Sky Lights & Fiber Optics

[OPEC BUSTER]

In a recent post someone had a problem making enough power for lighting. Now I've been reading this site for a few months and it appears we need to reduce all power consumption as a priority before power production! I have yet to read a discussion from you fine experts on the benifets of SKY lights. I have seen them installed in the home improvement shows and they appear to produce a lot more light than conventional lighting! They have flexible ducts that can direct the light to remote spaces. I also have heard about fiber optic lighting but I haven't seen any of these!

I know the fiber optics would have the benifet of eliminating heat gains and easy routing for installation!

I would like to hear your comments about this conservation topic!

Thanks to all!

Otis

[Volvo farmer]

I've bought a couple of those tubular skylights for my new house, a 12" and a 8". I've got a room in the basement that I was unable to put any windows in so I'm running the big one in there. We had to build a chase to run the tube though the upper floor. I haven't quite got it insalled yet but I bet it will work fine and allow me to use that room in the day without flipping on a light. The smaller one goes in a windowless upstairs bathroom.

In a grid conected house, I'm not sure retrofitting one of these would make sense from a dollar point of view. Cutting holes in one's roof and ceiling can get challenging, the tubes cost over $100, and they don't work at night. But for my application, using them was a no-brainer.

[GaryGary]

Hi,

There is a link to one the outfits that makes a system that uses a a tracking dish to collect light, and then transmits it through the building with fiber optics here:

http://www.builditsolar.com/Projects/Lighting/lighting.htm

(down the page a ways)

It looks like a very pricey system -- maybe someone knows of a simplier one?

Gary

www.BuilidItSolar.com

[rotornuts]

Off the top of my head here in Canada I'm thinking it would be about $450.00 materials including cheap 2'x 4' sky light to install. I have no problem doing the install myself because I have experience with roofing, framing, drywall, etc but for those who do not they could possibly expect an additional $350.00 - $600.00 for installation.

I think most folks mills come in cheaper than that so over the short term generating more power seems cheaper.

A skylight is by far cheapest to do at the point of initial construction.

Sky lights are indeed a great addition to most spaces if you can fit it in(my storage shed has one as well as the kids playhouse)but it's not really cheap epecially if you have to hire out a retrofit. You'll also notice that some skylights come with shade kits to shade out the light in the summer so you don't bake the room.

Mike

[pyrocasto]

That's a very nice setup though. The direct solar setups use a dish to track, put the light into fiber optics, and when it starts to get dark the lights slowly turn on keeping the same amount of light all day long if you want it.

[Phil Timmons]

Hey all,  

I have been considering some of this for a new shop/office building I am working on the design of - For better or worse, I am my own customer on this misadventure - so I can go pretty wild on any test designs.  This is a little broader than the fiberoptics of this starting topic, but is along the same general idea.

So I am still in some early pondering about the deep internal lighting of a building - or even a below grade structure -

This was how I was tending to break the elements of the problem down --

1.  Separating Heat from Light.

A major problem I see with this whole venture is that many light sources - including sunlight -- carry heat that is not always desirable.  I guess the use of fiberoptics tends to keep the heat out but let the light in?  If no, what ideas does anyone have regarding this?

2.  Concentrating

This seems pretty simple . . .  a trick with mirrors.  1 square foot tile mirrors go for about US$1 to 1.50.  I am guessing about using 16 to 20 in a concentrator fashion that tracks the sun and hits a 1 to 2 foot square target on the a gable end of a building.  It then requires [insert magic device, here - have not thought it through yet - but help is very welcome] that refocuses the concentrated sunlight into a beam through the attic.

3.  Distribution

After being concentrated into say a 16 or 20 "sunshines" beam the concentrated sunshine can be "beamed" through unoccupied attic space.  It requires no real tube, duct, or shaft for function, but one of those may be a good idea for preventing burns to eyes if someone were to pass through and look towards the source of the concentrated beam.  Within the beam small mirrors could be placed to reflect portions of the light beam towards targeted fixtures that backlight the fixtures for the room(s) below.

4.  Fixtures.

I am thinking of a 2 x 2 or 2 x 4 (feer) ceiling grid system - typical of commercial office space.  If you wanted to use the standard fixtures, cut the back out of them, and place translucent glass or plastic for the attic mirrors to target.  This backlights the translucent plastic and "lights" the conventional fixture for the room below.  At night, or on low light or cloudy days, the fixtures operate normally.

-------------------------------

Motivation on this is that it is SO cheap.  Review, comments, observations, or just plain help is welcome.

[cdg378]

A few other considerations from a "been there done that" standpoint would be climate, heat in a hot climate and cold weather problems in a cold climate.

I had a few skylights at my cabin and ice damming was a problem, especially if you are gone for days or weeks. When you ramp up the thermostat after a few snows the water gets trapped and leaks can become a problem.

Also being a boat shopper several times over the years, I always stayed away from situations where someone cut a hole in the roof bulkhead and put a hatch in there, they always leak and damage something along the way.

Skylights were very popular when they appeared on the market but are now extinct to a point, probably for lessons learned.

The fiber optic concept is very interesting though...

[cdg378]

I meant to mention also, I have been doing allot of experimenting with led lighting powered by lithium cells running 4 lights off of 1 run of cat 5 cable.

I picked up some 10 amp (not mA) D cells and I charge them everyday with some recycled solar cells from garden lights.

