+    Daylighting Environment in    Hong Kong    By Dr Ernest K W TSANG    Sustainability Consultant, Parsons Brinckerhoff
+                                                               2AgendaWhy Daylight?Parameters affecting Indoor Daylightin...
+                                        Improves Circadian Photobiological                                          Acti...
+    Parameters affecting Indoor    Daylighting Environment    A Snap Shot Study on 35 Buildings from 1960s to mid 2000.  ...
+                                       5    Key Parameters       Building Area and Orientation       Glass Type       ...
6+ Building Area and  Orientation  Effect – Increasing Internal Area reduces the  Daylight Factor (DF)  Building Area vari...
7+    Glass Type    Effect – Visible Transmittance of    Glass affects the DF directly    Major Glazing include Clear, Tin...
+                8    Glass Type
+                                                                  9    Window Area       Effect                         ...
+    Shading were found       for Buildings     completed before     mid-80s and after          late 90s                  ...
+                                                                       11    External Obstruction       Effect          ...
Daylighting Performances of+ Commercial Building in Hong  Kong  A study of Two Commercial Buildings by Simulation         ...
+                                Two Buildings were selected for Detail   13                                  Analysis   ...
+                                         14    The CIE Standard Overcast Sky       General Equation of Overcast        s...
+                                                                    15    Daylight Glare Index (DGI)       Glare from Wi...
+                                          16    Building A        Plan of Building   Model Details
+                               17    Building A - South-facing
+                              18    Building A - West-facing
+                               19    Building A - North-facing
+                                                                   20    Building A – DGI    Orientation                 ...
+                                          21    Building B        Plan of Building   Model Details
+                                   22    Building B - Northeast-facing
+                                   23    Building B - Southeast-facing
+                                   24    Building B - Southwest-facing
+                                   25    Building B - Northwest-facing
+                                                                   26    Building B – DGI    Orientation                 ...
+ Daylighting Assessment Criteria  for Green Buildings  Different Daylight Assessment Criteria                            ...
Green Buildings+                                       28    Commonly used Assessment Criteria       PNAP       LEED    ...
+                                                                         29    PNAP APP-130 Lighting and Ventilation    R...
+                                                                         30    BEAM Plus       1 Credit where at least 8...
+                                                                                 31    LEED 2.2       Option 1 – Glazing...
+                                                                                   32    LEED 2009       Option 1 – Simu...
+                                                                        33    LEED 2012 (based on draft 3)       Provide...
34+    Are We Ready for the New Version?    Parsons Brinckerhoff’s Approach
+                                                                          35    Which Option are we    recommended?     ...
+                     36Option 1Terms and Criteria
+                                                                       37    Spatial Daylight Autonomy    “The % of Aggre...
+                                                                          38    Criteria       achieve Daylight Autonomy...
+                                                              39    Problems Ahead       Weather Data           TMY doe...
+                                                                              40    Weather Data       Sun and Sky Illum...
+                                   41    Daylight Coefficient Approach
+                                                               42    Simulation method                 Indirect Sun      ...
