Making daylight?

January 14, 2008 8:24 PM

What is the cheapest, most cost-effective way to have a lamp (or lighting fixture of some variety) mimic (roughly) daylight hours, including fading in slowly in the morning and going off slowly in the evening?

Due to circumstances (poorly-laid-out house, new baby on the way, bad housing market), we're going to have to move our toddler's bedroom into the finished basement of our house, which is a fine area, except for the lack of windows. I would really like to create a false window or two using daylight lamps behind rice paper screens, but for the real effect, I would really like for them to roughly mirror actual daylight hours (bonus points for actually adjusting the length of the day with the season). I have some old X-10 firecracker controllers I could use connected to my house server, but I'd rather come up with some that's not computer-dependent if at all possible, since I'd like to replace my home server with something more energy-efficient. Are there any cool off-the-shelf solutions out there, or any hack-it-together solutions for someone with basic electronics, soldering, computer and electrical sklls?

posted by jferg to technology (15 comments total)

Use 2 timed outlets behind the screen. In the morning have it turn on with 2 bright (100W equivalent) blue-white bulbs compact florescent bulbs. Around 11AM have it turn on with a brighter (150W equivalent) warm compact florescent. Turn have the blue turn off around 4:30PM, and the warm around 6PM.
posted by mhuckaba at 8:37 PM on January 14, 2008 [1 favorite has favorites]

This may not be the cheapest, but here is a starting point: the Sun-Up Dawn simulator. You can set a sunrise time that will automatically occur each day. The sunset function, however, has to be started manually. I don't know if they are hackable. They are pretty cool, though. (I got mine at a thrift store for a couple of bucks, which makes it even cooler.)

One thing to consider, though, is whether you really want your toddler in a windowless bedroom. There are some safety issues to consider in case of fire, for example. Especially if you have hot lamps burning behind paper screens. A dawn simulator like that isn't supposed to be used with fluorescent lights, so you end up with bulbs that are putting out some heat. So be very very careful when you build your faux windows.
posted by litlnemo at 8:38 PM on January 14, 2008

IKEA has light timers for like $3, btw.
posted by mhuckaba at 8:38 PM on January 14, 2008

For a different take, why not a light-pipe kind of deal? Also known as a lightwell, you have a transparent dome on the roof, a reflective large-ish diameter tube down from there, and a translucent "lighting fixture" type thing at the other end.

Advantages are that you don't need to worry about tracking daylight at all, and it works without power. Disadvantages are that you need to be able to poke a hole from the top to the bottom of your house.

It's not electronic, but it is elegant (which counts for more geek points in my book)

If that's not practical, build a controllable dimmer for the lamps hooked to a light-dependent-resistor on the outside. Calibrate it on a cloudy day, beware mains power (keep power and signal parts of the circuit very separate), and see how you go.
posted by 5MeoCMP at 8:41 PM on January 14, 2008 [1 favorite has favorites]

You should have fire escape windows put in if you're going to have a child down there. Kinda expensive, but really, that's I think the best thing.
posted by TeatimeGrommit at 9:26 PM on January 14, 2008

I worked on a remarkably similar project for some persnickety zoo animals a while ago. The solution we came up with wasn't cheap, but the basic building blocks are available individually and in smaller packages and might be affordable. Check out the Lutron RadioRA Timeclock . It's a lighting control system that's based on a timeclock that can account for changes in the length of days and doesn't have to run on your network. I'd suggest incorporating it into a two or three color fluorescent fade (cool, to medium, to warm) like mhuckaba suggested. You might also look into mounting some kind of window or sky scene to milk plexi in front of linear fluorescents instead of using rice paper with compact fluorescents- the results are remarkably good and have been a popular solution in hospitals.
posted by Thin Lizzy at 9:42 PM on January 14, 2008

I would use a small solar panel or LDR mounted outside as a light sensor that controls the lamp brightness, so the brightness not only corresponds to day/night/dawn/noon/dusk, and seasonal length, but also to overcast or clear sky weather - it matches the brightness to the outside world.

