Not clear to me is whether you want the vines on the wall or roof (or both). Also, if there is little sunlight hitting that area, would you see much cooling if you shaded it with foliage?
Most structures were not designed to have vines growing directly on them. The foliage will raise moisture levels and encourage the growth of slime on paint,
wood rot, etc. Even on brick or stone, those lovely ivy vines can do a number on mortar over time. Much better to build a
trellis a few feet out to let the air circulate between the plants and structure. Or plant a hedge that will allow a space.
Roofs with standard shingles might also
experience problems if the vines trap moisture and decay.