ASHRAE Journal - June 2009 - 17

used approximately 100 hours per week. The ice is resurfaced Subfloor Heating Using Heat Recovery approximately 65 times per week. When an arena is used for more than seven months, it is The lighting of a nonefficient amphitheatre uses approxi- important to eliminate the possibility of freezing the subsoil. mately 32 kW for most ice activities. Most of the lighting In fact, the concrete slab under ice rinks had to be replaced in fixtures are installed above the ice rink (1.9 W/ft2 [20.5 W/ several arenas because of damages created by the formation m2]) and lower density lighting fixtures are installed above the of frost in the soil under the floor. To eliminate this problem, stands (0.7 W/ft2 [7.5 W/m2]). Elsewhere in the building, the 4 in. (102 mm) of polystyrene insulation is installed under the average lighting power is approximately (2 W/ft2 [21.5 W/m2]) concrete slab of the ice rink. Heating must be provided in the for a total of 15 kW. Exterior lighting could amount to 2 kW. soil under the insulation to prevent freezing. The average heating The ventilation requirements of the amphitheater are ap- requirement amounts to 20,500 Btu/h to 27,300 Btu/h (6 kW proximately 10,000 cfm (4719 L/s), but the author’s observations to 8 kW). It is used for the full eight months of operation. The show that ventilation is not continuously used. Ventilation of an heating of the subfloor could be provided by the heat rejection amphitheater is used for 15 minutes after each ice resurfacing of the condenser of the refrigeration equipment. to evacuate the pollution created by the propane gas combustion As this is a low-temperature requirement, it could be provided of the ice resurfacing machine. Several arenas use pollution at a condensing temperature that could be limited at 70°F (21°C) detectors to monitor the ventilation use, which explains why during winter months. The potential savings is equal to the total the ventilation is not in continuous operation. Other ventilation heat requirement of 35,000 kWh. systems with a total of fresh air of 7,000 cfm (3304 L/s) are used for the other spaces. DHW and Surfacing Water Requirement The refrigeration load of a standard arena, operating for eight Domestic hot water and water used by the ice resurfacer months, is 70 tons (246 kW) of cooling using an average 110 hp (82 require a higher temperature. The refrigeration gas superheat kW) for the refrigeration compresavailable at the outlet of the sors. The brine pump (850 gpm compressor offers an excellent [54 L/s]) generally uses a 25 hp opportunity for the heating of (19 kW) motor. The refrigeration DHW. The problem with DHW equipment is in use throughout the and ice surfacing water is the eight months of operation. wide variation of daily demand. Heating is provided either by Therefore, water storage is renatural gas, propane gas, oil or quired. Successful preheating of electricity. In the province of domestic water is achieved with Quebec, several arenas are heated a 2,000 gallon (7571 L) water with electricity, but most arenas storage tank (often two tanks of use a dual source of energy (ei1,000 gallons (3785 L) each). ther gas and electricity or oil and With this amount of storage, it electricity). Stands are heated in often happens that in the mornmost municipal arenas. When Typical municipal ice arenas consume 1500 MWh/year. ing after heat recovery of the heated, the stands are frequently gas superheat, the 2,000 gallons kept to a comfort level with radiant gas units. (7571 L) may be at 170°F (77°C), ready for the daily operation. As an exercise for evaluating the energy savings measures, Monitoring of energy savings in some arenas show that the full let’s assume that we have a nonefficient arena with an annual DHW and surfacing water requirement could be provided with energy use of 1,950,000 kWh. The total energy consumption heat recovery on the gas superheat. The annual savings could could be divided into the following uses as shown in Figure 1. amount to 130,000 kWh. Several energy-saving measures could be implemented in an existing building such as this one or when planning a new building. Brine Pump Several tests were conducted in the Montreal area by modifyHeat Recovery on Exhaust ing the distribution of the brine in the floor slab under the ice. In northern regions, the first energy saving measure to The modified distribution used a four-pass arrangement instead implement is usually the heat recovery of energy leaving the of the conventional two-pass arrangement. This modification building in the exhausted air. This can be used for preheating had a major impact on the energy use of the brine pump. It cut the outside air being introduced for ventilation. This measure the energy requirement by 50%. Tests conducted showed the has a significant impact on the whole energy balance of the ice quality was the same and that no noticeable change in the building. For instance, in this typical building, the energy activities carried out on the ice was reported during the test savings with the use of a thermal wheel at 75% efficiency period. It was once reported that the four-pass distribution could reach 250,000 kWh. This savings will appear on the was better than the two-pass distribution. This specific comheating usage. ment was for a central refrigeration plant for two ice sheets, June 2009 ASHRAE Journal 17

ASHRAE Journal - June 2009

Table of Contents for the Digital Edition of ASHRAE Journal - June 2009