Evergreen flowering climbers for a north west facing wall?
 

I am looking for suggestions for evergreen flowering climbing plants for a north west facing wall. This is for a new flower bed that we have put under the kitchen window at the entrance to our house which is fairly severe looking and which we want to 'soften' a bit with some greenery and flowers on the wall. I was thinking of climbing roses but a neighbour warned that although very pretty in the summer these don't provide much greenery the rest of the year. I take it a clematis won't prosper on a north west facing wall, so I'm looking for other suggestions if anyone has any please?

Thanks in advance.