Light tubes, done differently

I have seen light tubes for houses, they are a skylight through the roof, with a seriously shiny tube that goes down and outputs the light into the house. I have always loved the idea, and made a variant in my last house as an experiment. Worked well. Mine, however, eliminated one of the main problems with the commercial ones: The roof penetration. Roof leaks almost always start at a penetration. I suppose a few do not, but the places that generally leak are around pipes, chimneys and ... skylights. Much less likely to leak so fast is penetrations in walls.

I was thinking about this rental and the neighboring houses, all built by the same builder. They have a basic double pitch roof (look like a triangle from the end) and are too low to be useful attics.

I'm thinking if windows were set in the end gables of the attic, one at each end, with a reflector outside each window, and long shiny tube ran between them, then cut outs off the tube could reflect into each room. I'd probably put glass over the cut outs, to help with insulation. There could be several rows of glass in the line for insulation too. Think ductwork running light instead of air.

Would a large percentage of the light just shoot out the other end of the tube?  Maybe a "one-way" mirror at each end would bounce the light back the way it came.

Might it be better to just have the tube feed one skylight in a room?  Then there can be a 45 degree mirror to bounce all the light down into the room.

Cool idea!

Mike Haasl wrote:Would a large percentage of the light just shoot out the other end of the tube?  Maybe a "one-way" mirror at each end would bounce the light back the way it came.

Might it be better to just have the tube feed one skylight in a room?  Then there can be a 45 degree mirror to bounce all the light down into the room.

Cool idea!

Oh sure, you want a solar laser? because that's how to build a solar laser in your attic...

I think a lot depends upon the gable/roof orientation to the sun... Our house, for instance, has gables on the north and south sides, and the south gable is shaded by trees. I could see the north gable being a good entry point though.

Another cool part of this idea is that the light tubes could be routed in the narrow space closer to the eaves that really is poor storage (if you have any attic storage at all.)

Fiber optics could also be used, they're basically tiny light tubes.

Mike Haasl wrote:Would a large percentage of the light just shoot out the other end of the tube?  Maybe a "one-way" mirror at each end would bounce the light back the way it came.

I like that idea!! Kind of a one way valve for light :D

Might it be better to just have the tube feed one skylight in a room?  Then there can be a 45 degree mirror to bounce all the light down into the room.

Cool idea!

The way I had the one in my last house, there wasn't a shortage of light in there, it could have easily run more outputs, I had no way to move it around. I think light is less.... prone to running out?... than something like water.

Have one in our kids bathroom ... works great. The bath has a shower/tub against the external wall, so a window wasn't ideal. The tube keeps that room well lit up ...

They are expensive, so not sure how much it would cost to run the length of a house.

Alternatively, if a bathroom permits, might be possible to install thru the wall, vs thru the ceiling/roof. Wall penetrations should be less traumatic than roof penetrations. Most folks put in a window at that point, if bath layout is on an external wall, to get other benefits (air flow, see things, etc.)

Still, innovative idea ... might work in very specific applications ... architects are known to bounce light around, in their projects.

I dislike all roof penetrations after what I found when I tore the roof off my last home.  What a mess. And then they tried to repair the leaks...

The premade tubes are expensive, that's part of why I dislike them too. Very spiffy, but way too expensive. If you look at what they are, the kit has the skylight, and all the flashing etc to attempt to keep it from leaking, and tube. I believe the close to perfect mirror surface of the tubes is way overkill. I had a video store for a while giving me all their dead disks. I did a test run of a bunch in a box, being the reflective surface. Bounced a LOT of light around, and beat the mirrored one I tested it against in that the mirrored one made a slightly brighter, straighter light, but the disk made a more diffused light, bounced around the room more. Subjectively, the diffused light made the room look brighter than the single spot of more intense light did.

:D

The Egyptians used well placed mirrors to bounce the sun rays around and illuminate their structures.

For a reflective surface, mylar film isn't too expensive -- about $.11/sqft when bought in consumer quantities: https://www.amazon.com/gp/aw/d/B018VI77QW/?th=1

I love these ideas.  I had an old house (circa 1909).  Sound structure but crazy layout.  

To bring light into dark interior rooms, I had professionally installed tubular skylights.  They were expensive, but any leaks were for the professionals to fix, not me.  They had the super shiny tubes, and came with a diffuser to place at the bottom of the tube, which changed the bright spot phenomenon.

Instead of mylar, a DIY tube could be formed of reflective bubble wrap, adding some insulation, and some substance to the reflective material.

I’m hoping to see lots of improvised projects here!

Thanks for starting this thread!

