Oilers Rink Turning Heads in Edmonton
By Adam Freill
Young NHL phenom Connor McDavid is lighting things up in his first year as the captain of the Edmonton Oilers, but even he might understand if a visitor to Rogers Place pays more attention to the building than the team.
The new home of the hockey club is an impressive 819,200 sq. ft. structure that sits on 9.5 acres of land and features a pair of NHL-sized rinks, seven levels of seating for 18,347 fans, a 30,000 sq. ft. dressing room for the team, and a 400-ton ice plant designed to create some of the best ice anywhere.
That’s a big step up from the team’s former arena, the 497,700 sq. ft. Rexall Place. The new structure, which is the centerpiece of the city’s new 25-acre ICE District, actually approaches the size of a stadium, rather than an arena. Of course, Rexall Place has a great reputation for quality ice, but the team working the ice system at the new building is creating its own buzz for ice quality.
"We know what the history of Rexall’s ice quality has been," says Jason Rimmer, the assistant manager of engineering with Oilers Entertainment Group. "We have our own target to try to be the best in the NHL – of course everyone wants to be the best in the NHL."
Rogers Place, By the Numbers
1st – The first LEED Silver NHL arena in Canada
819,200 sq. ft. – Size of Rogers Place
9.5 acres – Size of the Rogers Place property
18,347 – Capacity for NHL games
20,030 – Capacity for concerts
46 ft. x 46 ft. x 36 ft. – Scoreboard size – the largest true high-definition centre-ice scoreboard in the NHL
8,321 – Number of workers who worked on the project
$483.5 million – Cost to build
Anatomy of the Rinks
At the heart of the ice plant at Rogers Place are four screw compressors that deliver a total of 400 tons of refrigeration that is split between the two rinks, the NHL surface and the attached Downtown Community Arena (also NHL-sized). The main surface sits on a slab containing almost 10 miles of 1-1/4" schedule 40 steel tubing on four-inch centres, while the community rink uses 1" polyethylene piping.
The ice plant is an ammonia-based system, with a heat exchanger in place so that glycol runs through the slab piping for both 200-ft.-by-85-ft. rinks.
Creating good ice starts by getting good information about system conditions, so sensors are included on the supply and return for each rink, and the system also makes use of in-slab sensors for each surface.
"In the NHL rink we installed an additional eight sensors that we’ve just put on the top of the slab, and we also have two infrared cameras on the NHL rink, and one on the community rink," adds Rimmer. "The advantage with our sensors is that we can tie them right into our DDC system. That way we can control right off those sensors, and we can base it on the lowest, the highest or an average temperature reading of those eight sensors."
Building Good Ice
Creating a fresh ice surface from a bare slab is a process that can take several days as thin layers are built up to reach a target ice thickness of an inch and a half.
The engineering crew cools the slab floor to between 15 and 16°F before hitting it with water. That allows each layer to freeze fairly quickly between building the layers.
"It can take about four days, depending on how much of a hurry you are in," says Rimmer. "We had a week to build it on our first go-around."
During a game, a typical flood will go through 100 to 130 gallons of 140°F water, but even that takes a bit of engineering control.
"When we are running a game here, we will throw 300 tons at the NHL rink during the pre-cool before the period ends, so that when the water hits during the flood we are freezing as quickly as possible," explains Rimmer.
Good ice requires a combination of slab temperature control, and appropriate ambient temperatures and humidity. "Our targets are 22°F on the surface for the ice, 40 per cent relative humidity, and 57°F for air temperature."
And while most arenas fight the issue of having too much humidity, that’s not an issue in Edmonton.
"For us, our biggest advantage is that we live in Edmonton and it gets drier than the Sahara in the winter here," says Rimmer, who explained that the team is monitoring the ice during this first season to determine whether they might need to add a humidification aspect to the existing HVAC system.
The arena is equipped with a dehumidification system, but mainly for shoulder seasons.
"With most hockey rinks, humidification is the last thing you want to add, but that is a reality of being in Edmonton," he states. "When the humidity gets too low, you start sublimating your ice and the ice shrinks, and you could potentially have challenges from that too.
"That’s something that we’ve talked about and we are going to go through the first year and see how it goes. If it does get too low, we are going to look at some humidification options for next year."
Tempering the Ice
One of the most striking differences when skating on a pro-level ice surface, in comparison to most local rinks, is the hardness of the ice. At Rogers Place, the ice undergoes a unique tempering process that helps with the quality of the surface.
"We warm the slab and the ice up to just below the melting point," explains Rimmer. "We normally target 29°F in the slab.
"We flood the ice, and flood and scrape and flood and scrape it. You are trying to saturate the ice, and you keep doing it until the ice doesn’t absorb any more moisture."
At that point, the ice crew brings the ice temperature down to 22ºF at a very controlled rate – generally about 0.4 degrees per hour.
With the compressors rolling, there’s waste heat that has to go somewhere, and rather than allowing that to dissipate into the atmosphere, the engineering team is finding creative ways to use that heat energy.
"Right now we are taking the waste heat and recovering it into the parkade," explains Rimmer. "It has been proposed to incorporate our domestic hot water into our heat recovery as well. With all four compressors operating, we are generating more than six million BTUs per hour, so that’s some substantial heat, which should result in some substantial savings."