Daylighting Model Study

Background

This was a project I did for an architectural daylighting course I took at Columbia University. My goal for this project was to explore the way in which light can be brought into an interior space through deep reflective "shelves". Rather than employing a skylight, which exposes the interior environment directly to the sky dome, I wanted to explore the effect of light brought into a space with a more mysterious, allusive, and diffuse quality.

Inspiration

I drew inspiration from various buildings that employed deep shading overhangs. Intuitively, it may seem that having deep overhangs as shown in the various examples below might shade too much of the light and create a dark environment. However, in the cases that I looked at, these overhangs were almost always paired with a complimentary reflective surface that actually captured the light and seemed to direct it into the interior space. Figure 1 shows a house designed by Miro Rivera Architects. The outdoor patio space has a deep overhang but also a floor that is quite reflective. Even in this image, which is taken at night, the reflection of interior lights can be see on the patio floor with decent detail. In this case, even though the overhang extends out quite a bit, the light can still be reflected off these surfaces and directed into the living space. Figure 2 shows the Sugamo Shinkin Bank, designed by Emmanuelle Moureaux Architects. I think it is quite typical to envision office buildings to be covered in shiny glass windows. This building however, takes a slightly different approach by enveloping the building in these closely spaced deep overhangs. It may seem that these would obstruct light from entering, however, the shelves are quite reflective, allowing the light to bounce through them. The overhangs also extend out various distances, which allows the light to hit more of the shelves. By having different colored shelves, this design also manipulates the color of the light that enters the space, an interesting concept that has numerous possibilities.

Concept Model

For the project, I still intend for the light to be brought in from the top of the room. However, rather than through a window in the ceiling, the light will be brought in through the sides and reflected off of the ceilings and into the space. I have chosen a simple design to explore this effect. The structure is south facing, with a single opening. The remaining walls are all blocked off in order to more clearly examine the effect of the light. The upper overhang protrudes several feet over the lower overhang. The overhangs are intended to be made out of highly reflective material as to more effectively reflect the light. The goal is for the light to reflect off of the bottom overhang and onto the upper overhang and create a diffuse light on the ceiling and also bounce light into the interior space.

Theoretical Analysis

Once I had established my basic model concept, my goal was to play around with a few variations of the design to determine the most efficient way for the light to be directed into the space and also to maximize the effect of the light. Since the basic design concept included two overlapping parallel overhangs, I decided to look at different orientations of these two overhangs in relationship to each other to determine the best placement to most effectively capture the light. The following figure shows a few of the orientations that I considered. These included 1) parallel plates 2) parallel angled plates 3) angled top plate 4) angled bottom plate.

Right off the bat I was able to eliminate two of the orientations just by doing a few rough sketches. I decided that the parallel angled plates and the angled top plate would not be effective and as efficient as the other two options. The diagram below shows the reflected ray patterns for the tilted upper plate orientation and it is evident that the rays actually get stuck between the two overhangs and begins to reflect out. This effect is dependent on the incoming ray angle but I decided to eliminate it because of this effect.

Prior to taking my model out into the sun, I conducted a few basic calculations to determine the theoretical maximum orientation or angle that would most effectively direct the light into the space. For the sake of the experiment, I used arbitrary dimensions and determined that the most efficient orientation would be the orientation that directed the light deepest into the space. Table 1 and 2 show the preliminary calculations for the parallel flat plates and angled bottom plate orientation (depth is calculated in feet).

As seen in Table 1, the penetrating depths are fairly shallow. The deepest that the light enters is around 2 feet. Granted, these calculations were based on arbitrary variables for the dimensions of the overhangs, they can be used to compare the two different orientations. In table two, I have tilted the bottom plate 20 degrees and it is evident that the penetrating depths are much greater than the parallel flat plates. During the winter months, the light penetrates as deep as 8 feet into the space. However, if we compare the penetrating depths for the summer months, we can see that there isn’t a huge difference between flat and angled plates. This is because the sun is must higher in the sky so therefore the angle of incidence is greater. This effect might even be desirable since light is more scare in the winter months and the more light the tilted overhang can bring into the space, the better. However, in the summer months the deep overhangs act more as shading to keep out the hot summer sun.

Model Analysis

After taking my model out into the sunlight, I discovered some interesting results. My hourly images are shown at the end of this analysis.

During the winter months, the penetration depths of light into the space is much more exaggerated than in the summer months. This is due to the low altitude of the sun in the sky. During the summer months, the sun does not make it very far into the interior space, which is almost opposite of what one might expect.

For every hour that I analyzed, I photographed the effect of the light in the room. Even though my theoretical calculations assumed that the deepest penetration of light would be the best, I noticed that the deepest penetration didn’t always produce the quality of light that I was looking for. The goal for my model project was to bring light into the space via reflection off of the ceiling. At certain times, including 9:00 am on Dec. 21st, tilting the overhang at 20 degrees actually brought the light too deep into the space and reflected it off of the back wall. This not only made the space slight darker, it also made it feel as if it was late in the afternoon when the sun is low in the sky and exhibiting a warmer light. Even though tilting the overhang at 20 degrees theoretically directs the light deeper into the space, I don’t feel that it is necessary to have such an exaggerated effect.

My recommendation would be for the bottom overhang to be fixed and inclined at 7 degrees. This directs the light somewhat deeper into the space while still keeping the quality of light that I feel is most comfortable for the space.