webinar: daylighting design · pdf file1 caroline m clevenger, pe, ra architectural energy...
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Caroline M Clevenger, PE, RAArchitectural Energy CorporationBoulder, Coloradowww.archenergy.com
Webinar: Daylighting Design
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Provides information and tools to architects, engineers, lighting designers, and building owners to create more energy efficient buildings in California. Administered by the following utility companies:
Energy Design ResourcesEnergy Design Resources
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OutlineOutline
Daylighting:– Motivation
– Challenges
– Design Goals
– Design Strategies
– Designer’s Tool Kit
– Case Studies
– Resources
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Daylighting MotivationDaylighting Motivation
Hagia Sofia, IstanbulPantheon, Rome
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MotivationMotivation
Kimball Museum, Fort Worth, Texas
"...Light is really the source of all being.... [a]ll material in nature, the mountains and the streams and the air and we, are made of Light which has been spent. . .” - Louis KahnGuggenheim, New York
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MotivationMotivation
• Potential of improved educational performance – A study of 21,000 students in three school
districts involving 2,000 classrooms– Daylighting through skylights and large
windows indicated a beneficial effect on educational performance, with a 99% statistical certainty
Daylighting in Schools (1999, 2001, 2003) -- Heschong Mahone Group
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• Educational study indicated that students in the most daylit classrooms progressed :
– 20% faster on math tests than those students with the least daylight
– 26% faster on reading tests than those students with the least daylight
Daylighting in Schools (1999, 2001, 2003) -- Heschong Mahone Group
MotivationMotivation
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• Potential of Improved retail performance
– A study of revenue from 108 stores of a chain retailer, where two-thirds had skylights and one-third did not
– Skylights indicated a positive and significant correlation to higher sales, with a 99% statistical certainty
Skylights and Retail Stores (1999, 2003) -- Heschong Mahone Group
MotivationMotivation
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• Retail study indicated:
– A skylit store had, on average, sales revenue 40% higher than a store without skylights
– If a non-skylit store averaged $2/sf in revenue, a skylit store would average between $2.61 to $2.98/sf in revenue
Skylights and Retail Stores (1999, 2003) -- Heschong Mahone Group
MotivationMotivation
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• “Artificial” windows installed in patient rooms:
– Patients hospitalized for shorter periods– Complained less– Required less pain medication
Stanford University Hospital Study
MotivationMotivation
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MotivationMotivation
• Achieve greater occupant well-being, happiness, and satisfaction
• Improve employee retention and reduce employee “churn”
• Reduce absenteeism• Reduce environmental impact of the
building
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• Enhances design
• Sets body’s circadian rhythm / biological clock
• Increases connection to outdoors
• Full spectrum lighting
• Potential energy savings
Benefits of Daylight
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Full Spectrum Lighting
www.lightingdesignlab.com/articles/cri/cribig.htm
Color Rendering Index
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Heat gain (watts) per 1,000 lumens
Incandescent
T12 fluorescent withmagnetic ballast
T8 fluorescent withelectronic ballast
Clear glass
Reflectivebronze glass
0 20 40 60
Spectrally selective,tinted low-e glass
Electriclighting
Daylighting
Heat Gain from Different Light SourcesHeat Gain from Different Light SourcesEfficient Heat Gain
Based on E Source
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Winter Day Electrical Load ShapeWinter Day Electrical Load Shape
Exterior lightingInterior lightingOther
CoolingVentilationWater heating, cooking,and refrigeration
Heating
Winter Peakaverage of all U.S. commercial buildings
1,500
500
04 8 12 16 20 24
Hours
1,000
Source: EPRI CommendDatabase
Potential Energy Savings
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Summer Peakaverage of all U.S. commercial buildings
2,000
1,500
1,000
500
04 8 12 16 20 24
Hours
Exterior lightingInterior lightingOther
CoolingVentilation
Heating
Water heating, cooking,and refrigeration
Source: EPRI CommendDatabaseSummer Day Electrical Load ShapeSummer Day Electrical Load Shape
Potential Energy Savings
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Why Use Daylight? A Review
• Architectural Factors– Space definition– Establishes character of space– Establishes exterior expression
