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Musings of an Energy Nerd

Martin’s 10 Rules of Lighting

Although most homes are poorly lit, they still use too much energy for lighting

Task lighting should be as close as possible to what you want to see.
Image Credit: Matthew Beckler

Most homes use too much energy for lighting. According to the U.S. Energy Information Administration, the average American household uses 1,667 kWh per year for lighting, which amounts to 15.3% of residential electricity use. Ironically, this energy devoted to lighting is used inefficiently, so the usual result is a dim house with dark, depressing corners.

Although many electric utilities have subsidized the cost of bulb swap programs for years, the typical house still has far too many incandescent bulbs. Even people who have swapped their incandencents for compact fluorescent lamps (CFLs) often install their bulbs in terrible fixtures with opaque shades or dark lenses. Fixtures are often installed in awkward spots. The dark corners that are common in a poorly lit house become more noticeable as we all get older; to see well, older people need more light than younger people.

Finally, many houses have too few switches, so that homeowners have to make an all-or-nothing decision about whether to turn on all six bulbs in a track-light fixture.

Once you become aware of some basic lighting principles, you’ll be able to solve the lighting problems in your own home and the homes you build. There’s only one downside to obtaining a lighting education: every time you stay in a hotel room, the bad lighting will drive you crazy.

Lighting designers have their own jargon. They call light bulbs “lamps,” for example, and they call light fixtures “luminaires.”

Lighting designers often tell us that there are four different kinds of light: ambient, task, accent, and decorative.

Ambient light is the soft, general illumination that fills a room and softens shadows.

Task lighting is a focused source of light near a work surface, a countertop, or a book.

Accent lighting is a type of directed illumination used to spotlight an…

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38 Comments

  1. Adam Flowers | | #1

    Controls
    Good read, it's great to keep some focus on those ever-important baseload energy users. One thing that I'd add to the conversation is the importance of controls, specifically occupancy sensors and dimmers. Occupancy sensors turn lights on when motion (or body heat, more specifically) is picked up, and turn them off after a preset amount of time. Many even have an on/off button that allows them to function as a standard switch, when the need arises. They're great in closets and bathrooms. And while it's not ideal (read "affordable") on CFLs, dimmers are great on LEDs and Incandescent fixtures. Wattstopper and Lutron are the industry leaders in both of these products. Thanks again for a great lighting article!

  2. Doug McEvers | | #2

    Daylighting and more
    Good article, Martin

    I would add this study as further reading for those interested.

    http://www.swenergy.org/publications/documents/Lighting_Technical_Report.pdf

  3. User avater GBA Editor
    Martin Holladay | | #3

    Response to Doug
    Doug,
    Thanks for the link to the useful resource. I'm happy to add it to the other links in my "More Information" box.

  4. Brennan Less | | #4

    Daylighting, the free and potentially best lighting
    Martin, I think that having not a single mention of daylighting in this article is a major mistake. I get that this article is about electric lighting strategies, but at least a mention of the use of daylight would be nice. Daylighting can be designed, just like passive solar design. It takes advantage of natural energy flows, links people to the progression of the day and the seasons, and if designed well, it works forever, never needing a new bulb. Granted, residential occupancy is probably more towards the night time hours, but major day time occupancy is still a reality.

    1. User avater
      Nils Bird | | #37

      In the late sixties I saw an invention showcased on TV which was basically a parabolic reflector which concentrated daylight into an optical cable which was then run into a building and provided daylight in the interior. The only application of this technology I've seen since has been for dashboard lighting in cars. Sometimes the future overtakes us before we notice and other times it needs to be dragged kicking and screaming into the present.

      1. Lance Peters | | #38

        Fixtures relying on sunlight conducted through optical fibers wouldn’t provide any light at night. I agree that daylighting can be used effectively, but that application sounds like a solution with very high up-front cost and questionable payback compared to ordinary fixtures, especially if equipped with efficient LED bulbs.

  5. User avater GBA Editor
    Martin Holladay | | #5

    Response to Brennan Less
    Brennan,
    Fair enough -- I accept the criticism, and there is much to be said about daylighting, especially in offices and commercial buildings.

    One reason that daylighting is less important in residential buildings than commercial buildings is that most U.S. homes are unoccupied during daylight hours -- especially from late September to early March, when the sun rises late and sets early.

