I think they call it 'Cognitive Dissonance' in marketing terms- did I get the best deal/product/service when I had my Solatube fitted. Are there better products out there? Solatube claim to be the brightest- I thought so- but is it true? What have been your experiences?

True- but isn't that more work Tony- with making good etc.?

Tony, I have found them to be very effective, even when it's an overcast day. We never turn the lights on in our lounge anymore during the day and it feels so much more inviting place to be. I considered the roof window, but with the making good etc, and the 2m drop from roof to ceiling (I live in a bungolow) it was very expensive- even though the unit itself (VELUX) was cheaper.

Posted By: tonyNormal roof window with a light well or even a normal window. Borrowed lights can work as effectively as a solar tube too.

Pardon my ignorance, but aren't solar tubes just a versatile - and expensive - way of having mirrored sides to a light well? In a straightforward situation such as Tony suggests above wouldn't lining all or most of the sides of the well with ordinary mirror glass work just as well?

I would beg to differ Tony. When my tubes were fitted there was a point when the roof and the ceiling were both open and a bright shaft of light came through. To my surprise, this was intensified once the reflective tube was put in place my installer.

The other factor regarding the Solatube specifically is that the done on the top has some special way of getting light that comes in at an angle to be thrown down the tube.

Mike - i've just looked into this in more detail - here's what the company claim:

"Raybender® 3000 Technology Fresnel lens in the roof dome ensures that low level daylight doesn't just pass through the dome - it is redirected down the tube aperture at a steep angle to ensure fewer bounces and thus minimum light loss"

I found this at http://www.lightupmyroom.co.uk/Solatube_components.htm

I have seen a lazer pen directed at the dome and not pass through- instead thrown downwards- so from eye witnessing- yes it does work.

The definition I was alluding to would be a "doubt that surfaces when a buyer becomes aware that an alternative product may offer more desirable benefits than the one purchased, the buyer wonders whether the right choice has been made, sometimes known as "buyers remorse"". The competitor sun tubes have their own USP's - I was keen to hear from people with other systems installed or had done their own research. Heck- i'm not taking them out now!

AFAIK, Solatube have world wide patents on the dome for bending the light downwards, preventing others from doing the same thing. In demonstrations I saw using their dome and a major competitors dome on the same tube with the same light source from different angles, the Solatube definitely seemed better.

I would tend to agree with Tony regarding light wells, but they are not practical when needing to get light downstairs. Granted light tubes lose efficiency with increase in length, but if it is the only way.....
Will report back on effectiveness once ours are fitted.

Regarding installation - it is quite feasable with DIY skills or a competant general builder. Instructions supplied so no specialist skils required.

Mirroring the sides of the tube and the ingenious dome (if it works) should ensure more light for a small area of opening than an ordinary window therefore saving heat loss. In practise however I suspect these have an inferior u value and are not green at all.

Since windows are inevitably weak points in a well insulated building unless solar gain can be stored (at least overnight but preferably interseasonally) the question is should they be there at all and especially in the roof since heat rises. Natural light is perhaps an unjustifiable luxury. Energy saved in electric lighting may not compensate.

I read somewhere that even moonlight travels down these things!

Amazing- and yet so simple. Which brand do you have Rachel?

Posted By: arthurSince windows are inevitably weak points in a well insulated building unless solar gain can be stored (at least overnight but preferably interseasonally) the question is should they be there at all and especially in the roof since heat rises. Natural light is perhaps an unjustifiable luxury. Energy saved in electric lighting may not compensate.

That sounds a bit spurious. Plenty of houses have been built that don't need any heating, but which have plenty of natural light. Besides, if the loss of heat at night was a problem, you could always fit an insulated shutter under the light-tube, hinged to one side and with a catch to hold it back against the ceiling when open. I'm actually planning something like that for the windows in a structure I'm hoping to build.

Posted By: arthurDo many passive buildings of roof windows? Don't they tend to arrange windows carefully on the south side and minimise them on other surfaces?

I don't know, to be honest; I was just responding to the idea that natural light is an unaffordable luxury. But in designing a passive house, it would surely be helpful to make the overall form of the building as compact as possible, approaching cubic as opposed to a long, flat rectangle; this might mean that some of the interior spaces would lack sufficient natural light. In that situation I would have thought that the combined gains from non-use of electric light and heat conservation through building form would make a rooflight worthwhile.