I know very little about lighting, I know there’s cool light and warm light, what’s generally the best light to look for for general bedroom ceiling bulbs?
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This is really an opinion question, so I will just explain the color frequency and a listing to look for so that you have the information to make your decision.
First, the different lamps have color ratings: 2500k through 6500k is the normal range. The color at 2500 is a yellow orange; many street lights using sodium vapor lamps are this color; very easy on the eyes, but they do not make the area as “bright” as perceived with the same lumens at 6500k.
At the other end of the spectrum is 6500k. This is close to bright daylight and is perceived as much brighter than the lower 2500k light. Many industrial facilities & offices have moved to 5500k and above as it is closer to daylight.
6500k and above are used in many office buildings in the Pacific Northwest to reduce Seasonal Affective Disorder (sometimes called cabin fever here); the wavelength and perceived brightness reduce the problems associated with a lack of natural daylight.
The down side to 5500k and above is your brain now thinks it is not time for sleep, so having a +5500k lamp in the bedroom is not the best choice. For a home office, kitchen, and living rooms, the 5500+ may be a better choice, keeping the 2500-3500k in areas of sleep and relaxation.
What I have in my home is the bedroom ceiling lights are 6500k and the bed side lamps are 3500k (2500k is just two yellow/oranges for me). When getting up in the AM, the overhead light is on, while at night prior to bed the bed-side lamps are on,. This works really well and I would recommend it.
The last big advantage is power savings. Most screw-in bulbs today are based on the incandescent 60w Edison lamp; a standard 60w provides ~800 lumens, a CFL bulb produces similar light using only 13 watts and a quality LED uses 6 watts. There are some lamps that are more efficient and some that are less efficient, but this can show that changing from all incandescent to LED could cut your lighting cost to 10% of what it is or 1/2 if on CFL/fluorescent. In my case the production areas appear much brighter at the same time.
The listing on your lamps I recommend you look for is DLC (design light consortium). These normally have a 5-year warranty and UL and CE listings. I have had really poor experience with non-DLC lamps, I find the electronic driver (power supply) in the lamp usually fails (I support a lumber mill that has thousands of lamps, tube style (T12, T8, T5) and flood lamps (400w to 1000w), and I have replaced almost all the T12 & T8 lamps with hybrid T8 lamps that can be direct wired (they will work with a ballast but I want to eliminate the losses and failure possibility of a ballast). Most of the big, power-hungry floods were my first swap outs with a 240w-320w LED flood replacing 1000w floods, and the equipment operators love them. (I love them because I probably won’t have to change the bulbs and repair ballast for the next 5-10 years.
I hope this info helps you to make your decision.
Added, I just remembered there are some new tunable lamps, (the color spectrum can be adjusted). I have not tried any of these smart lamps yet, but suspect they may be the next level in home automation and livability.
- Why not just experiment and see for yourself?
Get these variable CCT LED strips with the following options: 2400-5500K, 24V, 28.8W/meter, CRI95. These are the best high-CRI lumens per dollar I could find and look awesome. Make sure you get the 2400-5500K and not the 2700-5500K. The low 2400K color temperature is awesome for a bedroom, and it looks very much like the mood of the pictures you posted.
Get a corresponding length of aluminium LED profile like this or any shape you like. They're cheap on amazon. The thinner ones are great under kitchen cabinets. Larger ones are better at diffusing the light and look better where they're visible.
You'll also need a CCT dimmer (this one doesn't flicker, don't forget the remote), and a 24V power supply like Meanwell XLG-200-24-A.
Now after you assemble all this you got a portable light with high power, variable color temperature, and excellent color rendering. You can stick it everywhere in your house and see for yourself what looks best in each room, try all the color temperature and intensities to find what you prefer. Thus should be much more useful, and more fun, than advice on a computer screen.
Once you've done all the tests this should give you a much better idea of what you need. These strips put out about 90s lumen per watt, and the 28.8W/m rating means there's 14.4W of each color. The dimmer ensures constant brightness, so the dimmer setting will tell you how many lumens you got. If you set it to 100%, that's 1300 lm per meter of strip.
Also: if you have GU10 fixtures, get Osram 4058075260115 bulbs. Low price, excellent light. And click on this link.
- The Theory
The acronym for "Color temperature" is "CCT" so I'll use that. There are two big gotchas about CCT:
Higher Color Temperatures correspond to "colder" light (ie, more bluish). Lower CCT corresponds to "warmer" light (ie, more yellow/red). Yes it's a mess. At least using a CCT like "3000K" is more explicit.
