Calculating what led strip lights to put in (lumen per metre)

[Anak]

I have been redecorating the master bedroom and as part of this I have installed plaster in channelling for LED strip lighting. My current struggle is to work out what power strip lights I need.

The room is ~3.5m x 3.5m, the channelling is on the ceiling and goes round three sides of the room but in from the wall somewhat, the channelling length is ~7m total.

The strips start at 480 lumen per metre and head up to north of 5k lpm which is why I am confused...
At 480, 7 metres of channelling is 3360 lumens which is upwards of 300W in old school lighting terms. This seems crazy to me and 480lpm is marketed as feature / recess lighting. The general lighting is in the 1400+lpm range.

I assume somewhere my calculations are off and am hoping for someone who has used strip lights as a main lighting source can point out my error, or give a suggestion on what I should reasonably aim for.

 

[AndyPRK]

Is it a tall ceiling ?

 

[flameport]

I assume somewhere my calculations are off

They are not.

3360 lumens is correct for 7m of 480 lumens/metre.
Similar to about 8x 5W LED downlights, or a single 4ft fluorescent tube.

 

[SUNRAY]

They are not.

3360 lumens is correct for 7m of 480 lumens/metre.
Similar to about 8x 5W LED downlights, or a single 4ft fluorescent tube.

Lumens wise I accept the figures but in use I don't find downlighters to be anything like the same light quality and useability of fluo.

 

[ericmark]

Lumen is light output of light not light input to the room, light is energy and can be converted to other forms of energy, at which point it is no longer light, so a white ceiling and lights aimed up and reflecting off the ceiling can work better than lights shining down onto a darker floor.

I fitted two five bulb chandeliers, idea was to use 8W CFL in a globe format, total 5100 lumen, but the room was dark, Lidi did some 1.8W LED candle bulbs and I got a couple to try in table lamp, 160 lumen each, a couple of the CFL failed so until I could get replacements I fitted the 1.8W which seemed brighter, next time Lidi did bulbs they were 3W at 280 lumen so replaced the whole lot with LED, so dropped from 5100 lumen to around half, but room seemed brighter, that was until I tried to read.

Mothers house also needed LED lights and smaller room so Lidi LED went to mothers house and we fitted 10 x 5W so around 4800 lumen well below the 5100 original but far brighter.

When we bought the house it had 2 x 100 watt bulbs so 3200 lumen approx, room around 18 foot by 8 foot, always had white ceiling.

The problem is some LED lamps are pulsed to make them appear brighter, we did the experiment in Uni to get extra light out of LED's and pulsing the LED so average is still the same did make them appear brighter, however using a lux meter we got the same reading, which was not what we had expected, but the pulsing makes the room appear brighter, however try reading a book, and you find it may appear brighter but you can't read the book without a standard lamp as well.

Also in my old bedroom I had 2 x 7 watt GU10 lamps to read in bed with, mounted on the wall. facing down as designed they did not light the room very well, just the book. But turn them to point up at the ceiling and they did quite a good job, all down to what the light is reflected off.

It is a problem with fixed lighting, often ends up either too bright or not bright enough, that is the beauty of bulbs, you can swap them and correct errors, but my father-in-law added a room to his house, and there was a gap between ceiling and wall where he hid 8 fluorescent tubes, I would guess there were 4 foot tubes, so 36 watt each, so total for 12 foot square room around 288 watt so massive 20,000 lumen approx, yes it was bright, but not that bright, so much light did not actually get into the room.

 

[SUNRAY]

The big issue I have with spots and in particular downlighters is they are too directional and miss the reflective surfaces. They end up with horrible shadows, in kitchens I find the worktops are brilliantly illuminated until I stand there to do some work and at that time my head and shoulders are well lit but the food I'm working on is in deep shadow and now need under cupboard lights which these days reflects off the current fashion for high gloss finishes.

3 or 4 years back a friend had a new kitchen installed, the 6ft fluo was replaced with 22 50w downlighters in the ceiling and some more under the cupboards in silly triangular fittings. They complained several times about the lack of working light and the solution was some more under cupboard fittings.
After about 6 months he asked my advice and I simply asked how it was before the refit, I set-up a 4ft fluo on a tripod to hold it at ceiling height for a few days, result - instant improvement. Luckily the patch in the ceiling was just visible and managed to hook the original cable out quite easily to fit a new 6ft fluo. I don't think under cupboard lights have been used since.

 

[Anak]

Thanks for all the comments but I'm not sure I am any closer to a solution =/

The height is about 2.7m, so not high but a bit higher than a modern house.
Hopefully the strips around 3 sides should eliminate the worst of the shadowing, although in a bedroom I think I can survive if there are dark patches.

My current thinking is to get a dimmer controller with memory and hide it in the loft which could then be set up once, from then on operating the light switch at the wall would go to that pre-set value giving me a bit of customisation.
But even in this scenario I have no idea if I should get 480 / 960 / 1440 / 1920 or even higher... That and the fact that dimmers have a minimum value so getting the brightest and ramping it right down is not a valid solution.