If your chiller is drawing too much power, don't rush to replace the unit. When an ice rink's electricity bill won't come down, it is usually five problems stacking on top of each other: cooling capacity sized too large, evaporating temperature pushed too low, wrong brine concentration, pumps running at fixed frequency all the time, and no insulation blanket at night. The order of diagnosis is just as clear: first calculate the chiller's energy efficiency ratio, then check it against the sub-metering and the full-year bills. For a 1,200 m²-class indoor ice rink in China, a total power consumption of about 1.7 kWh/m²·day can serve as a project-planning benchmark; this figure covers the rink's overall operating electricity use and is not the same as the chiller's own power draw.
The basic COP calculation is: cooling capacity in kW at a given moment divided by the input power in kW at that same moment. EER is also a ratio of cooling capacity to input power, but you have to check which units, operating conditions and system boundary the equipment documentation uses. Standard-condition values in a catalog cannot be taken directly as the annual figure for low-temperature rink operation.
A more practical metric is plant-level system efficiency: the numerator is still the actual cooling output, while the denominator is the combined power draw of the chiller, the brine pumps and the condensing-side equipment. Counting the chiller alone misses the constant-speed pumps, which draw power over the long run.
| Metric | Calculation method or basis | Main use | Common misuse |
|---|---|---|---|
| Chiller COP | Cooling capacity at the same moment ÷ chiller input power | Assess chiller operating efficiency | Using sample conditions in place of actual site conditions |
| EER | Compare on the basis stated in the equipment documentation after verifying units and operating conditions | Check against equipment capacity | Comparing directly across different operating conditions |
| Chilled water plant system efficiency | Cooling capacity ÷ sum of power used by chillers, chilled water pumps and the condenser side | Identify the real points of power consumption | Putting only the chiller in the denominator |
| Annual comprehensive power consumption | Ice surface area × 1.7 kWh/m²·day × operating days | Estimate the annual bill | Treating it as the chiller's own power consumption |
Estimating the annual electricity cost takes two steps. Step one, calculate the electricity quantity: ice surface area × 1.7 × annual operating days. Step two, multiply by the average electricity price applicable to the project, and distinguish business hours, nighttime and closed periods. Do not multiply COP into this comprehensive power consumption formula as well, because the two serve different purposes; and do not double-count the savings from energy-saving measures against the reduction already reflected in the bill.
For indoor standard ice rinks, the cooling load is taken as 350-450 W/m² of ice surface area. A 1,200 m² ice surface corresponds to roughly 420-540 kW of cooling capacity. Ceiling height also needs correction: for every additional 1 m, the cooling load increases by about 3-5 percentage points. The building envelope normally uses 100-150 mm polyurethane cold-storage panels; you cannot have an envelope that is on the thin side and at the same time rely on oversizing the chiller to make up for the gap.
On this basis, blindly adding more safety margin means the pull-down phase appears to have spare capacity, while the business-hours hold phase runs at low load for long periods; start-stop and modulation losses increase, and the pumps may still run at full flow as usual. For new projects, it is better to stage capacity according to load variations—multiple units in parallel or staged control—which makes chiller power consumption easier to control than one oversized unit.
An unstable ice surface does not always mean the evaporating temperature should be lowered further. First check ice thickness, coil heat transfer, brine flow and ice resurfacing operations, then decide whether to adjust the temperature. After each adjustment, review continuous records of ice temperature and chiller power; do not look only at the cooling speed over a few minutes.
Ice thickness should not be judged by feel either. In China, operating thickness is usually 30-40 mm; for figure skating, control it at 40 mm. At 30 mm, there is a risk that jump toe picks can punch through to the coil. For the detailed logic, see How Thick Should the Ice Be? The Difference Between 40mm and 50mm Is Not Just Cost. If the required ice thickness is not achieved and the temperature is simply lowered, power consumption increases and the problem may not be solved.
If the concentration is too high, viscosity rises, pump load increases, and heat transfer conditions deteriorate; if the concentration is too low, the freezing-point margin is insufficient and operating risk rises. The correct approach is not to top up by feel, but to test against the design concentration and freezing-point requirements, circulate thoroughly after topping up, and then retest.
Concentration, flow and temperature should be kept on the same operating log. Topping up brine without checking the pump and heat transfer can easily turn a concentration issue into long-term high power consumption in the chiller plant.
Pump flow is sized at 0.32 m³/h·kW with a 3K temperature differential. For a typical 1200 m² system in the 390-460 kW class, flow is about 160 m³/h, which can be arranged as 2 duty and 1 standby at 80 m³/h each. This sizing addresses transport capacity; it does not mean the pumps must run at fixed speed and full flow all day.
