OT mini-rant. supermarket lights

[dave]

Sorry folks but I happened to be driving home late the other night (completely sober) and passing a large Tesco money-sponge establishment it was impossible not to notice that every light in the place was on. They might be energy saving lamps - but they were not 10 watt Xmas tree lamps - some large large blue-white beasties. Also their car park (which is on the ground floor) had every fluorescent striplight on! That's hundreds of lamps. I understand they have to have illumination for security but really, why all that waste of energy. They really must be raking it in. rant ends. Thanks for reading.

[Man at B&Q]

Maybe they are open 24 hours. Even if they aren't, there could well be staff replenishing the shelves.

MBQ

[pcb1962]

My 24 hour Tesco turns about half of the main lights off after 23:00, makes it a very gloomy depressing place to be.

[terry]

Similar question came up about a large government building, here. "Why lights on at 10.00 Pm etc." Not sure if the answer was that night staff were cleaning at that time and/or that the lighting load contributed to heating the building; even to a lower night time temperature level and in that case it was just as economic to use the heat from the lighting (which was almost entirely fluorescent) as having and switching on additional electric heating. As someone said the few nanoseconds that radiant light energy spends illuminating an area before it strikes something that is thereby warmed is immaterial.

[Huge]

I used to work in a large building in Canary Wharf. All the office area lights went off automatically at 20:00. You could switch the ones in your area back on by dialling a number on the phone (the switch put your call through to the building management computer which used the CLI who find out who you were and the on-line phone directory to find out where you were, so it could turn the lights in your area back on...)

[Adrian C]

And zoom in the CCTV cameras ...

[Grant]

If you could find the phone...

[Huge]

*Some* lighting stayed on all the time...

[Dave Liquorice]

B-) I suspect that all the lights is a slight exzageration. Being a work place I'd expect maintained emergency lights to be present.

[Huge]

Lighting in common areas (corridors, rest areas, round the printers, etc.) stayed on all the time. It was an open plan office, so there was enough light to navigate round.

[Chris J Dixon]

They would only come on if the mains supply failed, rather than selected lights being turned off by central control.

Chris

[Dave Liquorice]

Ah ha! Got one, knew I would. B-)

Maintained emergency lights can be on with mains power healthy, sometimes they cannot be switched off easily so are permenantly on mains present or not.

Non-maintained come on when the power fails.