The Colours of the Rainbow

Riding home from work, I was struck by the lively colours of this office block in Finsbury Square. So, I took advantage of having my camera phone on me. At least, not being green is not just green. Am I the only one who wonders why, in days like these when we are constantly admonished to save power and save the planet, why so many office blocks have all their lights blazing all the time?