A grommet (20, 30) as part of a fastening element for a building envelope essentially comprises a head (21), a tip (22) and a sleeve (23) therebetween, wherein the head (21) is essentially constructed as an extensive washer (24), the central hole of which is adjoined by the tubular sleeve (23). The tip (22) narrows essentially in a conical or tapered manner to a smaller diameter. The grommet (20, 30) has a sensor arrangement (25), with at least one RFID transponder with antenna and a sensor operatively connected to the transponder.