Vishal GargHead & Associate Professor, CBS, IIIT

HyderabadPresident, IBPSA India

Lighting simulation needed for…Lighting simulation needed for…

•Analysis•Analysis of illuminance level based on lighting layout input

•Design •Design of lighting layout based on illuminance level input

•Visualization •Photorealistic rendering for visualization of the design

Lighting simulation categoriesLighting simulation categories

Sun as the source of light

Daylighting

Artificial Lighting

Lamp as the source of light

Daylighting simulationDaylighting simulation

What it simulates

•Illuminance levels •Glare index•Controls

Expected Output

•Quantity & Quality of light at any given point of time during the day•Glare index during the day•Savings in artificial lighting due to daylight •Effect of daylight on thermal loads

Daylighting simulationDaylighting simulation

Simulation tools

Radiance, Ecotect, DaySim, Energy Plus, SkyVision, Superlite, Rayfront

Implication on Green Building Rating

•Energy Performance•Daylighting

Daylighting simulationDaylighting simulation

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RadianceRadiance

Able to simulate light through

• Venetian blinds,

• intricate building facades

• skylights

• built-in renders that will compute the solar position from time of day, year, and location, and generate accurate shadows.

•diffuse skylight and inter-reflection.

Ecotect

• Uses the BRE Daylight Factor method for daylighting calculation

• For more detailed analysis, it can both export to and invoke the Radiance Lighting Simulation software DAYSIM (Dynamic Daylight Simulations) is a daylighting

analysis software that calculates the annual daylight availability in buildings as well as the lighting energy use of automated lighting controls (occupancy sensors, photocells) compared to standard on/off switches.

DAYSIM

DAYLIGHTING:SIMPLEDAYLIGHTING:SIMPLE•• Specify useful fraction of solar gainSpecify useful fraction of solar gain

DAYLIGHTING:DETAILEDDAYLIGHTING:DETAILED•• Calculates illuminanceCalculates illuminance

Only one type per zoneOnly one type per zoneMay use different types in same runMay use different types in same run

EnergyPlusDaylighting:SimpleDaylighting:Simple

Sensible and Latent

Beam Solar

Sky Diffuse

Ground Diffuse

Light Control

Daylighting:DetailedDaylighting:Detailed

Sensible and Latent

Beam Solar

Sky Diffuse

Ground Diffuse

Light Control 1

Light Control 2

Uncontrolled

Reference Pt 1

Reference Pt 2

Electric Lighting Control

• Electric lights full-on assumed to provide the setpoint illuminance – regardless of schedule

• Electric lighting control system simulated to determine fraction of lighting for each lighting zone

• Based on daylighting illuminance level regardless of actual electric lighting input power

• Zone lighting electric reduction factor passed to thermal calculation

• Heat gain from lights and power input reduced

Continuous Dimming Stepped Lighting Control

Daylighting:Controls Inputs

• 1 or 2 illuminance reference points– Specific point(s) in zone (X,Y,Z position)– World or relative coordinates depending on option

specified in GlobalGeometryRules– Shown as small circles in dxf drawing– Illuminance setpoint(s) [lux]

• 1 to 3 lighting zones– Specify fraction of lighting power for each zone– Fraction controlled by reference point 1– Fraction controlled by reference point 2– Uncontrolled (implied if Fraction1+Fraction2<1)

Daylighting:Controls Inputs (cont’d)

• Lighting control type– Continuous – stay on at minimum– Continuous – turn off at minimum– Stepped – automatic– Stepped – manual with probability– Minimum lighting output and power levels

• Glare control of window shades– Direction of view– Maximum glare level– Only with Daylighting:Controls

EnergyPlus for Simulating Electrochromic Glazingfor

Enhanced Comfort and Energy savings

Electrochromic with dimmable lamps result in lighting energy and cooling energy savings

Decrease in heat gain result in thermal comfort and cooling energy savings

Appropriate lighting levels can be maintained which provide Visual comfort

Light, Tvis: 0.8

Dark, Tvis: 0.05 Illuminance level: 500 lux

•geometrically complex spaces can be modeled, such as L-shaped rooms, trapezoidal surfaces, interior partitions and external obstructions•window glazing can be clear glass, diffusing glass or clear glass with a diffusing sheer curtain•daylight calculations can be performed for a variety of sky conditions, for a given sun position or geographic location, or for user-defined irradiance data•illuminance data are calculated for points on user specified planes