    In any case, when talking about homes rather than offices, daylighting has a humbler name. In my day, we always called them "windows."

    Yes, every room needs at least one, and usually several, windows. And there is a lot to talk about there: where they belong, how big they should be, how to address sight lines, how to capture (or partially obscure, if you are Japanese) views, and avoiding glare. Not to mention glazing specification, a topic I have written about several times.

    However, an hour after the sun sets, every home still needs to consider artificial lighting.

  6. John Klingel | | #6

    one tiny fix
    Good article, but one minor "math" error. "...The amount of light striking an object is proportional..." should read "... inversely proportional".

  7. User avater GBA Editor
    Martin Holladay | | #7

    Response to John Klingel
    John,
    Good catch. You're right, of course; I've made the correction. Thanks.

  8. John Klingel | | #8

    Martin: I don't know a lot,
    Martin: I don't know a lot, but now and then I can be of use. Doug M: I just started reading that article. The first graph is quite informative; very hard to beat the sun, it seems. Thanks. j

  9. Kevin Dickson, MSME | | #9

    Fluorescents in the kitchen?
    Martin,

    Remember those big recessed flourescent fixtures in kitchens they built in the 70's and 80's? They were sort of like a dropped ceiling with the big 2'x4' lenses or egg-crates.

    This article makes me believe they should come back for efficiency's sake.

    Buyers and cooks hated them, and saw recessed cans as much more palatable.

    Is there a good way to get T-8s back out of the garage and inside the home?

    LED's may yet win the lumens/watt contest, here's one that cranks out 94.4l/w :
    http://www.amazon.com/Incandescent-Replacement-Illumination-G7-Power/dp/B005FU5406/ref=pd_cp_hi_3

  10. Richard Patterman | | #10

    Night Lights and Stair Lights
    Don't forget night lights. I like to be able to walk into the bathroom or kitchen in the middle of the night without either stubbing my toe or blinding myself by turning on enough light to cook or shave.
    LEDs in the toekicks of cabinets work well.

    Building code addresses adequate stair lighting, but does not address the importance of proper switching. I lived in a three story where, when coming home in the dark, I had to turn on lights for lower stairs, go up stair, turn off lights for lower stairs and turn on lights for upper stair, go up upper stairs turn off lights for upper stair. Multi floor lighting should turn switch all stair lights from top and bottom of all stairs.

  11. Buildingwell .org | | #11

    Beyond the light fixture
    Proper lighting goes beyond just the light fixture or bulb (luminaire/bulb). Proper wall coloring will also benefit your lighting pieces. Use lighter toned colors to help reflect the lighting around the room. Building off of Martin's statement regarding white ceilings, your walls act just the same way. By using a lighter color the room will not only feel more open but lighting will distribute better than if you used a deep/dark color. Also to build upon the daylighting discussion, installed light fixtures should be located deeper within a room rather than near a window. Utilize daylight for a majority of your lighting. Then have task lighting by this window areas for evening lighting. Otherwise, use switches for zone lighting throughout the room so an occupant does not have to turn on all lights at once but possibly just the more interior lights during daytime needs.

  12. Peggy Deras | | #12

    Re Daylighting in Residential
    Besides windows for daylighting, there is the Sun Tunnel/SolaTube option as well. Some even come with lighting so they work day and night. While they simply light the floors the same way recessed lights do, they don't cost watts. Also great for daylighting hallways and other rooms with no windows.

    You also forgot to explain the term "light layering", though you defined it. Very important to have separate switching to achieve functional layering. For instance: I put the ambient lighting in a kitchen on two switches, to give a low and high level of ambient light.
    Then I put task lighting for each work area on its own switch. Decorative and accent lighting are usually switched separately as well.

    Kitchens with ceilings over 8' high are candidates for lighting on the tops of upper and tall cabinets. Also rooms with attic space over them can have the ceilings lifted to accommodate uplighting.

    Here's a kitchen remodel I did a couple of years ago with 100% fluorescent lighting (except for a couple of LED recessed lights not shown in these images.

    http://kitchen-exchange.blogspot.com/2009/09/100-fluorescent-kitchen-lighting.html

    No reason why energy efficient lighting can't be drop to your knees dramatic too. The designer just has to be committed to do it that way and able to convince the client that it will be great.

