I really like the idea of staying out of the sun. For some reason, I can only see properly in low light levels, so I was perfectly happy living in a flat underground at Oxford Circus for an entire year (I occasionally went outside to lectures and to barter with the natives for supplies, of course).
Today’s invention is for my fellow troglodytes. Imagine a column of simulated windows, in the form of computer displays, on the wall behind a lift. Containing no real windows, the wall would thus provide greatly enhanced heat insulation and physical security.
Each of computer-driven screens would show a different view of the same scene, taking into account the change in perspective during the ascent. The images (e.g. beautiful parkland or idyllic beach, albeit with natural light levels somewhat muted) could even be made to darken appropriately as the day wears on.