Abstract

Ray-tracing calculations are employed to identify basic design rules for the configuration of microstructured daylighting systems. The results show the advantage of combinations of lenslike geometries in comparison to conventional microprism arrays regarding the overall light redirection efficiency as well as the producibility and cost efficiency. Measurements at silicone prototypes and large scale industrially produced acrylic panels confirmed the simulation results. Optimization leads to free-form geometries which can further be improved by selective roughening of specific microsurfaces.

© 2012 Optical Society of America

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References

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  1. W. J. M. van Bommel and G. J. van den Beld, “Lighting for work: a review of visual and biological effects,” Lighting Res. Technol. 36, 255–269 (2004).
    [CrossRef]
  2. IEA International Energy Agency, “Daylight in buildings, a source book on daylighting and systems and components,” Report of IEA SHC Task 21 (International Energy Agency, 2000).
  3. Saint-Gobain Glass, Product Information SGG LUMITOP, http://uk.saint-gobain-glass.com/upload/files/sgg_lumitop_.pdf .
  4. H. F. O. Mueller, A. Emembolu, M. Oetzel, H. Schuster, and I. Soylu, “Sonnenschutz und Tageslicht in Büroräumen,” in Bauphysik-Kalender 2005, E. Cziesielski, ed. (Ernst & Sohn, 2005), pp. 397–439.
  5. G. Walze, P. Nitz, J. Ell, A. Georg, A. Gombert, B. Bläsi, and W. Hoßfeld, “Combination of microstructures and optically functional coatings for solar control glazing,” Solar Energy Mater. Solar Cells 89, 233–248 (2005).
    [CrossRef]
  6. H. Hocheng, T. Huang, T. Chou, and W. Yang, “Microstructural fabrication and design of sunlight guide panels of inorganic-organic hybrid material,” Energ. Buildings 43, 1011–1019 (2011).
    [CrossRef]

2011

H. Hocheng, T. Huang, T. Chou, and W. Yang, “Microstructural fabrication and design of sunlight guide panels of inorganic-organic hybrid material,” Energ. Buildings 43, 1011–1019 (2011).
[CrossRef]

2005

G. Walze, P. Nitz, J. Ell, A. Georg, A. Gombert, B. Bläsi, and W. Hoßfeld, “Combination of microstructures and optically functional coatings for solar control glazing,” Solar Energy Mater. Solar Cells 89, 233–248 (2005).
[CrossRef]

2004

W. J. M. van Bommel and G. J. van den Beld, “Lighting for work: a review of visual and biological effects,” Lighting Res. Technol. 36, 255–269 (2004).
[CrossRef]

Bläsi, B.

G. Walze, P. Nitz, J. Ell, A. Georg, A. Gombert, B. Bläsi, and W. Hoßfeld, “Combination of microstructures and optically functional coatings for solar control glazing,” Solar Energy Mater. Solar Cells 89, 233–248 (2005).
[CrossRef]

Chou, T.

H. Hocheng, T. Huang, T. Chou, and W. Yang, “Microstructural fabrication and design of sunlight guide panels of inorganic-organic hybrid material,” Energ. Buildings 43, 1011–1019 (2011).
[CrossRef]

Ell, J.

G. Walze, P. Nitz, J. Ell, A. Georg, A. Gombert, B. Bläsi, and W. Hoßfeld, “Combination of microstructures and optically functional coatings for solar control glazing,” Solar Energy Mater. Solar Cells 89, 233–248 (2005).
[CrossRef]

Emembolu, A.

H. F. O. Mueller, A. Emembolu, M. Oetzel, H. Schuster, and I. Soylu, “Sonnenschutz und Tageslicht in Büroräumen,” in Bauphysik-Kalender 2005, E. Cziesielski, ed. (Ernst & Sohn, 2005), pp. 397–439.

Georg, A.