  13. Bill Burke | | #13

    Exposed Lamps / Daylighting
    Martin,
    I have to disagree with one comment. "Choose fixtures with clear lenses, if possible. Don’t be afraid of fixtures with a modern design that incorporate a bare lamp." To my eye, a fixture with a clear lens exposing a bare lamp makes no sense. If it's in your field of vision, it produces glare and compromises your ability to see. And if it's not in your field of vision, why have a lens? If you want a lens, it is possible to find diffusing glass that is as transmissive as clear glass.

    Regarding daylighting, I agree completely. I always tell people that if they need to 'daylight' a residence, it's typically a sign that the house is too big. During daylight hours, even a marginally competent design should provide adequate illumination through windows such that there is no need to turn on electric lights.

  14. User avater GBA Editor
    Martin Holladay | | #14

    Response to Bill Burke
    Bill,
    I am very sensitive to lighting anomalies and bad lighting design, but I am delighted with my Delray T-5 fixture (shown in the last photo on this page). It has a bare bulb. The great thing about it is that it is bright -- even though it doesn't draw many watts. To my eyes, there isn't any glare.

    If you start paying attention, you'll notice such fixtures in many modern office buildings. I saw some at Harvard University a couple of weeks ago. There really is no objectionable glare from such fixtures.

    Open your mind to new possibilities and experiment. Of course, opinions differ -- plenty of people like diffusers and shades.

    Below is a photo of the Delray fixture I spotted in a Harvard meeting room:

  15. Milton Pyron | | #15

    Cathedral ceiling lighting
    What do you recommend for lighting great room with cathedral ceiling?

  16. User avater GBA Editor
    Martin Holladay | | #16

    Response to Milton Pyron
    Milton,
    These rooms are difficult to light well, which is one reason that I'm not a fan of great rooms.

    1. Make sure that you have good task lighting for reading at every chair or sofa. You can use table lamps, floor lamps, or wall-mounted swing-arm lamps to accomplish this.

    2. For ambient lighting, you can use long linear fluorescent tube fixtures mounted on projecting shelves or cornices. The shelves should shield views of the bare tubes; the light should be aimed upwards toward the ceiling.

  17. User avater
    Andrea Lemon | | #17

    In defense of recessed cans
    Hi Martin,

    This article was my bible when we designed the lighting for our house, and it served us well. But we also got advice from a lighting consultant, and he talked us into installing some recessed cans roughly 24" from the wall. Instead of lighting the floor, they illuminate the (light-colored) walls, which bounce quite a lot of light into the room.

    I agree that mid-room recessed cans are not useful, and recessed cans on a cathedral ceiling are a terrible idea, but a well-placed can does quite well.

  18. User avater GBA Editor
    Martin Holladay | | #18

    Response to Andrea Lemon
    Andrea,
    Ultimately, lighting design is in the realm of aesthetics. De gustibus non est disputandum.

    I'm glad that you are pleased with you lighting choices. (I feel confident that you didn't install those recessed cans in an insulated ceiling -- right?)

    Certainly, it's easier to make an aesthetic error with recessed cans than it is with most other types of fixtures. But if you know what you're doing, and you like the effect they create, they have their uses.

  19. User avater
    Andrea Lemon | | #19

    Insulated ceilings
    Martin,

    Ha! You are correct that we didn't install recessed cans in the insulated ceiling. Indeed, we didn't install any lights in the insulated ceiling upstairs -- it's all wall sconces and indirect lighting up there.

  20. Bill L | | #20

    Angled recessed cans on a horizontal ceiling?
    I'm thinking of using angled recessed cans (originally designed for use in cathedral ceilings) on a horizontal (uninsulated) ceiling, in order to bounce light off of high walls. This seems a lot more efficient than those recessed fixtures which direct light toward the wall by shielding half of the opening to the can.
    Has anyone tried this?
    thanks,
    Bill

  21. User avater GBA Editor
    Martin Holladay | | #21

    Response to Bill L.
    Bill,
    You can do that if you want.

    It's also possible to possible to buy recessed fixtures that are designed to be directional and adjustable. These are called "recessed eyeball" fixtures. You can Google them to learn more.

