Reduce Costs Ice Rink Refrigeration

ice rink refrigeration equipment

Reduce Costs Ice Rink Refrigeration

Ice rinks use a lot of energy. Energy prices are rising and carbon taxes are increasing. Looking at ways to reduce costs for ice rink refrigeration should be a top priority.

Ice arenas are some of the most energy-intensive commercial buildings in a community using a chiller system (both NH3 and HFC), pumps, fans, heating, and lighting.  Ice arenas are typically in use 36 weeks or more per year with approximately 16h per day on weekends and 12h per day on weekdays.

In terms of energy consumption, this means that a typical single pad can use from 1,500 – 2,400 MWh/ year
.  An ice rinks freezing system cools a brine solution pumped through pipes under the ice. 
Brine temps are usually around 16°F – 17°F.

On top and in order to keep high-quality ice, the surface is flooded  6 to 12+ times per day depending on usage. This floodwater is usually heated to 140°F -160°F unless a rink de-aerator system is used to mechanically remove the micro air bubbles. This allows to use and resurface the ice with cold instead of hot water.

The largest portion of the energy use comes from the ice rink’s refrigeration systems, to ensure the necessary cooling to produce and maintain ice surfaces. The chiller removes heat from ice pads and the condenser disposes of it outdoors. On average, as much as 7.2 million Btu of heat, or more than 2,000 kWh, are generated each day by an ice plant. Luckily, there are many ways to reduce the load on the chiller system and therefore reduce the ice rink refrigeration cost.

How to reduce costs for ice rink refrigeration:

 

  1. Add an energy management system
  2. Recover waste heat from a chiller system
  3. VFD’s or variable frequency drives
  4. Remove micro air bubbles from resurfacing water
  5. Add energy-efficient motors
  6. Replace arena slab
  7. Use head pressure controls
  8. Optimize brine use
  9. Replace old compressors
  10. Optimize humidity levels
  11. Adjust inside air temperature
  12. Optimize ice thickness

 

1. Add an energy management system to your rink’s refrigeration system

A computer-controlled ice rink refrigeration system can provide 20% or more in energy savings in comparison to manually operated systems. Such an energy management system is able to adjust the plant to the present weather conditions and facility usage to run most efficiently. Pre-programmed settings make it easier to adjust the ice temperature depending on usage and can be applied for hockey, figure skating, and public skating. Off-hour programming will also help to reduce electricity consumption because it allows the ice temperatures to rise during nighttime hours, or inversely pre-chilling the ice prior to peak demand hours.

 

2. Reclaim waste-heat from the rink

Heat-recovery systems can harness heat as free energy from the ice rink refrigeration system. Most of the wasted heat comes from the refrigeration condenser, however, some heat can also be recovered from the building’s exhaust air. There are various usages for the waste heat such as space heating, domestic water heating, subfloor heating, slab heating, floodwater heating, ice melting, and preheating cold outdoor air for ventilation.

 

3. VFD’s or variable frequency drives

VFD’s allow induction-motor-driven loads such as condenser fans and brine pumps to operate at rotational speeds. Electric motors in industrial applications can be more efficient when using VFDs in centrifugal load service. A variable speed drive controls motor speed and torque by varying the motor input voltage and frequency. By controlling motor speed to correspond with varying load requirements, retrofitting electric motors with VFD controls can increase motor energy efficiency—in some cases by as much as 50%.

 

4. Remove micro air bubbles from resurfacing water

Removing micro air bubbles from the flood water instead of heating the resurfacing water eliminates big parts of your water heating costs for your flood water AND saves 10% – 12% energy from your ice plant. Using extremely hot water not only requires energy to heat but also increases the refrigeration load because warm water is being applied directly to the ice. Instead of using extremely hot temperatures (140-160°F) for the resurfacing water, air bubbles can passively be removed with a rink de-aerator, and the temperature on the resurfacing water is lowered. This treatment of the resurfacing water results in harder, smoother ice that requires less maintenance. In addition, de-aerated water has fewer impurities than boiled water and can therefore be frozen at a higher temperature. Operators are able to reset their brine 3-5°F warmer and therefore reduce the run time on the compressors and save more electricity cost.

 

5. Add energy-efficient motors

New energy-efficient motors help the glycol pump/brine pump, water pump, and compressor motors save electrical energy through decreased usage and make the ice rink refrigeration equipment more efficient. Arenas can install soft-start controllers on the compressor motors. Soft-start controllers reduce inrush current and the resulting peak demand loads and reduce the strain on the compressor during the high torque generated at startup.

 

6. Replace arena slab

In older ice slabs – for example more than 30 years – many components will need to be replaced. This will ensure its ongoing availability to the many local ice user groups and will avoid the added costs of emergency replacement. Over time, the ice slab will shift, which eventually causes the pipes underneath to crack and start leaking brine. Under the ice in arenas, there is a slab that is above the embedded brine (used to keep the ice frozen) tube network. A brand new slab and energy-efficient upgrades will result in gas, hydro, and greenhouse gas savings (GHG).

Here is a time-lapse video from the construction of the Saanich Pearkes Gold Rink:

7. Use head pressure controls

Ice rink chiller systems are often designed for higher outdoor temperatures. As a consequence, the head pressure is higher than needed. This leads to high condensing temperatures and increased electrical consumption. There is a benefit, especially in cold climates, to modulate the head pressure based on outdoor air temperature. This can yield refrigeration savings as high as 25%.

 

8. Optimize brine use

The brine should be kept at a specific gravity of 1.20 to 1.22 for the most efficient energy use. A hydrometer can be used to measure the specific gravity, or density relative to water.

Specific gravity is measured relative to water, which has a specific gravity of 1.0. To adjust the specific gravity, add calcium chloride flakes to increase, or dilute the brine with water to decrease. Experts recommend testing the brine annually by a lab regularly engaged in testing arena brine samples.

 

9. Replace old compressors

Ice rinks require a refrigeration system (direct or indirect), which removes heat and creates cold. Replacing old compressors saves a lot of energy and maintenance costs. The compressors are in the heart of a rink’s refrigeration system. It’s the only active main component maintaining the flow of refrigerant. The new equipment will increase the cooling efficiency of the compressor.

 

10. Optimize humidity levels

Humidity has a big impact on the energy consumed in the rink and it impacts the quality of the ice. If the humidity is high, the ice surface will be rugged and produce a lot of snow when in contact with the sharp blades of a skate. 50-55% is the optimal humidity. This is especially important when there are large crowds that often contribute to the increased humidity levels. Excessive humidity in the condensing moisture releases a tremendous amount of heat into the ice surface which has to be removed by the ice rink’s chiller system.

 

11. Adjust inside air temperature

Lowering the inside air temperature from 60°F to about 40°F  reduces the energy consumption of the ice arena. Inside air temperature has a great effect on the ice plant because the ice melts faster at higher ambient temperatures.

 

12. Optimize ice thickness

If the ice is too thick, it will increase the compressor load of the chiller system. The thicker the ice and concrete, the harder it is for the rink’s refrigeration system to maintain a desired ice surface temperature. Each additional 1 inch (25.4 mm) of ice adds approximately 10,000 kWh/yr to the required energy to maintain the ice surface. Most rink facilities maintain their ice thickness between 1 1/4” to 1 1/2”  as an industry-accepted standard. Finding the optimal thickness of the ice and the thickness of the concrete slab beneath are critical factors in rink refrigeration efficiency. Ice and concrete act as insulators, resisting the transfer of heat to the ice rink’s refrigeration system.

 

Check out:  More ways to reduce ice rink costs

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