G. Walze, P. Nitz, J. Ell, A. Georg, A. Gombert, B. Bläsi, and W. Hoßfeld, “Combination of microstructures and optically functional coatings for solar control glazing,” Solar Energy Mater. Solar Cells 89, 233–248 (2005).
[CrossRef]

Gombert, A.

G. Walze, P. Nitz, J. Ell, A. Georg, A. Gombert, B. Bläsi, and W. Hoßfeld, “Combination of microstructures and optically functional coatings for solar control glazing,” Solar Energy Mater. Solar Cells 89, 233–248 (2005).
[CrossRef]

Hocheng, H.

H. Hocheng, T. Huang, T. Chou, and W. Yang, “Microstructural fabrication and design of sunlight guide panels of inorganic-organic hybrid material,” Energ. Buildings 43, 1011–1019 (2011).
[CrossRef]

Hoßfeld, W.

G. Walze, P. Nitz, J. Ell, A. Georg, A. Gombert, B. Bläsi, and W. Hoßfeld, “Combination of microstructures and optically functional coatings for solar control glazing,” Solar Energy Mater. Solar Cells 89, 233–248 (2005).
[CrossRef]

Huang, T.

H. Hocheng, T. Huang, T. Chou, and W. Yang, “Microstructural fabrication and design of sunlight guide panels of inorganic-organic hybrid material,” Energ. Buildings 43, 1011–1019 (2011).
[CrossRef]

Mueller, H. F. O.

H. F. O. Mueller, A. Emembolu, M. Oetzel, H. Schuster, and I. Soylu, “Sonnenschutz und Tageslicht in Büroräumen,” in Bauphysik-Kalender 2005, E. Cziesielski, ed. (Ernst & Sohn, 2005), pp. 397–439.

Nitz, P.

G. Walze, P. Nitz, J. Ell, A. Georg, A. Gombert, B. Bläsi, and W. Hoßfeld, “Combination of microstructures and optically functional coatings for solar control glazing,” Solar Energy Mater. Solar Cells 89, 233–248 (2005).
[CrossRef]

Oetzel, M.

H. F. O. Mueller, A. Emembolu, M. Oetzel, H. Schuster, and I. Soylu, “Sonnenschutz und Tageslicht in Büroräumen,” in Bauphysik-Kalender 2005, E. Cziesielski, ed. (Ernst & Sohn, 2005), pp. 397–439.

Schuster, H.

H. F. O. Mueller, A. Emembolu, M. Oetzel, H. Schuster, and I. Soylu, “Sonnenschutz und Tageslicht in Büroräumen,” in Bauphysik-Kalender 2005, E. Cziesielski, ed. (Ernst & Sohn, 2005), pp. 397–439.

Soylu, I.

H. F. O. Mueller, A. Emembolu, M. Oetzel, H. Schuster, and I. Soylu, “Sonnenschutz und Tageslicht in Büroräumen,” in Bauphysik-Kalender 2005, E. Cziesielski, ed. (Ernst & Sohn, 2005), pp. 397–439.

van Bommel, W. J. M.

W. J. M. van Bommel and G. J. van den Beld, “Lighting for work: a review of visual and biological effects,” Lighting Res. Technol. 36, 255–269 (2004).
[CrossRef]

van den Beld, G. J.

W. J. M. van Bommel and G. J. van den Beld, “Lighting for work: a review of visual and biological effects,” Lighting Res. Technol. 36, 255–269 (2004).
[CrossRef]

Walze, G.

G. Walze, P. Nitz, J. Ell, A. Georg, A. Gombert, B. Bläsi, and W. Hoßfeld, “Combination of microstructures and optically functional coatings for solar control glazing,” Solar Energy Mater. Solar Cells 89, 233–248 (2005).
[CrossRef]

Yang, W.

H. Hocheng, T. Huang, T. Chou, and W. Yang, “Microstructural fabrication and design of sunlight guide panels of inorganic-organic hybrid material,” Energ. Buildings 43, 1011–1019 (2011).
[CrossRef]

Energ. Buildings

H. Hocheng, T. Huang, T. Chou, and W. Yang, “Microstructural fabrication and design of sunlight guide panels of inorganic-organic hybrid material,” Energ. Buildings 43, 1011–1019 (2011).
[CrossRef]

Lighting Res. Technol.

