Advanced cooling technology with thermally activated building surfaces and model predictive control

This research analyzes an advanced cooling system, termed a low-lift cooling system (LLCS), that comprises thermally activated building surfaces (TABS) and a parallel dedicated outdoor air system (DOAS) for dehumidification and ventilation. The system utilizes model predictive control (MPC) that, based on weather and load predictions, determines the cooling strategy over next 24h that minimizes energy consumption. Different objectives, such as minimizing the total cost of electricity, can be achieved by modifying the objective function. The LLCS performance was analyzed across 16 different U.S. climates relative to a variable refrigerant flow (VRF) for sensible cooling only, and to the VAV system for cooling, dehumidification and ventilation. Five dehumidification strategies that can be used in combination with the LLCS were also investigated. The results suggest that the electricity savings using the LLCS are up to 50% relative to the VAV system under conventional control and up to 24% relative to the VAV system under MPC. The savings were achieved through lower transport energy and better utilization of part-load efficiencies inherent in inverter-compressor equipment, a result of the TABS technology and the optimal control. The LLCS also had better performance than the conventionally controlled VRF system. (C) 2014 Elsevier B.V. All rights reserved.