Portable AC power use.

[JohnW2]

We have some cellars around here that are completely below ground and quite a few of them actually have openable windows to get air as well as a bit of sunlight too (a gap wall where the pavement starts and a metal grid above which should be raised for a clean out of dropped litter etc every now and then - some dont of course and they are completly surrounded by earth, never having had a cellar myself its not been a problem.

One sees a lot like that in/around London.

 

[JohnW2]

A cellar would be even better, with it all being below ground level. But the half-and-half means we still have windows. It was originally a garage.

Something like 70%-80% of the height of my (large) cellar is below ground level, such that there are just a couple of small windows at the very top.

I'm away from home at the moment, so haven't been able to 'benefit' from it, but last time we had a 'heatwave', the cellar was by far to coolest place around - and I then even got Mrs JW down there, amidst all my 'workshop tools' (and goodness knows what else!), when it got really hot 'upstairs'