Does anyone have any experience of fitting light tunnels in a high ceilinged room of , say, 4m height?

Is there anywhere that information can be found on the effects (quantifiable and/or subjective) of different ceiling heights on the amount of natural light introduced into a room?

Googling the subject gets little information back because all installations seem to assume a 'standard' ceiling height.

Is it all likely to be down to sucking it and seeing?

Thanks.

the amount of light is not dictated by the height of the ceiling, but rather the brightness outside, and the transmission through the tunnel.

the straighter the tunnel the better.

You are after daylight factors.

Light flux received on the 'working plane' e.g. your table top is inversely proportional to the square of the height of your light emitter (the light tunnel's bottom diffuser) above that plane. Twice as high, quarter the light flux. So ceiling height does matter, very considerably.

<blockquote><cite>Posted By: fostertom</cite>Light flux received on the 'working plane' e.g. your table top is inversely proportional to the square of the height of your light emitter (the light tunnel's bottom diffuser) above that plane. Twice as high, quarter the light flux. So ceiling height does matter, very considerably.</blockquote>

This is true for a point source of light however in the case of a Light Tunnel we have parallel light passing through a diffuser to create a diffuse beam. The arc of that beam is determined by the diffuser design, with typical prismatic diffuser that arc is probably close to 90 deg and not the 360 deg of a point source. So its not that bad.

If you can get a spec for the diffuser it can be helpful, there are several alternate designs specifically for larger spaces. There are some interesting models using fresnel lenses.

I would guess that if you double the volume of a room (vertically or horizontally) then you need to double the amount of light introduced to keep a constant overall light level.

Thanks a lot fellas. I was asking on behalf of someone else and have passed on the link to this thread which, as usual on this forum, has been instructive. I've also learnt something!