9. Lighting Projects to Save Energy

 

Lighting

Here are some helpful energy tips from the experts to illuminate your life:

  • Rooms that need a high level of illumination (kitchen, living room, family room) should be along the north-south axis of a house, for the maximum available daylighting (via sunlight through east- and west-facing windows). Laundry rooms, closets, and garages should be on the interior.
  • Ceilings should have a reflectance of at least 0.9 through the application of high reflectance paints, to project daylighting deep into the space from the windows. (Standard ceiling paint is a flat white.)
  • Put a motion detector light switch in the attic or basement to turn the lights off after thirty seconds without any motion.
  • Energy Star rates light fixtures, too.
  • Since 90 percent of the energy from incandescent lamps ends up as heat, they’re “more efficient” in the winter. That electric heat is equal in efficiency to an electric space heater.
  • Bright light right before you go to sleep can make it harder to nod off. Dim the lighting an hour or so before you turn in, especially if there are children in the household.
  • Capacitance in an electric circuit stores energy similar to thermal mass for a building. Capacitance limits power fluctuations in a circuit and harmonics.
  • Almost half of the kitchen lights and one-third of the living room lights are on at least three hours a day.
  • Install lighting controls for lights that are left on much of the day.
  • The light level necessary for good visual efficiency depends on (1) the size of the details in the task at hand, (2) the contrast level, and (3) the age of the viewer.
  • A small 10-watt spotlight on a colorful picture, bookcase, or tapestry can add character to the whole room (and meaning to the dark shadows).
  • Vary the light wattage in a multi-bulb track fixture for an interesting effect (and energy savings).
  • Get Energy Star holiday lights. Or, better yet, nix them altogether. Humbug!
  • Experiment with different wattage bulbs in a fixture, to end up with the lowest wattage lamp that provides the level of lighting you need.
  • Metal or heavy-paper lampshades block much of the light from a bulb. Semitransparent lampshades create a pleasant ambient illumination and mood!
  • Compact Fluorescent Lamps (CFL) contain mercury, so they require special disposal methods.
  • Don’t put CFLs in an enclosed space (with little or no ventilation) where they can heat up. CFLs don’t like hot situations and won’t last as long. Burn out!
  • The reflection of sunlight off water, snow, or ice can add 65 percent to the normal incident radiation. Windows facing a body of water get 165 percent of the usual daylight. That’s excellent news for passive solar heating applications.
  • If there’s nobody in a room, turn off the lights.
  • How many lights do you really need? What do you do when you arrive home from school or work? You move from one room to the next, turning lights on and then forget about them.
  • If you must, keep one light on in a strategic location, illuminating the den, dining area, and stairs just enough to get around. Technically, you should keep that light off, too, but who wants to live in a cave?
  • Which motel chain “keeps a light on for you?” Do you want to invite robbers into your house as well? Several people in my neighborhood keep lights on in the front of the house all night. Two 100-watt incandescent fixtures running ten hours each night for thirty days equals 30 kWh. At the going rate, those lights cost my neighbor $5 a month.
  • Put a dim bulb in a hallway bathroom off the living room for those nighttime excursions.
  • An LED light from the microwave (phantom load!) lights up the kitchen just fine (not phantom anymore but useful).
  • Small plug-in LED nightlights use very little power. They’re available with an integral light sensor, so they turn off during the day.
  • It’s okay to cycle fluorescent lights on and off. Engineers design fluorescents to safely cycle on and off several times a day.
  • Most houses have windows in the kitchen. On a sunny day, try to manage with only an under-counter light and the stove vent-hood light.
  • Daylight is free! Do your best to take advantage of nature’s illumination in every room.
  • Use only as much light as you need.
  • At night, turn on a bedside light to read, or the end table lamp when watching TV.
  • Don’t watch TV in total darkness (or a computer monitor). Have general lighting that is 25 percent as bright as the screen.
  • Older folks need extra light at night. Most of the (sometimes life-threatening) falls the elderly suffer are while navigating stairs. Stairways are often dark even during the day. Plug in a small nightlight halfway down the stairs. It gives the light you need, and you don’t lose your night vision from a bright overhead light, then stumble around half-blind after that.
  • Small children take comfort from nightlights, too. Keep a light with a light sensor in the kid’s bedroom, and a motion-sensing light in their bathroom.
  • Who hasn’t done their homework in the kitchen? The kitchen table is an excellent place for kids to do homework because help is only a holler away. You don’t need as much light to eat a meal as to study. You want a warm, cozy illumination when eating. Much more light is needed for reading.
  • The dining area is an ideal application for a dimmer switch, which you can install by replacing the light switch in the wall box—low setting for dining, high setting to study.
  • A three-level light bulb in a table lamp in the living room can provide ambient lighting for conversation, mid-level illumination for watching television, and the highest setting for reading.
  • LED lamps are also available with three levels, and six times the energy savings as incandescent bulbs (15 watts vs.100 watts for the same candlepower).
  • If you’re a fan of daylight, you need clean windows. In the winter, when the sun is lower on the southern horizon, you also get free heat through those windows. The cleaner the glass, the more sunlight shines through.
  • Aluminum mini-blinds offer privacy at night and block out the harsh western sun in the summer. Tilt them, to reflect daylight deep into an otherwise dark room.

If you’ve ever picked out paint in a hardware store, then put it on the walls back home, suddenly to realize the color is entirely different—blame it on the lighting.

Architects and interior designers devote quite a lot of effort to lighting. How else are they going to highlight their designs, but with carefully orchestrated lighting? Don’t you want to know how they do it?

10.1 INCANDESCENTS: THE GOOD, THE BAD, AND THE DIRTY.

The U.S. ban on incandescent bulbs, set to go into effect in 2020, was canceled. Why the ban in the first place? CFL and LED bulbs use 80 percent less energy for the same amount of light as incandescents. Why cancel the ban? Unknown. Maybe because it’s hard to match the warm, natural ambiance of incandescent lighting.

Fluorescent and LED bulbs add “harmonics” to the power supply. This “dirty power” makes all other electrical devices operate less efficiently. Fortunately, there aren’t enough luminaires in a house for this to be a problem, so not to worry.

