I wouldn’t pretend to know a great deal about house design. But obviously it’s more energy efficient to design a building so that as far as possible, in summer it is kept cool by shade (rather than by air-conditioning) and in winter kept warm by the sun (rather than by heating). Apparently this is called passive solar building design.
A friend of a friend lives in a highrise (built late-1990s, I think) where there’s no shade on the north-facing windows, and the air-conditioning needs to be run even on cool days. I can’t imagine what it was like during last week’s heatwave.
In contrast, my house (circa 1930) has eaves over the windows. I can’t quantify how much it helps keep the house cooler (or at least less hot), but this photo of one of the north-facing windows, taken at 3pm on Friday, shows clearly how the eaves keep the sun away.