When the ice surface load drops at night, if flow is still maintained by valve throttling or bypass, the chiller load changes but pump energy use does not change with it. During retrofits, verify the allowable operating conditions of the chiller and coils, then use variable frequency control with temperature-differential and pressure-differential control, while retaining the necessary protection and manual operating modes.
Covering the ice with insulation blankets at night, for a period of 22:30-09:30, can reduce the ice surface load from about 220 kW to about 25 kW, saving about 700 kWh per day. For a 1200 m² ice rink with total daily power consumption of about 2040 kWh, this is close to one-third of daily consumption, and its priority is usually higher than repeatedly fine-tuning chiller parameters.
Insulation blankets must also be paired with proper storage, full coverage, and opening/closing procedures. If they are only purchased and not used, the savings will not show up on the bill.
The following is for preliminary comparison only, not a project quotation, and the equipment scope also differs:
For the small-capacity range, chiller equipment using multiple parallel scroll units typically ranges from RMB 200,000-500,000, varies with configuration, and is ultimately calculated per project.
For the 1200 m² class, equipment using screw chillers and including the main chiller plant ancillaries typically ranges from RMB 600,000-1,200,000, varies with configuration, and is ultimately calculated per project.
When retaining usable chillers and carrying out combined retrofits such as pump variable frequency drives, sub-metering, and nighttime insulation blankets, the typical range is RMB 100,000-400,000, varies with configuration, and is ultimately calculated per project.
When comparing tiers, first clarify whether pumps, piping, controls, installation, and insulation blanket deployment equipment are included. For equipment scope, refer to the real ice rink equipment in our main products; do not compare only the chiller itself.
If your facility is around 1200 m² with a high ceiling and significant foot traffic fluctuations throughout the day, choose a solution sized at 420-540 kW and then adjusted in stages. First account for the load increase caused by each 1 m increase in ceiling height, then determine the parallel or staged configuration, and do not select a single chiller with excessive cooling capacity. Arrange the pumps as 2 duty + 1 standby, and provide for variable frequency drives and sub-metering, so as to avoid a situation where the main units are adjustable but the distribution system is not.
If your facility focuses on figure skating training, choose a solution that can stably maintain a 40 mm ice thickness and verifies evaporation temperature together with coil heat transfer. Do not use excessively low temperature as a substitute for ice thickness management, and do not treat 30 mm as the operating thickness for figure skating. When comparing equipment, look at continuous operation records and adjustment capability, and check the ice resurfacing, ice maintenance and overnight insulation procedures, to prevent a situation where the main unit parameters look good but the ice surface still relies on high power consumption to maintain.
If your facility is an existing ice rink where refrigeration is basically sufficient but electricity costs are high, choose operational diagnostics and partial retrofits first, and do not replace the main units first. Continuously record cooling load, chiller power, pump power, secondary refrigerant concentration and ice thickness, then check in sequence the cooling capacity margin, evaporation temperature, concentration, fixed-speed pumps and whether insulation measures are being implemented. Power consumption that can be solved through distribution and overnight insulation should not be directly counted as a need to replace the main units.
Based on general conditions: ice surface 1200 m², cooling demand approximately 420-540 kW; the comprehensive daily power consumption anchor is 1200×1.7, i.e., about 2040 kWh. Estimated on 365 days of operation, annual comprehensive power consumption is about 745,000 kWh, then multiply by the applicable electricity price for the project to obtain the annual electricity bill estimate.
If overnight insulation is consistently implemented every day, about 700 kWh is saved per day; annualized on the basis of daily implementation throughout the year, the order of magnitude is about 256,000 kWh, and actual values should still be corrected according to operating days and the bill. This example is used to determine the sequence of measurement and retrofits and does not represent the benefits of any specific project. For new construction or renovation, the chiller plant, ice surface and overnight insulation should be included in the same ice rink design and construction planFirst use 420-540 kW to verify the cooling capacity for a 1200 m² ice rink, and do not blindly oversize the chiller beyond the load calculation. Document the COP measurement time, operating conditions and electrical boundary in the acceptance documents, and install separate metering for the chiller and pumps. For the retrofit sequence, first check the evaporating temperature, secondary refrigerant concentration and fixed-speed pump operation, then ensure the 22:30-09:30 insulation schedule is actually implemented. Finally, use 1.7 kWh/m²·day to estimate annual electricity consumption and calibrate it against actual utility bills. Equipment and retrofit costs vary with configuration and are ultimately calculated on a project basis.
