiple air handling units (AHUs) are sub-optimal due to independent control based on return air temperature alone, failing to account for spatially skewed occupancy, which leads to inefficient energy consumption, as HVAC accounts for over 40% of total energy use.
Innovation Solution
A system comprising a zone thermal unit that obtains input parameters such as internal heat gains, surface convective loads, and air contaminant concentrations to generate optimal AHU flow rates, utilizing an optimizer to minimize HVAC energy consumption while maintaining thermal comfort by coordinating AHU fan speeds across multiple AHUs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If independent AHU control based on return air temperature alone is used, then each AHU can be controlled individually, but energy consumption is not optimized due to ignoring spatially skewed occupancy
Solution Approach 1:
The patent merges multiple independent AHU controls into a coordinated ensemble control system. The optimizer integrates occupancy information from multiple zones and coordinates the operation of multiple AHUs together, allowing the system to leverage spatial occupancy patterns and optimize energy consumption across the entire HVAC system rather than treating each AHU independently.
Solution Approach 2:
The system implements feedback by continuously monitoring occupancy information and using it to dynamically adjust AHU operations. The optimizer receives real-time occupancy data and adjusts the set-point temperatures and AHU flow rates accordingly, creating a closed-loop control system that adapts to changing spatial occupancy patterns to minimize energy consumption.
2Device complexity
If conventional PID controllers are used, then control implementation is simple, but occupancy information cannot be utilized effectively for energy optimization
Solution Approach 1:
The system changes the control parameters from simple temperature-based PID control to a more comprehensive optimization approach that incorporates occupancy information, AHU flow rates, and set-point temperatures. The optimizer solves for optimal operating parameters by integrating multiple input variables including occupancy data, thermal loads, and AHU performance characteristics, enabling effective utilization of occupancy information for energy optimization.
3Use of energy by moving object
If AHU operations are coordinated using occupancy information, then energy optimization is achieved, but control system complexity increases
Solution Approach 1:
The optimizer serves multiple functions: it processes occupancy information, calculates thermal loads, determines optimal set-point temperatures, and coordinates AHU flow rates. This multi-functional approach consolidates what would otherwise require separate control systems into a single optimization engine, managing complexity while achieving comprehensive energy optimization across the multi-AHU system.
Data Source
AI summary
A system and method for optimizing energy consumption in a plurality of air handling units (AHUs) in a zone is provided. The system comprising a zone thermal unit that is configured to obtain a first set of input parameters including an internal heat gains, a surface convective loads, an intra-zone mixing, a supply air temperature, a second set of input parameters including internal moisture gains, a supply humidity ratio, and a third set of input parameters including an air contaminant concentration and an ambient contaminant concentration of the AHUs and generates a first set of output parameters including a zone temperature, a humidity ratio and an air concentration. The system further includes an optimizer that is configured to generate a second set of output parameters including an optimum combination of AHU flow rates for the AHUs based on at least one of the first set of output parameters.