Steady-State Predictive Optimal Control of Integrated Building Energy Systems Using a Mixed Economic and Occupant Comfort Focused Objective Function

Christopher J Bay,Rohit Chintala,Bryan P Rasmussen

doi:10.3390/en13112922

Christopher J Bay, Rohit Chintala + Show 1 more

Open Access

https://doi.org/10.3390/en13112922

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Abstract

Control of energy systems in buildings is an area of expanding interest as the importance of energy efficiency, occupant health, and comfort increases. The objective of this study was to demonstrate the effectiveness of a novel predictive steady-state optimal control method in minimizing the economic costs associated with operating a building. Specifically, the cost of utility consumption and the cost of loss productivity due to occupant discomfort were minimized. This optimization was achieved through the use of steady-state predictions and component level economic objective functions. Specific objective functions were developed and linear models were identified from data collected from a building on Texas A&M University’s campus. The building consists of multiple zones and is serviced by a variable air volume, chilled water air handling unit. The proposed control method was then co-simulated with MATLAB and EnergyPlus to capture effects across multiple time-scales. Simulation results show improved comfort performance and decreased economic cost over the currently implemented building control, minimizing productivity loss and utility consumption. The potential for more serious consideration of the economic cost of occupant discomfort in building control design is also discussed.

Highlights

Energy use and consumption of natural resources has become a pertinent concern for current and future generations
By using Loss of Productivity (LOP) optimal temperature setpoints, a more direct performance difference can be determined between the current control method and the proposed steady-state optimal control method
The current control method was simulated on the Utilities Business Office (UBO) building under two operational cases: (1) with the building operator defined zone temperature setpoints (23 °C); and (2) with LOP optimal zone temperature setpoints

Summary

Introduction

Energy use and consumption of natural resources has become a pertinent concern for current and future generations. In a large building there may be multiple chillers that are used to chill a secondary fluid, such as water This chilled water is pumped to various systems and areas of buildings where heat exchangers in air handling units (AHUs) use the chilled water to cool and dehumidify air streams. A network of fans and ducts deliver the cooled air to the desired locations The flow of this cooled air into the zones can be controlled by variable air volume (VAV) units, in which there may be another heat exchanger that utilizes heated water to warm the air, if necessary. The zones themselves are connected to one another, either by conduction through barriers or convection through shared doorways/open spaces All these interconnections and couplings result in coordinated control problems

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