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35 Through our lighting analysis, we took measurements within the tunnel and in the 2 nodes connected to the tunnel, both during the day and night and ultimately identified the key problems with it. The analysis consists of both quantitative and qualitative measurements and observations.
Analysis: focus area
Lighting measurements It was decided that the measuring will be split in 3 areas, the Enghavevej entrance, the tunnel and lastly the Otto Busses Vej entrance (fig. 2.9). The first action of the lighting analysis was to take measurements on the entrance on Enghavevej. The values vary from 0 to 9 lux on the bicycle path and staircase, during dark hours, which was not surprising considering that there are no dedicated lights for it, and it is lit by the surrounding streetlights. Moving to the tunnel, there was a steady 30 lux value all the way through. There are ceiling lights placed every 2 meters, so the light in the tunnel is quite uniform. Furthermore, the walls in the tunnel have a reflectance of 48% and the floor has 13%. The last area of measurements was the most surprising one. On Otto Busses Vej entrance, it was quickly noticed that street luminaires with different light properties were placed together. After taking measurements, it turned out that 4 different types of luminaries were lighting it up. One type - the only fluorescent - was emitting a colour temperature of 3900 Kelvin, the second was emitting 3800 Kelvin, the third one was much colder that 4900 Kelvin and the last one a much warmer one at 3000 Kelvin. The lux values varied from 7 to 25. Due to the lack of access for borrowing equipment during the pandemic closure, we had to measure the colour temperature of the luminaries through a phone, using the app called “Color Temp Meter”, so the measurements may not be completely accurate.
• Creating with light
SUMMARY: The Enghavevej entrance is barely lit, since the only light it receives in the night is spill light from the surrounding street poles. Inside the tunnel, there is 30 lux strict, all around the tunnel and fixtures are placed every two meters. There is no coherence throughout the lighting on the focus area, and it appears that its goal is strictly functional. The lux values on the Otto Busses Vej entrance varies from 7 to 25.
Day vs. night To finish the chapter of the current lighting analysis, some conclusions on the difference between daytime and nighttime lighting scenarios are made. In addition to the disappearing daylight, the most notable change in lighting is, that during daylight hours the tunnel is very dark compared to the surroundings, and during dark hours the tunnel becomes very bright compared to the surroundings. This results in increasing visual dominance of the tunnel in the dark hours, and the accompanying effects this change brings within. One of the practical implementations that accompany this change in brightness-ratio, is the effect on the dark adaptation of human eyes. Having the ability to perceive details in a dimly lit space after entering from daylight takes several minutes, and full darkness adaptation can take up to 30 minutes. (Tregenza, Loe, p.38). It is difficult to measure exactly, how long time exactly it takes to adapt to the darkness in the case of this study, but it can be presumed that it takes more than the one minute that is spent in the commute. A general experience of the project team when entering the tunnel during daylight hours is, that it is rather dark, and it is difficult to perceive details. Adapting to brighter environments is not an issue, since it takes only few seconds for human eyes to adapt to brightness (Tregenza, Loe, p.38). Vice versa, when exiting the tunnel in dark time, the surrounding environments seem very dark for some time before the eyes adapt to darkness again.
bicycle path Enghavevej 9lx 3lx
#4 30 lx
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#2
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13 lx
22lx 23lx 7 lx 12lx 15lx #3
#3 25lx
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reflectance inside the tunnel: wall: 48% floor: 13%
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Fig. 2.9: Overview of horizontal illuminance measurements inside and outside the tunnel
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DAYLIGHT
DARK
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Fig.2.10: drawings of luminares
2.3 Lighting analysis
sky and exteriors
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visual dominance
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the tunnel
dark and cave-like
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atmosphere
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bright and exposed
entering the tunnel
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dark adaptation
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exiting the tunnel
Fig. 2.11. Illustrations of the change in visual significance of the tunnel between daytime and nighttime. In dark hours, the tunnel becomes visually dominant due to the high luminance compared to the surroundings.