10.2 R.I.P. INCANDESCENT BULBS.

I admit to a fondness for the warm, natural glow of incandescent lighting. It’s very old-fashioned, low-tech. Electric current heating up a filament—voila! Let there be light!

Fluorescent bulbs have an electronic ballast build in. LED lighting is highly electronic, too. Even a few years ago, you could buy twenty incandescent bulbs for the price of one LED. Thanks to the economics of volume (mass production), they cost about the same now.

10.3 R.I.P. COMPACT FLUORESCENT BULBS.

Twenty years ago, Compact Fluorescent Lights (CFLs) were all the rage, using onethird less energy than incandescent bulbs. Now LEDs use half the energy of CFLs. Incandescent bulbs last two thousand hours, CFLs eight thousand hours, and LEDs twenty-five thousand hours. The costs are roughly $1 each for incandescent and LEDs and $4 for CFLs. So, the clear choice is LEDs. And not just to replace incandescent bulbs but CFLs, too.

Lifetime hours

  • 2,000 – incandescent
  • 8,000 – CFLs
  • 25,000 – LEDs

10.4 SWITCHING TO LEDS.

LEDs are often rated in “equivalent illumination to a 60-watt bulb,” so you know what type of bulb to purchase. LEDs also have “warm white” and “cool white” ratings, so be sure to match the bulb to the application. (I buy “warm white” for everything.)

If you have a multi-bulb fixture, you’ll probably have to replace all the bulbs at once because even if you match the lumens and the color, you’ll still notice the difference between the old and the new bulbs.

 10.5 LIGHTS ADD A HEAT LOAD TO THE HVAC SYSTEM.

Ninety-five percent of the power to incandescent bulbs ends up as heat. The number for CFLs is 40 percent, and LEDs run 20 percent cooler than CFLs.

What? You don’t believe lights generate a quantifiable amount of heat? Next winter, when you’re working away in your home office, ask Oscar the cat when she jumps up on your desk and curls up under your desk lamp for a nap. (I know at least one somebody who misses the old incandescent bulbs.)

 Power lost to heat

  • 95% – incandescent
  • 40% – CFLs
  • 30% – LEDs

10.6 LIGHT OUTPUT IS MEASURED IN LUMENS.

People generally think about lighting as “the equivalent of a 40W incandescent bulb” (dim), a 60W source (brighter), or a 100W bulb (bright enough to read by). These illumination levels are hard-wired in our brains, to the point where we shop for CFL or LED bulbs as “equivalent to a 60W source.”

It’s easier to think the two bulbs have the same lumens rating. Except nobody knows what “lumens” are.

So: the efficiency of any process is the amount of energy required to do a certain amount of work. We know that “watts” are the electrical energy delivered by the utility company. The work done by the bulb in transforming those watts of energy into light is calibrated as “lumens.”

10.7 LIGHTING EFFICIENCY = LUMENS PER WATT.

It’s necessary to quantify lighting efficiency, and the way to do that is to calculate the ratio of light output to energy input.

Hence the ratio of lumens to watts or lumens/watts.

For example, we know instinctively that incandescent bulbs are much “less efficient” than CFLs or LEDs. How much less? Well. Incandescent bulbs give you 12 lumens/watt; CFLs close to 60 lumens/watt, meaning CFLs are five times more efficient. You get about 75 lumens/watt with LEDs; they use six times less energy than incandescent light sources for the same quantity of light.

Lumens/watt ratings

  • 12 – incandescent
  • 60 – CFLs
  • 75 – LEDs

10.8 HOW THE NUMBERS ADD UP.

When my folks retired, they built a “game room” in their dream house, featuring a pool table, front and center, and a sofa/bed (for the kids and grandkids come avisiting). There was a light fixture over the pool table, roughly two-foot-by-twofoot square, with nine bare light bulbs. Back then, the bulbs were all incandescent (this was long before the first CFLs).

Assume that game room light was on for three hours a day for the summer months, which equals three times one hundred days for a total of three hundred hours. Say the bulbs were 40W each, times nine equals 360 watts: 360 watts x 300 hours equals 108kWh x $0.15/kWh equals $162 total cost for the summer. Plug LED bulbs into the fixture, and the total is $27. Now we’re getting somewhere!

 10.9 ARCHITECTS AND INTERIOR DESIGNERS THINK IN TERMS  OF LIGHTING LAYERS.

Imagine a house with an open floor plan, with a living-dining room-kitchen as one, big, open space. There are many light sources: a chandelier over the dining table, table lamps on either side of the sofa, a reading light over a recliner, plus recessed overhead lights over the entrance foyer.

In the kitchen, there’s an under-counter light, a stove-hood fixture (with multiple lights), pendant lights over a giant wood-block island counter, plus a double row of recessed ceiling lights.

Many activities can take place in this area, often simultaneously: cooking supper, kids watching TV from the sofa, guests talking quietly as they set the dinner table for a holiday family event.

Layers of lighting define individual areas, facilitating different functions while providing the ideal illumination for each activity. There’s even a dim table lamp in the most distant corner, providing ambiance and spatial coordination, illuminating the darkest corner of the space.

 10.10 DON’T FORGET THE LIGHTING THAT’S 100 PERCENT FREE!

Don’t forget daylighting! All those fancy architectural layers of light, down to the smallest painstaking detail, and I didn’t even mention light streaming through large windows on three sides of the room. That natural lighting is the ideal source because the human eye evolved with nothing but the sun’s light.

Our visual senses work best in a full bandwidth of spectra. Daylighting adds new layers of light, plus a charming variation from morning to afternoon and evening.

 10.11 NOW, TO QUANTIFY THE LIGHT PRODUCED BY AN ARTIFICIAL  SOURCE.

Photography enthusiasts know what a light meter is. You can purchase one for $25 (or download an app for your smartphone). The readout is calibrated in either lumens/sq.ft. or lumens/sq.m. – i.e., in units of footcandles or lux, respectively.

There are roughly 10 lumens per lux, so there’s one decimal point difference (because there are 3.281 feet per meter and 3.281 squared is 10.76). I’ll use footcandles, abbreviated “fc.”

