# Lighting Design



## Movingshrub (Jun 12, 2017)

Anyone know squat on lighting design? If so, I've got some questions and would appreciate your help.

I am trying to hit a target level of Lux or foot candles and just cannot seem to find the right combination of fixtures and placement to hit my target.


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## corneliani (Apr 2, 2019)

You are getting mighty precise with this... whachu got cooking over there??


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## Movingshrub (Jun 12, 2017)

@corneliani I'm trying to update our kitchen. It's a 1960s house. There is a single dome light, an under cabinet fluorescent, another over sink fluorescent light, and then another hanging fixture over an eat-in kitchen table. The dome light is useless. The fluorescent fixtures are older than me and the color temps are too blue.

My plan was to replace everything at once to ensure harmony with all the temps. I'm getting tripped up on how much light I need. I turned to IES guidelines, indicating a mix of nine foot candles for the kitchen general area, 28 ft/cl for the cooktop, and 47 ft/cl for the counter. Another document I saw suggested 20-50 ft/cl, with up to 50-100 ft/cl for the counter top and sink.

My goal was to hit 30 ft/cl on the counter top. I have a 8' ceilings. I used both the Lux Meter and Light Meter App on my iphone. I haven't found a combination that gets me to 30 ft/cl. I turned on every light in the kitchen AND then used a 2100 lumen LED PAR 38 bulb mounted five feet above the phone and could only hit 24 ft/cl.

To put it another way, How the F does anyone get 50-100 ft/cl in their kitchen? These feel like unachievable goals and/or my phone is inaccurately measuring the light in the room. I've had a few friends measure the lighting in their kitchen using the same apps and were getting approx 10 ft/cl.

So I'm either going to give up on that ft/cl goal, learn that I'm measuring wrong and am in fact hitting that goal now, or I need to find someone who can explain to me how to achieve that much light.


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## corneliani (Apr 2, 2019)

You get deep, bro!! I love it. :thumbup:

Here's some feedback based on my experience building custom homes in my neck of the woods. To start, translate (into somewhat relatable terms) what a desired lighting output would look like (in watts) just so you can have some semblance of lighting output. How many 75-100w light bulbs (approx 1000-1500 lumens?) would you anticipate that space requiring? Depending on factors such as layout, exterior windows/lighting, and especially the color of your finishes, that can vary... but assuming that your kitchen is between 175-225sqft, and shooting for 20 lumens/sqft for general lighting, that equates to 3500-4500 lumens. That can be achieved with 4-6 can lights putting out 800-1000 lumens each. That's plenty of lighting, imo, especially when you consider the spacing (36" to 48") in such a space. Take the high end of this design, meaning 6 can lights at 1000 lumens each for 6000fc, divide by the 225sqft gives you 25fc/sqft. Bingo!
Now extend this to other task lighting areas and you're golden.

I'll try to upload some pics of my kitchen. I think I have 8 can lights at 800 lumens each (spaced at 48" in a 9' ceiling) and my wife says I built her an airplane runway when at full blast! I have dimmers installed, usually set at mid-strength, for general lighting and only take it up all the way when there's lots of activity going on. I measured my fc output with the app you mentioned and I get a consistent 20-30 fc throughout the open areas as well as the undercabinet lighting. If the app measures this correctly I can't imagine what 50fc looks/feels like! :shock: We do prefer softer lighting so maybe that's a factor, but still.. i feel like I went overboard on my lighting and i'm barely halfway to the 'recommended' fc reading. :?


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## corneliani (Apr 2, 2019)

My wife would sooo not approve of me posting this pic... but just for reference, this kitchen is about 250 sqft (20' x 14'), with a breakfast area off to the side that has a wall of windows. I get 6400 lumens from 8 can lights for general (dimmed) lighting, which is about as much as we'd ever need. Bkfst area to the side has its own fixture & the cabinet lighting is dimmable led puck lights. The Lux app is reading about 25fc +/-
50fc would require sunglasses indoors. 
100fc and I'd land a Boeing! &#128541;

Edit: deleted picture


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## Movingshrub (Jun 12, 2017)

@corneliani The approach you laid out at first of using lumens to derive foot candles was what I did at first. However, lumens is output at the fixture while foot candles is measured at the destination. I tried using a 1000 lumen LED light, along with an existing under cabinet light, and that got me to mid 20 ft/cl.

Are the 30+ ft/cL recommendations unreasonable or is my entire house insufficient illuminated?

I saw some 4" cans from WAC that do 1000 lumens. My plan was to get six of those, on a dimmer, and also replace the under cabinet and over sink light. Any insight as to how many lumens for the other fixtures?


