Did he look like this?

[![DVD season 1 cover][1]][1]

(Note the red t-shirt.)  This is the Sci Fi channel (note contemporary spelling) series ["The Invisible Man"][2]  It originally aired 2000-2002.

Darien Fawkes (the titular character) could control his invisibility, so he could have turned it off on the way into the building.  The building could have been the Agency that he works for.

A couple of notable things about the way invisibility was used in this show:

- Darien could turn his invisibility off and on at will (though it wasn't instantaneous);
- His clothes could turn invisible with him, so when he turned it off he was fully dressed;
- Because the invisibility stuff ("quicksilver") was excreted by his skin, he could turn an object he was holding invisible!
- When he was invisible he could only see using part of the spectrum (downshifted UV light or similar handwavium) so shots from his viewpoint were in black and white.

  [1]: https://i.stack.imgur.com/gT3In.jpg
  [2]: https://en.wikipedia.org/wiki/The_Invisible_Man_(2000_TV_series)