I was wondering if anyone could recommend a window sensor to use - I tried the Ecolink ones and they’re rather bulky; as well was looking at the Aetec one and Sensative strips which are rather expensive for as many windows as I’ll have to buy for.
I prefer the Sensative Strips as these can be hidden in the window shut. As you have said though they can work out expensive if buying a number of them.
The cheapest are the Xiaomi sensors which you can get from around £10 each.
They are small and work well.