Energy-efficient Daylighting Systems for Multi-story Buildings

International Conference on Modeling and Simulation 2013

Irfan Ullah Department of Information and Communication Engineering Myongji university, Yongin, South Korea

Copyright © solarlits.com

Energy and Buildings, vol. 72, pp. 246-261, 2014. http://dx.doi.org/10.1016/j.enbuild.2013.12.031

Contents

1. Introduction2. Objective3. Background4. Proposed system

a) Parabolic troughb) Linear Fresnel lens

5. Light transmission and distribution6. Simulation and results7. Conclusions and Future Work

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• Energy consumption• In South Korea, 46% of total energy is used in buildings (EIA 2007)• In buildings, 40–50% of total energy is consumed for electric lighting

Introduction

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CO2 emissions by regionInternation energy agency (IEA), 2009

IEA annual energy reviews, 2011

Introduction

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Annual energy outlook 2011 (EIA, U.S.)

• Artificial lighting cannot fulfill the needs of the human body• Required Vitamin D3 (Ultraviolet light)• 15% of office workers complain of eye strain

• Daylight improves • Patient recovery• Worker productivity

• Daylight can reduce• Seasonal affective disorder (SAD)

Benefits of daylight

Wavelength (nm)Electromagnetic spectrum4/27

Daylighting

• Daylighting• To illuminate interior by sunlight• Daylighting system (active and passive)• Capturing (reflectors and lenses)• Transmission (light pipe and optical fiber)• Distribution (lenses and diffusers)• Hybrid daylighting system• Daylight + Artificial light

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“Daylight building can reduce electric lighting energy consumption by 50–80%” (U.S. Green Building Council)

Overview of daylighting

Background

Microstructured daylighting system

• Sunlight transmission through• Window• Low-efficiency• Difficult to implement

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Background

Tabular guidance system Core daylighting system

• Sunlight transmission through• Light pipe and light guide• Low-efficiency• Nonuniform illumination

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Prismatic light guide

Background

Himawari daylighting system Parans fiber optic daylighting system

• Sunlight transmission through• Optical fiber• Costly (large amount of modules)

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Objective

• Highly concentrated sunlight through• Parabolic trough• Linear Fresnel lens

• Delivering sunlight in the interior• Large-scale building interiors• Multi-floor buildings

• Uniform illumination at• Capturing stage• Distribution stage

• Reducing electric lighting power consumption in buildings

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Parabolic trough

Linear Fresnel lens

Proposed System

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Flow diagram of the hybrid daylighting system

Compound parabolic concentrator (CPC)

Hardware design of daylighting systems

Design using CPC for the parabolic trough

Design using CPC for the linear Fresnel lens

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Light concentration

Non-imaging concentratorCompound parabolic concentrator (CPC)

Ray-tracing of daylighting systems

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Parabolic trough with parabolic reflector to make collimated light for optical fibers

Linear Fresnel lens with plano-concave lens to make collimated light for optical fibers

Measurements for Parabolic trough

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With trough CPCWithout trough CPC a : Diameter of entry aperture

a' : Diameter of exit aperture

θi : Maximum input angle

HPR : Rectangular aperture height

Wr : Width of receiver

To make collimated light

Measurements for linear Fresnel lens

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With trough CPCWithout trough CPC

Wp : Width of plano-concave lens

Wr : Width of receiver

r : Radius

n : Refractive index

NA : Numerical aperture

D: Diameter of collimating lens

f: focal length of the lens

Focal length of Fresnel lens

To insert all light into fibers

Light Transmission

• Area of each floor = 10x6 m• Silica optical fiber (SOF)• Length of single SOF = 130 mm• Plastic optical fiber (POF)• Length of single POF = 6 m• Total fiber = 285

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Optical fibers with index matching

2 mm

1.98 mm POF SOF 1.457 mm

1.8 mm

SOFncladding = 1.40ncore = 1.457

POFncladding = 1.40ncore = 1.49

Refractive index

Efficiency of POF = 80% for 6m length

Light Distribution

• One bundle = 19 optical fibers• Light distribution• Biconcave lens• Combination of lenses

