The picture you linked to is taken in A Coruña whose mean temperature is around 10 degrees higher[1] still than relatively mild[2] climates near the arctic circle.
I didn't mean to suggest they weren't also used to let light in. I've spent a lot of time in houses that have these installed, letting light throughout the day while keeping the house relatively cool is a constant balancing act. I meant that without the need for the thermal management you'd go for other sorts of systems, such as internal blinds.
I.e. I'd expect that in places like A Coruña you'd use these for thermal management in the summer with the outer windows open, whereas in Iceland there's maybe 1-3 days of the year where the outside temperature is anywhere near the inside temperature.
I didn't mean to suggest they weren't also used to let light in. I've spent a lot of time in houses that have these installed, letting light throughout the day while keeping the house relatively cool is a constant balancing act. I meant that without the need for the thermal management you'd go for other sorts of systems, such as internal blinds.
I.e. I'd expect that in places like A Coruña you'd use these for thermal management in the summer with the outer windows open, whereas in Iceland there's maybe 1-3 days of the year where the outside temperature is anywhere near the inside temperature.
1. https://en.wikipedia.org/wiki/A_Coru%C3%B1a#Climate
2. https://en.wikipedia.org/wiki/Akureyri#Climate