Date post: | 25-Nov-2015 |
Category: |
Documents |
Upload: | rana-ali-elgendy |
View: | 35 times |
Download: | 0 times |
Exponation AIA Provider Number: 70119700
Tile 24 Series: Improving
Daylighting Performance
Prediction - New Metrics and
Tools LSW13-S9
Mudit Saxena 10.23.13
Credit(s) earned on completion of
this course will be reported to AIA
CES for AIA members.
Certificates of Completion for both
AIA members and non-AIA
members are available upon
request.
This course is registered with AIA
CES for continuing professional
education. As such, it does not
include content that may be
deemed or construed to be an
approval or endorsement by the
AIA of any material of construction
or any method or manner of
handling, using, distributing, or
dealing in any material or product. _______________________________________
Questions related to specific materials, methods,
and services will be addressed at the conclusion
of this presentation.
Daylighting is an essential strategy to
get to zero energy commercial
buildings. However, simplistic metrics
that cannot account for climate location,
orientation or advanced technologies
have made it difficult to design
programs that require daylighting,
promote optimized design or
technologies, or ensure occupant
comfort in day lit spaces. A new
method of calculating climate-based
performance metrics approved by the
IES and recent improvements in annual
simulation programs offer new power in
assessing daylighting design, and thus
improve prediction of the energy and
comfort performance of the resulting
buildings.
Course
Description
Learning
Objectives
The new IES approved method of calculating climate-based daylight metrics (Spatial Daylight
Autonomy and Annual sunlight Exposure)
The latest developments in simulation tools to predict daylighting in spaces
Variables that affect daylighting performance
Examples of spaces with variety of daylight ratings per the new metrics
At the end of this course, participants will
learn:
Daylight
Is An Existing Resource In All Buildings!
Daylighting
An important strategy to
Achieve deep energy savings
Achieve deep energy savings
Daily Patterns of Lighting Circuit Current and Daylight
Illuminance in a Space with Aggressive Dimming Controls
0
1
2
3
4
5
6
12:0
0 A
M
6:0
0 A
M
12:0
0 P
M
6:0
0 P
M
12:0
0 A
M
6:0
0 A
M
12:0
0 P
M
6:0
0 P
M
12:0
0 A
M
6:0
0 A
M
12:0
0 P
M
6:0
0 P
M
Time of Day
Cu
rren
t (A
)
0
200
400
600
800
1000
1200
Dayli
gh
t Il
lum
inan
ce (
fc)
Lighting Circuit Current (A) on/off state
Daylight Illuminance on Window (fc)
Monitored energy savings from Sidelighting Photocontrols Field Study, Heschong Mahone Group, 2005. http://h-m-g.com
California Commercial End-Use Survey (CEUS) 2006 http://capabilities.itron.com/CeusWeb/Default.aspx
Daylighting
An important strategy to
Maintain a healthy and productive indoor environment
Improved school test scores
Improved retail sales
Improved office productivity
Better sleep, physical activity and quality of life
Daylighting And Productivity CEC PIER Studies. http://www.h-m-g.com/Projects/daylighting/projects-PIER.htm
Impact of Workplace Daylight Exposure on Sleep, Physical Activity and Quality of Life. http://www.journalsleep.org/resources/documents/2013AbstractSupplement.pdf
Can we mandate daylit buildings?
How do we optimize benefits ?
while minimizing energy use?
How do we describe good/better/best for daylight designs
How much daylight is needed for comfort?
What provides the productivity benefits?
What is needed for circadian health?
How is visual comfort under daylight conditions different than electric lighting?
Can we evaluate success? and failure?
Good daylight design
Climate Sunny / Cloudy Sun angle
Faade design Window layout Orientation Glazing area VLT
Space Geometry Small private office Large open office
Ceiling Height Window on one or more
facades Interior surface colors
Furniture layout High partition Low partition
Blinds/Shades Usage Type
Depends on many factors
Need for a daylight evaluation Metric
In order to establish requirements for daylit buildings, there needs to be a performance standard
that ensures that occupants needs for visual comfort will be met
that allows designs to be optimized for the most energy efficient means to deliver that comfort
We want metrics that are sensitive indicators of good daylighting
CEC PIER Daylight Metrics Research Project
GOALS
Establish new daylight metrics based on annual simulation output tied to qualitative evaluations
Build a consensus on these metrics for use in standards, codes and programs
TEAM
Lead by Heschong Mahone Group (Now a TRC Company) Supported by an international team of daylighting experts
Guided by IES Daylight Metrics Committee (formed 2006)
What is a Metric?