Now, a 60 W (equivalent) LED light bulb produces 800 lumens total, going in all directions. If you screw that bulb into a desk lamp and focus all those lumens downward onto a ten square foot area, the light intensity is 800/10 = 80 fc.

Except the lamp doesn’t reflect 100 percent of the light, and the light isn’t limited to just 10 sq. ft. but spreads out over a broad penumbra. So, let’s say you get 40 fc on a desk surface 2 ft. below the lamp. That’s the arrangement I have on my desk, and I can read okay there.

 10.12 ILLUMINATION LEVELS VARY PER EXACTITUDE OF THE  TASK YOU’RE DOING.

The first thing you do in the kitchen when you can’t read the instructions on a box of wild rice is to (1) put on your eyeglasses and, if you still can’t read the fine print, (2) you hold the item under a brighter light.

Typical ambient kitchen lighting is 10 fc, and the illumination needed for reading is about 40 fc.

The more detailed the job, the more light needed: 50 fc for sewing, up to 100 fc for a detailed task. (A 50-100-150 W three-level bulb can do all three.)

 Footcandles

  • 5 – stairway
  • 10 – corridor
  • 25 – bedroom
  • 30 – restroom
  • 50 – classroom
  • 75 – workshop
  • 100 – laboratory

10.13 WAS MOM RIGHT WHEN SHE SAID YOU’D GO BLIND  READING IN DIM LIGHT?

As people age, we need more light for reading. So, what may seem like dim light to your mother might be perfectly okay for tender young eyes.

Let’s say you’re reading ten-point type. A twenty-year-old needs about 30 fc; a fifty-year-old needs double that amount of light, 60 fc; at age sixty, people need about 75 fc to read ten-point type.

Mom’s perception was biased by her own vision. (Hence the convenience of having three-level bulbs in reading lights for a multi-generational household.)  Age vs. Fc to read

  • 20 – 30 fc.
  • 50 – 60 fc.
  • 60 – 75 fc.

10.14 THE COLOR RENDERING INDEX (CRI) OF LIGHT SOURCES.

Another plus for incandescent lighting is its almost perfect rendition of colors. Incandescent bulbs (with a CRI=100) are the touchstone against which all other bulbs are compared. Standard LEDs have a CRI of 83, “high-CRI” LEDs of 89, and “ultrahigh CRI” LEDs have a CRI of 99.

Manufacturers don’t usually specify the CRI on the packaging because not many people know what it means. Fluorescent lamps have a CRI of 51 to 89, depending on the source metal and the “color.” All you need to remember is that the lower the CRI, the more unnatural colors appear. 

The more critical color rendition is to the task, the higher the CRI you need. Proper perception of skin tone, for example, needs a higher CRI; in a bathroom or at a vanity mirror. (Guess what kind of lighting they use in art galleries? Incandescent!)

 CRI ratings

  • 100 – incandescent
  • 51-89 CFLs
  • 83-89 – LEDs

 10.15 COLOR TEMPERATURE RATES YOUR ATTENTION.

Have you ever noticed a dramatic difference in colors between two computer monitors? Maybe that sample of paint you bought at the hardware store (under harsh fluorescent lighting) looks completely different at home (in a warm/soft CFL or LED setting)?

It’s called color temperature because the temperature of the source determines the perceived color. Standard incandescents are at 2400° K.

0 degrees K is “absolute zero,” the lowest possible temperature. There are one hundred degrees Kelvin between the temperature at which water freezes, 273° K, and boils, 373° K.

“Soft white” is 2,700° K (orange hues) to 3,000° K (yellowish), and “cool white” is in the 4,000° K range (bluish color). Natural daylight is 6,500° K (outside on a cloudy day). The open sky is upwards of 10,000° K.

Color temperatures (°K)

  • 2400 – red
  • 2700 – orange
  • 3000 – yellow
  • 4000 – blue
  • 6500 – cloudy day
  • 10000 – blue sky

10.16 COLOR TEMPERATURE BRINGS OUT THE AMBIANCE IN A  SPACE—OR NOT.

Heating a filament, it glows at different colors as the temperature increases, from

“red hot” to orange, then yellow, blue, then “white-hot.”

Less than 2,000° K is a dim glow similar to candlelight; 2,400° K incandescent up to 2,700° K is cozy and inviting for kitchens and living rooms (table and floor lamps, chandeliers); 3,000° K “warm white” sources are warm and welcoming (foyers and bathrooms); 5,000° K “cool white” works for basements and outdoors, detail-oriented tasks.

Hospitals and manufacturing facilities sometimes have 6,500° K illumination: higher precision needs more lumens and also benefits from more natural light (in the blue spectrum and above). Why? Because our visual senses and perception are at their best under natural light. 

 Ambiance (°K)

  • 2000 – candlelight
  • 2700 – cozy, inviting
  • 3000 – warm, inviting
  • 5000 – cool, stark

10.17 SO MUCH FOR THE MATH. LET’S DO LIGHT!

The next time you’re in a high-end restaurant, hotel, or store par excellence, you’ll likely see multiple levels of lighting. This atmosphere is carefully designed by architects and interior designers. You may not be able to duplicate the setting at home, but you can now study your visual environs when you’re out and about: a seventh a sense for lumens, color, and temperature.

There’s an area with dim candlelight for intimacy. Splashes of brighter light, focused, from recessed ceiling fixtures, highlighting artwork on the walls or items for sale in display cases. When the doors to the back room or kitchen swing open— Doh! You’ll get a brief glimpse of bright, blue commercial lighting.

Discrete task lighting illuminates different tables from above in a penumbra of light that gives diners some conversational pretext but keeps them separated by a gentle gulf of darkness from adjacent tables.

Specialist bulbs create these subtle effects: spotlights with a reflective surface inside the bulb and a lensed surface to diffuse and focus the lumens.

You can see all these fancy fixtures in the raw, hanging in your local hardware store.

Further down the aisle, there’s a large assortment of bulbs: shape, size, and base configuration.

10.18 GLASS HAS ZERO INSULATION VALUE. 

When you’re talking about saving energy on lighting, there’s nothing more efficient than daylight. The problem is getting that light into your house. A typical two-byfour stud wall has an R-value of 17 (R-13 insulation + outside sheathing + gypboard inside), whereas an Energy Star double-pane window struggles to get R-3.

