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glowgirlinto

help calculating lighting needs

8 years ago
Are there any good websites or tricks for figuring out how many lumens/lux/Watts (no idea what it’s called officially) we need for a certain space? All the sites I’ve found on google are for 8’ ceilings.

We are putting in electricity at our rustic cottage. It’s got a beautiful vaulted ceiling running lengthwise down the main space and for many reasons we are limited to just pendants/chandeliers.

I’m trying to figure out how many of them we need to hang for good ambient lighting. It’s an open concept kitchen, dining, and seating area. The space is 30 x 12 with approx a 16’ ceiling peak. I found a few I like, some with four bulbs per fixture and some with six bulbs.

We also plan to have task lighting over the kitchen sink and a few wall sconces around the main space.

Comments (9)

  • 8 years ago

    Hire a designer. 16’ is not remotely user friendly to human scale. You’d be better off creating a loft space.

  • PRO
    8 years ago

    Laura, you are not alone being confused by this; what metric to use to figure out sufficient lighting with the added complexity of having high vaulted ceilings, which means the lights will possibly be mounted way up on the ceiling.

    Where to start: both NKBA and IES recommend 50 foot candles on the kitchen counters. Foot candles ( 1fc = 10.76 lux) are the only metric that matters. LUmens are a measurement up at the fixture, not delivered to the work surface. The type of lamp (bulb) you pick has an ENORMOUS effect on delivered footcandles; I"ve seen at 15 to 20 times improvement by switching from BR floods to PAR spots. I've written about this topic quite a bit for www.proremodeler.com. Look for lighting articles by Doug Walter.

    But in addition to task lighting, you'll want some large decorative chandelier type fixtures for ambient lighting. Wood ceilings and walls absorb a tremendous amount of light! See if you can't shine lights not only down, but UP onto the ceiling.

    My guess is you're probably going to be best working with some sort of suspended fixtures; pendants or hanging track, as much as I dislike track because of it's tendency to shine light in peoples' eyes if its aimed anywhere but downward. A lighting designer would be a good investment, preferably one with a certification from IES or ALA. Good luck!

  • 8 years ago
    Thanks.

    Sadly a designer isn’t in the budget. It’s a 1950s cabin buried in the woods and accessed only by water. Replacing the propane lighting system with hydro is a huge stretch financially and I’ll have to do the best I can.

    I hear what you’re saying about both down and up lights. I’ll look into some up-lighting options that could shine up from the beam edge around the 8’ height. We are also planning to paint out the wood panels to an off-white which will brighten the space considerably.

    My husband argues that any lights are an improvement over the propane lights and he does have a point! Lol
  • 8 years ago

    This link is specific to their fixtures but it helped me and it does take into account the height of your ceiling. I just did the math based on the fixtures I purchased against the details of their fixtures. Then I rounded up and added a dimmer.

    Lighting Calculator



  • 8 years ago
    Thanks Joe. That’s really helpful. I took the total lumens suggested and divided it by the lumens of my current favourite LED bulb and it says I need 13-14 bulbs for that area. So four fixtures of 4 bulbs each might work well. At the very least, it’s a good starting point.
  • 8 years ago

    That's exactly how I did it as well. And don't forget, all of the light doesn't come from the ceiling. There may be a floor lamp or buffet lamps or art lights, etc. -- you should add them all up for a total. And make sure you buy a gimbal version of whatever LED light you buy as your ceiling isn't parallel to the floor.

    When in doubt more on a dimmer is better (in my opinion).

  • PRO
    8 years ago

    Good advice from Joe and tatts. How do you measure the delivered foot candles? There's an app for that! And most of them are free. I use Light Companion and Light Meter Pro. They use the camera on your phone; and I've compared them to professional light meters, and they're pretty darn accurate. To figure out how much light you can expect, you need to look at photometric charts from the lamp manufacturer, and you'll see a chart that shows graphically the inverse square effect the tatts explains above. If the light is at 8 feet, and the counter is at 3 feet, look at what promised light level will be at 5 feet away.

  • 8 years ago
    Thanks very much. Lots of good information to help point me in the right direction.
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