We tend to build on smaller lots now with fewer options, in some cases, to take advantage of natural lighting. We also build with relatively energy efficient materials to help us hold in the heat or air conditioning to help make our lives a little more comfortable. Unfortunately with smaller more energy efficient windows further handicapping our capacity to use this valuable resource.
The good news though is we can actually "pipe in" sunlight. With products like the tubular skylight
There are actually other benefits to letting in a little UV. Ultra Violet light has been use for all kinds of sanitation purposes. They are using it to kill germs and bacteria, mold and mildew, apparently it also offsets some of the ill effects of less than friendly old magnetic ballasted florescent lighting.
This type of technology should definitely be remembered in the struggle to become a little more frugal and a lot more energy efficient. If its already there you may as well use it to your advantage.