mould in double glazed window casing

[ThanosM]

Most windows casings in the house have a lot of mould, see photo below:

Apart from being disgusting, do it have any negative effect? Should I clean it? It did clean most part of a single window and it took ages as it's not flat surface.

 

[crank39]

Your suffering with condensation, the mould needs cleaning and killing with bleach, trouble is because your causing further condensation it'll eventually come back

 

[JohnD]

A soft nylon brush, perhaps a washing-up brush, is good for cleaning surfaces that are not flat.

Have your windows got trickle vents?

 

[ThanosM]

Your suffering with condensation, the mould needs cleaning and killing with bleach, trouble is because your causing further condensation it'll eventually come back

A soft nylon brush, perhaps a washing-up brush, is good for cleaning surfaces that are not flat.

So is this something that I should be regularly doing and there is no real way to prevent this? (Apart from minimising condensation?)

Is it a real problem anyway since it's not in the inside of the window?

Have your windows got trickle vents?

They do, but I keep them shut to minimise heat loss, I sense that was a stupid thing to do...?