+                                  43    Questions    & Answer                Thank you                28th March 2012
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20120328 Technical Seminar on Daylighting Environment in Hong Kong

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20120328 Technical Seminar on Daylighting Environment in Hong Kong

  1. 1. + Daylighting Environment in Hong Kong By Dr Ernest K W TSANG Sustainability Consultant, Parsons Brinckerhoff
  2. 2. + 2AgendaWhy Daylight?Parameters affecting Indoor Daylighting EnvironmentDaylighting Performances of Commercial Building in Hong KongDaylighting Assessment Criteria for Green Buildings
  3. 3. +  Improves Circadian Photobiological Activation  Prevents Sick Building Syndrome  Enhances the Phase Synchronising Ability of Light  Has Positive Effects on Sociability and Hormone Patterns  Provides Energy Saving OpportunitiesWhy Daylight?“On studying the Causes and Motivesof Nature, the Observer isFascinated, above all, by Light.” –Leonardo da VINCI
  4. 4. + Parameters affecting Indoor Daylighting Environment A Snap Shot Study on 35 Buildings from 1960s to mid 2000. 4
  5. 5. + 5 Key Parameters  Building Area and Orientation  Glass Type  Window Area  Shading  External Obstruction
  6. 6. 6+ Building Area and Orientation Effect – Increasing Internal Area reduces the Daylight Factor (DF) Building Area varies No Strong Orientation Effect
  7. 7. 7+ Glass Type Effect – Visible Transmittance of Glass affects the DF directly Major Glazing include Clear, Tinted, Reflective and Low-e Trend is observed for the Selection of Glazing during the Past Five decades
  8. 8. + 8 Glass Type
  9. 9. + 9 Window Area  Effect Glazing Type WWR  Amount of Natural Light Clear 36.4% admits into Building Directly Tinted 42.0% Proportional to Window Area Reflective 44.0%  Window Area are expressed in Low-E 46.5% Window to Wall Ratio (WWR)
  10. 10. + Shading were found for Buildings completed before mid-80s and after late 90s Shading Shade Window from Direct Sunlight Penetration but allows Diffuse Skylight to admit 10
  11. 11. + 11 External Obstruction  Effect Obstruction Percentage  Obstructs Part of Sky Angle (θb) (%)  Reflects Skylight and Sunlight θb≤30° 25 30° <θb ≤ 60° 45 60°<θb ≤ 80°  Most of the External Finishing 30 are with Light to Medium Colour
  12. 12. Daylighting Performances of+ Commercial Building in Hong Kong A study of Two Commercial Buildings by Simulation 12
  13. 13. +  Two Buildings were selected for Detail 13 Analysis  Daylighting Analysis was Conducted using RADIANCE  The CIE Standard Overcast Sky was selected for Simulation StudyDaylightingPerformances of  The following three performances wereCommercial Building in analysisHong Kong  Indoor Illuminance  Daylight Glare Index  Annual Lighting Energy Projection 13
  14. 14. + 14 The CIE Standard Overcast Sky  General Equation of Overcast sky is shown as below:  The Luminance at Zenith is 3 Times of That for the Horizon  Independent with Solar Position
  15. 15. + 15 Daylight Glare Index (DGI)  Glare from Windows can arise from Excessive Contrast between the Luminance of the Visible Sky and the Luminance of the Internal Surfaces within the Field of View.  Threshold DGI of 22
  16. 16. + 16 Building A Plan of Building Model Details
  17. 17. + 17 Building A - South-facing
  18. 18. + 18 Building A - West-facing
  19. 19. + 19 Building A - North-facing
  20. 20. + 20 Building A – DGI Orientation Daylight Glare Index Lowest Floor Middle Floor Highest Floor North 14.0 16.3 19.1 South 13.8 18.5 19.0 West 10.9 16.4 17.0
  21. 21. + 21 Building B Plan of Building Model Details
  22. 22. + 22 Building B - Northeast-facing
  23. 23. + 23 Building B - Southeast-facing
  24. 24. + 24 Building B - Southwest-facing
  25. 25. + 25 Building B - Northwest-facing
  26. 26. + 26 Building B – DGI Orientation Daylight Glare Index Lowest Floor Middle Floor Highest Floor Northeast 19.6 18.6 19.4 Southeast 16.1 16.7 17.8 Southwest 17.6 15.9 17.5
  27. 27. + Daylighting Assessment Criteria for Green Buildings Different Daylight Assessment Criteria 27
