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 ,

Contents 1.Introduction 2.Objective 3.Background 4.Proposed system a)Parabolic trough b)Linear Fresnel lens 5.Light transmission and distribution 6.Simulation and results 7.Conclusions and Future Work 1/27

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 2/27 CO 2 emissions by region Internation energy agency (IEA), 2009 IEA annual energy reviews, 2011

Introduction 3/27 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 spectrum 4/27

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 5/27 “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 6/27

Background Tabular guidance systemCore daylighting system Sunlight transmission through Light pipe and light guide Low-efficiency Nonuniform illumination 7/27 Prismatic light guide

Background Himawari daylighting system Parans fiber optic daylighting system Sunlight transmission through Optical fiber Costly (large amount of modules) 8/27

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 9/27 Parabolic trough Linear Fresnel lens

Proposed System 10/27 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 11/27 Light concentration Non-imaging concentrator Compound parabolic concentrator (CPC)

Ray-tracing of daylighting systems 12/27 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 13/27 With trough CPC Without trough CPC a : Diameter of entry aperture a' : Diameter of exit aperture θ i : Maximum input angle H PR : Rectangular aperture height W r : Width of receiver To make collimated light

Measurements for linear Fresnel lens 14/27 With trough CPCWithout trough CPC W p : Width of plano-concave lens W r : 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 = /27 Optical fibers with index matching 2 mm 1.98 mm POF SOF mm 1.8 mm SOF n cladding = 1.40 n core = POF n cladding = 1.40 n core = 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 16/27 Single lens Combining two lenses Bundle 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 = 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 = $ /27

Interior view 18/27 Floor plan of test room 15 bundles of optical fibers 15 LED light sources Section view of room’s interior

Daylighting simulation 19/27 Light source and surface to measure illuminance Daylighting simulation LightTools®, DIALux TM, and SolidWorks TM Illuminance on the surface Outdoor average illuminance dS : Surface area dF : Luminus flux on the surface Illuminance (lx)

Uniform illumination 20/27 Uniform illumination into optical fibers Parabolic trough Linear Fresnel lens Candle power distribution curveEncircled energy of fiber bundle

Illuminance on work plane 21/27 Daylight illuminance distribution on the work plane for (a) parabolic trough and (b) linear Fresnel lens (a)(b)

Interior View 22/27 Indoor lighting simulation Daylight distribution in the interior

Illuminance and Uniformity 23/27 Daylight average illuminance on the work plane Uniformity on the floor Uniformity on the work plane

Hybrid daylighting system LED light OSRAM TM LW-W5AM, 130 lm/W 26 LEDS with a reflector Achieving illuminance of 500 lx all times 24/27 LEDs with parabolic reflector LEDs’ illuminance distribution

Hybrid daylighting system 25/27 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 26/27

Future work Installing system for multi-floor building Transmitting light at long distance Optical fiber Light pipe Integrated solar cells 27/27 Parabolic troughLinear Fresnel lens

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Irfan Ullah Dept. of Info. and Comm. Engineering Myongji University, Yongin, South Korea Homepage: sl.avouch.org Discussion