By their very nature, ice hockey arenas are large energy users requiring satisfaction of simultaneous heating and refrigeration loads in proximate space. The National Hockey League (NHL), however, is committed to a green building and sustainability strategy.
According to the American Society of Heating, Refrigerating and Air-Conditioning Engineers, an average sized hockey arena (34,000 square feet) consumes anywhere from 800,000 kilowatt hours (kWh) per year to nearly three times that much energy at 2,400,000 kWh per year.
Now the NHL has taken a proactive step towards reducing these figures by releasing the 2014 NHL Sustainability Report. Developed in partnership with the National Resource Defense Council, four key strategies – which are already in effect at some arenas – have been identified for wider implementation to help reduce energy usage effectively.
It is important that the ice hockey experience and the comfort of players and fans are not compromised. At the same time the energy needed to keep the stadiums at the correct temperature needs to be reduced.
The report calls for the application of reflective, low-emissivity, and white treatments to dark surfaces that radiate heat toward the stadiums and increase cooling costs.
This highly reflective barrier is usually a polished aluminium surface laminated to a vinyl, polypropylene, or fibreglass backing, often suspended from the ceiling. The barrier shields the ice surface from being exposed to the warm ceiling surface, thus reducing radiative heat gains.
In addition, the report says planting trees and other plants around stadiums will help cool the environment, making vegetation a simple and effective way to reduce urban heat islands.
Researchers have found that planting deciduous trees or vines to the west is typically most effective for cooling a building, especially if they shade windows and part of the building’s roof.
The emphasis here is on lighting, HVAC and dehumidification, where some NHL venue managers have already been able to provide a significant return on investment.
The report advocates upgrading to newer, more efficient models and using systems such as occupancy and daylight sensor controls, water reduction measures such as zero-water urinals, and building management systems.
Ideally, ventilation should be supplied only to maintain indoor air quality. Heating of spectator areas should be accomplished using radiant heating systems (floor or infrared). Installing programmable controls could save five to 15 per cent in annual refrigeration costs.
Deploying on-site alternative energy
Ice arenas have substantial refrigeration and heating loads, making them prime candidates for waste heat recovery from the refrigeration process. Waste heat can be used to heat sub-slab brine, control the temperature and humidity of the interior climate, heat resurfacing hot water, or melt ice scraped off by the resurfacer. Heat recovery on exhaust air to preheat incoming outdoor air should also be considered.
In terms of solar, geothermal and deep-lake water cooling opportunities, by conducting full reviews of financial incentives and return on investment, five member venues now supply part of their own energy needs with renewable energy.
Keeping a regulation ice sheet requires humidity to be carefully controlled, which can cause an excess load on the ice-refrigeration system.
The thickness and temperature of the ice sheet and how it is maintained all impact energy use. Keeping the temperature of the ice as high as possible reduces refrigeration loads, and increasing the ice temperature a single degree can save six per cent annually in refrigeration costs.
By using desiccant humidification systems, some NHL venues have been able to reduce the energy used to maintain the ice, though the report is quick to point out that such systems come with a significant initial investment.
“The report’s focus on controlling fossil-fuel use and greenhouse gas emissions is a mainstream wake-up call that climate disruption poses an existential threat to everything we hold dear, including sports and recreation,” said Allen Hershkowitz, senior scientist and head of NRDC’s Green Sports program.