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| Fig. 1: Diagram of an ice rink's layers. [2-4] (Image source: A. Zhou.) |
Indoor ice rinks are among the most energy-intensive recreational facilities, constantly maintaining a surface that is prone to melting. Ice rinks operate in a permanent battle against warm air, human activity, and indoor lighting which all feed heat into the ice surface, while the refrigeration system must continuously remove it. Because the ice must be kept between -3°C and -5°C for hockey and figure skating performance, even small fluctuations can degrade play quality and pose hazards. [1] This paper explains how the layered structure of the rink and the refrigeration cycle come together to mitigate heat transfer to maintain the frozen surface.
Although the ice surface appears simple from above, a modern ice rink is built as a robust, multilayer thermal system (Fig. 1). Each layer from the visible ice to the gravel base, is designed to manage heat flow, structural load, and moisture. The topmost layer is the ice sheet, typically 33-39 mm thick for hockey and slightly thicker for figure skating. [2] Paint, rink markings, and logos are added between early layers and sealed under the clear ice. Immediately beneath the ice lies a thick concrete slab. This slab serves as both the structural foundation and the primary heat-exchange interface. Embedded within the concrete is a dense grid of cooling pipes, through which the coolant, a chilled brine solution often of either calcium-chloride or ethylene glycol circulates. [3] Because the concrete slab must maintain uniform temperature across its entire area, pipe spacing, slab thickness, and brine flow rate are designed to avoid hot spots or unevenness. Below the concrete slab is a high-density insulation board, usually extruded polystyrene (XPS) or rigid polyurethane. [4] Beneath the insulation lies a second concrete layer containing the sub-slab heating system. This system circulates warm water through pipes to maintain the ground temperature at slightly above freezing. This layer prevents frost heave, a structural distortion caused when soil freezes, expands, and pushes upward on the slab, which could severely damage the rinks structural integrity. Under the heated slab is a compacted sand and gravel bed, which help to prevents moisture accumulation beneath the rink. Finally, at the bottom of the rink assembly lies a groundwater drain system whose job is to direct groundwater away from the structure, preventing water from pooling under the slab.
Indoor ice rinks experience heat gain from numerous avenues, with the major contributors being convection from arena air, thermal radiation from lighting, people on the ice, and heat from the various mechanical equipment used in a rink. All this heat generated must be transported away by the refrigeration system. Modern rinks use a large-scale vapor-compression refrigeration cycle that occurs in four key steps: [5]
Compression: The refrigerant enters the compressor as a cold, low- pressure vapor. There it is compressed, raising its pressure and temperature. After this step, the refrigerant becomes a hot, high-pressure gas capable of releasing the heat it has absorbed from the brine.
Condensation: The hot, high-pressure gas flows into the condenser, usually located outdoors or in a dedicated mechanical room. Here, it releases its stored heat to the outside air or to a heat-recovery system. As it loses this heat, the refrigerant cools and condenses back into a liquid.
Expansion: The liquid refrigerant then passes through an expansion valve, where its pressure drops suddenly. This rapid pressure drop causes the refrigerant to cool and temporarily become a colder liquid-vapor mixture.
Evaporation:d This re-cooled refrigerant enters the evaporator (chiller), where it runs in close thermal contact with the warmer brine from beneath the rink floor. The refrigerant absorbs heat from the brine and evaporates back into a vapor. The vapor then returns to the compressor, and the cycle repeats continuously.
A standard National Hockey League size rink is 61 m by 26 m, giving an ice area of about 1,586 m2. [6] Researchers estimate for a rink of that size that it is typically 135 watts m-2 under normal operating conditions, largely due to convective exchange with air, long-wave radiation from the building envelope, and moisture transfer. [7] That means the refrigeration system must remove approximately 214 kW of heat at any given moment. Spread over a full 24-hr day, this means 5,136 kWh of heat removed per day. Because the refrigeration system works as a heat pump, it removes a certain amount of heat for every unit of electricity it consumes. Lets say we have a coefficient of performance (COP) of about 3 for the rink's refrigeration system, basing off reported COPs from a study done by Natural Resources Canada. [8] With that, the electricity required is closer to 1,712 kWh of electricity per day. Over a 250-day operating season, the rink therefore needs roughly 428,000 kWh or 0.428 GWh of electricity for cooling alone. This aligns with published energy surveys of arenas, which show that total facility energy consumption (including lighting, ventilation, heating, and refrigeration) often falls between 0.77 and 1.48 GWh per year, with refrigeration consistently the single largest contributor. [9]
© Alice Zhou. The author warrants that the work is the author's own and that Stanford University provided no input other than typesetting and referencing guidelines. The author grants permission to copy, distribute and display this work in unaltered form, with attribution to the author, for noncommercial purposes only. All other rights, including commercial rights, are reserved to the author.
[1] Z. Zhang et al., "Parametric Evaluation of Cooling Pipe in Direct Evaporation Artificial Ice Rink," Energies 15, 7989 (2022).
[2] R. H. S. Hutchins et al., "Arena Ice Quality and Perspectives on Optimizing Performance and Addressing Emerging Challenges," Sci Rep. 15, 13600 (2025).
[3] W. Zhou et al., "Simulation of the Optimal Refrigerated Floor Design for Ice Rinks," Energies 14, 1535 (2021).
[4] J. Mun and M. Krarti, "Optimal Insulation For Ice Rink Floors," Energy Build. 108, 358 (2015).
[5] F. Alsouda et al., "Vapor Compression Cycle: A State-of-the-Art Review on Cycle Improvements, Water and Other Natural Refrigerants," Clean Technol. 5, 584 (2023).
[6] "2024-25 Official Rules," National Hockey League, 2024.
[7] L. Li, X. Liu, and T. Zhang, "Investigation of Heat and Mass Transfer Characteristics in the Ice Rink: Ice Making, Maintaining and Resurfacing Orocesses," Build. Environ. 196, 107779 (2021).
[8] "Comparative Study of Refrigeration Systems for Ice Rinks," Natural Resources Canaca, July 2013.
[7] X. Du et al., "Comparison of Light-Thermal Environment and Energy Consumption in Ice Sports Venues Between China and Finland," Energy Build. 349, 116523 (2025).