Skylights (or light pipes) are a great way to get natural sunlight indoors.
Unfortunately, installation is moderately complicated and is infeasible for renters and high-rise dwellers.
Also, skylights only provide light during the daytime (unsurprisingly).
Thanks to LED lighting, it is possible to create a convincing “artificial skylight” (Figure 1) for 50 American dollars (~4 hours of of 2021 California minimum wage).
The actual application of this light looks surprisingly convincing: in a dark environment, relatively little wattage is required to simulate sunlight.
The motivation for this DYI “skylight” is cost: commercial versions of this system are substantially nicer—and 1000x more expensive (Figure 3).
Materials / Build Process:
For prototyping, it’s easy to use a cardboard box (instead of a high-class trash can) with dimensions at least 8″ x 10″ x 20” (it’s also OK if it’s bigger in any dimension). From the outside, this will look like Figure 4.
The specific items in Figure 5:
- A: Extension cord (~$5.00).
- B: Light socket to wall outlet adapter (screw the light bulb into this, then plug it into the extension cord) (~$5.00).
- C: A 3000+ lumen directional floodlight (~$30.00).
- This means a ~30 Watt LED (or “≥250 Watt incandescent-equivalent”) bulb.
- I did not get good results from “corn cob”-style LED bulbs. The widely-spread-out LEDs create a weird and irregular final image.
- D: A cheap plastic magnifying sheet / “Fresnel lens” (~$10). This will be the “light” from the viewer’s perspective, so try to make it at least 8 x 10 inches!
- I cut a hole in the front of the box, then used Scotch tape to attach the lens. Quality workmanship!
I had to move the light bulb back and forth a bit until I found a good focus distance.
Note about burning your house down:
Don’t! Surprisingly, these bulbs are passively cooled (i.e. there’s no fan). A 30W LED should normally not get especially hot, but you should double check this.
This skylight has turned out to be extremely pleasant in practice! It’s especially convincing if there is still some external light (e.g in the late afternoon / twilight hours).
Psychologically speaking, it’s almost like getting two extra hours of full sunlight every day!
PROS: Only 1% as expensive as a professional “artificial skylight” solution!
CONS: Might also only look 1% as good as a professional “artificial skylight” solution!