W. J. M. van Bommel and G. J. van den Beld, “Lighting for work: a review of visual and biological effects,” Lighting Res. Technol. 36, 255–269 (2004).
[CrossRef]

Solar Energy Mater. Solar Cells

G. Walze, P. Nitz, J. Ell, A. Georg, A. Gombert, B. Bläsi, and W. Hoßfeld, “Combination of microstructures and optically functional coatings for solar control glazing,” Solar Energy Mater. Solar Cells 89, 233–248 (2005).
[CrossRef]

Other

IEA International Energy Agency, “Daylight in buildings, a source book on daylighting and systems and components,” Report of IEA SHC Task 21 (International Energy Agency, 2000).

Saint-Gobain Glass, Product Information SGG LUMITOP, http://uk.saint-gobain-glass.com/upload/files/sgg_lumitop_.pdf .

H. F. O. Mueller, A. Emembolu, M. Oetzel, H. Schuster, and I. Soylu, “Sonnenschutz und Tageslicht in Büroräumen,” in Bauphysik-Kalender 2005, E. Cziesielski, ed. (Ernst & Sohn, 2005), pp. 397–439.

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Figures (12)

Fig. 1.
Fig. 1.

(a) Light-directing glasses are placed above eye level to establish a glare-free environment. (b) Cross section of LUMITOP and the presented microstructured system: the microstructured light-directing element is slimmer and less complex.

Fig. 2.
Fig. 2.

Light redirection by microprism arrays: diagram depicts the amount of light which is redirected in an upward direction as a function of the solar altitude. Prisms on the inner surface redirect light from high-solar altitudes (top left and solid graph) while sun-facing prisms are better suited for low-solar altitudes (bottom left, dotted graph).

Fig. 3.
Fig. 3.

Systems with microprism arrays on both surfaces may significantly change their performance due to small profile variances, e.g., by vertical shifts Δ.

Fig. 4.
Fig. 4.

(a) Microlenses at the sun-facing panel side spread the incident light widely and reduce the amount of sudden critical glare significantly. (b) Comparison between two daylighting configurations which only distinguish in panel thickness (2.8 and 4 mm between the structures). Coming below a critical minimum thickness will result in an oscillating redirection performance.

Fig. 5.
Fig. 5.

Influence of different refractive indices (PMMA n=1.49; PDMS n=1.41) on the redirection performances.

Fig. 6.
Fig. 6.

Cross sections of PDMS prototypes with structure dimensions of 250 µm.

Fig. 7.
Fig. 7.

Large-scale prototype with dimensions of 1500×400×4mm for implementation in windows/skylights.

Fig. 8.
Fig. 8.

(a) Principle of goniometrical measurements. (b) Diagram of redirection performance: Comparison between microstructured PDMS prototypes and a LUMITOP sample.

Fig. 9.
Fig. 9.

Demonstration of light redirection performance: light distribution without (a) and with inserted daylighting system (b).

Fig. 10.
Fig. 10.

(a) For solar altitudes of about 45° the redirection efficiency is decreased due to internal deflections. (b) By roughening the marked surface, the inner deflection is reduced due to light scattering.

Fig. 11.
Fig. 11.

(a) Measurement of light distribution after scattering at the roughened surface. (b) Light distribution for a surface roughness of about 900–1000 nm.

Fig. 12.
Fig. 12.

(a) Redirection efficiency of the basic system and the modified system. The modification leads to an increase in redirected light for solar altitudes of 40° to 65°. (b) Light distribution for light with a solar altitude of 30° (simulation results): Peaked graph is based on a system with straight bottom flats. The shaded graph corresponds to a modified system which uses curved geometries and a specifically applied roughness.

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