SUPERLITE

•Detailed calculation of skylight optical characteristics and indoor illuminance•Ray-tracing-based modelling to compute the skylight optical and daylighting performance.•Side-by-side comparison of design performance.•Results in graphical or tabular formats that can be used as inputs for third-party software such as building thermal simulation software.•Attached glass product database to build skylight products.•Climate file database to simulate scenarios with real, dynamic sky conditions.•Automatic lighting and shading control effects.

SKYVISION- models & simulates skylights

Artificial lighting simulationArtificial lighting simulation

What it simulates

•Quantitative analysis-Illuminance levels

•Design-Lighting layouts

•Controls

Expected Output

•Illuminance level•Lamp layout•Savings by lighting controls•Effect of lighting on thermal loads

Simulation tools

Photopia, Radiance, FOLD1, Virtual Lighting Simulator, OPTIS

Implication on Green Building Rating

•Energy Performance•Light pollution reduction

Artificial lighting simulationArtificial lighting simulation

PhotopiaPhotopia

•Fast and accurate photometric analysis program

•Produce virtual luminaires in a fraction of the time

•Can test a number of design variations

RadianceRadiance

FOLD1FOLD1

FOLD1 (Fast Online Lighting Design 1), easy luminaire selection and quick lighting design calculations for indoor lighting

• Web Based tool• It allows to quickly and easily see the effects of key parameters

in day lighting and electric lighting designs• It contains a very large number of rendered images, which were

computed using the Radiance lighting simulation software• Allows users to change the values of key design and context

parameters and displays the corresponding images and data for qualitative and quantitative assessment of luminous performance

Virtual Lighting SimulatorVirtual Lighting Simulator

Using a large number of simulations and visualisations, the subtle effects of many small lighting design decisions can be assessed. All the Radiance images shown are from a direct export from ECOTECT, showing the ability to include textures and object instancing (in the case of the seating).

Visualization- photorealistic renderingVisualization- photorealistic rendering

•3D lighting design and rendering software package for electric lighting and daylight analysis.•AGI32 produces full-color renderings and predictive lighting system calculations simultaneously for all applications of electric lighting and daylighting in interior and exterior design projects.• Complex architectural environments are easily created internally, or externally created 3D environments can be imported via DWG or DXF format files. •A comprehensive library of manufacturers lighting product data is included.

AGI32AGI32 AGI32- for daylighting & artificial lighting analysisAGI32- for daylighting & artificial lighting analysis

AGI32- VisualizationAGI32- Visualization DAILuxDAILuxDesign•Planning of indoor and street lighting•Automatic positioning of the right number of luminaires on the walls and in the room•Intelligent building components

Analysis•Illuminance map showing lighting levels

Visualization•Interactive 3D visualization allows to just wander round the room•Film the camera run through the photorealistic visualization•Realistic textures and furniture•Integrated ray tracing module for photorealistic presentation

DAILux- for daylighting & artificial lighting analysisDAILux- for daylighting & artificial lighting analysis

DAILux- for designing DAILux- for designing

DAILux- for visualizationDAILux- for visualization

•IBPSA India at: http://www.ibpsaindia.org/An India affiliate of International Building Performance Simulation

Association, IBPSA (I) is founded to advance and promote the science of building performance simulation in order to improve the design, construction, operation and maintenance of new and existing buildings in India.

•Lighting research group: http://lighting.lbl.gov/

•Lighting simulation tools directory: http://apps1.eere.energy.gov/buildings/tools_directory/subjects.cfm/pagename=subjects/pagename_menu=materials_components/pagename_submenu=lighting_systems

•Green Building discussion group at: greenbuildingsindia@googlegroups.com

•Energy simulation workshops: http://cbs.iiit.ac.in/short_courses.html

•Simulation research group at: http://simulationresearch.lbl.gov/

Thank you

Vishal Gargvishal@iiit.ac.in