I have not heard of one but you could contact Onset Technologies which create data loggers of all sorts. They may be able to supply you a light sensor that could be paired with a mechanism to turn off the lights when enough natural light was present. I share your concern about energy waste. What is your goal? Do you someday want to build a commercial operation or are you looking for a hobby structure? We are in the process of building an energy efficient greenhouse and we considered artificial light to supplement the natural light but in the end did not really pursue it. We do have LED lights but just in normal fixtures and using typical warm white light. We were not interested in the blue and red LED lights because when we artificially light our greenhouse, it will mostly be for spending time in it. However, that might make sense for your application. No matter what artificial light you use, nothing comes close to the intensity of the sun. If you can use natural light for most -if not all- of your needs, you will be in good shape. For our GH, we are using windows strategically to get the most light and heat by putting them on the south side and a few on the east but none on the north. Everywhere else is R29 insulation which keeps things at a steady temperature. Another thought, Logee's Greenhouse is an hour away from me in Connecticut and they sell tropical plants and trees. They use NO supplemental light and they are a commercial grower that sends their plants all over the country (Martha Stewart is a big fan). Their visiting hours are restricted in the winter because there is not enough light after 4pm for people to look around so they actually reduce hours when most stores are extending them for the holiday shopping season. They have a lemon tree that is over a century old that is producing HUGE fruit and many other fruiting trees that are pretty productive. Maybe you don't need supplemental light at all.

I'm very happy with it. We use it with Porcelanosa Eternity White 5/8" glass and marble mosaic on the outside of our shower. -Babka

Okay...all the junk is out! Plan: clean up/mop dust, mortar chips, etc. and spend the evening with my paint samples...narrow down to three or four...paint sample boards, and pick a color. I would love to have time to see the sample boards in different light etc.; but my get-er-done DH scheduled plumbers on Monday and convinced the tile setters to partially grout the shower and come back to finish on Monday too....Grrrr! So...I plan to only paint behind the toilet and area and by bullnose edging. If I pick wrong.....I will not have to do redo the whole room. If I pick the wrong color, I am not worried about repainting near the bullnose; it is the toilet area that worries me. Anyone have a tip for painting behind a toilet that is 1/2 inch from the wall just in case. This is our attempt to correct a horrible inefficient layout...not thrilled about looking at the side of a toilet; but that compromise meant a towel closet in the bathroom (finally), a 60x60 angle shower, and room for a 77" double vanity while eliminating the 3 right angles in the second entrance from the master bath.

When there are several different natural lights coming into the room, I go with the one which delivers the most light…so, guessing the light from the slider is the dominate light (West). Try B.M. I know you really want a white for the walls, but with all the different light neutrals you have in the tile and the cabinets, give a moment’s thought to White Winged Dove, as it has a LVR of 76 (meaning not a whole lot of undertone) I think you need to consider your floor tone more.