Air Conditioned Pitches - The Science Behind Qatar's World Cup

One of many issues flagged when Qatar was 'awarded' the 2022 World Cup was the proposal that pitches would be air-conditioned in an attempt to combat the extreme heat and humidity faced by the players.


Air conditioning an indoor stadium, fine, but an outdoor one? Impossible, isn't it?


Despite the seemingly impossible task at hand when the World Cup kicked off this week it did so on pitches which despite being open air boast pitch side air conditioning.


So how does it work?


Tiny nozzles sitiated around the pitch emit air conditioning which shoot out air at varying angles and speed in order to cover as much of the playing surface as possible. In essence the same principal that is used in the sprinkler systems at football grounds. Spectators are also catered for with nozzles under the seats.


Emitting the cool air is however the simple part, encasing that air within the stadium is what makes the WC venues geuinley unique engineering. Through carefully designed air flows which are all custom to the shape and design of the stadiums the cool air is able to be trapped and circulated, in essence turning open air stadiums into their indoor equivalents.


Chris Lee from Populous Architects who designed the Lusail Stadium which will host the final in a couple of weeks;

“If you think of a stadium roof as a little bit like an airplane wing, you can direct the prevailing wind quite a lot by how you orientate the stadium and how you tip or dip the leading edge of the roof. So if you think of how an airplane wing tips up and the air rushes up and effectively jumps up on a different trajectory, that’s more or less how it’s done.


“The whole principle works in a very simple, thermodynamic way: cool air is heavier and sinks to the bottom, and hot air rises, as we all know. So you put the cool air in, it sits on a lower level, then you design the roof and the orientation so the hot air doesn’t ingress into the opening and down to the pitch.”


The intention is to keep all stadiums at around 21oC.


“You’re never really taking super-hot, 40C air in (from the outside) and cooling it,” says Chris Lee. “Once it’s pre-cooled, it’s filtered and re-used through the life of the game.”


Once the air has been cooled and pumped into the stadium it is sucked back in through vents and then filtered, cleaned, re-cooled and pumped back out.


In principal then these outdoor stadiums have found a way to emit and entrap cooling. This task is of course hugely complex and comes with a wide range of in-stadium climate control. The man in charge of this? Dr Saud Abdul-Aziz Abdul-Ghani, or Dr Cool for short.


Dr Saud is a professor at Qatar University but he spent many of his early carrer years in the UK completing his PHD at Nottingham University which even involved working on the air conditioning in Ford Mondeo's.


In order to win their WC bid Qatar promised the AC solution without knowing whether it could be implemented.


“People knew the heat would be an issue, so they came to the university because it’s the hub of knowledge,” says Dr Saud.


The initial steps for Dr Saud and his team was a comprehensive computer simulation which simulated the weather in Doha over the past 30 years to find out the amount of cooling required as well as the areas of the stadium which would need to be cooled. 3D printed models of each stadium were then prepared and put into wind tunnels to simulate air flow and wind direction.


“It’s the first time stadiums like this have been led by science,” says Dr Saud. “I had some influence in what colour the stadiums should be, what height the stadiums should be. The architect chose the shape, but I had to make that shape work in this environment, to do things like minimise wind infiltration and optimise the cooling package.”


Another key element has been the design of the stadiums which have all been constructed with consideration to path of the sun so as to maximise natural shade is provided for both the fans and players alike. The exteriors of the stadiums were also designed to absorb as little heat as possible.


“I found in my experiments,” Dr Saud, “that if we changed the colour from a darker to a lighter brown, we can reduce the temperature by five degrees, just by the reflection of solar rays.”


Like with most design the real beauty lies in the unspoken detail.


For example, only parts of the stadium are cooled which is the opposite of your home of office AC which simply pumps out cold air indiscriminately.


“I don’t want to cool the whole volume (of the stadium),” says Dr Saud, “because nobody is going to be standing on a bridge in the middle of the oculus (the open section at the top of the roof) watching the game — although it would be a very nice view.”


The stadiums are fitted with hundreds of sensors which measure the temperatures in different zones. These readings allow the central control system to alter the temperature in different areas. Therefore, if say the sun is heating up a particular section of stadium, the cooling can be turned up in this section as opposed to another section in the shade whose cooling can be reduced.


This is mirrored in the stands where only the area around 2 meters above spectators heads is being cooled.


“My number one task is to make a safe environment for the players,” says Dr Saud. “These players don’t measure temperature, because it’s not a true reflection of the heat stresses.


“Players cool themselves with sweat, but if the weather is muggy or humid, it’s very difficult for that film of sweat to evaporate. So my task is to give the players a climate which is not very dry, but not very wet, in a controlled environment. We have something called WBGT (Wet Bulb Globe Temperature), which is a measure of 70 per cent humidity and 30 per cent dry temperature.”


What's the environmental impact?


With 8 stadiums all being kept at an 'ambient' temperature for the best part of the next month while all being situated in the middle of the dessert, there are rightly environmental concerns about the enviromental impact this engineering feat will have.


“It’s a valid concern,” says Dr Saud. “All engineers should have sustainability and looking after the environment as their first priority.”


All power for the stadiums is sourced from a solar farm outside of Doha.


“Most of the time, in most of the stadiums, we generate enough chilled water at night. The weather is more merciful, so they will store the chilled water for use during the day. That also minimises the carbon footprint.”


“Using air conditioning in an open stadium doesn’t strike me as the most efficient use of energy,” says Gilles Dufrasne, from Carbon Market Watch.


John Barrow who was once a director at Populpous even voiced concerns commenting that the plans were “not good from a long-term sustainability point of view” and that he was lobbying for air-conditioning to be abandoned.


There is also the question of whether AC was even needed in the first place. Temperatures in November and December are far more manageable in Qatar with high 20's to low 30's expected. Warm, but not unsafe and no hotter than we have seen in some Premier League games of late with seasons now running well past Spring and starting earlier and earlier in the Summer.


“Even after it was moved from summer to winter,” explains Dr Saud, “our executive management said, ‘Look, we don’t want any white elephants, we want these stadiums to be used all the time’. We need to use them in the Qatar Super League (this season’s QSL was able to start in August, a month earlier than usual and when the average temperature is 40C, thanks to the air conditioning), we want to have concerts, we want them to be community and civic centres. We need air-conditioned stadiums that people can use, not just spend all that money and just use them for the tournament.”


There is also the fact that at a test event in September the reports from on the ground reported sweltering temperatures with whole areas receiving no cooling. Whether these were teething issues or not they only further added to the questions surrounding the air-conditioning and indeed large sporting events in general.


With temperatures on the rise is this a glimpse into a dystopian sporting future where even elements such as the weather are now coerced and controlled? For all the technology behind Qatar's stadiums is impressive it perhaps begs a bigger question of where this technology fits within our global quest for sustainable and renewable design.