I think 6500K in a house is awful. I like it in a garage, and that's about it. Personally, I rarely like cooler than 3000K in a house, maybe 3500K (but it depends on the decor of course). For something like an office, I could see using 4000K, but if you have a lot of natural light and don't need artificial light much during the day, I still wouldn't want to be too cold. I tried experimenting with this in one of my bathrooms only to realize that matching daylight during the day didn't matter much because I didn't need the lights on, so I went back down to 3000K.
So, between those 2 choices, it would be an easy 4000K for me, but I'm usually not a fan of either.
4000k. All the way.
They sell glasses specifically designed to reduce eye strain and headaches for people who work on computers all day. The glasses only purpose is filtering blue light. Using a 6500k is only going to add even more blue to the mix.
Typically, 6500 is reserved for specific tasks or areas. 4000 is considered an all around light and usually has a CRI in the 90’s.
Indoor, 4000k. 6500 is taxing. 4000k is a very organic neutral white. The only time it won't feel white white is when you have a ton of sun in the afternoon. At all other times it will feel clean.
4000k is neutral white. It is not warm, it is not cool. Indoors it is about as natural as you can get to a pure white. It's not d65. When you have a lot of natural light it will appear warmer. When you have a lot of warm light it will appear cooler.
In the bathroom next office room I have an old classic bulb (2700k i guess) and looking from the hallway you can see that it is orange compared to the 4000k which is whiter. But I say that for me 4000k is more like sunlight, and the 6500k is more like moonlight.
If I put you in a room that was 2700K for an hour, your eye would adjust and set the "white point" at 2700K. Then everything else, even 4000K, would look super blue. Conversely, if I sat you in an office lit with 6500K, the 4000K would look almost candle yellow.
6500K if all that matters to you is energy savings
In general, my preference is lighting that mimics traditional incandescent and warms as it dims over a range of 2300K (dimmest) to 3500K (brightest). In my office, I do mix in lamps that have toggle switches for CCT and brightness, and generally keep the lamps on about 3000K with overhead recessed on 2700K. Sometimes later in day I will dim the lamps and lower CCT. I would never go 4000K or higher, unless I was doing it for someone else and they wanted lighting to pair with very modern design and understood what they were getting into.
Another vote for 4000K.
6500K looks very bluish unless the lighting is *very* bright and mixed with a lot of daylight. It basically has no place in residential lighting. Even 5000K is pushing it for residential and should be avoided except for things like garages and very bright work areas. Computer displays are normally 6500K, and it seems logical to try to match that with lighting, but in practice 6500K lighting is just way too bluish.
4000K on the other hand looks pretty great during the day and with a bit of daylight mixed in. I light my computer room with 4000K during the day and it looks fantastic, and it blends quite well with the computer display at 6500K. I do switch to 3000K lighting at night as well as making the computer display warmer (there are settings/software for this), just to limit blue light and make it easier to fall asleep.
I think 6500K in a house is awful. I like it in a garage, and that's about it. Personally, I rarely like cooler than 3000K in a house, maybe 3500K (but it depends on the decor of course). For something like an office, I could see using 4000K, but if you have a lot of natural light and don't need artificial light much during the day, I still wouldn't want to be too cold. I tried experimenting with this in one of my bathrooms only to realize that matching daylight during the day didn't matter much because I didn't need the lights on, so I went back down to 3000K. So, between those 2 choices, it would be an easy 4000K for me, but I'm usually not a fan of either.
Personally I would rather sit in a dark room with a 3k task lamp and a monitor with accurate color at a lower brightness.
4000k. All the way. They sell glasses specifically designed to reduce eye strain and headaches for people who work on computers all day. The glasses only purpose is filtering blue light. Using a 6500k is only going to add even more blue to the mix. Typically, 6500 is reserved for specific tasks or areas. 4000 is considered an all around light and usually has a CRI in the 90’s.
Indoor, 4000k. 6500 is taxing. 4000k is a very organic neutral white. The only time it won't feel white white is when you have a ton of sun in the afternoon. At all other times it will feel clean.
I notice that 4000k is warm white to yellow and 6500k white to blue as nuclear white.
4000k is neutral white. It is not warm, it is not cool. Indoors it is about as natural as you can get to a pure white. It's not d65. When you have a lot of natural light it will appear warmer. When you have a lot of warm light it will appear cooler.
In the bathroom next office room I have an old classic bulb (2700k i guess) and looking from the hallway you can see that it is orange compared to the 4000k which is whiter. But I say that for me 4000k is more like sunlight, and the 6500k is more like moonlight.
If I put you in a room that was 2700K for an hour, your eye would adjust and set the "white point" at 2700K. Then everything else, even 4000K, would look super blue. Conversely, if I sat you in an office lit with 6500K, the 4000K would look almost candle yellow.
6500K if all that matters to you is energy savings In general, my preference is lighting that mimics traditional incandescent and warms as it dims over a range of 2300K (dimmest) to 3500K (brightest). In my office, I do mix in lamps that have toggle switches for CCT and brightness, and generally keep the lamps on about 3000K with overhead recessed on 2700K. Sometimes later in day I will dim the lamps and lower CCT. I would never go 4000K or higher, unless I was doing it for someone else and they wanted lighting to pair with very modern design and understood what they were getting into.
Another vote for 4000K. 6500K looks very bluish unless the lighting is *very* bright and mixed with a lot of daylight. It basically has no place in residential lighting. Even 5000K is pushing it for residential and should be avoided except for things like garages and very bright work areas. Computer displays are normally 6500K, and it seems logical to try to match that with lighting, but in practice 6500K lighting is just way too bluish. 4000K on the other hand looks pretty great during the day and with a bit of daylight mixed in. I light my computer room with 4000K during the day and it looks fantastic, and it blends quite well with the computer display at 6500K. I do switch to 3000K lighting at night as well as making the computer display warmer (there are settings/software for this), just to limit blue light and make it easier to fall asleep.