Measurement Metric Criteria
Individual bits of information
Measurements assembled into a meaningful
scale
The goal of the metric
Example (Body Mass Index): Weight Height
Research Methodology
Assess study sites (61)
Across US (7 cities)
Collect expert (5) and occupant (10) assessments of daylight quality
3 types of spaces considered
Classrooms
Offices
Libraries
Survey Form
Research Methodology
Create detailed annual simulation models
Standardized methodology for all study spaces
Simulation tool that models annual hourly climate of site, evaluates interior daylight illuminance
Simulation Results
Hourly Illuminance Results Per sensor (1ft x 1ft)
Processed into Annual Daylight Autonomy per sensor
More hours with daylight Less hours with
daylight
Research Methodology
Compare quality assessments to simulation metrics
Metrics Investigated: DA, sDA, UDI, DSP, DAMax, cDA ...
To determine best predictors of daylight quality
Use nested linear regression to find metrics which best predict occupant and expert assessments
Results - New Daylight Metrics
Two new climate based daylight metrics identified
Best correlation with occupant and expert assessment
When the occupants and experts told us
Daylight is sufficient
I enjoy being in this room
I can work with electric lights off
These metrics also predicted better values
Adopted by the IES officially in 2012 (LM-83-12)
Spatial Daylight Autonomy (sDA300/50%)
A measure of daylight illuminance sufficiency for a given area
Reports a percentage of floor area that exceeds a specified illuminance level, e.g., 300 lux, for a specified amount of annual hours, e.g., 50 percent of the hours from 8:00 am to 6:00 pm
Preferred threshold: sDA300/50% 75% of analysis area.
Nominally acceptable threshold: sDA300/50% 55% of analysis area.
Annual Sunlight Exposure (ASE1000,250h)
Evaluates the potential source of visual discomfort from direct sunlight.
It is defined as the percent of an analysis area that exceeds a specified direct sunlight illuminance level, e.g., 1000 lux, more than a specified number of hours, e.g., 250 hours per year.
Preferred threshold: ASE1000,250h < 3% of analysis area
Nominally acceptable threshold: ASE1000,250h < 7% of analysis area
Example 1: Daylight Autonomy Plot
More hours with daylight
Less hours with daylight
Total space area = 500 sf
Example 1: sDA300/50% Calculation
340 sf or
68%
sDA300/50% = 68% for this space
Total space area = 500 sf 75%
55%
Preferred
Nominally Acceptable
sDA300/50%
Example 2: sDA300/50% Calculation
Total space area = 1200 sf
More hours with daylight
Less hours with daylight
Example 2: sDA300/50% Calculation
216 sf or
18%
sDA300/50% = 18% for this space
Total space area = 1200 sf 75%
55%
Preferred
Nominally Acceptable
sDA300/50%
What are the new metrics sensitive to?
Climate Sunny / Cloudy Sun angle
Faade design Window layout Orientation Glazing area VLT
Space Geometry Small private office Large open office
Ceiling Height Window on one or more
facades Interior surface colors
Furniture layout High partition Low partition
Blinds/Shades Usage Type
sDA and ASE rating of a space depends on
Orientation
South North North w skylights
Blinds Operation
Blinds open Blinds operated
(using 2% sun penetration trigger, blinds closure by blind group)
Blinds closed
Metrics sensitivity
Rewards spaces with little sun penetration Spaces with well designed overhangs Spaces with North orientation.
