A Light at the End of the Tunnel – Daylighting!

How is it that I, a person who is highly sensitive to light – or rather the lack of it – works in not one, but two spaces that are as dark as the inside of a pocket?

The presence of sunlight offers amazing benefits to a building’s inhabitants and/or owners. Studies have shown that adequate “daylighting” can increase building lease rates, reduce worker absenteeism and sick leave, increase production, result in higher sales, and speed patient recovery times in hospitals.

Here's what the window looks like at noon with the room lights turned off.
Here’s how dark my office is at noon on a sunny day lit only by the south-facing window and an east-facing interior door.
Here’s how it looks a few steps farther back with all of the lights turned on.

I know from experience that a lack of sunlight can cause depression. When I lived in gray and overcast Chicago, I suffered from SAD (Seasonal Affected Disorder). After a move to San Francisco my mood brightened, except during bouts of summer fog. Another move to the border of the sunny Mission District has helped me escape both gray skies and blue days.

Even so, the rooms where I spend the most time are both dark: my home office and my office at Alliant International University. At the university, I’m privileged to have a private office, but it’s an interior space that is wholly dependent on artificial light. My office has no windows. A vertical glass panel beside the door would let in light from the hallway – if there were any. On three occasions, I have been in that office during power failures, and each time, I was instantly plunged into darkness. I found my way out to the hallway – an equally dark space – only with the help of the small flashlight on my keyring!

View of artemisia bush from inside the daylight model
View of artemisia bush from inside the daylight model, same south orientation as the real window. This shows how much light should be getting into the room - quite a contrast to the real room above.

Frankly, this is the result of bad design. Alliant’s offices were built out only about five years ago, and the folks who planned them should have known better. The offices on the perimeter do have some glass walls, and they do let light. But due to the floor plan, internal walls quickly block the light.

The layout spaces multiple windowless interior offices like mine along long windowless hallways. The halls receive natural light only at the far ends, rendering the glass insets beside the doors pointless. A couple times, when we had extended power outages, the staff wearied of waiting and groping in the dark and went home.

My home office, which doubles as a dining room, is not much better, however. You can see the problem in the photos at the top of the post. I have complained to the management. The manager (me) has assured the tenant that despite serious fiscal limitations, there are some possible options for brightening up this dark space. In this post, I will tell you a little about a model of the room I have built, and how I’m using it to weigh my options for improving the room. Later (perhaps quite a bit later, given the current economy), I will tell you about how my lighting renovations come out.

Modeling the Room

I have created a scale model to test changed paint colors, a light shelf, a light reflection pad, above-head-level clerestory windows, and changes to the reflectance qualities of the surfaces outside the window. Eventually, I will also need to redesign the outside stairs that partially block and shade the room’s one window, but I decided to start by seeing how much I could lighten the room with the easier, cheaper, indoor fixes.

The scale model in the garden. The camera opening is facing you and the windows of the room look south, in the same orientation as the actual room. What the window "sees" is that artemesia bush, the view shown in the previous photo.

The first steps in this experiment have involved testing how the surfaces outside the room impact the light and color inside. I’m conducting my tests using the scale model, pictured at right. This little box is made of foam core, which is easy to use, but too translucent for a daylight model in most cases. But in this instance, the interior walls have been finished with the same wall texture, flat pink latex wall paint, and white gloss wood trim enamel, as in the actual room. The paint and its underlayment (rubber cement sprinkled with grainy brown flour to create wall texture) make the foam board opaque.

The real room (pictured at the top of this blog as it looks when lit by artificial and natural light together), is nine and half feet wide, 11 feet long, and has a 10-foot high ceiling. All of this, plus the window and doors, have been replicated in the  model at a scale of 1.25 inch equals 1 foot. The model even includes an appropriately placed picture rail and high baseboards similar to those in the real room.

Why Daylighting is a Bright Idea

With all the lights on, the room pictured at the top of this blog is fairly attractive – and one made even more attractive by my cat Bridget, who is sitting on the table. What’s wrong with turning on the lights, you might ask?

As it turns out, quite a few things. It takes energy to keep those lights burning. As much as one-third of your total energy bill may be going to light your house.

A beautifully daylight room
A beautifully daylit room

To my way of thinking, that’s ridiculous! To adequately light a space, you need to capture only about 2% of the outside light, and all that’s required for that is proper fenestration. But over the past couple decades, architects, who have been DUI (designing under the influence) of cheap oil, haven’t thought much about daylighting and energy efficiency.

