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Lighting simulation i

Sói Đồng Hoang

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Lighting simulation i

  1. 1. ARCH 447 Electrical Services - LightingARCH 447 Electrical Services - Lighting Christoph Reinhart, Ph.D.Christoph Reinhart, Ph.D. Oct 20: Lighting Simulation I - EcotectOct 20: Lighting Simulation I - Ecotect Shading analysisEcotect Daylight Factor analysis
  2. 2. 1 Sep 1 Vision and Color 2 Sep 8 History of Lighting 3 Sep 15 Electricity 4 Sep 22 Lamps 5 Sep 29 Field Trip – custom fixture manufacturing workshop tour 6 Oct 6 Building Simulation & Daylighting Principles 7 Oct 13 Fixtures & Introduction of Studio project 8 Oct 20 Lighting Simulation I – Ecotect 9 Oct 27 Lighting Simulation II – Radiance 10 Nov 3 Lighting Simulation III – Radiance 11 Nov 10 Midterm project critique and introduction of final project parameters 12 Nov 17 Field Trip – tour of Montreal architectural lighting installations 13 Nov 24 Daylighting Techniques 14 Dec 9 Final Project Critique Course Outline
  3. 3. Does the course web site work for everybody? (online courses >> Electrical Services – Lighting ARCH 447) Any questions on term project? Take attendance. Kristina Bondy & Daniel Juck: You should have access to ARCH software. Request SketchUp/Form Z. Demo will follow in this lecture for SketchUp. FormZ demo in drop-in lab. Square One shop closed until next Monday. Misc
  4. 4. Sketch Up, FromZ,...Sketch Up, FromZ,... EcotectEcotect 3ds file3ds file Radtool (Radiance)Radtool (Radiance) rad filerad file Simulation Tools used in this Course
  5. 5. Sketch Up Installed on all ARCH computers. Sketch Up Installed on all ARCH computers. Ecotect Installed on all ARCH computers. Site license, maximum number of five sessions at the same time. Ecotect Installed on all ARCH computers. Site license, maximum number of five sessions at the same time. Availability of Tools Desktop Radiance Installed on all ARCH computers. Desktop Radiance Installed on all ARCH computers.
  6. 6. Sketch Up Download from License issue unfortunately still unresolved. Sketch Up Download from License issue unfortunately still unresolved. Ecotect Download from Square One website. $US90 oer student licence (Windows only). Ecotect Download from Square One website. $US90 oer student licence (Windows only). Setting up your own computer (optional) Desktop Radiance Download from LBNL web site (Windows or Mac). Desktop Radiance Download from LBNL web site (Windows or Mac). More details under: online courses >> Electrical Services – Lighting ARCH 447 >> 1.2 software
  7. 7. (1) Installation Instructions on Course web site (2) Download from LBNL web site (3) Install preferably under “C:Radiance” (4) Set link in Ecotect Install Desktop Radiance on your PC
  8. 8. • introduce some daylight performance metrics • daylight factor calculations in Ecotect • simulation models • avoidance of direct sunlight Objectives for this lecture
  9. 9. Daylight Performance Metrics
  10. 10. Review - Photometric Quantities Characterize how a space is perceived. Luminous Flux Luminance Luminous Intensity Illuminance Computer simulation: luminances and illuminances
  11. 11. Luminous Distribution, cd/m2 Luminance L (absolute brightness) Photo
  12. 12. sunny summer day 70000 - 100000 lux cloudy summer day 20000 lux cloudy winter day 3000 lux requirement for reading 100 lux requirement for office work 300 - 800 lux Review - Typical Illuminance Values
  13. 13. category material classification example of materials lighting illuminance limiting annual exposure I insensitive metal, stone, glass, ceramic no limit no limit II low sensitivity canvases, frescos, wood, leather 200 lux 600 000 lux h /yr III medium sensitivity watercolor, pastel, various paper 50 lux 150 000 lux h/yr IV high sensitivity silk, newspaper, sensitive pigments 50 lux 15 000 lux h/yr Museum Lighting CIE TC3-22 ‘Museum lighting and protection against radiation damage’
  14. 14. Review - Daylighting Definitions Architectural definition: the interplay of natural light and building form to provide a visually stimulating, healthful, and productive interior environment Lighting Energy Savings definition: the replacement of indoor electric illumination needs by daylight, resulting in reduced annual energy consumption for lighting Building Energy Consumption definition: the use of fenestration systems and responsive electric lighting controls to reduce overall building energy requirements (heating, cooling, lighting) Load Management definition: dynamic control of fenestration and lighting to manage and control building peak electric demand and load shape Cost definition: the use of daylighting strategies to minimize operating costs and maximize output, sales, or productivity ** *
  15. 15. Green Building Rating Systems I LEED and Green Globe provide daylight credits for: ! daylight factor ! view to the outside ! specification of shading devices (Green Globe only) Compliance is verified via spreadsheet method. Do daylight factor & view LEED to good daylighting?
  16. 16. Daylight Factor Definition E point E outside horizontal DF = (E point/E outside horizontal) * 100% The DF is only defined under overcast skies!
  17. 17. Credit 8.1 Daylight 75% of Spaces 1 Credit • Archive a minimum Daylight factor of 2% (excluding all direct sunlight penetration) in 75% of all space occupied for critical visual tasks. Spaces excluded from this requirement include copy rooms, storage areas, mechanical plant rooms, laundry and other low occupancy support areas. Other explanations for spaces where tasks would be hindered by the use of daylight will be considered on their merits. Green Building Rating Systems II
  18. 18. Credit 8.2 Views for 90% of Spaces 1 Credit • Achieve direct line of sight to vision glazing for building occupants in 90% of all regularly occupied spaces. Examples for exceptions copy rooms, storage areas, mechanical, laundry and other low occupancy support areas. Other exemptions will be considered on their merits. Green Building Rating Systems III
