Thermal Energy Storage Can Lower Utility Bill Costs for Buildings Owners

Thermal energy storage (TES) can play a vital role in enabling more building-sited renewable electricity generation, especially when there are high demand and variable time-of-use (TOU) charges. A model predictive control (MPC) strategy can offer additional savings over a schedule-based control with added complexity and reliance on forecasts. Research conducted by the National Renewable Energy Laboratory (NREL) has shown that MPC can save up to 66% in annual chiller plant operating costs for medium office buildings with building-installed solar photovoltaics (PV).

Key Takeaways:

• Thermal energy storage (TES) can enable more building-sited renewable electricity generation and lower utility bill costs for buildings owners and occupants.
• A model predictive control (MPC) strategy can offer additional savings over a schedule-based control with added complexity and reliance on forecasts.
• The MPC strategy can save up to 66% in annual chiller plant operating costs for medium office buildings with building-installed solar photovoltaics (PV).
• The study found that regularizing the NLP solutions can lead to reasonable results that can be followed by the building model, with an average error of 9% across the cases.
• The research concluded that demand management, energy arbitrage, and load reduction can lead to savings in TOU energy costs, minimum TOU costs, and minimum monthly demand costs.
• The study showed that PV and TES are complementary and mostly independent, but a load with PV often results in better performance for the schedule.
• The research highlights the importance of modeling and optimization for complex rates, but also the circumstances wherein a simpler strategy achieves the same performance with less potential for error.

Statistics:

• 66%: the maximum savings in annual chiller plant operating costs achieved by the MPC strategy.
• 9%: the average error across the cases when regularizing the NLP solutions.
• 35-66%: the additional savings in annual chiller plant operating costs achieved by the MPC strategy compared to the schedule-based control.
• 1-33%: the additional savings in annual chiller plant operating costs achieved by the MPC strategy above the schedule-based control.

Sources:

• "Ice Storage Model-predictive Control In an Office Building With Pv: Scenario, Error and Sensitivity Analysis" (Energy and Buildings, 2025; 341).
• National Renewable Energy Laboratory (NREL) (2025).
• Elsevier Science Sa, PO Box 564, 1001 Lausanne, Switzerland (www.elsevier.com).
• Energy and Buildings (www.journals.elsevier.com/energy-and-buildings/).