The best of everything

If you want to maximise light and thermal efficiency with privacy, you can do worse than use acid-etched glass - perhaps with a pattern in it to make it more interesting. You can find suppliers who will actually acid etch the glass before it's made into a sealed unit of whatever sort, or you can use a stick-on film that does the same thing. People who supply stick-on Fablon signs for vans will supply the stuff. I have a local supplier in Rugby whose front door is done in the stuff, and I can't tell the difference from my own front door which has the real thing. A 5mm line as a pattern acts pretty much as a secret viewer if you stick your face close to the glass, although it does work in both directions if your visitor does the same. It certainly works for me: U-value 1.3 centre pane, bright hallway and a high degree of privacy.