Though operational measures and equipment maintenance are low-hanging fruit, greater investments in retrofits and equipment upgrades can provide large persistent savings with potentially short payback periods.
Install LED lighting. LEDs offer several advantages over conventional light sources, including high efficiency, long life, and superior control. These characteristics, along with falling prices, have made LEDs a viable solution for a growing number of applications.
In particular, LED troffers offer a number of benefits in the right applications, and prices continue to fall. Troffers are long, recessed lighting fixtures that are typically installed with the opening flush with the ceiling and with their inner surface serving as a reflector. The best LED troffer products currently outperform their fluorescent cousins, and replacement options include new LED troffers, LED retrofit kits, or fluorescent tubes swapped for tubular LED products.
For more information on choosing LEDs, see the section “How To Make The Best Choice” located on our LED page.
Add heat recovery. On average, as much as 7.2 million Btu of heat, or more than 2,000 kilowatt-hours, are generated each day by an ice plant—more than enough to satisfy the entire daily heating load of the ice rink while having excess thermal energy available for other purposes. By implementing heat-recovery systems, ice rinks can realize overall heating savings of more than 75 percent. Most of the waste heat available comes from the refrigeration condenser, but some heat can be also recovered from the building’s exhaust air. Recovered heat can be used for space heating, domestic water heating, subfloor heating, floodwater heating, ice melting, and preheating cold outdoor air for ventilation.
Add pressure controls. Many refrigeration systems are designed for outdoor temperatures of 86°F and, as a result, often have higher head pressures than needed, resulting in high condensing temperatures and increased electrical consumption. Particularly in cold climates, modulating head pressure based on outdoor air temperature can yield refrigeration savings as high as 25 percent.
Install adjustable-speed drives. Adjustable-speed drives match a machine’s motor output to its real-time load. They can be an effective way to save energy in condenser and brine pumps. By reducing pump speed when possible, ASDs can reduce not only the energy consumption of the pumps themselves, but also the amount of heat added to the brine through friction (which increases cooling loads).
Optimize brine use. Brine should be kept at a specific gravity of 1.20 to 1.22 for most efficient energy use. To measure the specific gravity, or density relative to water, use a hydrometer. Make sure to let the brine sample warm up to 60°F before testing. 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 (mix in a barrel and add through mixing valve), or dilute the brine with water to decrease. Insulating the brine storage tank will reduce cooling losses and heating costs in the compressor room.
Use the brine line as a dehumidifier. Using a return brine loop in the corner of the ice rink can be a great trick to keep humidity—and thus refrigeration loads—under control. Set the brine to 22°F, which will cause frost to form on the line, removing water from the air. A defrost cycle is required to melt the frost and drain the melt water into a drain pit. This will help to keep humidity levels under 50 percent and prevent cooling loads from increasing significantly. An alternative is to use a refrigeration dehumidifier, which extracts moisture by cooling the air on coils.
Use ceiling modifications that radiate less heat. Nearly 30 percent of the total refrigeration load in heated rinks is radiated from the arena ceiling. After reflective paint or ceiling curtains are installed, making the ceiling less emissive, ice rinks may demonstrate energy savings of up to 80 percent of the radiated heat (equivalent to around 24 percent of total refrigeration load), particularly when they are located in warm, humid climates. Low-emissivity ceilings can also help to boost illumination levels and reduce ceiling condensation.
Implement a building automation system. Installing a computerized building automation system (BAS) is an expensive commitment with substantial up-front costs, but it can provide many benefits. Considering the costs of a BAS, a thorough economic analysis should be performed before the system is installed. Using a BAS can be a particularly good option for large facilities with high energy consumption. Facility management should explore additional applications that the system may be able to automate to help substantiate its feasibility. For example, many systems can also handle registrations, inventory, and accounting. In ice rinks, a computerized BAS can control:
- Refrigeration systems
- Brine pumps
- Ice temperature
- Lighting and illumination levels
- Ventilation equipment
- Heating systems
- Other electric equipment
- Domestic water heating
- Demand functions
Some of the main energy-saving functions available include:
- On/off switching
- Dimming and setback
- Thermostat adjustments
- Time of day scheduling
- Demand control
- Equipment monitoring
- Alarm functions
De-gas resurfacing water. According to ASHRAE, domestic hot water and resurfacing generally accounts for 7 percent of an ice rink’s total energy use. The more impurities water contains (both minerals and dissolved gas), the colder it needs to be before it will freeze. More energy is required to do lower that temperature, and the resulting ice will have poorer quality. To address these issues, most ice rinks boil water to remove dissolved gas before resurfacing the rink. However, this technique not only requires energy to heat the water but also increases the refrigeration load because warm water is being applied directly to the ice.
Instead of boiling resurfacing water, a new approach called vortex water treatment can remove air bubbles passively: It creates a vortex in the water line that isolates bubbles in a low-pressure zone, removing them from the water. This results in harder, smoother ice that requires less maintenance. Vortex-treated water has fewer impurities than boiled water and can therefore be frozen at a higher temperature. The process saves energy in several ways: Natural gas is saved by eliminating the need to heat resurfacing water. Electricity is saved by directly reducing the refrigeration load and through raising the ice slab temperature.
Consider synthetic ice. When planning new construction or major retrofits, consider installing synthetic ice. Synthetic ice is a solid polymer material designed for skating using normal metal-bladed skates. Synthetic ice will wear down the skates faster and must be cleaned regularly to maintain rink attractiveness. Although you’ll need to evaluate the performance of the synthetic ice product with respect to your facility’s needs, this measure can effectively eliminate almost all major sources of energy consumption in ice rinks.