What It Means

Thermal Energy Storage (TES) is a technology that stores thermal energy—either heat or cold—for later use. It allows buildings and infrastructure to balance energy demand by capturing excess thermal energy when it’s available and releasing it when it’s needed.

There are three main types of thermal energy storage used in the built environment:

• Sensible Heat Storage (e.g., using water or concrete to store heat by raising its temperature)
• Latent Heat Storage (e.g., using phase-change materials that absorb/release heat during melting/freezing)
• Thermochemical Storage (e.g., chemical reactions that store or release heat on demand)

In the AEC industry, TES is often used in building systems like HVAC, district heating/cooling, and renewable energy integration (e.g., solar thermal).

Why It Matters

Thermal energy storage in buildings offers several performance, sustainability, and cost-saving benefits:

• Reduces peak energy demand, lowering utility bills and grid strain
• Improves system efficiency by decoupling energy production from use
• Enables greater use of renewable energy, especially solar thermal
• Contributes to decarbonization by shifting energy consumption to off-peak or low-carbon periods

TES is becoming increasingly important in climate-responsive architecture and net-zero energy buildings.

Best Practices for Thermal Energy Storage

• Use TES in climates with high daily or seasonal temperature swings.
• Integrate with HVAC systems to store chilled or heated water during off-peak hours.
• Model TES performance using energy simulation tools early in design.
• Select phase-change or storage materials appropriate to your building’s thermal profile.
• Coordinate with MEP engineers to size and locate storage components efficiently.

Real-World Use

A university campus uses large chilled water tanks to store cooling energy produced at night, when electricity is cheaper. The system releases this energy during the day to meet cooling demand, reducing both energy costs and carbon footprint. In smaller buildings, TES might be integrated with radiant floor systems or solar thermal collectors.

Limitations

• Space requirements can be significant for tanks or other storage components
• Upfront cost may be high depending on system size and complexity
• Control strategies must be well-coordinated with HVAC or energy systems
• Thermal losses can occur if systems aren’t properly insulated or designed

In Simple Terms

Thermal energy storage is like charging a thermal battery—storing hot or cold energy so your building can use it when it needs it most, instead of when energy is most expensive.

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