Interfacing the sensor is obviously a tricky bit if your electronics is rudimentary. I'd suggest buying a lamp-dimmer, and taking it apart - it is likely (hopefully) a switch-mode system where a low-voltage potentiometer controls a circuit that controls the mains-voltage lamp brightness, allowing you to interface with a low-voltage (ie safer) part of the device, eg, you can look at the specs of the potentiometer and make your light sensor into a matching substitution for it. Total cost could be under $10.
(Don't do this if you can't work out how the dimmer works, or don't know enough to do it safely. Find someone more knowledgeable who either owes you a favour or can be easily bribed :-)
posted by -harlequin- at 9:58 PM on January 14, 2008

If you have doors down there, put in windows on the top half of the door. But yeah, you'll need to have some kind of fire escape if you're spending any kind of time down there.
posted by barometer at 10:01 PM on January 14, 2008

A few more thoughts. Getting fluorescent fixtures with dimming ballasts would make the effect quite a bit more elegant. Also, perhaps it goes without saying, but if you're going to do it yourself, make sure you check up on the applicable electrical codes and have the proper type of enclosures, etc. for anything you plan to stick in a wall.
posted by Thin Lizzy at 10:15 PM on January 14, 2008

If you do go with fluoros, make sure they're ultra-high CRI (color-rendition index). If you look at the color spectrum of your typical tube, you'll see something like this--notice the peaks of light output. Natural daylight is a continuous spectrum--no gaps. People who suffer from SAD (seasonal affective disorder) respond well to these "daylight" tubes.

The thing to remember is that if you go looking for "daylight" fluorescents, you'll find prices in the $50+ range, whereas looking for "high CRI" fluorescents can get you things in the $20 range. Same tube, different market. High CRI is marketed to people who work in the arts: photographers, graphic designers, etc. "Daylight" tubes are marketed to healthcare industry folks and hypochondriacs, who tend to have more cash to shell out.
posted by Civil_Disobedient at 11:42 PM on January 14, 2008

Oh, also, "high" CRI typically means anything around 93-95+ CRI. 100 means full spectrum. Incandescent lights (your basic lightbulb) are full spectrum, surprisingly enough, just by the nature of the mechanism for light emittance.

If you've ever tried color-correcting a photo taken under incandescents vs. a photo taken under fluorescents, you'll quickly understand why you need a full spectrum. To fix incandescent shots, you merely have to shift the spectrum up a couple thousand degrees (~3500K -> ~5500K). Fluorescents, on the other hand, have actual gaps in the light. And if you remember how light works, all you can see (and photograph) is reflected light. So, if there's a gap in the spectrum, you don't get that reflected back to you, which means your pictures are hard as hell to adjust properly.
posted by Civil_Disobedient at 11:46 PM on January 14, 2008

Thanks for saving me a question, jferg. I've been researching this exact topic lately and had planned to ask about it here.

I need my bedroom to be very dark when I sleep. Living in the city, that means I have to use heavy, light-blocking blinds and curtains. The only problem is that it still looks like it's nighttime at one o'clock in the afternoon.

This programmable dimmer switch allows you to enter your latitude and longitude, which it will use to calculate sunrise and sunset throughout the year.

I need something similar, but for 220-240 Volts.
posted by syzygy at 1:55 AM on January 15, 2008

Just for completeness, several of my co-workers have actually gone to the opposite extreme, papering the windows over in their toddler's rooms. Obviously this is only anecdotal but it does seem to work well for them. You may want to try it without before going to the trouble so you have something to compare to.
posted by Skorgu at 5:32 AM on January 15, 2008

If you want to stick with your X10, you can buy software a controller that holds the lighting programs, and is sold on ebay for less than $20. Search for CM11a. This is an older model that I've had for 10 years or so. It hooks up to your PC using a serial cable, but the difference from the firecracker is you actually download the timers and a PC need not be connected full time. The software allows you to program the lights to turn on and off as well as dim according to your schedule. You can also program the unit to your location and it recognizes variable dawn and dusk.

It looks like there's a newer model (1132CU) that connects via USB, but it's a little more expensive (~$50), but might be easier to deal with than a serial connection.
posted by SteveInMaine at 6:55 AM on January 15, 2008

Great answers, all - the hivemind for the win. For those concerned, there are windows (and a door) in the basement - it's just that they don't illuminate the portion that is going to be his sleep/play area very well. But the concern is appreciated. A long-term solution may be putting a window in that area, but that requires cutting through the concrete foundation which is not something that's in the cards right now.

I'll probably end up going with the X10 CM11A and some ultra-high CRI fluorescent tubes and dimmable ballasts, because I have the X10 switches laying around.
posted by jferg at 7:42 AM on January 15, 2008