When Qatar was bidding to host the 2022 World Cup, the plan, despite summer temperatures
regularly over 40 centigrade, was to hold the tournament in June and July as usual.
And they promised the most technologically sophisticated stadiums to cope with it.
Even so, FIFA balked at the prospect, then
turned the global football calendar upside down, and shifted Qatar 2002 to November and December.
Nevertheless, the afternoon games may still feature conditions of 25-30 degrees
and in the future, Qatar plans to use these venues for much more of the year.
So, how do you air condition a stadium?
Air conditioning is, in fact, the last line of defence against the heat.
Qatar’s stadiums deploy all the passive forms of cooling that any hot weather architecture uses.
First, the stadiums have been carefully oriented on their East-West axis to allow for the movement
of the sun over Qatar, and to create maximum amount of shade on the pitch and in the stands.
Second, colour schemes matter. The Al Bayt Stadium, whose facade takes the shape
of a Bedouin tent, was initially going to be black. Stunning but intensely heat absorbent.
The stadium has been built in white
which had dropped the pitch temperature by around 5 degrees centigrade.
Third, the stadiums are designed to not let the heat in, in the first place.
The surfaces and shapes of their external facades have
been designed to reflect heat and divert the warming winds.
Fourth, most of Qatar’s new stadiums have retractable roofs. When
closed these considerably improve the efficiency of cooling process, meaning that
the water and energy usage needed for the air conditioning systems will not be overburdened.
But in the heat of Qatar all of this will only take you so far.
Bring on the air conditioning – and all air conditioning systems require power.
Electric power to run the pumps and fans that move air and water in refrigeration and cooling
systems, and power as electricity or heat that is used to run the refrigeration systems themselves.
Qatar’s stadiums use both.
At the Khalifa International Stadium, for example, photovoltaic panels on the
roof generate electricity that powers the motors of huge dual compressor chillers.
The stadium also draws on systems of district cooling in which centrally
chilled water is piped to the stadium and then used to cool the air inside.
However, most of the cooling work at Qatar 2022 is being done by extraordinary, expensive
and energy hungry machines called absorption chillers.
Amazingly, they use the energy stored in water superheated by solar power, to chill a separate
circuit of water.
The cooled water is then pumped through a set of heat exchange pipes, which cool air.
The cool air is then blown by solar powered fans through large pitch side
nozzles set into the walls at the front of the stands, and through grills beneath the seats.
Behind the seats are another set of grills that suck the air back into
the air conditioning system, where it is filtered, and cleaned of dust and microbes,
before being cooled down again and sent back into the stadium.
None of this is particularly groundbreaking,
but Qatar has also invested in a decade’s worth of research in fluid dynamics - examining the air
flows in stadium spaces - and in the creation of sensor systems that allow an incredibly detailed
and accurate picture of the movement of air and changes in temperature to be built up.
On the basis of this work, the angle and speed of air movement have been very precisely calibrated
to maximise cooling and minimise discomfort for spectators, and designed to create just
a thin layer of cooled air around them, rather than cooling the whole stadium space.
Seats and other fixtures have been designed with materials that absorb and store as
little heat as possible, making the task of keeping them cool easier.
Generously, Qatar has chosen not to patent these innovations,
offering them to any nation that would like to use them. And as climate change drives global
temperature rises and heatwaves become more frequent, there should be plenty of takers.
Whether they will be able to afford the immense investment in solar technologies,
district cooling and high-end chillers that this all requires, however, remains to be seen.