Hi Leo. I don't know if it's accredited or what the U values are. I've read a bit about it but can't figure out how it compares to other types of insulation. That's because I don't know if they're talking about insulation of equal thickness or comparing a 9mm sheet of aerogel to thicker other types.
If you have time, can you, or anyone else, take a look at these links and see if you can figure out how it relates to either fibreglass or solid insulation.
It's quite expensive. Something around €40 per square metre, but I'd use it if I thought it was really good.