Yes it is happening I know, I remember a 99% Invisible podcast episode talking about it. Also there was a documentary on London millionaires doing it. I find i

Yes it is happening I know, I remember a 99% Invisible podcast episode talking about it. Also there was a documentary on London millionaires doing it. I find it striking it is not done even more. I recognize the technical difficulties but the costs are surely lower than the potential value of easily doubling the sq ft. There are interesting tricks you can do with fibre optic cable and mirrors to send daylight down there. Not to mention CoeLux and similar products.