  22. Erica Downs | | #22

    where to find CRI for bulbs?
    Where does one find the CRI for CFLs? I've looked on packaging for many brands, and it seems lucky to find the degrees K -- I've never found the CRI. Thanks!
    Erica

  23. User avater GBA Editor
  24. Vara Ramakrishnan | | #24

    Ambient and accent lighting in bedrooms
    Hi, We're in the middle of new construction in California, and our electrical plans call for recessed adjustable lights to wash ceilings and walls for ambient and accent lighting. I saw your comment to Andrea Lemon "I feel confident that you didn't install those recessed cans in an insulated ceiling -- right?" and am wondering what I'm supposed to use instead. We have flat roofs, so there's only about 12 inches of insulation possible at most, so I'd love to not eat into that in a lot of spots, thereby reducing the overall R-value. How else can I accent art on the walls? Track lights wouldn't be pleasant. Thanks!

  25. User avater GBA Editor
    Martin Holladay | | #25

    Response to Vara Ramakrishnan
    Vara,
    Installing recessed can lights in an insulated ceiling is an unmitigated thermal disaster. You don't want to do it. For more information on why, read Recessed Can Lights.

    The usual way to hide recessed can lights in your type of ceiling -- in a way that is responsible from an energy perspective -- is to build a false ceiling about 10 inches below your real (insulated) ceiling. Of course, that means that you need to start with a house that has been framed for 9-foot or 10-foot ceilings.

    If your architect or designer doesn't know these facts, that's a sign that your designer is not very energy-savvy.

    If you are stuck with 8-foot ceilings, it's hard to drop your ceiling any lower. One way to do this is to build soffits around the edge of your room. Of course, you lose some ceiling height at those soffit areas, but at least you don't lose the ceiling height in the entire room. If you go this route, make sure that your ceiling plane is airtight before the soffit framing begins -- otherwise this type of soffit will be a disastrous air leak in your air barrier.

  26. User avater
    Ethan ; Climate Zone 5A ; ~6000HDD | | #26

    LED update...
    I think it is time to really rethink lighting... even since this article was written, lighting has changed significantly.

    It is very difficult to find a CFL bulb, let alone an incandescent. LED lighting has improved, but there is still much misunderstanding. Also, the economics have shifted

    A basic $2.50 Ecosmart LED bulb is advertised for 15,000 hours... $20 3M Dimmable Bulbs are advertising 50,000 hours (~25 years of use!).

    The problem is, in my experience LED bulbs too often have a rated life of about 30 minutes because I install them and then the light quality is substandard, or owners experience buzzing, so they quickly dig out an old CFL or incandescent and replace the 50,000 hr LED bulb and toss it in the trash or the bottom of the junk drawer...

    I have had good experiences installing LED lighting, but it was basically a crap shoot, and I got lucky on brightness, light quality, buzzing, etc.

    So, if we're going to be living with lighting solutions for 25 years, much more attention has to be paid to light quality and controls... and the idea that CFL or incandescent is a viable option to fall back on is quickly going the way of the dodo.

    Also, as we begin to look at 50,000 hr lighting solutions, and the multitudinous form factors that LED lights can come in (strips, panels, points) and the way that LEDs can be mounted (surface mounted, cove lighting, undercounter, etc) the whole thinking about lighting has shifted.

    In addition, controls are changing, so that smart phones can control lights... I don't like this idea... but pezioelectric and other forms of remote switching is here, and controls need no longer be hardwired to individual light sockets, even if smart phones aren't used. So switches can be wall mounted on a magnet but then moved periodically if need be, or reprogrammed as room configuration changes.

    I'm sure there are electricians leading this charge, but in my own experience, they are still wiring switches to old Edison screw-in fixtures... I think there is a balance between the pie-in-the-sky smart home surveillance all the time model and the old three-way copper wiring of old... I think there are solutions which are functional and elegant and not confusing... light switches your grandmother can still use, but which save energy, last a long time, and create pleasing interior environments.

  27. Charlie Sullivan | | #27

    Standby power
    Ethan,

    Thanks for the good comments on the rapidly changing landscape. Another aspect is that with the expansion of various kinds of controls, we should pay attention to the energy consumed by the controls. Considering the efficiency improvements in the lights themselves, it's possible to have a situation in which the controls consume as much energy as the lights, at least for lights that are not on for much of the time.