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## bhutchinson87 (Jun 25, 2018)

30 footcandles in a residential kitchen is correct when referring to the IES tables, however I think most homes do not reach this level. Anything between 20-30fc will be plenty. For some persepective, 50fc is good for a private office, 150fc would be on the floor of an NBA court, and outside on a sunny day is probably close to 1,000fc. The correlation between lumens and footcandles is that 1 lumen from 1 foot away over 1 sq.ft.= 1 footcandle , but it's difficult to say x amount of lumens = y amount of footcandles because there are so many factors at play that corneliani eluded to. Light from the source disperses and loses intensity over distance (inverse square law).



And if your downlights are offset from the island it reduces their efficacy of delivering lumens to its surface (cosine-cubed law)



Not sure how your kitchen/lights are laid out, but since your ceiling is 8' I would shoot for 800-1,000 lumen/fixture. You said that you tried a 1,000 lumen light and your app read mid 20fc levels. Did you like the way it looked? If it was pleasing to your eye, then I don't see any reason why to pursue 30fc.


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## Movingshrub (Jun 12, 2017)

bhutchinson87 said:


> 30 footcandles in a residential kitchen is correct when referring to the IES tables, however I think most homes do not reach this level.


Why is that the case? Cost? Unachievable goal?



bhutchinson87 said:


> The correlation between lumens and footcandles is that 1 lumen from 1 foot away over 1 sq.ft.= 1 footcandle , but it's difficult to say x amount of lumens = y amount of footcandles because there are so many factors at play that corneliani eluded to. Light from the source disperses and loses intensity over distance (inverse square law).


Understood, which is why I am hesitant just to use lumens based on sqft of the room as the guiding approach.

In my case, no island; work area is shaped like an L. My plan is to replace all of the lighting so I'm not bound by the existing installation.

I used a Halo 6" 1025 Lumen LED, which got me to 16 ft/cl. I also tried using a Cree 250W equiv LED at 2100 lumens. That got me to 24 ft/cl. The other thing that got close was a 1200 lumen PAR 38 LED bulb which got me to 26ft/cl. Nothing else got into the 20s. I would love to be able to decipher the ies files so I could project the amount of lighting making it to the surface, based on the combination of fixtures installed and their location. I know there's software to do this but it's $$$.

I'm leaning towards these http://www.waclighting.com/product/pop-in-4-round/ spaced every 2'-3' apart, resulting in a total of six in an area about 125 sqft.

Any suggestions on hardwired under cabinet lighting? Also, do I match the over sink light with the undercabinet, or do I use something like a recessed light for that application? Thank you.


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## Movingshrub (Jun 12, 2017)

Also, just stumbled onto this http://www.waclighting.com/downlighting-estimator/


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## bhutchinson87 (Jun 25, 2018)

Movingshrub said:


> Why is that the case? Cost? Unachievable goal?


The IES charts are just a recommendation and not a requirement. I believe a lot of builders use their rules of thumb saying something along the lines of 4 downlights per 100sqft and then throw in a couple pendants.



Movingshrub said:


> Understood, which is why I am hesitant just to use lumens based on sqft of the room as the guiding approach.
> 
> In my case, no island; work area is shaped like an L. My plan is to replace all of the lighting so I'm not bound by the existing installation.
> 
> I used a Halo 6" 1025 Lumen LED, which got me to 16 ft/cl. I also tried using a Cree 250W equiv LED at 2100 lumens. That got me to 24 ft/cl. The other thing that got close was a 1200 lumen PAR 38 LED bulb which got me to 26ft/cl. Nothing else got into the 20s. I would love to be able to decipher the ies files so I could project the amount of lighting making it to the surface, based on the combination of fixtures installed and their location. I know there's software to do this but it's $$$.


Sounds like the app on your phone is reporting low lighting levels based on what it probably actually is. Have you thought about purchasing a light meter to get more accurate results? We use Extech for our engineering reports. Also, if you want to PM me dimensions of everything I can get you some results.


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## Movingshrub (Jun 12, 2017)

@bhutchinson87 I'll PM you a layout.

I tried two different light apps and also had a friend try the app in their house just to get an idea if the issue was with my phone. I *believe* the apps are reading correctly. I would consider a formal meter if it's value added to this task at this point.

My concern with the Halo 6" was how diffused the light was across the room. The upside to that fixture was, it's cheaper, the temp is adjustable, and it has a smaller installation foot print in the ceiling. I *think* the trim foot print on the ceiling is about the same for both products.


