A1259827207rIPTl

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Automated Calculation of Lighting
Regulations Y.C. Huang and K.P.
Lam Center for Building Performance and
Diagnostics Pittsburgh, Pennsylvania
14 July 2008 COBEE (Dalian, China)
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Context and Motivation Performance benchmarks in
building design 1. Benefits of performance-based
design and performance benchmarks - High
performance buildings (integration,
sustainability) - Vision, goals, objectives,
tracking, assessments - Lindsey, 2003
Hitchcock, 2003 Deru, 2004 2. Lighting
regulations (standards) as performance
benchmarks - Fundamental (ir)radiance
calculations might not provide operative
information - Lighting regulations (standards)
as performance benchmarks - Logistical effort in
acquiring parameters - Time and effort in
calculation procedures 3. Automated calculation
of lighting regulations - Dual purposes
reduction in calculation and documentation
effort - Market demand - Prevalence of BIM,
opportunity for automation - Need to formulate
calculation procedures as computable
Automated Calculation of Lighting Regulations
Y.C. Huang
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Context and Motivation Performance benchmarks in
building design 1. Benefits of performance-based
design and performance benchmarks - High
performance buildings (integration,
sustainability) - Vision, goals, objectives,
tracking, assessments - Lindsey, 2003
Hitchcock, 2003 Deru, 2004
Automated Calculation of Lighting Regulations
Y.C. Huang
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Context and Motivation Performance benchmarks in
building design 2. Lighting regulations
(standards) as performance benchmarks -
Fundamental (ir)radiance calculations might not
provide operative information
Lighting simulations address low-level
objectives, not higher-level questions typical of
primary design inquiries.
Automated Calculation of Lighting Regulations
Y.C. Huang
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Context and Motivation Performance benchmarks in
building design 2. Lighting regulations
(standards) as performance benchmarks -
Fundamental (ir)radiance calculations might not
provide operative information - Lighting
regulations (standards) as performance benchmarks

• USGBC LEED Rating System
• EQ 8.1 8.2 Daylight and Views
• Provide for the building occupants a connection
  between indoor spaces and the outdoors through
  the introduction of daylight and views into the
  regularly occupied areas of the building.
• EQ 8.1 (Opt 1) Achieve a minimum glazing factor
  of 2 in a minimum of 75 of all regularly
  occupied areas
• EQ 8.2 Achieve direct line of sight to the
  outdoor environment via vision glazing between
  26 and 76 above finish floor for building
  occupants in 90 of all regularly occupied areas.
• Voluntary rating system
• Widespread use by both governmental and private
  industry (Landman, 2005)
• 2 lighting performance benchmarks

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Context and Motivation Performance benchmarks in
building design 2. Lighting regulations
(standards) as performance benchmarks -
Fundamental (ir)radiance calculations might not
provide operative information - Lighting
regulations (standards) as performance
benchmarks - Logistical effort in acquiring
parameters - Time and effort in calculation
procedures
Automated Calculation of Lighting Regulations
Y.C. Huang
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Context and Motivation Performance benchmarks in
building design 3. Automated calculation of
lighting regulations - Dual purposes reduction
in calculation and documentation effort - Market
demand - Prevalence of BIM, opportunity for
automation - Need to formulate calculation
procedures as computable
Automated Calculation of Lighting Regulations
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Objectives Integration with Design Support
Tool Availability of benchmarks throughout
design process Reduction of time and
effort Formulation of benchmarks as
computable Formulation of calculation procedures
as computable problems that can be evaluated by a
computer automatically Resources required must be
within the constraints of typical design
practices Improvements Formulation of
procedures as algorithms allows insight into
benchmarks, and how they might be improved
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Objectives Integration with Design Support
Tool Availability of benchmarks throughout
design process - Fast, automated calculations -
(Design) Performance metrics, performance
indicators and tracking Design support tool
reduces time and effort - Reduce manpower,
training and computational resources - Eliminate
time-consuming and error-prone manual
processes - Interoperability of parameters and
information Formulation of benchmarks as
computable Formulation of calculation procedures
as computable problems that can be evaluated by a
computer automatically Resources required must be
within the constraints of typical design
practices - Additional user interventions should
be kept to a minimum, - Highly specialized or
tacit knowledge requirements for operation should
be avoided - Hardware requirements must be
affordable - Entire process must be completed
within minutes if not seconds Improvements Formu
lation of procedures as algorithms allows insight
into benchmarks, and how they might be improved
Automated Calculation of Lighting Regulations
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Framework CMU Lighting simulation Tool Version
0.5 Java based application ease of
prototyping General Parser Revit-exported gbXML
files extended XML schema Radiance engine
integration automatic simulation files
generator External Libraries Location
Construction complete, rule based context
recognition Visualizations HDRI support,
False-color, Inspector, Comparator, Luminance
Ratios Post-processing LEED Credit EQ 8.1 8.2
calculators and tabulations
Step 2 Missing information such as sky data and
camera positions are set automatically
Step 1 User selects input file (as exported
from Revit)
Step 3 Default values are highlighted in red.
User can edit values if necessary
Prototype of 2007 CMU Lighting Application v.0.5.
The 3-step process to saving time.
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Framework Reduce resources required to conduct
lighting simulation Integrated tool part of
effort (and tool) to reduce resources Benefits of
LEED automation tracking performance during
design iterations, documentation effort
LEED Credit EQ 8.1. Glazing Factors
Revit Model
Material Properties Inspection and Editing
LEED Credit EQ 8.2. View-out Availability
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Framework CMU Lighting simulation Tool Version
0.5 Integrated tool part of effort (and tool)
to reduce effort resources Benefits of LEED
automation tracking performance during design
iterations, documentation effort
LEED Credit EQ 8.1. Glazing Factors
Revit Model
Material Properties Inspection and Editing
LEED Credit EQ 8.2. View-out Availability
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Formulation as Computable LEED EQ 8.1 (Opt 1)
Daylight Availability Achieve a minimum glazing
factor of 2 in a minimum of 75 of all regularly
occupied areas Mainly logistical task, variable
values retrieved from BIM, minimal computation