  28. User avater
    Ethan ; Climate Zone 5A ; ~6000HDD | | #28

    Charlie, I believe...
    ...the controls can be very low energy. Some, like the Lightning Switch (http://www.lightningswitch.com/) are even "peziolectric"(sp?). But maybe you're referring to sensors. I was recently thinking that the old mechanical rotary timer that I have controlling some lights is probably at this point consuming about as much electricity as if they were just on 24/7.

  29. Charlie Sullivan | | #29

    Receivers draw power continuously
    In the system you linked to, the controls the user touches don't need a power source, other than the user pushing the button, but they send a signal wirelessly to a receiver, and that receiver needs power 24/7 in order to be "listening" for the signal. Unlikely many such products, these list the power consumption on the technical data sheet. It's 1.1 W on and 0.55 W off. A house could easily have 40 lights, so that's 22 W continuously, or 193 kWh/year. That's perhaps not a disaster but it's not helping if you want to aim for very low electric consumption.

  30. User avater
    Ethan ; Climate Zone 5A ; ~6000HDD | | #30

    I hadn't thought of the receivers!
    Thank you for illuminating this for me! (Pun intended). So are my 3W LED bulbs that can be turned on and off by remote control creating a 24/7 current draw?

    In general, LED power usage is abut an order of magnitude lower than incandescent, and about 1/2 CFL, so I guess we have to take our lumps somewhere, and perhaps in controls might be where we do it.

    I also don't know what the power draw is on the AC/DC converters and drivers for LED lamps, which should be factored into their energy usage.

  31. Trevor Lambert | | #31

    mid room ambient lighting
    So I'm trying to imagine how to put this "illuminate the ceiling" into practice. At the edges of the room, I guess upward pointing wall sconces would be good. What about in the middle of the room? Track lighting, but pointed upwards? Pendant lights with an opaque or highly diffused bottom shade?

  32. User avater GBA Editor
    Martin Holladay | | #32

    Response to Trevor Lambert
    Trevor,
    At the perimeter of a room, cove lighting (lighting above a decorative ledge) is a good approach.

    In the middle of the room, pendants make sense. Many pendant fixtures are designed to throw most of their light upward, and only a small portion downward.

    Check out newer fluorescent fixtures installed in offices or schools: Most of them are designed to send their light upward.

    .

  33. lynstrand | | #33

    Hi Martin,

    Thank you for the advice.

    You mention steer clear of dark shades, but if you have a tv in the room, isn't it better to have the light source obscured somewhat because of the reflection on the screen. I personally don't like sitting in total darkness when watching a movie.

    Also, I have a large window next to my dining room table. Is there a rule of thumb as to what kind of hanging light is best when you want to avoid the glare bouncing off the window?

    Also, I am noticing a trend where there is a consistency in the kinds of lights used through out a home. Does that meant that If you use a white lamp shade in a room, that one should use white lamp shades or something of a similar glow throughout?

    Sorry for all the questions.

  34. User avater GBA Editor
    Martin Holladay | | #34

    Lynstrand,
    Here's the most important part of my advice: It's your house. You get to choose the type of lighting that you want -- what works for you. Of course it makes sense to choose a dark shade for a lamp if you are doing so for a deliberate reason -- if you like the effect provided by that dark shade.

    If you're having a problem with an irritating reflection from a window, it makes sense to select a different type of fixture -- perhaps one that hangs lower or hangs higher, or one without an exposed light bulb.

    I have no interest in the question of whether the window shade in one of the rooms of your home matches the window shade in another room. They can match if you want them to -- but if you prefer them not to match, that's fine with me. It's your house.

  35. Lance Peters | | #35

    Hey Martin, great article. Perhaps with the advances in LED lighting it’s time for an update? Also, with LEDs as efficient as they are, I don’t think nearly as much attention need be paid to task vs whole room lighting.

  36. User avater GBA Editor
    Martin Holladay | | #36

    Lance,
    You're right -- rapid improvements in LED lighting have made the references in my article to CFL bulbs obsolete. These days, there is no reason to choose CFLs over LEDs.

    On the issues of lighting design, however, the principles stated in the article are, I think, timeless. That said, if you prefer to install lots of whole-room lighting rather than task lighting, you can -- but the effect is a little like living in a WalMart or a supermarket. Most homeowners prefer lighting where it is needed -- on the page of the book they are reading, or on the kitchen countertop where they are cutting vegetables.

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