26 degrees too hot for classroom?

[Marsaday]

I am a teacher, and am 25 weeks pregnant. My classroom is 26 degrees by about 11am on a sunny day even when cold outside, because the building is designed like a greenhouse. Leaving windows open all day makes no virtually difference as they only open a few cm and closed curtains block all airflow anyway. Have to leave curtains closed as otherwise 12 children get slowly roasted by the sun shining directly on them, plus sun shines directly onto board making it impossible to read. Have tried a fan - that just moves hot air about.
School central heating is not yet on, but once it is the problem will only worse as it's a central system and there is no way to turn off the heater (hot air blower) and the sun will still shine.
On a sunny day teaching 6 hours in this heat is exhausting me. There are also times when i feel close to fainting after a couple of hours as i just cannot cool myself down.
It is not just me that struggles, the kids are miserable and cannot learn effectively when overheating.
AIBU to ask the school to do something to reduce the temperature?

I would suggest reflective film on windows, adding an isolator switch to radiator, or getting me a portable air con unit.

Apparently boys learn best when the classroom temp is at 19 degrees, girls at 23, so 26 is really bad for all concerned.

Been there done that and it's shit. I started taking the kids outside and teaching them on the lunch benches instead. Could you take them to the hall for the hottest parts of the day?

Propping the door open to get a through breeze with a fan helped it to be less stuffy.

Yep there is no maximum temp. I know as I've worked in places where it got to 34.

There is not max temp under HASAWA 1974 but there is under the DSA amendment, not for people but for computers. OP under that law you can also request not to be working with DSE at all.

Have you had a H and S assessment?

Approach this from the pregnancy risk assessment angle and it should be resolved for the short term

I had a classroom like that, years ago in Primary.
I bought two vertical fans and got them PAT tested by the premises officer.
I bought sheer tuille curtains from IKEA and pinned them up. There may have been some irate staplegunning involved.
We painted a stained glass design on the worst offender.
You have my sympathy, it's harder when the temperature plummets and you can see your breath and fingers freeze to pencils.

Are other teachers feeling the same? Band together and ask something to be done. If not, Contact your union!

Oh that is just TOO hot!!! You poor thing.

Hope You find a solution for it, I would find it extremely uncomfortable x

Union has little to say about it as it's not unlawful. Try the Governors/PTA.
The PTA refunded me the money for the fans.