In an ideal world, we'd use natural light to brighten every darkened nook that needs illumination. But in reality, skylights and windows can let only so much light into a structure, and the amount of light varies based on the time of day. The Sundolier robotic skylight from Boulder-based Sunflower aims to change all this by actively "pumping" natural light into interior spaces, illuminating areas of up to 2,500 square feet with a single unit.
The Sundolier employs a large dual-axis tracking mount with a couple of reflectors that gather light into a two-foot tube, which in turn feeds into a "sun chandelier" that lights up the room below. The rig tracks the sun as its position changes in the sky, so regardless of the time of day, the light intensity inside the building stays relatively stable. Once the sunlight is captured, it can be distributed in several different ways, so a single Sundolier atop a roof can channel light to many different fixtures in the building below.
Of course, as with any solar harvesting scheme, Sundolier is hamstrung by Earth's atmospheric processes; when the sun is out, the Sundolier provides ample lighting, but overcast skies render it somewhat ineffective.
Even so, the power savings on a good sunny day are pretty remarkable. In a public building like a large school that contains lots of interior space that must be well-lit, piping in natural light could save a good deal in energy costs over the course of a year. The company claims Sundolier can also help cut cooling costs (all those light bulbs really do add to the ambient heat of a building), and since the sunlight doesn't come in directly as it does through skylights and windows, it doesn't contribute any appreciable heat gain.
Check the video below to see the Sundolier pumping natural light into the Douglas County Library.
Will there be a filter to block some of the more harmful UV rays? Or will children have to apply SPF 1000 cream before they sit down in class?
Would someone please explain how reflecting light allows a room to avoid the heat gain caused by direct sunlight? This seems counterintuitive to me, but I have very little knowledge in this area. I'd also like to see some cost comparisons to other options, like large, south-facing skylights.
They are most likely using fiber optics of some type. Utilizing only the visible spectrum would produce no more heat than the light coming from a florescent fixture. The savings could be very real. Put your hand next to an incandescent bulb or florescent ballast and you will notice the heat radiating from them.
Imagine a medium to large office turning off 1/2 of its electrical lighting for 8-12 hours a day for 250-300 good weather days a year. The saving are not trivial. Look up at each fixture in your office and assume that each fixture uses .5-1amp. Do some math and you can see that over a year this unit would easily save money.
An interesting idea.
The benefits of real sunlight are many: produces vitamin-D, treats seasonal affective disorder, improves mood, reduces energy use. The Japanese first did this years ago. Not sure why it's suddenly news, but it's still a good idea.
Addressing some of the responses:
There are several bonuses to this concept, especially in sunnier and warmer (southern especially)climates:
On a sunnier day, this concept can provide nearly all the light needed (multiple units, designed properly, etc)... a sunnier day is typically a HOTTER day as well (ambient outdoor temp)... so by using the sunlight, you can power off the bulbs, reducing their heat output and power consumption, reducing the cooling and power load required for climate controlling a building, thus helping tremendously with cooling bills.
More overcast days, the temp effects (ambient, and directly radiated onto the building heating) are not quite as severe, so when the artificial lights are turned on to supplement, it's not as big a deal... basically your overall average power consumption drops.
Regarding UV, glass, especially quartz or UV coated, easily blocks UV rays (the HID sodium vapor bulbs in most "school gymnasium" lights are HIGHLY dangerous UV emitters, but the UV is mostly blocked by the cover glass, down to humanly safe levels.
Between multiple reflections in the tube, and glass outer covers, and probably glass or plastic fiber-optic distribution, UV will be absorbed well before visible light reaches the interior.
IR (the most efficient heating of your building by directly-radiated heat from the sun) will also be nearly lost to ambient by the transmission systems before entry into the climate controlled/insulated spaces. The tubing involved will be absorbing it along the way and radiating it outwards, as well as the glass and transmission tubes, so most will be lost in "exterior" (uninsulated) space before it reaches the interior insulated space.
Looking strictly at the numbers...
The solar energy reaching earth in the "visible light" spectrum is roughly 400 watts per square meter at the equator at noon. If we look at southern US latitudes and average it over a sunny summer day from say 8AM to 8PM (DST), maybe 200 watt/hours per meter average is usable by this type of system (based on size, the reflector looks like maybe 1 to 2m^2).
An incandescent / halogen bulb is roughly 17-20% electrically efficient. So a 60-watt bulb is producing at best 12 watts of "usable" light. So in a room that has 4x60-watt bulbs, you'd need 48 watts of actual "light" equivalent.
