Hi Marie

This glass pergola faces east but western sun is often low and very hot as you know. So you need vertical shade as much as horizontal shade. take a look at a newer product called Danpalon it is cost efficient, has a tint or can be frosted. I would then grow deciduous vines or battens under it to give you shade in summer and then have some vertical glare blinds or vergola type louvres running to the ground to block the wind and afternoon sun.