I have to scratch my head on this one, BUT, about forty years back, I started playing with bastardized fiberoptics, then got side track (you guys couldn't begin to guess, as to how many shiny things there are all around my shop and house).  As an avid yard sailor, I pick up many things experience tells me I PROBABLY need. One is, cheap Plexiglass and its equivalent.

One of the things I did was, cut 1/4" Plexi into strips about 2" wide. Then I cut them off at different angles. To see what would happen I played with sanding and polishing the various edges and shining light into the bottoms of the strips.  It made for some interesting results.

The idea was inspired of the fiber optics craze of banding hundreds of 1/32" tubes together and pumping light into them, and my purchase of an interesting display, which was an aluminum tube with a light in it that shined into a piece of glass that was locked into a slit made into it. You could write things on the glass, OR you could glass etch it and gets some interesting results.

Regarding the strips of Plexi I cut, the light would travel up the strips and seem to, primarily, exhaust on the end cuts.  The effects all depended on what I did in the way of sanding and polishing.  It was neat watching the plastic throw light from the angled and polished cuts.  I ended up making a art piece using three pieces of 6" PVC pipe I, also, cut at angles, before filling the cuts with wood I cut and into which I mounted the Plexi, with lights under them. Have ZERO idea of whatever became of that.

Any way, the conversation about light tubes (I installed about 5 of them and love what they did for rooms at the center of customer houses) makes me think there is so much potential here. In fact, it reminds me I wondered why the concept was no applied to, for example, sky scrapers, whether by way of the optics or the tube I learned about many years later.



NOW, all the foregoing aside, I, many times, wondered what would happen if I dumped a 4' diameter, 6 or 8 foot long culvert into the ground, vertically, and filled it with fine shale. THEN, used the parabolic lens, from a projector TV directed at it to heat the shale.  

SIDE NOTE: I have the parabolic lens (about 1/16th thick by about 3' wide and 4' long) in the overhead of my garage, to keep it out of the sun, because of the EXTREME danger it poses.  If the sun hit it and it was directed at my car, a board or something else not tolerant of super high heat, it would blister all the paint off my car, melt the plastic, tire or what have you, or it would start something on fire.

Directed at a brass padlock, the lens will melt it.

The stored heat could be released back into the house. To stop the lens from heating the rock, it would have to be covered.

I guess a great place to experiment with that would have been out in the cattle pen, in a built up (tires stacked with dirt, area to protect them from wind) pen in the nasty cold of the winter. If the culvert came up out of the ground, about 5 feet, the outer area of the filled culvert would throw off heat, giving the critters at least a little comfort.

For those not aware, the parabolic lenses on old projector televisions are like big magnifying glasses. They will melt metal, so they will heat rock and can even cause them to explode, if moisture is trapped in the rock.

Here, electric runs around 5 cents a kilowatt. Someone was saying they were paying 47 cents in Europe. It might not be long before the cost of a tube would seem cheap.

The nice thing is, they are easy to install. Just have to remember to follow the tiling rules for roofs, so water run off doesn't penetrate the structure.

Pearl Sutton wrote:I dislike all roof penetrations after what I found when I tore the roof off my last home.  What a mess. And then they tried to repair the leaks...

The premade tubes are expensive, that's part of why I dislike them too. Very spiffy, but way too expensive. If you look at what they are, the kit has the skylight, and all the flashing etc to attempt to keep it from leaking, and tube. I believe the close to perfect mirror surface of the tubes is way overkill. I had a video store for a while giving me all their dead disks. I did a test run of a bunch in a box, being the reflective surface. Bounced a LOT of light around, and beat the mirrored one I tested it against in that the mirrored one made a slightly brighter, straighter light, but the disk made a more diffused light, bounced around the room more. Subjectively, the diffused light made the room look brighter than the single spot of more intense light did.

:D

Hello

I like to locate all roof penetrations as high up on the roof slope as possible. Ideally, just below the ridge cap. Easy to avoid leaks that way. The light tube in the attic is a good idea. Bigger windows where possible helps too.

Steve

Warning visitors to a restroom with solar tubes tend to spend futile time flipping switches trying to turn off the light before they leave.
But mine works great even moon and star light when available.

The elementary school I went to was a fairly new building at the time, and while I didn't fully comprehend it back then it was a pretty amazingly advanced place. The windows had tint that was extremely dark to look in but not nearly as dark looking out. Above those windows was a series of smaller windows without tint. There may have been special coatings like you find today to allow visible light through while blocking damaging UV and heating infrared.