Fancy new ultra-efficient windows claim R-5, but is the payback worth the extra cost? You may get free light, but you pay for it in higher heating and cooling costs. The scales are usually tipped in favor of windows because they also have intrinsic value in a view outside.

 10.19 IF YOU WANT MORE LIGHT, INSTALL A GLASS–BLOCK WALL.

Winters up north are precisely the time to get some extra light into the house. The days are short, often very cloudy, and people spend more time indoors. But really, glass blocks? How sixties is that?

The modern high-tech solution is translucent insulation. It can have an insulation value of R-20 and transmit almost 50 percent of the visible light. M.I.T. researchers have recently found “an optically transparent, thermally insulating aerogel,” which is clear enough to be put in the air space between double pane windows, increasing its R-value to that of a triple-pane window.

Sometimes you don’t need “clear” but just diffuse lighting. Translucent insulation is excellent for skylights. Clear glass can be a distraction, especially for large areas like an entire ceiling above a stairwell. An opaque, diffused light simulates an alto cirrus veil (thin, very high clouds).

These “translucent insulation” panels also dampen sound by an amount equivalent to that of an interior wall. Finally, they’re impervious to moisture, hence applicable for roof or exterior wall applications.

10.20 LIGHT TUNNELS MAKE SKYLIGHTS EVEN MORE VERSATILE.

You’ve seen light tubes on virtually every electronic device: Flexible tubes that transmit light from an LED on the motherboard to the keys on your keyboard, or buttons on the monitor, TV, or laptop. The same principle applies to getting light from your roof, through the attic, down to the kitchen or bathroom.

Central to the residential “light tube” is a dome on the roof that captures light from all directions, bouncing it down an internally reflective, circular duct. The light exits a recessed ceiling fixture in the room that looks just like a regular light fixture. Except that light is free, it’s daylight, and you can grow happy plants underneath all year long. 

These light tunnels are flexible, to divert the light wherever you want! Well, flexible in the sense that the shiny, smooth duct can exit the roof at an angle, and terminate in the ceiling at an angle. Truly flexible, as in twisty-turning duct, is possible as well, but light losses are much greater because the corrugated tube dissipates most of the light before it reaches the ceiling fixture.

10.21 A PSYCHOLOGY OF ARCHITECTURAL LIGHTING.

Although architects have a knack for lighting design, they’re not particularly concerned with saving energy. They use light to create atmosphere, to sell merchandise, to put commercial products “in their best light.”

For example, a dining room with a chandelier over the dinner table in the middle of the room looks dark if the only light is over the table—i.e., if the walls are dark, the entire space appears dark. Their solution? Light the walls!

The engineering solution switches out the chandelier bulbs to natural-type lighting to bring out all the colors in the tablecloth, the food, the people! Then nobody will even notice those “dark” walls.

 10.22 DAYLIGHTING ITSELF DOESN’T SAVE ENERGY. 

I have a dark living room, so I keep one table lamp on most of the time. It’s near a wall, so it provides general, dim illumination and also lights up an uncomfortably dark corner (with colorful artwork and books nearby).

When it’s sunny outside, I tilt the blinds (near that dark corner) to reflect daylight deep into the room. That gives me enough light so I can turn that table lamp off. That’s when the energy-saving begins. Daylighting is no help at all unless you turn off one or more electrical lights. 

Kitchen nooks often surround an informal “breakfast table” with glass and natural light. Why break the spell and turn on an overhead light?

If you can read comfortably at the desk in your home office with the help of natural light from the windows, how is a task light going to help you read better?

 10.23 READING IN DIM LIGHT IS GOING TO RUIN YOUR EYES.

Eye doctors debunk that myth all the time. (Yet the myth persists.) Dim illumination may make it harder for your eyes to focus, which can cause eye fatigue. You might blink less often, which can cause your eyes to dry out. But reading in dim light won’t cause any long-term damage to your eyes.

Reading with too much light can also cause fatigue, headaches, stress, anxiety, hypertension, and even sexual problems. (Looking at the sun directly, lasers, or any intense light source can damage the retina, which is very bad.)

If you’re at the beach, reading in direct daylight, you’re probably wearing sunglasses.

Why is it any different in your home office, with direct sunlight on the desk surface? Tilt the blinds to modulate the light level. Don’t ever read when it’s uncomfortable for your eyes.

 10.24 NOW, ABOUT THAT GIANT SUNLIGHT OVER THE KITCHEN  ISLAND.

When the sun is directly overhead, or sunlight comes directly into the room—Wow, that’s bright! One bright spot makes all the rest of the room seem dark (especially if you stand in that light and your pupils close), so you turn on other lights.

The solution is a diffuser. Overhead fluorescent fixtures often have an acrylic, diffusing lens: You see only a vague outline of the fluorescent tubes, and the area below the luminaire has a consistent light level with no bright spots. With a diffuser in the window, that bright daylight is spread evenly out over a wide area, and no additional electrical lighting is needed.

 10.25 SOMETIMES, TOO MUCH DAYLIGHTING COMES IN.

Direct sunlight through a west-facing window late on a summer afternoon can project a lot of unwanted light—and heat—into a room. Even with the air conditioning running, too much light can make a place feel warm. Close the curtains or blinds to darken the space, and it feels like you’re in a cool, comforting shade.

My folks had roll-down blinds on all the west-facing windows to block out that hot, summer afternoon sun. The blinds were just porous enough to allow pinholes of light to diffuse into the space. The outside surface of the blinds was white (reflecting light and heat away), and the inside was dark, for a “shady” sensation.

Someday I’ll remove a section of the metal roofing on my upstairs porch and replace it with a clear panel to give the cats an extra splash of sunshine to enjoy when the sun’s directly overhead.

 10.26 PASSIVE–SOURCE HEATING.

Any time you have direct sunlight streaming through a window, you have a strong, steady heat source. The sunlight warms up whatever surface it touches. That’s not good in the summer because the air conditioning has to extract that heat. However, it’s great in the winter—free heating!