Rewards spaces with deep daylight penetration Higher window head height Light redirecting technologies
Rewards spaces with multi-directional daylight Spaces with windows on more than one wall Spaces with windows and skylights
Metrics sensitivity
Penalizes spaces with no blinds/shades (and no overhangs) Spaces that admit too much direct sun
Penalizes deep spaces Spaces with large floor plans where a large portion of the
occupied space is away from a daylight source
Penalizes spaces with low daylight levels Spaces with dark windows Spaces with small windows
Metrics limitations
Quantifying visual discomfort Annual Sunlight Exposure is a proxy for visual discomfort
Not a luminance based metric
A luminance based glare metric likely to provide better correlation to visual discomfort
No luminance based glare metric (yet )
A space-level metric Needs to be calculated for each space in a building
Cannot be very easily translated to the whole building
Simulation tools for daylight metrics
To calculate the new metric, the simulation tool needs some minimal capabilities
Annual hourly simulation - using a weather file
Report results for a sensor grid
Assign blinds/shades to window groups in a space
Model blinds operation based on sun penetration
Minimum sky patch resolution
Minimum solar disc resolution
Simulation tools for daylight metrics
Radiance 3-Phase method (aka. Dynamic Radiance)
Open Studio
DaySim
Autodesk 360 Rendering
IES-VE
And others
Radiance
Radiance is a set of lighting simulation and rendering tools made freely available by LBNL since about 1990
Considered the gold standard for simulation accuracy
Uses ray-tracing (slow, but powerful)
Point calculations are pretty fast
Nice images take longer
Annual simulation even longer
Radiance 3-Phase Method
Also known as Dynamic Radiance Approach
Is a new method to use Radiance for fast, matrix-based annual daylighting calculations
Developed along with the PIER Daylight Metrics Research Project with funding from Southern California Edison
Addresses the needs for
Annual analysis using weather files
Parametric simulation runs capabilities
Realistic blinds and shade modeling assumptions
Radiance v4.1
A suite of programs for the analysis and visualization of lighting and daylighting based on reverse ray-tracing http://radsite.lbl.gov/radiance/
Daylight Metrics: Calculated using Radiance 3-Phase Method
SimBuild 2010 Paper: http://www.ibpsa.us/pub/simbuild2010/papers/SB10-DOC-TS08A-01-Saxena.pdf
Tutorial: http://www.radiance-online.org/learning/tutorials/Tutorial-ThreePhaseMethod.pdf
DaySim
Radiance-based annual daylighting analysis software with an easy to use user-interface
http://daysim.ning.com/
Daylight Metrics:
Outputs sensor grid illuminance, sun penetration hourly results
Capable of outputs range from climate-based daylighting metrics
DAYSIMps developed by Penn State can calculate and output sDA and ASE
Open Studio (NREL)
A collection of software tools to support whole building energy modeling using EnergyPlus and advanced daylight analysis using Radiance https://openstudio.nrel.gov/downloads
Daylight Metrics: Capable of performing an annual climate-based daylight
simulation, using the 3-phase method with BSDFs https://openstudio.nrel.gov/getting-started-developer/getting-
started-radiance/openstudios-radiance-functionality-documentation
Autodesk 360 Rendering Illuminance
A cloud-based rendering service that can generate illuminance images for Revit models to quantify the effects of natural and artificial lighting on rendered surfaces or sensor points http://rendering.360.autodesk.com/index.aspx
Daylight Metrics Capabilities limited to generating rendered scenes and sensor outputs
for now
sDA and ASE calculation from within UI coming soon
http://autodesk.typepad.com/bpa/2013/04/illuminance-learning-about-lightingdaylighting-analysis-1.html
IES-VE
A whole building energy performance modeling software, with a Radiance module (RadianceIES) that allows detailed daylight calculation and rendering http://www.iesve.com/software/download-centre
Daylight Metrics Capabilities limited to generating rendered scenes and sensor outputs
for now
sDA and ASE calculation from within UI coming soon
Which simulation tools will NOT work
DOE 2 based simulation programs eQUEST
Visual DOE
EnergyPRO, etc.
EnergyPlus (Split flux)
These programs use the split flux method which has many approximations of daylighting calculations
Also in-built restrictions on number of sensors (limited to 2 per space) means a sensor grid cannot be developed
Implications for Codes and Standards
Voluntary codes LEED LEED version 4 (launching November 2013) has adopted the
new metric
Up to 3 points for showing that the building is well daylit using the new sDA and ASE metrics 2 points for showing 55% sDA300/50%
3 points for showing 75% sDA300/50%
Alternatively, using old method found in LEED 2009 2 points for showing 75% of reg. occupied space that at 9am and
3pm on the equinox, will be between 300 lux and 3000 lux
Note additional point awarded for using the new metrics!
Implications for Codes and Standards
Energy codes Title-24
Title-24 2013 version does not include a performance path with the new metrics
Current compliance calculation tool is DOE 2 moving to EnergyPlus in the next round (?)
Both tools in current versions cannot calculate the new metrics
However, development of Open Studios Radiance module opens the possibility of EnergyPlus simulation with Radiance
Implications for Codes and Standards
Energy codes Title-24 Current daylighting requirements
Require photocontrols in most spaces with windows and skylights
Requires large open buildings to have skylights
A future version of the code can potentially require a minimally daylit building By referencing a minimum threshold on the new metrics
This would ensure that building is designed to optimize occupant comfort - while providing energy savings
This concludes The American Institute of Architects
Continuing Education Systems Course
Mudit Saxena Associate Director
Tel: (916) 962-7001