Predicting Daylight for Energy Savings

President, byHeart Consultants Limited Ian Ashdown, FIES, P. Eng.

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Daylight Harvesting • “Daylighting use is critical if we are to achieve

huge leaps in building energy efficiency.”1

1. CBC. 2011. Next Generation Technologies Barriers & Industry Recommendations for Commercial Buildings. Final Report, Zero Energy Commercial Buildings Consortium.

Source: Energy Information Administration, 2003 Commercial Buildings Energy Consumption Survey, Table E3.

38%

Energy Code Requirements • ASHRAE 90.1-2010, Energy Standard for

Buildings Except Low-Rise Residential Buildings – Automatic daylighting controls

• LEED 2012 BD&C EQ Credit: Daylight – Daylight autonomy analysis required for full credit – Daylight factors analysis has been deprecated

• IES TM-29-11, The Commissioning Process Applied to Lighting and Control Systems – Supplement to ASHRAE Guideline 0-2005

• … and more to come

Daylighting Design Tools • Zero Energy Commercial Buildings Consortium1

– Estimates “probably” about 2% of buildings designed with daylight simulation tools for decision-making analysis

– Identifies inadequate design and simulation tools as key barrier to daylight harvesting adoption

– Existing daylight simulation tools lack: • Multiple view points (view-independent analysis) • Luminance levels and visual glare • Climate-based metrics (e.g., daylight autonomy) • Building Information Modeling (BIM) interoperability • Dynamic daylight harvesting systems analysis

1. CBC. 2011. Daylighting Report, Zero Energy Commercial Buildings Consortium.

Existing Software Products

Product Technology Manufacturer 3DS Max Design mental ray Autodesk AGi32 Helios32 Lighting Analysts Daylight Visualizer Luxion Velux Group DaySim Radiance1 NRCC DIALux RadiCal DIAL GmbH EcoTect Radiance1 Autodesk IES <VE> Radiance1 IES Desktop Radiance Radiance1 LBNL SPOT Radiance1 Architectural Energy

1. Radiance is a set of Unix command-line tools under continuous development by Greg Ward of Lawrence Berkeley National Laboratory since 1984.

Lighting Design Software • Excellent photometric tools • Good visualizations • Poor energy analysis tools

– Climate-based daylight metrics – Sun shadow studies

Autodesk EcoTect • Building energy analysis tools

– Solar / Wind / Thermal / Acoustic

• Limited daylighting analysis – Illuminance (direct only) – Daylight factors

LBNL Radiance • Primarily a lighting research tool

– Consists of hundreds of Unix command-line tools

• Dynamic Radiance development – Dynamic Radiance requires 16 hours and 700 MB of

memory to precalculate a single empty room – Ongoing advanced fenestration research and

development

• Sensor Placement and Optimization Tool (SPOT) – Excel and Python front-end to Desktop Radiance – Runtime of hours for an empty room

Design Communication • Daylight design is an architectural design issue

– Mostly dependent on architectural form and function – Visualization necessary for communication with clients – Daylighting design solutions must not detract from

architectural design goals

• Daylight harvesting is a lighting design issue – Mostly dependent on lighting controls implementation – Lighting metrics necessary for building code compliance – Daylighting design solutions are constrained by

architectural design

• Separate approaches to a common problem!

Daylighting Design Software • Facilitate communication

– Accessible to both architects and lighting designers – Easy to use and understand

• BIM integration – Part of existing workflow procedures – Provide both calculations and visualizations

• Interactive – Fast calculation and rendering times are essential

Dynamic Daylighting - kăDD • Interactive daylighting design for lighting

designers and architects – Arbitrary model complexity – Real-time daylight modeling – Annual per-hour daylight analysis in 30 seconds – Advanced daylight metrics (inc. daylight autonomy) – Energy analysis tools (similar to SPOT) – Perez sky model (same as Radiance) – EnergyPlus weather data (same as 3DS Max Design)

• Autodesk Revit 2013 integration – Lighting Analysts ElumTools 2013

kăDD Virtual Commissioning • kăDD will enable virtual commissioning of

daylight harvesting systems – Daylight controller algorithms – Photosensors – Automatic blinds – Advanced fenestration – Interactive modeling – What-if scenarios

• Analyze and refine daylight harvesting systems during the building design phase

Building Management Systems • “In the future, automated continuous

commissioning tools will be designed to track the real-time performance of lighting systems.”1

– kăDD expressly designed for this purpose (US patent pending)

– Real-time predictive modeling and machine learning – Looking for technology partners for further product

development

1. CBC. 2011. Next Generation Technologies Barriers & Industry Recommendations for

Commercial Buildings. Final Report, Zero Energy Commercial Buildings Consortium.

Market Acceptance • “Many building owners and design team

members do not believe that lighting control systems are reliable yet.”1

• Market acceptance will come when architects and lighting designers have the engineering tools to reliably and quickly analyze their daylight harvesting designs.

1. CBC. 2011. Daylighting Report, Zero Energy Commercial Buildings Consortium

Thank You!

ian_ashdown@helios32.com Ian Ashdown, FIES, P. Eng.

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