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Single lens

Combining two lensesBundle of optical fibers

Economics

• Cost of parabolic trough = $400• Cost of linear Fresnel lens = $200• Cost of tracking modules = $400

• Total optical fibers = 285• Total length of SOF = 33.28 m• Cost of SOF = $1.2/m• Total cost of SOFs = $ 44

• Total length of POF = 1330 m• Cost of POF = $0.514/m• Total cost of POFs = $ 684

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Interior view

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Floor plan of test room

• 15 bundles of optical fibers• 15 LED light sources

Section view of room’s interior

Daylighting simulation

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Light source and surface to measure illuminance

• Daylighting simulation• LightTools®, DIALuxTM, and SolidWorksTM

• Illuminance on the surface

Outdoor average illuminance

dS : Surface areadF : Luminus flux on the surface

Illuminance (lx)

Uniform illumination

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• Uniform illumination into optical fibers

Parabolic trough

Linear Fresnel lensCandle power distribution curveEncircled energy of fiber bundle

Illuminance on work plane

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Daylight illuminance distribution on the work plane for (a) parabolic trough and (b) linear Fresnel lens

(a) (b)

Interior View

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Indoor lighting simulationDaylight distribution in the interior

Illuminance and Uniformity

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Daylight average illuminance on the work plane

Uniformity on the floor

Uniformity on the work plane

Hybrid daylighting system

• LED light• OSRAMTM LW-W5AM, 130 lm/W• 26 LEDS with a reflector • Achieving illuminance of 500 lx all times

24/27LEDs with parabolic reflector

LEDs’ illuminance distribution

Hybrid daylighting system

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Daylight and LEDs’ illuminance distribution

Conclusions

• Highly concentrated light• Parabolic trough • Linear Fresnel lens

• Solution of high concentration by CPC• Uniform illumination into optical fibers• Illumiated large-scale building interior• Multi-floor buildings

• Increased light quality• Illuminance of more than 500 lx all time• Can save about 40% energy

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Future work

• Installing system for multi-floor building• Transmitting light at long distance

• Optical fiber • Light pipe

• Integrated solar cells

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Parabolic trough Linear Fresnel lens

References

1. A. Rosemann, G. Cox, P. Friedel, M. Mossman, and L. Whitehead, “Cost-effective controlled illumination using daylighting and electric lighting in a dual-function prism light guide,” Light. Res. Tech. 40, 77-88 (2008).

2. C. Tsuei, W. Sun, and C. Kuo, “Hybrid sunlight/LED illumination and renewable solar energy saving concepts for indoor lighting,” Opt. Express 18, A640-A653 (2010).

3. V. E. Gilmore, “Sun flower over Tokyo,” Popular Science, Bonnier Corporation, America, 1988.

4. D. Feuermann, J. M. Gordon, “SOLAR FIBER-OPTIC MINI-DISHES: A NEW APPROACH TO THE EFFICIENT COLLECTION OF SUNLIGHT,” Sol. Energy. 65, 159-170 (1999).

5. D. Feuermann, J. M. Gordon, M. Huleihil, “Solar fiber-optic mini-dish concentrators: first experimental results and field experience,” Sol. Energy. 72, 459-472 (2002).

6. A. Kribus, O. Zik, J. Karni, “Optical fibers and solar power generation,” Sol. Energy. 68, 405-416 (2000).

7. C. Kandilli and K. Ulgen, “Review and modelling the systems of transmission concentrated solar energy via optical fibres,” Renewable and Sustainable Energy Reviews, 13, 67-84 (2009).

8. I. Ullah and S. Shin, “Development of Optical Fiber-Based Daylighting System with Uniform Illumination,” J. Opt. Soc. Korea 16, 247-255 (2012).

9. I. Ullah and S. Shin, "Uniformly Illuminated Efficient Daylighting System," Smart Grid and Renewable Energy, Vol. 4, No. 2, pp. 161-166 (2013).

Irfan UllahDept. of Info. and Comm. EngineeringMyongji University, Yongin, South KoreaEmail: irfan@mju.ac.krHomepage: sl.avouch.org

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