  19. 19. Historical Background: “Right of Light” Waldram 1945Waldram 1945
  20. 20. Daylight Factor Use in Design Pro: ! intuitive quantity ! overcast sky as a worst case scenario ! venetian blinds (even if closed) still admit sufficient DL 7% 3,5% 0%
  21. 21. Daylight Simulations in Ecotect
  22. 22. • Performance Metrics (daylight factor, avoidance of direct sunlight) • Building Model • Area of Interest (analysis grid) • Sky Model • Simulation Model • Material Properties Elements needed for a DL Simulation
  23. 23. Ecotect Demo - Prepare a simple model, add a grid, start a simulation
  24. 24. CIE clear sky CIE overcast sky Overcast sky: zenith to horizon 3-1 Sky Models: CIE Sky Model
  25. 25. Square One web site Design Sky values are derived from a statistical analysis of outdoor illuminance levels. They represent a horizontal illuminance level that is exceeded 85% of the time between the hours of 9am and 5pm throughout the working year. Thus they also represent a worst-case scenario that you can design to and be sure your building will meet the desired light levels at least 85% of the time. Limitation in Ecotect. Climate files are not used by lighting simulation. Design Sky Values
  26. 26. Average Daylight Factor (spread sheet method, similar to IESNA method) Original Split Flux Method (Daylight Factor Protractors) Points of Equal Sky Illuminance Split Flux Method in Ecotect Daylight Factor Calculation Methods
  27. 27. W = The area of each window (m²), ττττ = Transmittance of each glazing material θθθθ = Vertical angle of the sky as seen from the centre of each window m = Maintenance factor based on angle of glazing and the cleanliness of its environment (0.5 – 0.9), A = Total internal surface area of the space, including walls, floors, ceilings and windows (m²), R 2= Area weighted average reflectance of all surfaces making up A, (use 0.1 as reflectance for glass). Average Daylight Factor Calculation
  28. 28. SC = direct component ERC = externally reflected component IRC = internally reflected component DF= SC + ERC + IRC UK Building Research Establishment (BRE) Split Flux Method
  29. 29. Daylight Factor Protractors SC ERC Square One web site
  30. 30. Square One web site
  31. 31. DF = SC + ERC + IRC = 1.52% + 0.0456% + 1.7586% = 3.324 % In Montreal: Design sky = 7215 Lux Light Level = 7215 Lux x 3.324% = 240 Lux
  32. 32. Square One web site Points of Equal Sky Illuminance
  33. 33. Square One web site A geometric version of the Split Flux Method (BRE) Raytracing: each ray represents an approximately equal solid angle of sky Split Flux Method in Ecotect
  34. 34. Split Flux Method in Ecotect Square One web site A Sky Component (SC) is modified by: • relative sky illuminance of that particular sky patch •relative angle of sky patch makes with a horizontal surface •visible transmittance of each glazing material through which it travels
  35. 35. Split Flux Method in Ecotect Square One web site An Externally Reflected Component (ERC) is modified by: • luminance of the sky it would have hit • reflectance of the material assigned to the external object • relative surface angle and glazing transmittances
  36. 36. Split Flux Method in Ecotect Square One web site An Internally Reflected Component (IRC) is modified by: • store internal surface reflectance of the object • altitude angle of the ray is used to determine which parts of the IRC formula the ray contributes to.
  37. 37. Split Flux Method in Ecotect Summing up over ray contribution and comparing it against the total unmodified illuminance gives the Daylight Factor.
  38. 38. BRE Daylight Factor method uses a relatively simple formula for the effect of internal reflections. To be fully compliant with this method, Ecotect cannot consider multiple reflections. Therefore, Ecotect underestimates indirect daylight solutions that rely on the reflection of light off multiple surfaces to illuminate a space. Limitations of the sky model (Ecotect does not use annual climate file data for daylighting). Limitations of the Ecotect Approach
  39. 39. Ecotect Demo – Open GL & parameter study
  40. 40. Daylight Factor – design implications window head height !!!!reference glazing type !!!! narrow floor plan !!!!
  41. 41. Daylight Factor – design implications II The daylight factor optimized building is fully glazed.
  42. 42. Daylight Factor – design implications III Daylight factor does not take glare or solar gain control into account. The consequence of too large glazings: The blinds are closed most of the time.
  43. 43. Avoidance of Direct Sunlight Avoidance during cooling period (often assumed to be Apr 1st to Oct 1st) or according to climate file. For Montreal: May 1st to Oct 1st. Resulting building design form is improved from an energy standpoint. optimized for static shading device louvers, lightshelves etc. !!!!
  44. 44. Assign Shaded As… Save As Bitmap… Open GL … Ecotect Demo – Shading Analysis & design of a simple lightshelf
  45. 45. Ecotect Demo - import a SketchUp file
  46. 46. Material Properties visual transmittance: windows, skylights, lightshelves reflectivity of internal surfaces external elements site obstructions and applied shading devices
  47. 47. Material Properties – Opaque Surfaces specular reflectance diffuse reflectance mixed reflectance For a perfectly diffuse surface (Lambert surface) holds: E.g. paper, drywall π ρE L =
  48. 48. Material Properties
  49. 49. Ecotect Demo – Electric Lighting
  50. 50. (1) Submit your project proposals. (2) Carry out a daylight factor and avoidance of direct sunlight analysis in an office building of your choice. Required minimum illuminance level: 300 lux. Avoid direct sunlight from Apr 1st to Oct 1st. Assignments for next week
  51. 51. Questions…Questions…