Passive architectural techniques endeavor to direct daylight onto a bulky, dark surface (a concrete floor or wall, for example). This thermal mass absorbs all that heat, and after the sun goes down, it re-radiates that heat to keep the area warm for many hours.

10.27 LARGE SKYLIGHTS IN THE SUMMER VS. WINTER.

Imagine a “sunroom” off the dining room, with lots of windows and a translucent roof. What a great place for lots of plants!

In the summer (or in warm climates like South Florida), an opaque roof isn’t a terrible problem because heat rises and then forms a static thermal layer at the ceiling. As long as the AC doesn’t disturb that layer, you won’t lose an excessive amount of heat through the roof.

However, heat rises in the winter, too. When that warm air interacts with the cold, translucent roof, the air gets cold, drops to the floor, and you have a convection current going. This is a useful application for a layer of transparent insulation, either built into the roof or added in the winter as removable modules.

 10.28 IT’S NEVER EASY.

What happens when humid indoor air meets the cold glass of the skylight? You’ve seen it before: You forget a boiling pot on the stove in the winter, and the windows nearby get a thick glaze of condensation.

Cold milk carton, “sweating” on the back seat on the way home from the grocery store in the summertime? Condensation on the glass shelves when you stand in the refrigerator door, deciding what to fix for supper? Fog on the bathroom mirror after a hot shower?

A skylight represents all of these problems and more. Hot air rises, directly to the ceiling. The skylight glass has very little insulating value, so the inside surface is almost as cold as the outdoor air.

Condensation is insidious. The process never stops. It may not drip to the floor but seep into the drywall in the ceiling, then wick across the ceiling to the walls. Bottom line? At a minimum, get skylights installed by a qualified contractor, and, well, skylights are for fancy office buildings and malls designed by architects with liability insurance.

 10.29 NOT ALL WINDOWS HAVE A GREAT VIEW.

The usual solution for a window with no view is blinds or curtains. Venetian blinds or thin curtains let some of the light through and still block that unsavory view.

You can maximize the daylight even better by installing diffusers (a film or acrylic sheet made out of a prismatic material) on the inside surface of the window. A diffuser doesn’t block any light but scatters it up to the ceiling for greater daylight penetration. (You can always dress up the diffuser window with curtains and blinds to match the decor.)

You can put ¼-inch spacers between the window and the diffuser panel to increase the insulation value (similar to how storm windows work).

 10.30 NOT EVEN DIFFUSERS GIVE TROUBLE–FREE LIGHT.

I hope you’ve been mindful so far that any time you put something like a skylight into a roof, you have to be sure and seal it against rain and moisture. Placing a diffuser sheet inside a window can cause moisture problems of a different kind. Ouch, unpleasant surprise!

The window-diffuser installation creates an insulating layer between the prismatic sheet and the glass. In the winter, the inside surface of the glass is now colder than it was before. Cold glass meets warm, humid air inside, and you have a condensation problem.

You can either (1) put the diffuser far enough away from the window to allow airflow (thus negating any insulating value) or (2) seal the diffuser and make it an integral part of the window (in effect, a storm window).

Option three: stained-glass artwork hanging a comfortable distance from the window. Imagine the colors!

 10.31 VAULTED LIVING ROOM CEILINGS.

I know they’re mostly second homes in the countryside, and rich people don’t care about saving energy, especially if they’re only in residence a couple of weeks out of the year. I know those country mansions have the kind of view working stiffs could never hope for, but still, talk about a total waste of energy. Sure, you’ve got daylight, a ton of it, from a whole two-story façade of glass.

At least half the monthly utility bill is dealing with heating and cooling the thermal load imposed by that grand display of conspicuous consumption. They could at least put a light shelf at the intersection between the two levels (where the regular ceiling line would be, at the bottom of the vaulted), a reflective surface that projects light from the clerestory windows above the typical ceiling line, into the living area.

Notice how this light shelf (1) sends daylight deep into the space, where it (2) heats up the vaulted ceiling, which (3) isn’t a thermal load in the summer but (4) adds to the thermal envelope in the winter. Try explaining that to your houseguests after their third pink martini.

 10.32 EXTERIOR SHADING WITH A GREEN TWIST.

Bright idea: Horizontal exterior shades, about one-fourth of the way down from the top of a tall window. Angled slats in the shades reflect incoming light through the top of the window, deep into the interior of the room. Meanwhile, the slats shade the bottom half of the interior room from direct sunlight (which is what exterior shades do, right?), without affecting the view from inside. (I saw this installation in a photo somewhere.)

Put a hinge on the whole device so it can be pivoted down, and you have a hurricane shutter to protect the glass from flying debris in a windstorm.

All of which is to say, exterior shades block sunlight in southern homes to lower the cooling load. Why not also design exterior shades to send that (otherwise blocked) sunlight into the house for some free daylighting, and a double-whammy of energy savings?

10.33 LIGHT–COLORED WALLS ARE WORTHY OF REFLECTION.

Daylight projecting into a room with light interior colors illuminates a space brighter than the same room with darker wall colors. The same goes for any light source: it takes more lumens to light a room with dark walls than for light-colored walls.

Anything on the walls that absorbs light reduces the light level—bookshelves, tapestries, even a heavily textured wall (which diffuses light instead of reflecting it).

The relevant technical term is reflectance. The reflectance value will be on the label of any can of paint you buy at the hardware store. The higher the reflectance, the fewer lighting watts needed to achieve the same level of illumination. Not that you save enough energy to justify painting a whole room over again, but it’s a consideration.

 10.34 PUT A GLOSS ON IT. OR NOT.

Gloss also impacts reflectance, but it’s not quite as variable. Ceilings are universally given a flat finish paint. Walls are the next step up, typically painted in an eggshell finish.

Satin is slightly more reflective and also much more durable. Bathroom walls are suitably satin both for durability and reflectance. Semi-satin is even more durable (and shiny), suitable for rooms that see rougher use: laundry, garage, closets.

The eggshell finish imparts the warmest ambiance. Shinier walls seem antiseptic, but can be scrubbed clean as needed. Semi-gloss is suitable for a hospital operating room or I.C.U., where the walls are cleaned even more often.

