What's your opinion on ventilation in rolling stock? Should new trains have aircon? Or should they be provided with opening windows as is tradition? Aircon to my mind is a bloody waste of money. It's noisy and half the time it does not work. The other half it's working when its not supposed to. It also harbours dust and dirt which carry disease. You look inside any domestic fan heater and see the amount of muck in there and you'll see what I mean.