Today's state-of the art sports venues enhance the experience of fans by providing real-time game updates on giant digital screens and free high-speed Wi-Fi allowing them to share their emotions on social media. But behind the scenes in stadiums, the latest lighting and sensor technologies also play a vital role in making events as compelling, comfortable and safe as possible for spectators who might otherwise choose to watch live sports on widescreen TVs in the comfort of their own homes.
Stadiums increasingly host different types of events, such as sports, concerts and theatre performances. Floodlights and other lighting must be adaptable, enabling the playing arena to be illuminated to specified levels at night or in low light conditions or to provide stage lighting, all the time ensuring glare and light pollution of the local environment are minimal.
The global value of the sports lighting market is estimated at more than USD 6 billion, according to the South Korean company LG Electronics.
The most common floodlights used as primary lighting in stadiums are HID (high intensity discharge) lamps such as metal halides, which can pack a lot of lumens into a small package. In these venues there is usually a requirement for at least 50% of the floodlights to have a hot restrike facility so they will come back on straight away in the event of a power dip.
Broadcasters also require the flicker present with these types of lamps to be eliminated for slow motion recording. This can be achieved by careful aiming, using mixed electrical phasing or electronic control gear which completely eliminates flicker.
Advances in LED (light-emitting diode) technology mean that LED floodlights are now bright enough to be used for illumination purposes on large sports fields. Although they can cost nearly four times as much as traditional metal halide floodlights, they radiate very little heat and last significantly longer. They can be switched on and off instantly, requiring no warm-up period. IEC TC (Technical Committee) 34: Lamps and related equipment, and its SCs (Subcommittees) prepare International Standards for all types of lamps and luminaires used in sports venues.
Mike Simpson, Technical and Design Director of Philips Lighting and member of six TC 34 WGs (Working Groups) and PTs (Project Teams), who was responsible for lighting the London 2012 Olympic venues, told e-tech: "Although there is little in energy savings compared with a 2 kW metal halide system, the gain is in flexibility and reduced maintenance costs".
LED floodlights are also able to provide the high lumen output required for high-definition broadcast standards, with a significant reduction in flicker during slow-motion broadcast replays on high-definition TVs.
Ever changing moods
Flexible colour-changing LED lighting is used in conjunction with sound and motion sensors to reflect the mood of spectators inside stadiums. The ability to switch and dim each floodlight individually allows venues to produce special light shows and create the appropriate atmosphere before and after matches. The interior and exterior of the arena can be illuminated based on fan sentiments on social media and on other factors such as goals scored and crowd noise.
One of the uses for laser technology in stadiums is to project field markers. A laser-projected marking displays a line of contrasting colour across playing surfaces, similar to the on screen lines seen by TV viewers, as a visual aid to help officials and spectators visualize important markers. Such systems have been demonstrated, but not yet adopted by international sports federations.
Give us a sign
Another use for LED lighting in stadiums is in digital signage, using ribbon boards and video boards to display advertising, show scores and play videos. A 2014 survey of 70 leading American sports venues by MSR (Mobile Sports Report), a US website on stadium technology news, indicated that the primary use of signage was for advertising, followed by game information and player statistics, details of concession stands, video replays and safety announcements and messages.
Typically, a stadium will have two enormous digital video screens and scoreboards high above opposite ends, positioned so that at least one is visible from every seat, even in bright sunlight, complemented by a vast number of smaller flat screen video displays installed throughout the venue.
Analysts predict that stadiums could soon be exploiting the commercial opportunities of interactivity between digital signage and apps on spectators' mobile phones.
Sport represents only a small part of the growing digital global signage market, which is dominated by the retail sector. The total worldwide digital signage market could be worth up to USD 14,87 billion by 2020, according to a March 2014 report by US research consultants MarketsandMarkets. The company expects the global market to experience a CAGR (Compound Annual Growth Rate) of 8,94% between 2014 and 2020.
In November 2014, California-based consultants Grand View Research published even more optimistic figures, stating that the global digital signage market was expected to grow to just over USD 20 billion by 2020.
The spread of sensors
A wireless sensor network consists of spatially distributed autonomous sensors to monitor physical or environmental conditions such as temperature, sound or pressure, and to pass their data through the network to a main location. Modern networks are bi-directional, also enabling control of sensor activity.
Wireless sensor networks installed in stadiums collect an ever-increasing amount of data.
Sensors play a major role in hazard detection and maintaining a safe and comfortable environment. Smoke and fire detectors can send information about the cause and precise location of a fire to a control centre within seconds.
As part of a smart building management system, they can monitor and programme power usage to reduce energy costs, for example, by controlling the heating and cooling of certain rooms according to the stadium's booking schedule. Motion sensors in areas such as toilets can switch off lights and air conditioning when these areas are not in use. Carbon dioxide sensors, as well as keeping temperatures regulated, can alert maintenance crews if certain gas levels become hazardous.
Sensors are able to record large quantities of weather data inside stadiums, from temperature and relative humidity to air pressure and precipitation. In the 2014 Football World Cup in Brazil, sensors in the 12 stadiums spread across several climate zones in the vast country allowed predictions of extreme heat, downpours and storms that might affect matches.
Other applications inside stadiums include acquiring vibration data to monitor the venue's structural integrity and detect the onset of structural damage, and using soil temperature, moisture and flow sensors to manage automated irrigation systems or shut them down automatically in the event of pipe breakages or leaks.
A number of IEC TCs and SCs prepare International Standards for components and systems in the fields of lighting and sensors.
The TC primarily responsible for drawing up International Standards for lighting is IEC TC 34: Lamps and related equipment. TC 34 includes four SCs which prepare international standards for specific fields: SC 34A – Lamps including LEDs, OLEDs (organic light-emitting diodes) and glow starters, has published over 130 Standards covering, among other things, metal halide lamps and LED lamps; SC 34B – Lamp caps and holders; SC 34C – lamp controlgear, with the focus on controlgear standards for metal halide lamps (square wave operation), fluorescent lamps and LED modules; and SC 34D – luminaires.
IEC TC 47: Semiconductor devices, includes sensors in a number of its publications and SC 47E: Discrete semiconductor devices, prepares International Standards for components used in a variety of sensors.
The scope of TC 76: Optical radiation safety and laser equipment, is to prepare International Standards for equipment incorporating lasers and LEDs. With an emphasis on safety, the scope includes the preparation of standards applying limits to human exposure to optical radiation from artificial sources. These are important in sports venues.
With sports fans tending to be early adopters of new technology, some venues, notably in the US, are experimenting with proximity sensors and beacons, partly for merchandizing applications by sending messages to fans' smartphones but also to allow them to upgrade their seats.
Attempts to make money from social media notwithstanding, the primary goals in future stadium design for architects, engineers and facility managers alike remain greater safety and energy efficiency.