I am moving on to building 4 volt 3 amp panels to get them charged back up within a few hours a day with a solar tracker built from cds photocells and a 3.6 volt cordless screwdriver motor...so far I lit the under sides of the kitchen cabinets, the dogs room and now I'm working on my office.

I've built bigger systems and not had as much fun with those as I've had with this project. I'm learning fast that big flooded cells are overkill for lighting.

The future goal is to have a spare bank of lithiums charged at all times from the panels, enough power for several nights just by switching over to stand by.

[georgeodjungle]

you could make an home brew solar tube with:

1. 3" pvc pipe
   
2. 3" roof jack or boot
   
3. a gator aid or power ade bottle.
   
   

and a lil silcone

cut bottle in middle of first wide rib or second.

the top goes on top and bottom goes yep.

fits pref over pipe..

how ever you want the lens or shade to look.

if you don't cut the sheetrock right just cut a lil trim with like a router.

nobodys ever figerd out it's just the bottom of a plastic bottle.

p.s

i realy need to get a dumb digital camera.

if you can't peace it together you problaby shouldn't be cutting holes in you roof and ceiling any ways.

p.s.s.

you'll have to replace the top every 4 years or so.

it's a sun thing.

[maker of toys]

So, when we built our house (23 years ago, in Kalifornia) we put in a couple of skylights for the interior bathrooms.

note that we put them in before shingling the roof, but after the decking was done-- that's the nice thing about being your own contractor- change orders are cheaper.

the bathrooms are nice and bright during daylight hours, and we only used painted drywall to guide the light in though a (8'?) distance. We did not disturb the joists or rafters other than nailing the drywall to them where convienient and painting them.

heat gain and loss has not been an issue,(the bathrooms are usually the most comfortable temperature of the whole house) but that might be a factor of the climate more than anything else (monterey bay area-- it's more or less 60'F all day, year around.

anyhow, we put in your basic, cheap, domed, double-wall, air-gap insulated, plexiglas skylights, of about 2' x 4'. We put them on during an el-nino winter. They haven't leaked since we finished the flashing. . . and we've done squat to them. Haven't even been up to inspect them in something like 5 years; they're about due. The one thing we did was to make sure that they were framed well above the surface of the roof, and used aggressive amounts of flashing and roofing tar to seal the hole in the deck before the shingles went on.

the lessons to be learned:

1. skylights do bring in good, cheap light. I think we've spent more on 23 years of lightbulbs (we're grid connected) in those bathrooms than we did on the skylight install. . . and the lights only get used at night. (can't even tell they're on during the day)
   
2. as in everything, massively overbuild every part you can, and you'll save upkeep headaches. 23 years, and nothing. . .
   
3. plexiglas isn't always a problem in the sun. . . but do keep an eye on it. a good glass unit will probably stand up better, but hey, 23 years. . .
   
   

of course, your mileage may vary.

one thing to watch with actual fiber-optics (other than cost) is the directionality of the output light. . .

[inode buddha]

I saw something about these fiber optic lights on slashdot lately and the first thing I thought was "I wonder if there's some way to use these for RE" say extend the daylight time for collecting light.

[OPEC BUSTER]

Thanks to all that responded! Phil sounds like you have a good plan. you could possibly use your outside mirrors to replace the dish posted on Garys' website.

Maybe you could project the light to a reciever in the buildings gable end. Then use the fiber optic cable to transmit the light with out any heat gain to the desired spaces.

The dish system is nice and that technology should have a bright future.

George your $10 homebrew plan will also have a place in the RE campaign.

I thought this topic needed more discussion. I think the benifets are; Natural lite is better for health reasons, it can eliminate the need for batteries,let the wind gennies run a little cooler,also many sunny days there is no wind,no light bulbs needed!

Otis

[Oso]

Four years ago we put an addition on our house. The addition covered the Kitchen and one bathroom windows. My wife wanted skylights, particularly for the kitchen area. We ended up using the solar tubes because the new roof rafters run at right angles to the existing roof and the contractor was worried about trying to build the tunnel required for a normal skylight up through the criss crossing rafters.

We put a 12 inch in the bathroom. In the kitchen, we initally installed one 18 inch. For some reason, it was not installed in the center of the room and it left a shadow area near the back of the kitchen, so we added a second 18 incher.

The kitchen is the brightest room I have ever seen. The bathroom is also bright and cheery.  We are now going to install one at the end of the hallway to add light to that area.

I would recommend that anyone wanting natural light take a look at the solar tubes. Because of their interior reflective finish, the throw a lot more light than a conventional skylight of the same size, particularly a skylight with a long tunnel.

They do not contribute any substantal heat build up to the room. I cannot address any problems about snow or ice damming, but we have had zero leaks from rain.

[GaryGary]

Hi,

Skylights can be great in bringing light in and turning dark cave rooms into very pleasant places to be.

One caution is that skylights on south facing roof slopes can be a very large heat gain in the summer.  They end up being oriented very close to "ideal" for maximum summer solar gain.  Two 4X4 ft skylight on a sunny day in July on a 30 deg slope roof at 40deg latitude will gain:

      (2400BTU/sqft-day)(0.8 transmission) (2*16 sqft) = 61,000 BTU per day

Kind of like turning the furnace on for an hour :-)

The light tubes seem better this way.

Gary