Thermal storage is a system that captures and retains thermal energy during off-peak periods for later use during peak demand hours, reducing HVAC system runtime and energy costs by 15-40%. Common thermal storage methods include ice tanks, chilled water tanks, and phase-change materials that absorb heat or cooling capacity. This strategy significantly reduces peak electrical demand and utility charges while improving system efficiency.
Storage Technologies
Ice storage systems freeze water during off-peak hours (10-12 p.m. to 6 a.m.) when electricity rates are lowest, storing 400-600 Btu per gallon. Chilled water tanks (50,000-500,000 gallons) store cooling at 40-45°F during low-demand periods. Phase-change materials in thermal batteries store 150-250 Btu per pound and respond rapidly to load changes. Hot water thermal storage (120-180°F) captures heating capacity from solar systems or high-efficiency equipment for later space heating use.
Operational Benefits
Thermal storage shifts 30-60% of cooling loads to off-peak hours, reducing peak demand charges by 20-35 kW for medium commercial buildings. Systems reduce chiller run time by 40-50%, extending equipment lifespan. Integration with demand response programs provides utility incentives of $500-$5,000 annually. Zone-based thermal storage enables precise temperature control while minimizing simultaneous compressor operation across multiple building sections.