lighting simulation i
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Lighting Simulation I tính toánTRANSCRIPT
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
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
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
Sketch Up, FromZ,...Sketch Up, FromZ,...
EcotectEcotect
3ds file3ds file
Radtool (Radiance)Radtool (Radiance)
rad filerad file
Simulation Tools used in this Course
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 RadianceInstalled on all ARCH computers.
Desktop RadianceInstalled on all ARCH computers.
Sketch Up Download from www.sketchup.comLicense issue unfortunately still unresolved.
Sketch Up Download from www.sketchup.comLicense 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 RadianceDownload from LBNL web site (Windows or Mac).
Desktop RadianceDownload from LBNL web site (Windows or Mac).
More details under:
online courses >> Electrical Services – Lighting ARCH 447 >> 1.2 software
(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
• introduce some daylight performance metrics
• daylight factor calculations in Ecotect
• simulation models
• avoidance of direct sunlight
Objectives for this lecture
Daylight Performance Metrics
Review - Photometric QuantitiesCharacterize how a space is perceived.
Luminous Flux
LuminanceLuminous Intensity
Illuminance
Computer simulation: luminances and illuminances
Luminous Distribution, cd/m2
Luminance L (absolute brightness)
Photo
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
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 LightingCIE TC3-22 ‘Museum lighting and protection against radiation damage’
Review - Daylighting DefinitionsArchitectural definition: the interplay of natural light and building form to provide a visually stimulating, healthful, and productive interior environmentLighting Energy Savings definition: the replacement of indoor electric illumination needs by daylight, resulting in reduced annual energy consumption for lightingBuilding Energy Consumption definition: the use of fenestration systems and responsive electric lighting controls to reduce overall building energyrequirements (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
**
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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?
Daylight Factor Definition
E point
E outside horizontal
DF = (E point/E outside horizontal) * 100%
The DF is only defined under overcast skies!
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
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
Historical Background: “Right of Light”
Waldram 1945Waldram 1945
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%
Daylight Simulations in Ecotect
• 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
Ecotect Demo - Prepare a simple model, add a grid, start a simulation
CIE clear sky CIE overcast sky
Overcast sky: zenith to horizon 3-1
Sky Models: CIE Sky Model
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
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
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
SC = direct component
ERC = externally reflected component
IRC = internally reflected component
DF= SC + ERC + IRC
UK Building Research Establishment (BRE)Split Flux Method
Daylight Factor Protractors
SC
ERC
Square One web site
Square One web site
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
Square One web site
Points of Equal Sky Illuminance
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
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
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
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.
Split Flux Method in Ecotect
Summing up over ray contribution and comparing it against the total
unmodified illuminance gives the Daylight Factor.
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
Ecotect Demo – Open GL & parameter study
Daylight Factor – design implications window head height !!!!reference
glazing type !!!! narrow floor plan !!!!
Daylight Factor – design implications IIThe daylight factor optimized building is fully glazed.
Daylight Factor – design implications IIIDaylight 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.
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 devicelouvers, lightshelves etc. !!!!
Assign Shaded As… Save As Bitmap…Open GL …
Ecotect Demo – Shading Analysis & design of a simple lightshelf
Ecotect Demo - import a SketchUp file
Material Propertiesvisual transmittance: windows, skylights, lightshelves
reflectivity of internal surfaces
external elements site obstructions and applied shading devices
Material Properties – Opaque Surfaces
specular reflectance
diffuse reflectance
mixed reflectance
For a perfectly diffuse
surface (Lambert surface)
holds:
E.g. paper, drywall
πρEL =
Material Properties
Ecotect Demo – Electric Lighting
(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
Questions…Questions…