Underfloor Heat Storage

Enjoy the comfort of in-floor heat and use the heat-storing properties of the earth!

Underfloor heat storage systems are installed before cement slabs are poured during construction. The system is buried in a bed of sand to create a heat reservoir beneath your home, business, garage, or other building. Radiant heat is distributed evenly from every square foot of the floor, keeping air temperature constant and comfortable even on the coldest winter days.

Properly designed systems can store adequate heat reserves to meet space-heating requirements for many hours. This technology works great on one of our low off-peak rates because spaces stay comfortable during peak energy-control periods.


  • Electric panels or cables. In a fully electric system, electric cables or panels are buried 8 to 12 inches deep in a bed of sand and create a heat reservoir.
  • Hydronic heat storage. An in-floor hydronic system consists of an electric boiler or hydronic central-storage furnace that heats liquid which circulates through tubes embedded in sand to create a heat reservoir.

Sizing is important

Regardless of the technology you choose, we encourage you to work with a qualified contractor that will properly size your system to create adequate stores to warm the space and maintain comfort during the maximum control period allowed by the rate on which it's served.


  • Warmth at your feet. You’ll enjoy comfort as heat is distributed evenly across the floor reaching people and objects with no drafts, dust, or uncomfortable dry air.
  • Cleanliness. No dust is circulated, so these systems are clean and quiet.
  • Effectiveness. Heat an entire building or use it to supplement another heat source.
  • Convenience. Place your furniture wherever you choose with no vents to get in the way.
  • Efficiency. When you combine the system's 100% energy efficiency with our low off-peak rates, heating is economical and efficient. 

Rebates are available

Systems installed on our Fixed Time of Delivery, Residential Demand Control, or Deferred Load Rates may qualify for a rebate of $40-per-kilowatt (kW) for up to 500 kW of heating capacity installed. To qualify for a rebate, your system must have adequate storage capacity to heat the space during the maximum control period allowed by the rate.

A rebate of $500 is available for 9 kW to 25 kW, or a $20 per kW rebate for systems 26 kW or larger, for electric cable or panel underfloor heating applications installed on our Dual Fuel Rate when installed in a new construction slab foundation.

A minimum of 9 kW must be installed. Rebates totaling $10,000 or more require prior approval.

Learn more

Contact our Idea Center or call 800-493-3299 to find out if underfloor heat storage is right for you.

You also can consult this technology provider:

This is not an endorsement of this site’s products or manufacturer.