  28. 28. Green Buildings+ 28 Commonly used Assessment Criteria  PNAP  LEED  BEAM Plus
  29. 29. + 29 PNAP APP-130 Lighting and Ventilation Requirements – Performance-based Approach  Vertical Daylight factor: 8% for Habitable Room; 4% for Kitchen  Assume the window area is 10% of the usable floor area.  Under the standard CIE Overcast sky condition
  30. 30. + 30 BEAM Plus  1 Credit where at least 80% of Floor Area in all Normally Occupied Spaces is adequately lit with an Average Daylight Factor of 2% or more.  1 Credit where provision of Suitable Daylight Glare Control and Maintaining the Average Daylight Factor of 2%.  -> the CIE standard Overcast Sky
  31. 31. + 31 LEED 2.2  Option 1 – Glazing factor Calculation  Achieve a min Glazing Factor of 2% in a minimum of 75% of all Regularly Occupied Areas.  Option 2 – Daylight Simulation Model  Min Daylight Illuminance level of 25fc achieved in a min 75 %of all Regularly Occupied Areas.  The CIE Standard Clear Sky in noon of Equinox  Option 3 – Daylight Measurement  Option 4 - Prescriptive
  32. 32. + 32 LEED 2009  Option 1 – Simulation  75% or more regularly Occupied Space achieve daylight illuminance levels of a min. of 25 fc and a max 500fc in a clear sky condition on 21 September 9:00 and 15:00  Option 2 – Prescriptive  Option 3 – Measurement  Option 4 – Combination
  33. 33. + 33 LEED 2012 (based on draft 3)  Provide manual or automatic glare devices for all regularly occupied spaces  Option 1 – through Annual Computer Simulations, achieve Daylight Autonomy value of 55% (2 points) or 75% (3 points) regularly occupied spaces.  Option 2 – Using a model, achieve required illuminance levels for 75% (1 point) or 90% (2 points) regularly occupied spaces  Option 3 – Using direct measurements, achieve required illuminance levels for 75% (1 point) regularly occupied spaces
  34. 34. 34+ Are We Ready for the New Version? Parsons Brinckerhoff’s Approach
  35. 35. + 35 Which Option are we recommended?  Option 2 is recommended.  Only two different sets ofSimulation  Similar to LEED 2009 Option 1 with followingRefinements:  1. Standardise outdoor illuminance levels from Typical Meteorological Year (TMY)  The AVERAGE of the Two Time Slots  Reflectance (Ceiling 0.8; Floor 0.2; Wall 0.5)  No Furniture layout is required  What are still unclear?  How to calculate Illuminance for Sun and Sky Components?
  36. 36. + 36Option 1Terms and Criteria
  37. 37. + 37 Spatial Daylight Autonomy “The % of Aggregate Floor Area of Regularly Occupied Spaces which achieves a minimum highly Illuminance value of 300 lux at task level for at least 50% of the hours between 8am to 6pm, Local Clock Time, after accounting for Typical Weather Conditions, Exterior Obstructions, Attached Furniture Systems and after Blinds have been operated hourly to block direct sun predicted to enter the space that would fall on more than 2% of the calculation grid.”
  38. 38. + 38 Criteria  achieve Daylight Autonomy value of 55% (2 points) or 75% (3 points) regularly occupied spaces.  No more than 10% of any qualifying daylight space could receive direct sunlight for more than 250 hours per year at task level before operable blinds or shades are deployed and after accounting for exterior obstruction, typical weather, and attached furniture system
  39. 39. + 39 Problems Ahead  Weather Data  TMY does not include any Illuminance Information  No Sky Distribution Pattern is Defined  Simulation Time  Over 3,650 sets Simulation  How to predict Direct Sun/Shadowing?
  40. 40. + 40 Weather Data  Sun and Sky Illuminance values  Illuminance Data would be calculated from Irradiance Data of TMY  Sky Luminance Distribution Data  Based on ASRC-CIE Model/Perez’s sky Model  Based on the latest the CIE Standard Skies
  41. 41. + 41 Daylight Coefficient Approach
  42. 42. + 42 Simulation method Indirect Sun Component Direct Sky (145 or 580 Component sets (aimed ray) simulation) Direct Sun Indirect Sky Component (by Component neglectable (145 or 580 time for sets simulation) Overall simulation) Illuminance Level
  43. 43. + 43 Questions & Answer Thank you 28th March 2012

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