according to this the total land area of built up human development and infrastructure is also around 1%, seems a hell of a lot easier to mandate every building have a white roof. Especially considering most buildings have black roofs, it will be even more of a difference. Also will reduce energy consumption from AC because, as said in the article buildings panted with it have reduced need for cooling.

Roads could also maybe be painted or have a whiter material used, might make it harder to drive though