• Algorithm
• Step 1 Find list of occupied spaces
• Step 2 Find list of windows in each space
• Step 3 Determine window type
• (subdivide window if necessary)
• Step 4 Retrieve Tvis and calculate GF for all
  windows
• Step 5 Tabulate GFs in each space (check if gt2)
  
• Step 6 Tabulate eligible floor area (check if
  75)
• Analysis
• O(nlogn) retrieval of lists and values from BIM
• Step 3 O(nlogn) retrieve window geometry
• O(n) orientation and height determination
• O(n) subdivision
• O(n) GF calculations and tabulation
• LINEARITHMIC TIME PERFORMANCE

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Formulation as Computable LEED EQ 8.1 (Opt 1)
Daylight Availability Real-time implementation,
dynamic update as building model is modified
REVIT Model
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Formulation as Computable LEED EQ 8.1 (Opt 1)
Daylight Availability Real-time implementation,
dynamic update as building model is modified
Import Model into Lighting Tool
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Formulation as Computable LEED EQ 8.1 (Opt 1)
Daylight Availability Real-time implementation,
dynamic update as building model is modified
Parameters Inspection in Lighting Tool, no user
intervention
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Formulation as Computable LEED EQ 8.1 (Opt 1)
Daylight Availability Real-time implementation,
dynamic update as building model is modified
Real-time calculation of LEED EQ 8.1
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Formulation as Computable LEED EQ 8.1 (Opt 1)
Daylight Availability Real-time implementation,
dynamic update as building model is modified
Tabulation for LEED EQ 8.1 submittal
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Formulation as Computable LEED EQ 8.2 External
Views Achieve direct line of sight to the
outdoor environment via vision glazing between
26 and 76 above finish floor for building
occupants in 90 of all regularly occupied
areas. Determine the area with direct line of
sight by totaling the regularly occupied square
footage that meets the following criteria - In
plan view, the area is within sight lines drawn
from perimeter vision glazing - In section view,
a direct sight line can be drawn from the area to
perimeter vision glazing Line of sight may be
drawn through interior glazing. For private
offices, the entire square footage of the office
can be counted if 75 or more of the area has
direct line of sight to perimeter glazing. If
less than 75, actual compliant area is
counted. For multi-occupant spaces, the actual
square footage with direct line of sight to
perimeter glazing is counted.
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Formulation as Computable LEED EQ 8.2 External
Views 2 step graphical calculation procedure (2D
line-of-sight projections, 2nd pass
confirmation) Implicit checks for internal wall
openings
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Formulation as Computable LEED EQ 8.2 External
Views Formularization as computable, possible
finite-element approach
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Formulation as Computable LEED EQ 8.2 External
Views Ambiguities/limitations - Exhaustive
testing takes quadratic time (for all zones,
n points, m windows, k samples per window) -
Infinitesimally small areas of vision windows
constitute a view to the exterior - No
consideration of the combined visual effects from
several windows

• Algorithm
• Step 1 Find list of occupied spaces and vision
  windows
• Step 2 Generate list of points in each space
• Step 3 Generate list of candidate rays to vision
  windows
• Step 4 Trace candidate rays for obstructions
• Step 5 Tabulate compliant area in space
  (occupancy and if 75)
• Step 6 Tabulate eligible floor area (check if
  90)
• Analysis
• O(nlogn) retrieval of lists
• O(n) generation of points
• O(n2) generation of candidate rays and raytracing
• O(n) Calculations and tabulations
• Large n (candidate rays), QUADRATIC PERFORMANCE

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Formulation as Computable LEED EQ 8.2 External
Views Ambiguities/limitations - Exhaustive
testing takes quadratic time (for all zones,
n points, m windows, k samples per window) -
Infinitesimally small areas of vision windows
constitute a view to the exterior - No
consideration of the combined visual effects from
several windows
USE STERADIANS

• Algorithm
• Step 1 Find list of occupied spaces and vision
  windows
• Step 2 Generate list of points in each space
• Step 3 Generate list of candidate rays to vision
  window vertices
• Step 4 Trace candidate rays for obstructions
• Step 5 Calculate steradians subtended by
  external views
• Step 6 Tabulate compliant area in space
  (occupancy and if 75)
• Step 7 Tabulate eligible floor area (check if
  90)
• Analysis
• O(nlogn) retrieval of list
• O(n) generation of points, generation of
  candidate rays
• O(nlogn)raytracing
• O(n) Calculations and tabulations
• Small n (candidate rays), LINEARITHMIC PERFORMANCE

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Formulation as Computable LEED EQ 8.2 External
Views Dynamic implementation, fast update as
building model is modified
Imported building model, no user intervention
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Formulation as Computable LEED EQ 8.2 External
Views Dynamic implementation, fast update as
building model is modified
Dynamic calculation of LEED EQ 8.2
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Formulation as Computable LEED EQ 8.2 External
Views Dynamic implementation, fast update as
building model is modified
Tabulation for LEED EQ 8.2 submittal
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Summary of Results Formulation of LEED EQ 8.1
8.2 as computable - Interoperability - Ray
tracing - CMU Lighting Tool Algorithm
optimization data structures Benchmark
clarification steradians (computing speed-up)
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Thank you
14 July 2008 COBEE,(Dalian, China)