Residential Heat Pump + Thermal Storage Cuts On-Peak Electricity 38.4% in Field Demonstration
A 2026 field study listed by Oak Ridge National Laboratory tested a phase-change thermal store integrated with a residential split heat pump in an occupied home.
Why thermal storage is interesting for heat pumps
A heat pump normally has to meet thermal demand at the same time electricity is consumed. Thermal storage can decouple part of that timing by storing cooling or heating capacity for later use.
What the field test found
The study reports a phase-change-material thermal energy storage unit connected to a conventional split heat pump in an occupied residential building. During the tested cooling operation, the system shifted load away from the peak period while maintaining indoor thermal performance.
Do not read the percentage as a universal savings claim
The reported reductions belong to one field-demonstration configuration and operating strategy. Tariffs, climate, equipment size, control logic, storage size and building load will change both energy and cost outcomes.
Commercial readiness
WattCostLab classifies this as Field demonstration. The important next step is repeated performance across climates, equipment types and utility rate structures, followed by integrated products that installers can commission reliably.
Source & verification
This analysis is based on the primary research or institutional source below. WattCostLab has paraphrased the technical findings and added homeowner-oriented context.
Oak Ridge National Laboratory / Applied Thermal Engineering — original source
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