Sports Arenas & Stadiums
Sports arenas are typically enclosed, high-bay, long-span buildings that can accommodate a wide variety of sports functions. They subsequently require a complex energy system designed to provide power, light, complete environmental control, fire/life safety, water, telephone systems, and communication lines to the main arena as well as individual, ancillary spaces. All systems must be highly flexible, since the building income is dependent on the time it takes to change from one function to the next. These functions can vary widely; from basketball, ice hockey, ice shows, boxing, track and field events, circuses, rock concerts, and huge banquets, beauty pageants, and special exhibitions.
Stadiums are typically not enclosed, except for the press boxes, sponsor boxes, any enclosed restaurant and/or lounge areas overlooking the arena, and, at some racetracks, an enclosed grandstand. If windows are involved, these can pose fogging problems during cold-weather operation.
Domed stadiums have a different problem, particularly where the design has air pressure supporting all or part of the dome. Some designs trap stratified air within the dome and include a requirement for pre-conditioning the air for 24 hours before and 4 hours after an event in order to develop a heat sink. Dampered exhaust fans can exhaust heated air and offset roof conductive heat gain.
For example, the cable-supported Georgia Dome operates as a football stadium for part of the year and for the rest of the year, it hosts other sports, events, and floor exhibitions. As a concert and entertainment center, it seats up to 80,000 people and includes facilities for large-screen video, fiber-optic cabling, and global transmission of voice, data, and video. The air-side is designed to cool only the 15 feet of air immediately above the seating areas and playing field, not the entire spectator bowl. An efficient air cleaning and filtering system reduces the amount of outdoor air that must be cooled or heated. [Ref: HPAC January 1993 p. 92-100]
Arenas and stadiums also include other indoor facilities like restaurants, food courts, club houses, concession stands, bars, sports stores, visiting team locker rooms, training rooms, service tunnels, parking garages, administration buildings or offices, and TV and radio broadcasting studios. Occupancy can range from 15 to 30 people up to thousands. In some cases, exhibit halls and auditoriums are also included in the center.
HVAC system flexibility is obviously key. High volume ventilation systems may be satisfactory; however, multiple speed fans are often considered, but the performance of air diffusers and the cooling system at low fan speed must be factored into the design.
Seating and lighting for the full range of functions are the most important load considerations. Boxing has the least seating and arena area, and a high latent load. The large ice surface required for hockey events sizably reduces the sensible and latent load, but poses potentially difficult problems of fog and condensation on interior surfaces. The sensible lighting load in the arena area improves the sensible heat ratio.
Enclosed stadiums may have fixed roofs or ones that open. Ventilation is not needed in the arena area where the roof can be opened, however ducts must be run over the permanent sections. Long air throws and high air volumes are usually involved.
Open stadiums can have radiant heating coils in the seating area floor slabs and may also use infrared, radiant heating panels above the seating areas. Enclosed grandstands require careful design consideration due to variations in the solar, convective, people, and lighting loads and the fact that the arena may operate for both day and night events. They may require double-glazing, radiant perimeter heating, and dehumidified air movement across the glass in order to avoid fogging.
Air-supported structures require continuous fan operation to keep them inflated. The insulating characteristics of the roof must be good enough to prevent condensation at the lowest expected ambient temperatures. Heating and cooling may be combined with the inflation system in these designs.
Locker rooms should be very well ventilated; not less than 2 to 3 cfm per square foot. To reduce the use of outdoor air, excess air from the main arena may be introduced; however, some reheat or recooling may be needed to maintain locker room temperature and keep it from being too hot or cold. To maintain air balance, locker rooms should have separate supply and exhaust systems.
As these are usually large facilities, these buildings typically use a multiplicity of air-handling units served from a central chilled/hot water plant to service the wide HVAC load variations. All-air systems with multiple speed fans and/or VAV systems are commonly used, with provision for operating with 100% outdoor air. Provisions for direct exhaust are also made to accommodate situations where trucks are in the hall loading or unloading and when malodorous events are in progress (rodeos, circuses, etc.)
The concourse areas and their concession stands are heavily populated during entrance, intermission, and exit times. Considerable ventilation is needed to offset the many odors that are prevalent.
Box offices, office, and restaurant spaces operate at higher and differing hours from the main arena and should be supplied by separate systems like individual air-handlers, roof-top units, or a VAV system.
Energy Saving Recommendations
Central plant designs may also incorporate heat recovery, thermal storage, and other energy conservation opportunities such as variable speed drive water pumps, and temperature reset on chilled and hot water distribution circuits. These complexes are also excellent opportunities for a central control system for fire, smoke, security, maintenance control and operations, and energy management.