This also means that 240-48=192 watts of heat are being produced in the living space as waste, an at a 1:1 ratio (it's not, but that's simple), it means another 192 watts worth of cooling capacity are required to maintain the initial non-lit state (not counting the heat generated by the usable light, which is a constant for comparison's sake). So 48 watts of usable light, and 384 (192+192) watts of power "wasted" as heat (in summer anyhow, in winter you might want to use these little "room heaters).
A fluorescent or modern LED is roughly 20-28% efficient, and HID are typically also around 28-30% efficient bulb output. A typical 4-bulb fluorescent office fixture is 4x40-watt tubes, for a total of 160 watts electrical, however the fixture itself limits the efficiency, so for all these, let's say 25% efficiency of electrical input as light actually leaving the fixture (that's being generous). This gives us 160*.25=40 watts of useful light output.
As above, this means 120 watts of heat generated, and another 120 watts of "cooling" energy required, so 240 watts of "waste" heat.
So using these numbers, the solar light collector could replace on an average sunny day, roughly 4-5 bedrooms worth of incandescent, or roughly 5 overhead office fluorescent "fixtures" (enough for about 2 typical offices, or 6 cubicles worth of area lighting, based on our office). And it would save 480*4=1200 watts of electrical energy for (5*4*6) incandescent bulbs, plus the cooling equivalent of another 192*5=960 watts electrical.
If your utility charges a premium for daytime hours (many are now in power-constrained areas), this could save substantial money... 8 hours a day, this could save (1200+960)*8=17280 w/h or 17.28kwh each sunny day. At $0.20/kwh, you'd save $3.50/day (and since cooling isn't 1:1, but more like 80% efficient,, it'd save more... ).
From the picture, it looks like their is a built-in solar (photovoltaic) cell on the receiving mirror pedestal (perfect placement) so it's self-powered for tracking (no grid usage, no utility cost).
Nearly all the numbers I used here are conservative (useful efficiencies are all going to be lower on current bulb tech), so $4-5/day savings per light collector are reasonable.
Keep in mind this is based on a 1 meter collection area (the collector mirror, not the concentrated 2ft diameter mirror), if it's actually 2m in collector area, then double those savings to roughly $10/day.
So if we say say only 150 days per year these numbers are solid for, that's $1500/year in potential utility savings (and lower grid usage so better for the environment as well). that's PER UNIT... It is also a more pleasing (natural) light, and another neglected factor, less bulb usage = less replacement costs over time (less harmful mercury used and lost in fluorescent bulbs especially).
Realistically, in areas that need this most, you might save $2000/year/unit plus all the peripheral benefits. The article didn't mention cost, so it's hard to say how long it would take to pay for itself, but it's effectively "free" forever after installation (until it wears out). When it isn't useful (too overcast, winter), then turn on the lights as usual. So long as initial cost isn't too prohibitive, and durability is significant (5+ years minimum, more realistically I'd hope for 10+ years before "major maintenance" is required), there isn't much to NOT like about this solution.
Here is some more information that may be helpful:
Back up lighting is required on cloudy days or at night time. If you want to turn the daylight off, you can do this by taking the system off axis, this feature is available today with wall mounted switches for classrooms or office areas where dimming for Audio Visual would be needed.
The ROI is dependent on solar map, building lighting and what benefit streams from daylight are included - energy, carbon, health and wellness, productivity, etc.
The system can also be directly tied to the grid. The draw is small, typically less than 1 amp for less than an hour a day. The off-grid zero carbon lighting option is a great way to approach new or existing buildings to power tracking system.
The product is available now.
The idea presented here is fantastic: to redirect sunlight into a building to save electricity. Correct? Let's make a modification to this idea and instead of redirecting sunlight into a building (or do it alongside the second part): track the sun and focus it at a steam generator to produce electricity.
Dan Rojas has been perfecting this design. All we need to do is design an efficient way to mass produce parabolic mirrors of size (say 60 inches or so). At this time, one 60 inch mirror is over $2000 and that doesn't make it a very practical solution for alternative energy, but if there was a way to mass produce them at low cost and high speed (while maintaining efficiency i.e. highly reflective material), we could have one or two of these on every household in the entire world and the possibilities would be endless. Not only would they be low to no maintenance by making it a closed loop system where the steam would pass through a heat exchanger and feed back into itself, but the generator would power the servos that allow it to track the sun.
The materials would have to withstand the elements, but besides that, the end result would be limitless free energy for decades.