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## corneliani (Apr 2, 2019)

I've built some high-end homes and foot-candles specs on the residential side isn't something that I've come across. I can see how it makes sense in commercial/office situations though as light at the destination is, and should be, the ultimate determination. On the residential side we mostly reference lumens, and even that is a recent upgrade from the traditional wattage reference. But most importantly we focus on location/placement & aesthetics as the driving factor.. with a focus on creating softness by washing walls, etc. If we illuminate a home to the extent that a hospital or office does it would take away all the softness out of it, imo. Not to mention aesthetically we'll be puckering up our ceilings with some many lights that it gets unsightly for most consumers. I feel like my 8 can lights (9 if you take the hallway path lighting into account), two pendant lights, and two in-ceiling speakers are borderline cluttering my ceiling.

You have piqued my interest with this thread though... and have been turning up the lights at different levels to see what kind of reading I get. My wife keeps asking what the hell i'm doing and I don't really want to tell her I'm taking light readings for no apparent reason at all. :lol:


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## Movingshrub (Jun 12, 2017)

corneliani said:


> I've built some high-end homes and foot-candles specs on the residential side isn't something that I've come across. I can see how it makes sense in commercial/office situations though as light at the destination is, and should be, the ultimate determination. On the residential side we mostly reference lumens, and even that is a recent upgrade from the traditional wattage reference. But most importantly we focus on location/placement & aesthetics as the driving factor.. with a focus on creating softness by washing walls, etc. If we illuminate a home to the extent that a hospital or office does it would take away all the softness out of it, imo. Not to mention aesthetically we'll be puckering up our ceilings with some many lights that it gets unsightly for most consumers. I feel like my 8 can lights (9 if you take the hallway path lighting into account), two pendant lights, and two in-ceiling speakers are borderline cluttering my ceiling.
> 
> You have piqued my interest with this thread though... and have been turning up the lights at different levels to see what kind of reading I get. My wife keeps asking what the hell i'm doing and I don't really want to tell her I'm taking light readings for no apparent reason at all. :lol:


Understood on the risk of over doing it on both the lumens and the number of fixtures. My real concern was cutting holes in my drywall and still not having results I liked, hence finding a way to quantify the results prior to installation. I think I can get away with six to eight fixtures, if they are 4" can fixtures. The ft/cl guidelines seem to be lower for residential versus commercial. However, I would love my garage to be illuminated like an operating room.


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## corneliani (Apr 2, 2019)

Movingshrub said:


> However, I would love my garage to be illuminated like an operating room.


Hell ya!! I'm right there w you bro. My next project... once I build out the closets, build a LEGO table for the boys, a storage system for their toys .... damn the list is long ! 😖


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## Movingshrub (Jun 12, 2017)

@corneliani What did you use for under cabinet? The tape LEDs or something else?


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## corneliani (Apr 2, 2019)

Movingshrub said:


> @corneliani What did you use for under cabinet? The tape LEDs or something else?


We went with dimmable LED puck lights .. a big-box purchase, not sure which brand or specs unfortunately. Preferred puck lighting over tape due to the soft edges it gives. We spaced them at approx 28" (centered on upper cabinets) and it really lights up the countertop. Here's lit up all the way and the associated foot candle readings.





Edit: Here's a pic of where we usually keep it (dimmed at mid-level). It's giving me readings of about 10-15 foot candles.


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## Movingshrub (Jun 12, 2017)

In terms of soft edges, you're saying that the LED lights are too consistent across the surface to blend with the ambient lighting?


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## corneliani (Apr 2, 2019)

Not as much as blending with the ambient, as I'm surprised at how well mine blend in now that you've got me all interested in this stuff :lol: ... the softness I'm referring to is the shadowing in between the pucks. The strip lighting tends to be more linear, same intensity across the width of the counter. It works well in modern designs, I think, complementing those linear lines associates with that style. Lots of customers prefer that, and they do hide much better than the pucks.

Edit: btw my puck lights are LEDs as well. Wouldnt consider anything else.


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## Movingshrub (Jun 12, 2017)

I ended up installing 6ea WAC 4" recessed lights. I also ended up replacing the T8 36" fluorescent fixture above the sink. I found a 36", 1200 lumen, CRI 98, LED fixture on sale at the orange box store. When both are on, they bring the light level to 26 foot candles, which is a substantial improvement.

Up next is going to be replacing the under cabinet lighting. I am leaning towards wall switch activated LED tape lights. I'm open to other solutions. With that said, I think I can run 24v wire in areas where I might not be inclined to run 14ga 120v NM cable. The WAC Pro 3 and Pro 2 got my attention primarily because I'm assuming the temperature color is more likely to match the overhead lights. Everything I've installed so far has been 3000k temp.


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