I've seem some people argue against it because it uses energy which contributes to climate change, even though we never apply that argument to heating, and our electricity grid is increasingly decarbonised and rightly so. But for some reason we still have a few people who believe that despite other developed nations that deal with heat using air conditioning that Europe must remain a continent of academics and activists where the greenest thing to do is suffer as penance for our sins that lead to climate change (somewhat hyperbolic on my part).
My portable air conditioners have run almost entirely off my solar generation, and overnight from the battery. Yes, it does mean I've exported less energy and lost out on the 12p per kWH I could have earned - so there has been a cost to me, but it's worth it.
And my systems are incredibly inefficient.. using almost 3kWh if all three are on at once.
An air to air system is more likely going to be around 1-1.5kWh and be so much more effective that it won't need to be on almost permanently to maintain a decent temperature.
Given how many panels a school could likely fit on their buildings, or at a push at ground level even if it reduces some playground/field space, I am sure they could be totally green. Not only would be cooling be free, but any export to the grid means nearby properties are getting totally green energy too.
I'm surprised we've got through three pages without someone suggesting buying portable units, one for each classroom. For the sake of a few weeks a year (given that schools are off for most of the summer), they don't need to be very energy-efficient. Even in the current funding crisis that could surely be afforded?
To be honest, it would be next to useless and only help those sat directly in front of it. I suppose the kids could rotate to be near it, but that wouldn't be disruptive at all!
We have three at home and on the hottest days last week, when the schools had to close early, I moved one into our living/dining room. The hose went out the back door and blinds were closed and curtains drawn. I used a towel to try and close the gap as best as possible.
Working flat out, it couldn't get the temperature down to under 26 degrees (outside temp maybe 35-37). Again, if you sat in front of the cooler, you got cooler - but it was near useless.
Maybe that would be better than nothing, but I am sure that in a large classroom complete with lots of bodies giving off 100s of watts of heat each, it wouldn't even make a dent.
You can get more powerful portable A/Cs that are around 14,000BTU and maybe higher (the sort the school would likely get from a specialist company, not the local B&Q or Lidl!) but I still don't think it would help. It would need to be on all day, from very early on to work before it got too hot outside, and if the classroom has loads of glass then you need to block that all off too.
Ceiling fans might offer some more comfort, and dehumidifiers can dry the air to make it more comfortable - but they usually generate heat (my Maeco certainly does) which is nice in the winter for drying clothes in the living room, but maybe not wanted on an already hot day.
