The west patio that cooks at five

What changes after dark?

During the day distance hides you. At night being the brightest thing in the frame puts you on stage.

Reading

At 21:00

At this hour the seat is much brighter than the ground the observer is standing on, which is what makes a person read clearly from outside.

Light on the seat

8.4

lux

Thrown sideways and up

per cent of output

Most visible to

Neighbour's upstairs window

Who can see you, and why

Who	Line	On you	On them	Contrast	Reads as
Neighbour's upstairs window	open	8.7 lx	0.6 lx	14×	lit up

Contrast is the ratio between the light on you and the light where they are standing. Being three or four times brighter is what makes a person read clearly at a distance a daytime sightline would hide.

The fixtures

Back door light

bare

900 lumens at 2.3 m, on from 19:00 to 23:00.

Puts about 8.4 lux on the seat.

Back door light throws about half its output sideways and upward. Shielding it keeps the same useful light on the ground and takes the glare out of the sightline.

Shielding guidance follows DarkSky International. The principle that does the work is simple: light the ground, not the sky, the neighbour or yourself.