Physics-informed linear regression is competitive with two Machine Learning methods in residential building MPC

TL;DR

This study compares physics-informed ARMAX models with machine learning models for building predictive control, demonstrating that ARMAX models are more computationally efficient and accurate, achieving significant energy savings in real-world applications.

Contribution

It provides a direct comparison of physics-informed and machine learning models for building MPC, highlighting the advantages of ARMAX models in real building control scenarios.

Findings

Predictive control reduces energy use by 26-49%.

ARMAX models outperform ML models in accuracy and efficiency.

All models achieve satisfactory control performance.

Abstract

Because physics-based building models are difficult to obtain as each building is individual, there is an increasing interest in generating models suitable for building MPC directly from measurement data. Machine learning methods have been widely applied to this problem and validated mostly in simulation; there are, however, few studies on a direct comparison of different models or validation in real buildings to be found in the literature. Methods that are indeed validated in application often lead to computationally complex non-convex optimization problems. Here we compare physics-informed Autoregressive-Moving-Average with Exogenous Inputs (ARMAX) models to Machine Learning models based on Random Forests and Input Convex Neural Networks and the resulting convex MPC schemes in experiments on a practical building application with the goal of minimizing energy consumption while maintaining occupant comfort, and in a numerical case study. We demonstrate that Predictive Control in general leads to savings between 26% and 49% of heating and cooling energy, compared to the building's baseline hysteresis controller. Moreover, we show that all model types lead to satisfactory control performance in terms of constraint satisfaction and energy reduction. However, we also see that the physics-informed ARMAX models have a lower computational burden, and a superior sample efficiency compared to the Machine Learning based models. Moreover, even if abundant training data is available, the ARMAX models have a significantly lower prediction error than the Machine Learning models, which indicates that the encoded physics-based prior of the former cannot independently be found by the latter.