The independent London newspaper

Cool suggestions for Sadiq Khan and the capital

03 August, 2018

Mayor of London Sadiq Khan

• NOTING the recent announcements on current air quality and temperature issues in the capital, perhaps the Mayor of London, Sadiq Khan, might take an example from cities where hot and dusty conditions prevail with greater frequency.

They patrol the streets with water bowsers, soaking the pavements of carriageways and footways, to combat heat and wash down dust. Remember Boris Johnson helpfully bought three such vehicles, which are currently standing idle.

With a few adjustments to disperse water as an atomised spray, rather than a powerful jet, the cooling effect of adiabatic evaporation at 2.5 million calories of heat per gallon is maximised, typically delivering a 10 degrees Centigrade cut in air temperature.

Further emergency cooling options are available. On the Class 378 trains used on London Overground someone sensibly included the provision of lockable opening windows for when the air conditioning system was unable to function due to high external air temperatures.

There is one way in which emergency cooling, with dry air (to reduce humidity, which increases comfort) could be provided for short periods on tube trains in tunnels, and on the “Boris” buses; but this could not be a continuous cooling option.

As yet I’m not aware of this being tested on a tube train or a bus. Note air conditioning on tube trains without tunnel cooling is akin to the task of Sisyphus as a futile exercise since the heat you take out of a tube train has to get dumped in the tube tunnel where… it then heats up the train.

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