But the alleyway is open although the ventilation duct has long been switched off.

BBC: Forum 28 in Barrow

The firm has taken samples from the ventilation duct and access to the ceiling voids has now been prohibited unless a pre-assessment has been carried out by a qualified consultant.

BBC: Asbestos-riddled Rhyl hospital could be revamped

The silver cylinder at the top is actually a small power generating device that converts micro-vibrations into usable energy, so stick one of these on, say, a ventilation duct and you should just about get enough juice to power a calculator or even an LED.

ENGADGET: Mitsumi exhibits micro-vibration power generator and batteryless RF switch (video)