Other opportunities include:
- Additional odor control (carbon filters and controlled re-circulation) to reduce fresh air intake
- Older and/or inefficient systems should be upgraded or replaced, particularly if CFC refrigerants are used
- Where demand and/or on-peak energy costs are high, look into thermal storage
- Implement any energy conservation concepts discussed above that are not already in use
- Replace antiquated or inappropriate control systems
Hot water is primarily used for food preparation, cleanup, locker room showers, and restrooms. Dishwashing is usually not a significant load. In most facilities, peak usage occurs during the cleanup period, typically soon after opening and immediately prior to closing. Hot water consumption varies significantly among individual facilities.
Most water heating is done separately from the building heating system and uses direct resistance or gas heaters, and, in some cases, point-of-use heaters.
Since sports arenas are seldom limited to a single sport, or even to sports in general, lighting is an interesting challenge. Most of the main area lighting will be metal halide, with the main concentration on the playing area and the secondary lighting in the stands. Hallway, concession stand, and office lighting may be fluorescent and/or metal halide.
Lighting in outdoor arenas will usually be supplied by lighting stanchions located at the top and back of the seating areas. Indoor arenas will usually integrate the lighting into the roof structure directly above and surrounding the playing surface.
Since the arena will probably also be used for concerts and other low level lighting events, dimming capabilities are a must. However, this may be accomplished by installing multiple lighting circuits that allow selective on/off switching of the overhead lighting. Pulse-start metal halides should looked into in order to allow quick restart at the end of an event or halftime show.
Each facility needs adequate levels of both horizontal and vertical light. Without proper vertical illumination, the players and spectators can't see the ball in the air. For high-speed sports especially, uniformity of illumination is very important.
Even higher levels of uniform illumination are necessary for televised sports fields. Reducing any disabling and uncomfortable glare are both important. Fixtures must be located away from the normal lines of sight of both players and spectators. To bring out the three-dimensional form of the ball, it's best to provide lighting from two or more directions; varying the intensity of the light also helps.
You can find more detailed information on sports lighting in the IES RP-6 publication. Also, most manufacturers' reps can provide you with further information.
Many sports arenas include skating and ice hockey capabilities. Careful attention must be paid to site conditions; including ability to support heavy equipment, drainage, groundwater, foundations, insulation, and water-proofing to prevent soil freezing and buckling under the ice surface. Ice melting pits with steam coils may be needed. Low air velocities over the rink surface are essential to reducing the refrigeration load.
The refrigeration system is a major energy consumer when the rink ice is being made or maintained. The heat loads consist of conductive (37%), convective (28%), and radiant (35%) components. The rate of ice making will have an effect on the size of the refrigeration plant.
Some considersations regarding indoor ice making include, but are not limited to the following:
- The lighting design over the rink should be flexible for rink use and non-use, and factored into the cooling load. In some cases, incandescent lights are more applicable than those that have a long warm-up time.
- Energy usage can be reduced by using variable-speed brine pump control, low emissivity ceilings, demineralized water, minimal ice thickness, and ice temperature controls. The use of treated floodwater also improves the ice quality.
- Ice temperature control permits the rink operator to provide the exact ice temperature needed for hockey (22°F), curling (24°F), figure skating (26°F), or recreational skating (28°F). The higher the ice temperature, the lower the energy consumption.
A separate rink defogging system should be used to dehumidify the air, because increased ventilation tends to worsen the ice conditions, especially when outdoor conditions are humid. Rink coolant can be used as the dehumidifying medium, with a bypass pump to keep the coil inlet above 32 F, and a reheat coil served by warm condenser cooling water. A typical dehumidifying load would be about 1-ton per 2,000 square feet of rink surface.
Energy Saving Recommendations
Corrosion of steel brine headers is a common problem found in pre-existing rinks; however, PVC replacement has proven helpful on some rinks. To reduce the pumping cost, two-pass rink piping with parallel brine coolers can be re-piped during header replacement to become four-pass piping with brine coolers in a series. [Ref: Dumas, C. Energy Savings for Skating Rinks, p. 127-135, HPAC Feb 1996]
[Source: 2011 ASHRAE Refrigeration Handbook]
|Use of Ice Surface||Sq. Ft. of Ice Per Ton of Refrigeration|
|Sports Arena||100 to 150|
|Sports Arena, Accelerated Ice Making||50 to 100|
|Ice Recreation & Figure Skating Practice||130 to 175|
|Curling||150 to 225|
|Ice Shows||75 to 130|