Years ago I wanted to cool a second-floor apartment I lived in (the top floor of a two-floor house) a bit during the summer, and decided on the simple solution

Years ago I wanted to cool a second-floor apartment I lived in (the top floor of a two-floor house) a bit during the summer, and decided on the simple solution of painting its entire flat roof with white rain-proofing sealant. It worked, and was useful as far as that goes, but for someone who also used their flat roof as a terrace for barbecues and etc, there was one very obvious drawback that I so obviously should have foreseen: On a sunny day, forget about relaxing up there. The reflective glare was enough to induce something like snow blindness.