Hot nights in the bedroom! (Ugh it's about window restrictors)

[Mum5net]

This thread could have been so much more fun, but sadly it’s about night-time security rather than night-time romping.
I’ve got three downstairs bedrooms with side-hinged (outward opening) aluminium windows, all easily accessible from outside (low wall + fence = step up 🙄).
The rooms get really hot apparently, so I need to leave windows open at night — but I’m not comfortable doing that without something in place.
Does anyone use a good window restrictor that:

• allows a bit of airflow
• is genuinely secure (can’t be forced or reached through)
• works on aluminium frames

I've checked Screwfix so I see window restrictors are a thing.
I have roller blinds.

Locklatch UK do great ones that would be perfect for this. They are rather expensive but do solve the problem and are very secure.

We have downsized to a bungalow. Our alarm system is linked to the windows.They can be left open but the alarm would detect movement. Your windows sound bigger than ours though.
We have 2 very noisy dogs too!

These look much more secure than the cable-tie version. Thank you. They have gone straight to the top of the contender list.

I think houses are built with minimal opening devices on upstairs windows now. Ours open an inch or two, but there’s a slider thing that will open them further if necessary.

Window is about 1.20 m x 30 cm so a person could easily get in and out.
@24Dogcuddler our dog is a very light sleeper so I don't want her anywhere near!
I think we would just choose to open just one side and not two sides when it is warm and buy a fan.
@Buscobel this is the first time in my life I actually have a downstairs room. I would imagine regulations for window openings have changed to reflect both toddler safety and fire escape protocols.

Do remember that even if you create a steel bar, you are securing an easily broken glass pane...

I would also think about other security and ventilation:
Plant really spiky bushes below and around window or wall.
Use greenery on wall, on floor, everywhere you can to stop heat getting into brickwork or concrete floor etc
Use external window shades like the Belgian, Dutch, French, Germans...heck, most of Europe, through the day.
Use reflective film externally on windows.
Use window blinds during day.
Look at how you can creat airflow - a fan in a corridor pulling air one way and out windows, or in windows and out another way.
Use wet towel or ice and the fan for 'cheat' Aircon.

The summer heat in the UK is only going to get worse, particularly if you are south and east of Birmingham...and really awful in big cities with London being the worst.

I would seriously consider changing the window so you can have a small top opening that only a toddler or a cat can squeeze through, with noisy tin foil on window sill overnight to warn you of said cat or toddler if you feel the need. Okay. Just cats. I find a small but fully opened area is better for cooling airflow compared to a restricted thin area even if they are equivalent in actual area iyswim.

Great! I'm in a first floor flat and have bought one for each bedroom. Real peace of mind and I don't think there's anything better out there. I did loads of research!