Use full-gloss in the bathrooms if you have young kids in the house. Crayons wipe right off a semi-gloss wall, but make a permanent impression on flat, eggshell, or satin finishes.

When it comes to paint finishes, functionality often takes priority over saving energy.

 Wall finishes vs. room type

  • Flat – ceilings
  • Eggshell – family room, bedrooms
  • Satin – kitchen
  • Semi-satin – bathroom
  • Gloss – closets, garage

 10.35 DAYLIGHT COMES IN DIFFERENT COLORS, TOO.

In the morning, when the sun is low on the horizon, its light makes a space feel warm. That daylight gives a room a yellowish cast.

At noon, when the sun is most intense, daylight imparts a bluish tint to a room (recall blue light has the shortest wavelength and the most energy). Direct “bluewhite” light from the sun can be so intense that it washes out all other colors!

As the afternoon progresses, sunlight becomes orangish, and rooms get a reddish coloration.

You can use these properties to customize the colors in different rooms to their quality of daylight. Paint manufacturers can simulate the color of light so that the wall color you choose enhances the room and compliments the prevailing daylight.

 Sunlight colors

  • Dawn – yellowish
  • Noon – blue tint
  • Afternoon – orange
  • Sunset – red

 10.36 ARTIFICIAL LIGHTING IN A ROOM CAN COMPLEMENT  THE DAYLIGHTING.

Recall that incandescent bulbs produce a warm, yellowish light. Incandescents complement colors in the orange-yellow spectrum but dull blues. The cool, blue light of fluorescent bulbs enhances blues and greens but dulls other colors.

“Soft white” fluorescent lamps may appear as warm as incandescent but tend to fade all colors from their peak.

You can max out the warm, comfy feeling of the late-afternoon daylight (when everybody is sitting down to dinner, for example) through the bay windows, with incandescent bulbs in the chandelier.

Or get the kids in gear at breakfast when the sun’s yellowish, relaxing light hits the breakfast nook, with some “blue-white” overhead fluorescent lighting.

Architects pull subtle tricks like that on us all the time. Why not take advantage of the same ideas at home?

10.37 LIGHTING FILLS SPECIFIC BIOLOGICAL NEEDS.

Windows do more than introduce daylighting into a room. They also provide “time orientation.” Directional light gives “form to objects” (essential in the kitchen), whereas diffuse light ends to “flatten details” (a chandelier over a formal dining table).

Illumination levels organize a space by focusing on what’s important: the desk in a home office, stairs, the countertop in a bathroom. Variable light levels, moreover, can define personal space in a large, open room. Consider a kitchen-dining-living room space, where table lamps by comfortable chairs give a reader some privacy and boundary.

Lighting defines meaningful structural relationships: the ambient light from point-sources in the kitchen, dining room, and living room illuminates chairs, a coffee table, even cat toys on the floor.

Lighting also provides orientation: a guest entering the foyer, gazing into an open area, can see who wants privacy (the reader, the cook), and who’s available for conversation (folks setting the dinner table).

If individual point-sources of light are inadequate for this orientation, more lighting is needed: perhaps a wall sconce or a reading light by an empty chair (an invitation to relax?).

All of these subtle functions make the space attractive, and with just enough light to make things cheerful.

 10.38 LIGHTING AND BASIC HUMAN NEEDS.

We started off this chapter by merely illuminating those things that need light: the kitchen counter, the dining room table, and a reader’s book. These task lights give each activity a measure of privacy.

What remains is a matter of geometry—several bright lights in a large, open area leave deeply shaded areas. Darkness can be useful, too; it gives contrast and boundary. But too much dark can endow a sense of insecurity. Hence the need for “unnecessary,” not-strictly-functional lights, to flesh out the three-dimensional aspects of a space, its occupants, and furnishings.

Often daylighting provides this spatial orientation, but at night you need artificial lights to fill out the whole visual geometry. Notice that too much daylighting or too-bright non-task lights can wash out all the subtle refinements we’ve made.

10.39 PAINT CAN MAKE AN OTHERWISE INTERESTING SPACE COMPELLING.

So, our open common area is well lighted, organized, and visually appealing. What’s missing? A fire in the hearth (great add-on, but only when it’s snowing outside), the TV blaring (talk about destroying the whole mood), music—candlelight!

No, paint on the walls is what’s missing. Warm, cheery colors on the walls can do all of the above, and with enough reflectance that non-task lights prove unnecessary at night.

Tilting blinds when there’s too much daylight can transition from a visual wash-out to a cozy-cool interior-escape from the glaring sunlight outside.

Dark colors give drama to a space, but one dark wall does too! Rich, deep color in various shades of light can take on a range of compelling and complementary hues, night or day.

Paint gives your iris a hearty workout and invites you to enjoy the opportunities.

 10.40 EXTERIOR LIGHTING FOR SAFETY AND SECURITY.

Exterior lighting for any purpose other than security only tells people you’re happy to waste energy, for whatever reason. A garage light kept on late on a winter afternoon (when the sun sets at 4 P.M.) for the kids coming home from soccer practice? That’s safety. The same light burning all night long? That’s what motion sensors are made for (and dogs).

If you need to light a back patio or pool deck at night, at least choose an energy-efficient light source. High-pressure sodium is more efficient than fluorescent and ideal for outside lighting. Halogen isn’t much more efficient than incandescent.

Yellow “bug” lights may be appropriate for your situation in the summertime.

10.41 SOLAR OUTDOOR LIGHTS SAVE MORE THAN ENERGY.

There are many kinds of outdoor lights with a small solar panel built into the top to charge an onboard battery. You don’t have to remember to turn them on or off. The light comes on automatically at dusk, burns all night long, and extinguishes at dawn.

These solar-powered luminaires may be a little more expensive up-front—or not, if you factor in the cost of running a long underground electrical conduit from the house.

If you live in a rural setting and have a bona fide security concern, talk to your utility company about installing a “street light,” even on private property. The utility handles all the maintenance. They simply bill you a modest, fixed charge each month. This is the lowest-cost option when you need mega-lumens (to illuminate a large area) per dollar.