The really cool part relevant to this thread was the light shelves. It acts as a shade to the lower window and reflects light through the upper window, bouncing it upward towards the ceiling to add light fairly deep into a room. I can remember many times when the teacher would shut off the lights and do various things to get everyone to calm down a bit after running around outside, and the room felt more than 3/4 as well lit just from the sun.

I believe the light shelves were aluminum, which is highly reflective and probably had a coating to reduce oxidation, and the ceilings were high and particularly white to scatter the light once inside. There was a Mythbusters episode about Indiana Jones myths where they tried getting sunlight deep inside their set where the mirrors worked to get the light in, but it wasn't until Jaime stepped in front of that light beam with his bright white shirt that it scattered the light for better illuminating the space.

I always thought it was an interesting way to do solar lighting inside a house. In a lot of cases, you could probably upgrade a house without having to modify the structural members of the framing. If someone was already looking to upgrade their windows to something more insulating, better UV protection, and a higher impact rating like modern windows have, then it wouldn't be that much more work to plan for a light shelf. If the header is at the top of the wall, you could make the opening larger both up and down without needing a framer, engineer, and more permits and inspections. Or you could do like the school did and add a small window above a regular window. With the right combination of shade, light, and efficient design, you could potentially save a fair bit of energy on lighting and cooling.

With light shelves there are more benefits for warmer climates. Interior rooms without a direct line of sight wouldn't get any light, where the light tube idea would work really well. I guess like most things it depends on a lot of factors like house orientation, roof size, and other factors of the design and location of the house. I could potentially see some sort of manifold that instead of optimizing for the flow of fluid, you optimize for light. Perhaps it is much larger at one end, with a bit sticking down to direct a portion of the light downwards, and then a smaller section to the next angled reflector for the next room and so on. You could even do two coming from opposite ends of a house for morning and evening light.

I couldn't find any pictures that really expressed my understanding of light shelves, but I found a short video that shows the basics of how they work. They seem to make it out like the shade part can't also be reflective, but The Wikipedia Page on Light Shelves says exterior ones are more effective.

Hans Quistorff wrote:Warning visitors to a restroom with solar tubes tend to spend futile time flipping switches trying to turn off the light before they leave.
But mine works great even moon and star light when available.

Yes, Hans, I had that too, people trying to turn off the light, and I loved the moonlight and starlight coming in at night.

Never was one for “night lights”.  I don’t use them, and seldom have visitors that want them.  Unless it’s a moonless night and or very thick clouds, plenty of light!😊

Remember when a tornado hit Greensburg, Kansas?
After they rebuilt the high school, I had an in-depth conversation with one of the teachers.  They had used curved mirrors on the north corner of the roof to bring light into the rooms on the north side of the building.  They said it worked well and cut down on electricity usage.

My earth sheltered home has seven SolaTubes. They were installed during construction and I put them in enclosed spaces, closets, laundry room, an interior bathroom and guest space. (Shamefully I forgot about the garage where they would have been of good use.) Keeping them well beamed on top helps prevent leaks. We have one cracked dome that will be replaced and isn’t a problem for the moment. They penetrate ten inches of concrete and three feet of dirt so are truly permanent. Even on cloudy days we have plenty of light, and yes, it took a while to quit turning off lights that weren’t on.

Snort. One lady, who had me install a light tube in the bathroom in the center of her home, commented that she found herself sitting and reaching for the light switch for the first month or so, because it was so bright there in the early morning, after the install.

Hans Quistorff wrote:Warning visitors to a restroom with solar tubes tend to spend futile time flipping switches trying to turn off the light before they leave.
But mine works great even moon and star light when available.

Cool information., Daniel.  Well worth considering in home construction and to get soft lighting.

The light shelves you mention could have been aluminum.  When I worked for the Navy (civilian capacity), we'd refurbish those monster digital-analog monsters you may have seen in a movie. A sailor sat in front of them and the screen had little blips that would appear to show the positions of ships and things relative to Navy operations.

The blips were made using projectors with bulbs powered by 10,000 volt capacitors and shot light at an aluminum mirror inside the unit. The mirrored surface was used, rather than shooting the light through the glass in front of that surface (to avoid a thing called parallax, which can be seen when you put your finger on a mirror and note the gap between it and the mirrored surface.

Aluminum was used because there was no coating on the aluminum surface. If silver had been used, like most mirrors with which we are familiar, the black tarnish you may have seen when protective paint (keeping the air off the surface) fails on a mirror commonly used in homes and businesses. The aluminum will, slowly, oxidize, but will still function.

Daniel Schmidt wrote:The elementary school I went to was a fairly new building at the time, . . .