Happily, that’s changing. With buildings responsible for gobbling up 38.9% of America’s total fuel – more than industry (32.7%) and more than transportation (28.4%) – many building owners are undertaking energy-efficiency retrofits. One example is Chicago’s Sears Tower, which has just been rechristened the “Willis Tower” by its new owners.

The Willis Tower, like its glass-box cousins, bleeds energy. This year, it’s getting a $350 million sustainability retrofit that will reduce its base electricity use by up to 80 percent. Like me, the Tower’s owners have little ability to change the building’s basic shape, but they are replacing 16,000 single-pane windows with thermally efficient models and are also installing “daylight harvesting” systems that dim the artificial lighting when the sunlight is adequate. They expect to save up to 150,000 barrels of oil – megabucks – every year!

Green is for Greenbacks

This might be a good place to note that energy costs drive both efforts to improve daylighting and efforts to improve the thermal performance of the building’s envelope. A few months back, in a post entitled “Saving My Energy for a Greener Tomorrow“, I wrote about plugging heat leaks in my house. Last month, I found out how effective my investment of a couple days time and around $100 had been. I received a rebate check from PG&E for reducing my energy use, and that prompted my husband Mason to compare current and past utility bills. A year ago, our June bill totaled $142, and this June it was $49. Since the house was fully occupied both months – Mason is retired so he’s there during the days – and the weather was quite similar, I think the credit goes to mostly to me.

But the financial benefits of daylighting aren’t limited to energy savings. One big box store noticed that the skylit-half of its store consistently showed 40% higher sales than the side that was artificially lit. Wondering whether that might be due to unpopular merchandise or to the way it was displayed, they flip-flopped the store layout, so that the slower-selling products were now under the skylights. To their astonishment, they found that the under-the-skylight sales pattern persisted. This chain is now working on installing skylights in all their stores.

Health Benefits of Natural Light

Natural light also has a positive impact on human health. It makes us feel happier, perhaps because we feel more connected to the environment. We also see a fuller spectrum of color in daylight.

But there’s more to it than that. The depressive impact of SAD (Seasonal Affected Disorder) – also known as “cabin fever” – is well documented. Studies show that people who suffer from SAD exhibit many of the signs of depression: sadness, anxiety, irritability, lack of interest in their usual activities, social withdrawal, and inability to concentrate. They often suffer from fatigue, lack energy, crave sleep and carbohydrates, and experience increased appetite and weight gain.

Less well known are several studies done in schools, where natural light has been linked to reduced absenteeism, higher test scores, and even to less tooth decay!

Meanwhile, Back in My Office

A southwest view from the daylighting model.
Because the daylighting model is turned about 30 degrees and facing southwest, there's far less light on the right side wall. It's also interesting how much what's outside the window affects the interior color. Compare the color of the walls here, with the San Diego red bougainvillea reflecting on them, with the image above, where the green from the artemesia creates a complement effect that greatly tones down the pinkness of the room.

It’s far easier of course, to orient the windows correctly in the first place than to later attempt to correct the problem – as I will be trying to do with my office/dining room. In my case, the room should have adequate light.

As the daylight model at right shows, the south-facing window gets quite a bit of light. Light also comes through the door on the left side of the room – though not quite as much as this model would indicate. In reality, that door opens into my living room, a space I have not yet added to the daylight model. My living room does have adequate light, but it filters the light that enters the dining room.

The real problem here can be seen in the photo at the top of the post: wooden stairs with closed backs block much of the light that should be entering my office. To fix this problem, I will need to have those outside stairs rebuilt in addition to changing the inside of the room.

What kind of changes can help improve daylighting in this room – or one you want to brighten up? Here’s a list, starting with the simplest and moving to the most difficult and costly:

  • Change of wall color: Light colors reflect significantly more light, and a change to a wall inside or outside can help. I will be repainting some walls inside my model to test this. I will also be experimenting with changing the color of the “ground” surface outside the window; currently, that landing is covered with a black tar roof. I would get more reflection if that surface were a light color.
  • Mirrored wall: Mirrors reflect light; I will be experimenting with putting mirrors on the wall opposite the windows, and also with hanging something reflective outside the window.
  • Light shelf: Light shelves are horizontal panels that are placed near the top of window and used to bounce light into the depths of a room. I’m not sure I have enough direct sunlight to make one work – at least until the stairs are redesigned to let light through – but this, too, is easy to test in a model.
  • Light-deflecting panels hung from ceiling: I have seen these in only one place, the LEED-certified offices of the Energy Foundation in downtown San Francisco. In that office, interior designers have hung a V-shaped panel from the ceiling over a conference table. The angled sides of the panel catch light from the windows and reflect it down toward the work surface, brightening a room that is otherwise somewhat dark. My room is shaped somewhat similarly, and I’m eager to try this approach.
  • Drop ceiling: The best light comes from the tops of windows, at eight feet and above, and windows are most effective when they directly abut walls and ceilings. The top of my window is separated from the ceiling by a two and a half foot margin. The ceilings throughout the house are 10 feet up, and it may be that much of my available light is escaping up into the area above my picture rail. An experiment with the box will tell.
  • Install clerestory windows: Those wide, short windows located up near the roof are called clerestory windows, and they are great for letting light travel from perimeter rooms into interior rooms. Installing clerestory windows probably would let more light travel from my living room into my dark dining room – but it might be an expensive option, because to add them, my contractor would need to pierce a load-bearing wall that provides support to the building’s upper floor.
  • Install skylights
  • Install tubular skylights: I can’t add a skylight in my room (because of that upper floor), but some tubular skylights can channel light down inclined paths by reflecting it down a tube, and I might be able to use one of these to import sunlight into my space.

Resource Links


It was the sun that made ancient Egypt prosperous, and they worshipped that life-giving source of energy. The god Ra, the god of the sun, was regarded as the source of everything.

6 thoughts on “A Light at the End of the Tunnel – Daylighting!

  1. Nicolette,

    There are all potentially viable solutions, but mostly quite costly, and many of them would not be as suitable for the style and period of your house. Light shelves and ceiling panels are extremely contemporary designs, for example, as well as very commercial-looking, and would not look so great in your space.

    Less expensive places to start would include painting the ceiling with a light color in a highly reflective formula such as semi-gloss, or to use some kind of other reflective coating such as perhaps a metal veneer wallcovering, and to paint the walls in at least an eggshell sheen, which will also reflect more light than the usual flat paint most typically used on walls, or to also use a reflective wall treatment there. Maya Romanoff makes some amazing things.

    The point is, don’t neglect the existing ceiling as it is as a reflector source, and put more reflective materials to work for you as well as lighter colors.

    If you do decide to use a higher gloss level of paint, you’ll need to also make sure that every possible blemish in the walls and ceiling is dealt with, because higher gloss levels will highlight flaws much more than flat paint will.

    If you really want to maximize the reflectance, go with some shade of white or off-white, as even pastels will typically eat up close to 20% or more of the available light. You’ll want a paint color with the highest light reflectance value (LRV) that you can find.

    Wide-slatted wooden blinds angled upwards would also help direct what light is available upwards to the ceiling as well, probably less expensively and much more in line with the style of your house than a light shelf or a dropped ceiling. They will also help hide the eyesore of the stairs.

    I’d also look at mirroring the long wall opposite the door to the living room and adjacent to the window, rather than the wall opposite the window. Not only would that pick up the light from the window better, and make it look like the room has another window, but it will also reflect any light coming in from the living room, which would be a huge bonus – and will also make the room look bigger. Since the room is already somewhat more long than wide, mirroring the wall opposite the window will create more of a tunnel effect, and not make anywhere near as effective use of what light there is, because the light will have to travel further to get to it than along the side wall.

    You might also want to speak with a contractor about the stairs. It could be that the risers could be removed without compromising the stair structure, and without having to rebuild the whole thing, and that alone would let a ton more light into the room, if it’s doable. I wouldn’t count on this, but it’s worth investigating.


  2. Thank you, Wendy! I didn’t know I was going to get a collegial consultation from this post, but it’s very kind of you to provide one. I hadn’t thought about putting the mirrors on the side wall, but I will definitely try that out when I experiment with the model.

    You’re right about the gloss paint too – but the wall surfaces are just awful. That’s one of the reason we originally got rid of the gloss paint that used to be in the room. However, if I wind up with a dropped ceiling, it’s going to have a new surface, and presumably, it would be much friendlier to a gloss surface.

    The stairs are going to have to get fixed anyway, as some point. Not just that flight, but the flight below. Part of a pricey earthquake retrofit project I need to do, but can’t afford at present…

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