 10.42 DOES EXTERIOR LIGHTING SCARE ROBBERS AWAY OR  LIGHT THEIR WAY?

If the idea is to alert a roving police patrol to the enhanced risk of property theft, why not have your security lights controlled by a motion sensor? That saves energy, plus it scares the robber more.

My last cat friend used to wander over into my neighbor’s yard after dinner, and when I went to find her, a security light popped on in the driveway—yawn— pthen I heard sounds. Music! VOICES! It was years before I finally figured out all that sound was all from a CD soundtrack playing in the garage.

Another neighbor would email me photos of that same naughty cat (Jaxx by name), caught in a flash, like a deer in the headlights, digging into her prize germaniums.

 10.43 WHO NEEDS SECURITY LIGHTS WHEN YOU HAVE A DOG?

Dogs protect your property better and more aggressively than any passive floodlight. Or a recorded sound of a dog barking! (Didn’t fool Jaxx, not for one minute.)

The dog doesn’t even have to be there all the time. One chase by my new neighbor’s boxer dog and I stopped walking down that street for good.

Of course, big dogs might need an expensive fence, although those wireless, buried “invisible fences” can corral canines just fine.

Maybe all you need is some of those Warning: Bad Dog signs to put up along the wireless fence line.

As far as that goes, a well-placed “This House is Protected by Security” sign in the yard keeps working just fine, long after I disconnected the whole security system. How will the bad guys know if the system is functional or not? (I’m screwed after they read this book.)

 10.44 THE OLD FROZEN–FOOD–ISLE LIGHTING TRICK.

You’ve been in a grocery store frozen-food section where the lighting in the standup refrigerators flickers on as you walk down the aisle.

Why can’t neighborhoods and gated communities transition the streetlights off after midnight, say, like stoplights start blinking yellow late at night? That would save a ton of electricity and be just as cautionary as keeping the streets lit all night.

When somebody lawfully opens the gates to the community, the streetlights come on for five minutes, then go into a motion-detection mode. That keeps kids from sneaking out of the house for a smoke or a pint of beer (a joint!). No cheating spouses in the neighborhood, either.

If they make cameras that can take your photo when you run a red light (then, to add harm to injury, send you an effing ticket in the mail), why can’t they do the same for somebody breaking curfew?

The payback on that project (cost of the camera system divided by the energy saved per year) should be swift and merciless.

 10.45 THE LIGHT AT THE BEGINNING OF THE TUNNEL.

In residential applications, you can’t do much better than to turn the light off if you don’t need it. Who leaves a bedroom or bathroom light on if nobody’s inside? It’s just plain common courtesy.

However, what about those rooms where, if you forget and leave the light on, it can stay on for days or weeks! For example, a basement or attic light, a storeroom or garage closet light. You might not even notice for a whole month—until your utility bill arrives. Panic city!

That’s where timer switches come in handy. Just replace the light switch with an electronic timer (expensive!), or on a spring-wound device that you twist – and it TICK-TICKS, loud enough to say, “Hurry up whatever it is you’re doing.”

10.46 WHAT DO YOU DO WITH ALL THE OLD BULBS WHEN YOU  REPLACE THEM?

Incandescent bulbs that you replace with more efficient light sources still have their use. Recall that “payback” is a function of time: the less energy you save, the longer the payback.

A corollary is: if you use the device very little, it’s almost impossible to justify replacing it with the energy-saving equivalent.

Hence, those old kilowatt-guzzling incandescent bulbs work just fine in the attic or basement or storeroom fixtures that see only occasional use, and for short periods. (Of course, you’re screwed if you forget and leave the fixture on!)

10.47 IT HELPS TO GET YOURSELF ORGANIZED.

When engineers do bulk renovations of thousands of fixtures in a building, we advise our contractors to label everything: Put a tag inside each fixture, identifying the bulb type (sometimes the date as well). Then, when maintenance replaces burned-out bulbs, they don’t mismatch and either use less energy-efficient bulbs or put the wrong color bulb in and make their mistake stand out like a sore foot.

No, maintenance people aren’t morons (nor homeowners), but sometimes the bulb isn’t marked well, it breaks, or the identification text is faded and illegible. All of which means, if you go to all the trouble of matching light levels, colors, lumens, watts, and bulb types—make a record of it. A paper list can get lost. A list on the computer can be deleted (or lost when the hard drive dies).

The most uncomplicated “record” is to use a magic marker and jot down the bulb type on the base of the lamp, on the lampshade, or some other accessible but not visible location.

 10.48 BUY NEW BULBS, NOT NEW FIXTURES.

Although there are limits to the wattage some fixtures can handle, you can normally switch out bulbs, as long as the screw-in base matches. If the new bulb is more energy-efficient, wattage isn’t a problem. (Some fixtures have a maximum wattage rating for bulbs.)

If, after reading this section, you aren’t convinced there are a multitude of lighting options available—color, color-temperature, warm/soft/natural, light source (incandescent, halogen, CFL, etc.)—then visit a hardware store and browse the “lighting aisle.”

Or, better yet, visit a store dedicated to lighting. Just don’t tell the salesperson you’re not shopping for a new fixture, and pump them for new bulb ideas.

Switching out a wall-mounted or recessed fixture in your house can be expensive. Changing out the bulb is the thrifty, fun way to go.

10.49 SOME BULBS PROJECT MORE LUMENS PER WATT THAN  OTHERS.

Floodlights have a conic base coated with a highly reflective metal inside that maximizes the lumens delivered out of the lens. Some floodlights emit a diffuse light, illuminating a large area; others deliver a more focused beam of light.

If you want to go from diffuse to focused, you don’t need to change the entire fixture. Of course, if you go to a specialty lighting store, what do you expect? They’re going to try and sell you a whole new, righteously expensive fixture. Buy the bulb instead. 

If your local hardware store has a limited selection of bulbs, go online and find a more extensive selection. Look for flood-type lights with a different lensed surface and the illumination pattern you require.

 10.50 SOME FIXTURES PROJECT LUMENS MORE EFFICIENTLY  THAN OTHERS.

Many light fixtures, especially wall sconces, depend on a metal shade to reflect light from the source. (Recessed ceiling-mounted luminaires invariably rely on the bulb to focus the light.)

