Why did they specify that?

Because it cleans itself

Architects wanted Pilkington’s self-cleaning glass for windows at the Museum of the Earth, in Ithaca, New York State, to save on maintenance costs. All it needs is an occasional hosing down. The 18,000 sq ft site houses 650 specimens from the USA’s largest fossil collection. The glass uses UV light to break down organic dirt deposits so that rain washes it away.

Because it’s perfectly posh

If you’re building apartments by the Thames in London, any old door just won’t do. These TDSL doors, White American Oak veneer with dark timber inlays, have been selected for a variety of luxury waterfront developments including Chelsea Bridge Wharf.

To keep an eye on patients

Staff need to check that patients are safe at the new Ardenleigh Centre, a medium security mental health unit. The Vistamatic panels allow quicker routine inspections than a fish-eye aperture would. The toughened-glass windows comprise clear and opaque panels in one frame and can be opened with a twist of a knob or lever.

Because it reduces feedback

Housebuilders and manufacturers, including JELD-WEN, have agreed a range of standard partition widths and corresponding doorset and doorkit lining sizes to meet Part E of the Building Regulations, which deals with noise. The cooperation should reduce lead times and create more cost certainty.

Isn’t it glaringly obvious?

This is the £10.7m Welsh National Pool in Swansea, double-glazed with Pilkington units. The outer pane is 8mm toughened and heat-soaked glass and the inner pane is 8.8mm laminated glass. In between are venetian blinds, specified to control light ingress.