

Easy and cost effective? Vines. You’ll pay in labor tho.
Depending on your local climate, and also house’s construction & siding, theres probably some non-destructive vines you can get going on trellises or wall-holds. They’ll act as shade barriers to your wall, cool the surrounding air with evapotranspiration, and you can even get some beans out of it.
Downside is that same evapotranspiration is going to act as a wind barrier and potentially hold too much moisture in your siding, but thats usually easily fixed with regular pruning, and it’ll be worst on the off-sun walls that need the least shading anyways.
Wrong type of vines can anchor roots directly into mortar/siding & damage the wall. so do your research. English Ivy can fuck off. Beans & cucurbits work well. Ive personally got Virginia creeper running up some of my brick side-walls.
One possibility