• Human Factors– Psychological connection to outdoors– Improve occupant health and well-being– Improve worker productivity – Improve occupant satisfaction with indoor
environment• Energy Efficiency
– Lighting a major building load & cost– Reduces coincident electricity demand
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Daylighting ChallengesDaylighting Challenges
• Variable Solar Resource• Heat Gain• Problematic Glare• Contrast Ratios• Unbalanced Luminous
Environment • UV damage
Opryland Hotel, Nashville, Tennessee
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Daylighting GeometryDaylighting Geometry
Winter
Altitude A = 90 - Latitude L +/- Declination D
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Daylighting GeometryDaylighting Geometry
Parallel Solar Rays
Solar Intensity
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UV3%
Visible(45%) Near-infrared (52%)
300 500 700 900 1,100 1,300 1,500 1,700 1,900Wavelength (nm)
Spectral distribution of solar radiation
Eye sensitivity curve
Relativeintensity
Solar SpectrumSolar Spectrum
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Diffuse and Direct ComponentsDiffuse and Direct Components
Earth’s Atmosphere and Daylighting
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Variable Solar ResourceVariable Solar Resource
Relationship of Clouds and Solar Resource
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Luminance RatiosLuminance Ratios
• Background of visual task: Environment 3:1
• Background of visual task: Peripheral field 10:1
• Light Source: Adjourning field of view 20:1
• Interior in general 40:1
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Glare Index Glare Index
Electric Daylight
• Public Spaces (dark surroundings) 22 24
• Working spaces 19 22(occasional visual task)
• Visual Task (high contrast) 16 20
• Visual Task (low contrast) 10 16
Weighted ratio of the light source and background illuminance
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Daylighting DefinedDaylighting Defined
The purposeful use of daylight to meet the illumination requirements of an architectural space.
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Daylighting Design Goals
• Provide 100% of ambient lighting
• Meet illuminance requirements
• Minimize glare and high contrast ratios
• Provide balanced luminous environment
• Integrate with electric lighting system
• Integrate with HVAC system
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Design Goals
• Provide 100% of Ambient Lighting
– Employ ambient - task - accent lighting scheme
– Reduce/eliminate need for electric lighting– Compatible with VDT work environments– Create peaceful, calming luminous
environment
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Design Goals
• Meet Illuminance Requirements
– Address the visual requirements of the space
– Address requirements of the visual task (IES-RP-1-1993 Office Lighting, etc.)• Provide adequate levels of light• Provide proper placement/directionality of light• Provide adequate visual acuity
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Design Goals• Minimize Glare and High Contrast Ratios
– Use reflected light when possible– Light from the sky-dome, not the sun – Use care in selecting window and interior
finishes and colors– Avoid direct sunlight penetration and
associated sun patches on workplane
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Design Goals• Provide Balanced Luminous Environment
– Provide even illuminance in daylit space– Provide balanced lighting
• Light from multiple directions, if possible• Avoid high contrast ratios
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Design Goals• Integrate with Electric Lighting System
– Blend with architecture and interior design scheme
– Match colors of light– Provide reliable automatic control
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Design GoalsDesign Goals
• Integrate with Mechanical System– Account for reduced cooling load in HVAC
equipment sizing– Combine with daylight - occupancy controls
-- to regulate supply air delivery to the daylit space
http://www.hpac.com/member/feature/2002/0212/0212daley6.gif
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Savings from Daylighting ControlsSavings from Daylighting Controls
Source: Scott Ellinwoodand Associates
Energy use(kWh) inthousands
0
20
40
60
80
100
Lights HVAC(Heat pumps)
Total
No controls Two-step on/off controls
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Source: SouthernCalifornia Edison
Top daylighting
Side daylighting
Daylighting StrategiesDaylighting Strategies
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• Side Daylighting
– Daylight access from perimeter
– Orientation dependent– Typical for multi-story
buildings, such as offices, schools, etc.
– Control of direct sunlight penetration onto work surfaces essential
– Control of glare and contrast ratios essential
– Creates perimeter zone (up to 70% of floor can be perimeter space.)
