
The SL9 and SL10 have really good air cooling
Only a small amount (13% based on FOI requests and rough estimates) of buses have true air conditioning, and the rest have air cooling, at least on the upper deck. Most of the time the ‘’air cooling’’ only works whenever the bus is moving, which is often not the case for most buses in London (at least the ones that I’ve taken), which makes it boiling hot during heatwaves (and quite stuffy on buses with fewer windows).
However while circumnavigating London on the Superloop I’ve noticed that the SL9 and SL10 have buses that blow strong air out from vents whether the bus is moving or not. It’s not air con, as the air isn’t chilled, but it’s still pretty good.