Introduction
Across the commercial building sector, refrigeration systems represent a large untapped source of recoverable thermal energy. Supermarkets, grocery stores, cold storage facilities, and other buildings with large refrigeration systems continuously release heat as part of the process of keeping refrigerated areas cold. Every time compressors remove heat from refrigerated display cases, freezers, or coolers, that energy is rejected outdoors through condenser fans. Without refrigeration heat reclaim, this valuable resource is simply released into the air—representing a lost opportunity for energy savings.
Refrigeration heat reclaim, also called heat recovery, is a technology that captures and repurposes this otherwise wasted heat. This reclaimed heat can then be used to support a building’s domestic hot water and space heating, reducing the demand on conventional gas or electric heating equipment. When paired with a building’s HVAC or DHW systems, reclaimed heat can meet a large portion of a facility’s heating demand, significantly reducing energy use, utility costs, and carbon emissions.
Refrigeration heat reclaim supports California’s energy efficiency and decarbonization goals, while helping building owners meet code requirements such as Title 24, Part 6, which mandates heat reclaim for certain grocery and retail facilities. For new construction projects, integrating heat reclaim early in the mechanical system design provides a cost-effective pathway to long-term operational savings and environmental performance.
How It Works
Refrigeration heat reclaim systems capture waste heat from refrigeration equipment and DX air conditioning systems and reuse it for beneficial heating within the building. As refrigerant leaves the compressors, it carries significant thermal energy that would otherwise be rejected outdoors through condenser fans. A heat exchanger installed in the refrigerant discharge line recovers this heat and transfers it to a separate water or water/glycol loop.
The heated fluid is then circulated through the building by a small pump, supplying recovered heat to DHW storage tanks, hydronic coils for space heating, or air-handling units for reheat or dehumidification. If the building’s heating needs exceed the available reclaimed heat, a conventional boiler or heat pump water heater can provide supplemental capacity. When no heating demand exists, the system automatically bypasses the heat exchanger and rejects excess heat outdoors, ensuring reliable refrigeration performance.
There are two primary types of refrigeration heat-reclaim systems: partial-recovery (desuperheating) systems and full-condensing systems. Desuperheating systems capture only the hottest portion of the refrigerant’s discharge gas—known as “superheat”— and are typically used to preheat DHW. Full-condensing systems capture both the superheat and the larger amount of latent heat released as the refrigerant condenses. While more complex and costly, full-condensing systems can meet a significant portion of a facility’s heating or hot water demand and provide greater long-term energy and emissions savings.
What Are the Benefits?
- Minimizes energy use for water and space heating.
- Reduces utility costs by lowering the building’s gas or electric heating demand.
- Provides a low-carbon heat source when integrated with HVAC systems, improving efficiency and supporting sustainable design.
- Offsets fossil-fuel heating, lowering greenhouse gas emissions and helping meet decarbonization goals.
What Are the Challenges/Constraints?
- Can have significant capital costs for equipment, engineering, and commissioning, though long-term energy savings often offset these expenses.
- Requires regular maintenance and performance checks to prevent fouling, valve issues, or pump wear.
- Knowledge gaps among design teams and operators—combined with limited field data and broader industry awareness—can create uncertainty around optimal operation, control strategies, and system reliability, slowing market adoption.
References:
- Copeland. (n.d.). How to leverage heat recovery in your industrial refrigeration system [White paper]. Copeland. https://media.copeland.com/05aa2593-774b-42b1-b5a4-b16d004e86b4/C011%20Heat%20Recovery%20white%20paper%2013257-EMR-Vilter_WhitePaper_LR2.pdf
- Reis, C., Nelson, E., Armer, J., Johnson, T., Hirsch, A., & Doebber, I. (2015). Refrigeration Playbook: Heat Reclaim — Optimizing Heat Rejection and Refrigeration Heat Reclaim for Supermarket Energy Conservation (NREL/TP-5500-63786). National Renewable Energy Laboratory. https://docs.nrel.gov/docs/fy15osti/63786.pdf
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