Strategies: Side-lightingStrategies: Side-lighting
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Lightshelves
Light Redirecting Systems
Strategies: Side-lightingStrategies: Side-lighting
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• “Tune” glazing optical properties by function and by orientation
• Separate “view” glass from “daylight” glass
• Direct daylight to ceiling
• Control occupant view of daylight glazing
View Glass
Daylighting GlassInterior Light She lf
Daylighting Glass Shade Control
View Glass Shade Control
Strategies: Side-lightingStrategies: Side-lighting
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• Top Daylighting
– Daylight access from roof– Typically limited to top floor or
single story buildings – Can provide uniform
illumination– System orientation
independent of building orientation
Strategies: Top-lightingStrategies: Top-lighting
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Clerestories
Tubular Skylights
Strategies: Top-lightingStrategies: Top-lighting
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• “Tune” glazing optical properties by orientation
• Control (minimize) direct sunlight penetration to reduce solar heat gain and glare
• Diffuse daylight for uniform illuminance levels
Strategies: Top-lightingStrategies: Top-lighting
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Strategies: Solar ControlStrategies: Solar Control
http://gaia.lbl.gov/hpbf/techno_a.htm
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Daylighting Designer’s ToolkitDaylighting Designer’s Toolkit
Use Analysis:– Physical Models
– Computer Simulations
To Inform:– Architectural Design
– Solar Control Systems
– Glazing Selection
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Designer’s ToolkitDesigner’s Toolkit
Spectrally Selective Glazing
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Computer ModelingComputer Modeling
Radiosity Backward Ray Tracing
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• SkyCalchttp://www.energydesignresources.com/tools/
skycalc.html
• SPOT™http://www.archenergy.com/SPOT
• SuperLitehttp://eetd.lbl.gov/btp/superlite20.html
Software SurveySoftware Survey
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• Radiancehttp://radsite.lbl.gov/deskrad/
– Desktop Radiancehttp://radsite.lbl.gov/deskrad/
– Rayfronthttp://www.schorsch.com/rayfront/
• AGI3.2http://www.agi32.com/
• Lightscape http://www.lightscape.com/
Software Survey, cont.Software Survey, cont.
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• Trace-Prohttp://www.lambdares.com/
• Lumen Microhttp://www.lighting-technologies.com/
• Ecotecthttp://www.squ1.com/
Software Survey, cont.Software Survey, cont.
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Computer Simulation: RadianceComputer Simulation: Radiance
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Photographs Simulations
Computer Simulation: RadianceComputer Simulation: Radiance
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Computer Simulation: RadianceComputer Simulation: Radiance
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Computer Simulation: RadianceComputer Simulation: Radiance
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Computer Simulation: RadianceComputer Simulation: Radiance
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Daylighting Case StudiesDaylighting Case Studies
Xilinx Corporation, Longmont ColoradoDTJ Design, Inc.
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Case Study : CTLMCase Study : CTLM
Center for Technology and Learning Media, Golden ColoradoAnderson Mason Dale Architects
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www.energydesignresources.com• Design Briefs and Guidelines• Case Studies• Software tools (Skycalc, SPOT, eQuest)• Online Tools: EDR Charrette• eNewsletter• Training Seminars (webinars, on-site,
on-line)
Daylighting Tools and ResourcesDaylighting Tools and Resources
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• www.savingsbydesign.com• Set guidelines for exceeding T-24
standards• Design assistance• Incentives for owner ($150k max)• Incentives for design team ($50k max)• Two approaches:
– system or component– whole building
Savings By Design ProgramSavings By Design Program
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• www.pge.com/biz• New construction design assistance• Cash incentives• Customized energy efficiency/demand
response incentives• Energy efficiency equipment rebates• Self generation incentives and rates• Education and training
PG&E Tools and ResourcesPG&E Tools and Resources
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• www.pge.com/pec/• PEC architectural
programs provide information to assist designers
• Tools available such as the Heliodon for shading studies
• Education and training classes and printed material
Pacific Energy Center ResourcesPacific Energy Center Resources
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• LEED Green Building Rating System®– www.usgbc.org
• Whole Building Design Guide– www.wbdg.org
• Smart Communities Network– www.smartcommunities.ncat.org/buildings
/gbintro.shtml• Collaborative for High Performance Schools
– www.chps.net
Other Relevant ResourcesOther Relevant Resources
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• Building Green– www.buildinggreen.com
• Great Energy Efficient Buildings– www.greatbuildings.com/types/types
/geeb.html • National Renewable Defense Council
– www.nrdc.org/buildinggreen/• State of California
– www.green.ca.gov/default.htm
Other Relevant ResourcesOther Relevant Resources