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Outdoor Ice Season and Energy Savings A timing based approach to energy savings and ice quality improvement at Toronto's 49 Outdoor Ice Rinks Prepared by Corey Chivers for the Centre for Local Research Into Public Space CELOS Slide 2 Toronto's Outdoor Ice Rinks at a Glance Toronto has more outdoor compressor cooled ice rinks than any city in the world 4 outdoor rinks at central locations and 45 outdoor rinks scattered in neighbourhoods throughout the city Ice rinks provide a much needed social gathering space during the winter months Source: www.cityrinks.ca Slide 3 Watching the Rinks For over 10 years, CELOS has been keeping a close eye on Toronto's outdoor rinks One thing that we have consistently noticed (and have been told by rink users across the city) is that ice surfaces seem to deteriorate in the spring despite air temperatures still being fairly cold. We wondered, what is going on here? Slide 4 Dispelling Misconceptions The rink hotline at Dufferin Grove AIR receives dozens of calls a day during warm spells asking is there any ice left? What makes Toronto's outdoor ice rinks so special is that they don't leave it up to Mother Nature to keep them frozen... Slide 5 Warm air Skate On! Slide 6 Rinks: Giant Refrigerators The rinks work just like your kitchen refrigerator (sort of...) Big electrically driven compressors cool ammonia, which in turn cools a salt brine or glycol solution. Slide 7 Rinks: Giant Refrigerators Electrically driven pumps pump that cold brine through a series of tubes underneath the ice surface This process removes heat from the ice slab keeping the rink frozen Slide 8 Saving Energy In 2000, City Council voted for an environmental plan (EP), meant to reduce community- wide carbon dioxide emissions by 20% by 2005 (from 1990 levels), and also to reduce energy use by 15% in all its departments. In 2002 the City hired CINERGY Solutions to undertake a $10.2 million energy retrofit of the city's arenas and rinks. Source: toronto.ca Slide 9 Saving Energy without Spending Money CELOS recommends opening the rinks during the weeks of the year that are best suited to outdoor artificial ice This will save energy costs and deliver better ice to Toronto's skaters Slide 10 Better Ice, Happier Skaters Slide 11 The Season Since amalgamation, the rinks have been opening later and later in the year, shifting the rink season toward the spring months. Not only is this not ideal from an energy perspective, but census counts of skaters carried out at Dufferin Rink over the past four years show a marked decline in interest in skating in March. Slide 12 Slide 13 Modelling the effects of temperature and sun on energy consumption and ice quality Cooling load depends on the ambient air temperature as well as the radiative heating contribution from the sun The relative contributions of each were modeled mathematically over the period of November 1 st to March 31 st Slide 14 Results When sun and average air temperature are taken together, we see that the compressors must work beyond their capacity to keep ice after March 1st. It can also be seen that ice is more viable throughout the month of November than in March. Slide 15 Figure 1 Slide 16 Results We then ran the model to compute the maximum temperature for each day of the season at which skateable ice could exist. Figure 2 shows this curve compared with the average daily temperatures (from Environment Canada). Slide 17 Results Figure 2 Slide 18 What's going on? During the winter months the sun stays low in the sky throughout the entire day. For this reason, there is drastically less solar input than there is in the summer. (In fact, this is why we have summer and winter!) Let's take a look at what happens when we rerun the model to simulate all overcast days... Slide 19 Figure 3 Slide 20 A Closer Look Figure 4 Slide 21 The sun is our culprit! Outdoor ice rinks can hold ice at almost 20 C in overcast skies in December. Providing you've got a cloudy day, the time interval over wich ice can be held in air temperatures over 15 degrees is November 1 st to February 9 th. The capacity to hold ice is drastically reduced beyond March 1 st (for both sunny and overcast) Slide 22 Are Outdoor Rinks Doomed? These results have interesting implications for those who would suggest that outdoor ice rinks are on their way out in the face of climate change. Even with an increase in average air temperatures, the outdoor compressor cooled rink will live on! Slide 23 Recommendations Operate the city run outdoor ice rinks from the First of November to the end of February This will result in: Energy savings Better ice over the entire season Happier skaters Slide 24 Further Measures for Easy Energy Savings Ice thickness is directly related to energy consumption According to a study by Marbek Engineering, reducing depth 12mm will result in an average reduction of 6,000 kwh/yr/refrigeration plant for seasonal rinks. Slide 25 Ice thickness vs Energy Consumption Adapted from: Manitoba Hydro, URL: http://www.hydro.mb.ca/ Slide 26 Produced By The Centre For Local Research Into Public Space CELOS, Toronto 2008