Human's perception of the "right" CCT depends on light intensity (measured in lux).
Some science was done on this (see Kruithof curve). It's pretty intuitive: high CCT feels best at high illumination levels (measured in lux) and low CCT feels best at low illumination levels.
Additionally, CCT sets the mood: 2400K-2700K with typical "living room" illumination (ie, pretty low) is cozy, 3000K is relaxing but not sleepy, 5000K at high illumination is energetic. All this requires the proper intensity though: high lux with low CCT, like too many 2700K bulbs, feels like an overdose of yellow. Low lux at high CCT, like a single 5000K bulb in a big room, feels bluish and cold, like a car park.
Next we have illumination levels, measured in lux, which are lumens per square meter. Say you get a 1000 lumen bulb, put it on your ceiling, and if its light output was spread uniformly over a surface of 10 square meters, that would be 100 lux. Of course the light output of bulbs isn't spread uniformly, it varies with angle, but you get the idea. So how many do you need?
That should give you a rough idea, you can also google "recommended lux levels" for more. For example on the living room couch, if you read a book you'll need more lux than if you watch TV. So either you put a powerful and dimmable light on the ceiling, or you'll add spotlights, or other kinds of lamps.
Aaaaand... we're back to the "best CCT depends on intensity" as I said above. So you can put 2700K bulbs on the ceiling, but have a 3000-3200K lamp on the side of the couch (or properly aimed spots) for reading.
There is also the issue of color rendering of course. This is measured (badly) by "CRI" or "Color Rendering Index" which is between 0% (pure yellow sodium lamp) and 100% (daylight). Unfortunately, since this measurement was invented long before LEDs, it is almost completely unsuitable for the purpose of knowing if a LED will look good or not. Well, anything below 90 CRI is for car parks, but if you buy an expensive 90 CRI light... the CRI doesn't tell you anything about tint, especially about the annoying greenish tint some LEDs tend to have, and it tells you almost nothing about how the reds will look. So it is very easy to waste a lot of money for very little result.
Now this is getting a bit complicated, we'll have to talk about spectrum. So, white LEDs do not exist. They are really a blue LED with chemicals on top, called "phosphor" that absorb some of that blue light and convert it into other colors, so you get "white". Different wavelengths of light (in nm at the bottom of the graph) correspond to all the colors in the rainbow. Here's a garbage quality 5000K LED:
Notice it has a huge blue peak, very little cyan, and where are the reds? There are no reds. Color rendition will be awful, and under this light people will look sick.
This spectrum illustrates the three main points that make colors look good or bad with a LED: blue peak, cyan dip, and red extension. For low CCT LEDs you want minimum blue peak and cyan dip, and good deep reds, so the peak of the reds should be around 630nm. Here's an example of a good and cheap 5000K LED. Notice the yellow peak is gone, there's much more red, the blue peak is relatively lower, and there is more cyan.
Here's a much better one, but it will make your wallet bleed:
The visual difference between the first two is HUGE. The last one brings a more subtle improvement, but at a much higher cost.
The reason is simple: doing better costs more. Red phosphors are inefficient, and human eyes are not very sensitive to red, so emitting enough deep red, especially to make people look healthy and food appetizing, requires dedicating some watts to emit that red light. The bulb would be much brighter for the same watts if it emitted yellow and green instead. This means sacrificing some efficiency, which means lower lumens per watt, which means the customer will buy from a competitor because "bigger numbers better". But it looks like crap.
For the sake of completion, here's a low quality 2700K LED:
Notice the spectrum is much more tilted than the 5000K one, it has less blue and more yellow, so it looks "warmer". But the red peak is yellow, not red, so it'll look like something is wrong. It's difficult to describe, it has a superficial look of "warmth" but it isn't pleasing. Better quality LED below, with proper reds, looks much more natural.
Now that you know what you're looking for, there's an excellent (and cheap) method to evaluate the color quality of a LED:
Go outside and look at your hand. Remember how it looks.
Put your hand under the light of the LED and look at it.
If you see huge blue veins popping out that you don't remember having, the LED has a huge blue peak. If the skin on the inside of your hand looks pale and yellowish/sickly, then it doesn't have enough deep reds. And if your hand looks like a dead zombie's, the LED has a green tint.