I have a couple of decorative wall sconces at my desk. One glance: the interior of the shade is a dark color. How’s that going to reflect any light? I rarely use them, but if I did and wanted more light, it’s easy to just paint over the interior with a couple of coats of white spray paint.

Hey, if you’re in the market to replace the fixture anyway, why not have some fun and experiment with the old one! (I love spray paint.) White has a high reflectance, so a white-colored interior will send more light out instead of absorbing it and heating the fixture so hot it burns your hand to the touch.

Note: that blue or green “painter’s helper” tape is a must for any painting project. You also need high-temperature-rated paint for light-fixture jobs.

10.51 WHY DO THEY MAKE FLOODLIGHTS ANYWAY?

Light spreads out evenly in all directions from a point-source light bulb. A 100watt bulb in a small room lights it up nicely. Put the same bulb in a much larger room, and you only get a couple of shades above dark.

A bulb inside a ceiling fixture with a reflective surface sends light into a larger area (dimly lit) than a focused spotlight in the same location. Raise the ceiling, and the effective lighting level is diminished for both. Raise the floor (i.e., illuminate a tabletop), and the light level increases.

If you want a lot of light anywhere, use a task light—a desk lamp, for example. If you want a lot of light on a surface where you can’t put a task light, hang a pendant light from the ceiling. If you want general, space lighting, the ceiling is the place for your luminaire.

Illuminating specific tasks, you need to get the light closer to the working surface. Energy-wise, the closer your bulb is to the visual task, the less energy required.

Lights in thirty-foot ceilings at a Big Box store, providing enough light to read a label? Solution: hang the fixtures from pendants and get the light closer to the source. (And create a compelling dark space above.)

 10.52 WHAT ABOUT VERY LARGE HOUSES?

How do people who live in McMansions save energy? They move into a smaller residence.

However, assuming our quintessential mansion is occupied by a multi-generational household, there are certain unavoidable lighting requirements. A busy house needs a specific, nominal lighting level throughout the night or day, so older eyes can get around and avoid the kids, cats, and their sundry toys.

Daylighting fulfills that need during regular business hours. Artificial lighting is needed when it’s dark outside. How do you provide that ambient nighttime lighting? Ceiling fixtures with non-flood lights.

How do you make cavernous spaces seem cozier? Subtle wall illumination from sconces and the random table light.

What improves everything? Colors, paint, light-colored floors (carpet absorbs light) – area rugs add atmosphere and class, versus wall-to-wall carpeting.

 10.53 MOTION SENSOR DEVICES.

Busy restrooms are a great place to install motion-sensing tech, which can be incorporated into the light switch or via the lamp (which has a motion sensor built into the bulb).

Consulting engineering maxim: When your CEO client comes to inspect your wonderful re-lighting project, you can be certain the motion-sensors will turn the lights out while they’re in the restroom.

Light-sensing controls and bulbs are also ideal for exterior applications or any situation where folks tend not to turn things off. They even make motion-sensing power strips.

10.54 BE STINGY WITH YOUR ENERGY CONSERVATION BUDGET.

Don’t install motion/light-sensing devices indiscriminately. Spend your valuable money where it’ll get the most use (and, therefore, the best return on your investment). If you’re in your home office all day, that’s not a wise place to put a motionsensing light switch. Likewise, if the on-and-off lighting is a distraction (to older folks, for example), consider other solutions.

Conversely, maybe you want the lights to be a distraction—even a warning— such as near the pantry (snacks and kids!). Motion-sensing lights in a pool area outside can signal when young children stray where they shouldn’t. Motion-sensing lights in a study area might signal who’s still doing their homework and who’s fallen asleep.

10.55 FREE DAYLIGHTING.

A really large open area (indoor sports court or play area) with a window exposure may not need overhead lighting for much of the day. A low-wattage task light on each play-station can provide all the illumination necessary. The overhead lights can be on a light-sensor control.

A large area (indoor pool, baskeball court, or fitness room) bordered by windows can put the outermost fixtures on a separate circuit to accomplish the same end. As a retrofit, this may or may not be a viable energy-conservation project (lots of re-wiring is needed). The installation cost is, of course, critical to the decision process, but also if the occupants will take advantage of and benefit from the new arrangement.

Multi-level lighting can be a positive change to any area, with dim ambient light plus special task lighting at different activity areas (wood-working shop machines, workout equipment). A sophisticated lighting environment lends a level of privacy to each person, a subtle intimacy not possible with a large area lit uniformly from above.

Enhanced comfort and privacy always convert into higher productivity. That’s a vital payback consideration for any retrofit project, even if it can’t be quantified exactly into a formal payback calculation.

10.56 “LIGHT” SHOPPING SPREE.

A scientific study showed that people purchase as much as 40 percent more in stores illuminated with natural light. Daylighting puts people in a better mood and makes the merchandise look more appealing! Perhaps the solution, if you’re on a tight budget, is to wear sunglasses whenever you go shopping.

How can you use this daylighting phenomenon at home? Put the desktop computer where family members make online purchases in a dark corner, far away from a window!

 Future Tech! 

10.57

The light pollution ordinances of Flagstaff, Arizona, should become the national standard, and the United States should become the first International Dark Sky Nation, with zero unnecessary night pollution by lights. (Well, after North Korea.)

10.58

Since lights are the most common electronics in a house, and which operate the most during the day: a new type of bulb is needed with capacitance to correct power factors below 1.0, correcting the PF back to unity and ensuring 100 percent utilization of the electrical service.

10.59

Hoover Dam wasn’t built to waste all that hydroelectric power on Las Vegas’ extravagant night lights.

10.60

Interior lights for all buildings should have a lighting budget approved by the city building department, based on space use and occupancy. No lights after hours except for limited maintenance operations.

10.61

If a city needs extra lights for crime prevention; well, all the world will know (via Google Earth pix and photos from the International Space Station). People in that city will know not to venture into those areas at night. Residents will know “Big Brother is Watching.”

10.62 

Enact the 2020 Incandescent Bulb Ban as originally written.

10.63

More efficient street lights, including universal photovoltaic panels for each streetlight (or group thereof) and traffic light.

10.64 

Light bulbs with a light sensor that turn off when the daylight gets strong.