Well, the more light you reflect out the better (I would expect that, for example, darker color curtains would be a problem) and ideally you want that whatever light does get converted into heat does so outside.
As it so happens, were I live the heat has been a problem in the Summer since well before AC was invented, so roll-up external shades are standard for all houses and apartments and that stuff definitely works if used as I described it.
It looks a lot like in a way History is repeating itself: the Democrat Establishment in the US (who are a hard neoliberals, not lefties) fielded directly and without a Primary a guy like Biden who is less than in his prime and even supports an ethno-Fascist regime commiting Genocide (and, more importantly, is unwilling to walk back on that support even to improve his odds of winning against Trump, which is what we are being told is the most important thing in the World) all of which is making it far more likely that the Fascists will get power.
There are vast contradictions between what we are being told is the danger of Trump getting elected and the DNC and Biden persistently making choices that increase the chances of Trump getting elected and not walking back on those.
Surelly if “Stop Trump” is the most important thing in the World for them, the Democrat Establishment too would be walking towards the wishes of the electorate not just trying to push the electorate to do all the walking towards the wishes of the Democrat Establishment.