De Beleving van Daglicht - Nicolas Roy

VELUX Daylight Visualizer 2 An Intuitive and User-Friendly Simulation Tool for

Accurate Daylighting Predictions

Daylighting Seminar, 26 May 2010

Nicolas Roy, ArchitectVELUX A/S, Department of Daylight, Energy and Indoor Climate

VELUX Daylight Visualizer 2

Lighting engine

• Global illumination using bidirectional Monte Carlo ray tracing and photon mapping.

Main objectives

• Provide professionals with an accessible and user-friendly tool which can perform accurate daylight simulations.

• Predict and document daylight levels and appearance of a space prior to realization of the building to promote good daylighting design.

Target group

• Building professionals/architects/engineers/students

• Professional house builders/developers/specifiers

Input areaUser input area includes predefined settings, product databases (windows) and numerical entries

Edit viewA view from the top is used to define the 3D model and insert windows

• Pan• Zoom in• Zoom out• Fit• Measure

Intuitive user interface

Screenshot of Daylight Visualizer 2 user interface

Progress barSimulation process has been divided into 8 distinctive steps • Floor/Plan• Roof/Ceiling• Windows/Doors• Surfaces• Furniture• Location• Camera• Render

3D viewThe model can be viewed in real time as a ”wire shaded” rendering

• Zoom in• Zoom out• Fit

Section viewThe model can be viewed as a ”wireframe” section


Guidance textStep by step instructions following the user actions

3D Modeller


Screenshot of Daylight Visualizer 2 user interface – 3D Importer

3D Importer

Progress barSimulation process has been divided into 5 distinctive steps

• Scale/Units• Surfaces• Location• Camera• Render

Plan viewThe 3D Importer uses a ”Plan” view instead of an ”Edit” view



Screenshot of Daylight Visualizer 2 user interface

Perspective camera

Camera previewThe 3D view changes to a camera preview when defining the perspective view

Perspective viewA perspective view is defined by placing and orienting the camera icons in the ”Plan” and ”Section” view ports

Predefined settingsDaylight Visualizer 2 uses predefined settings to ensure realistic inputs and the validity of the models and simulations.

Screenshot showing the assignment of predefined surface properties.

Screenshot showing the predefined render specifications for still images.

Custom settingsUser defined settings can also be specified in order to ensure a good level of flexibility

Efficient workflowUsers can perform quick comparisons between different scenarios such as window layout, pane properties, room surfaces, sky conditions, locations, and orientations.

Room 1 Room 2 Room 3

Efficient workflowUsers can perform quick comparisons between different scenarios such as window layout, pane properties, room surfaces, sky conditions, locations, and orientations.

Room 1 Room 2 Room 3

Results and metrics

Luminance

Daylight Visualizer 2 uses recognized metrics and performance indicators, including luminance (cd/m2), illuminance (lux) and daylight factor (%).

Illuminance Daylight factor

Results and metricsRendered images can be viewed in photorealistic, false colour and/or ISO contour modes.

Photorealistic False colour ISO contour

Results and metricsSimulations can be performed as still images, annual overviews and animations.

Validation against CIE 171:2006

Description of test case 5.9 (CIE 171:2006)

Description of test case 5.7 (CIE 171:2006)

Average error between the simulation results obatined with Daylight Visualizer 2 and the CIE 171:2006 analytical references (ENTPE)

Calculations have been validated against CIE 171:2006,Test Cases to Assess the Accuracy of Lightning Computer Program, in collaboration with ENTPE, l‘École Nationale des Travaux Publics de l‘État in France.

Validation against CIE 171:2006

Conclusions from ENTPE’s report

• VELUX Daylight Visualizer 2 can accurately predict daylight levels and appearance of a space lit with natural light, prior to realization of the building design.

• VELUX Daylight Visualizer 2 passed the CIE 171:2006 test cases dedicated to natural lighting.

• For the custom setting, VELUX Daylight Visualizer 2 simulates natural light transport with a maximal error lower than 5.13 %, and an average error lower than 1.29 %.

ExampleHome for Life (Aarhus, Denmark)

Illuminance renderings – Overcast sky conditions


Luminance renderings – Sunny sky conditions


Luminance renderings – Overcast sky conditions


Daylight factor simulations

Ground floor First floor


Luminance renderings – Annual overview – Sunny sky conditions (21st at 12:00)

DecemberNovemberOctoberSeptember

AugustJulyJuneMay

AprilMarchFebruaryJanuary


Luminance renderings – Annual overview – Sunny sky conditions (21st at 12:00)

DecemberNovemberOctoberSeptember

AugustJulyJuneMay

AprilMarchFebruaryJanuary

ExampleSolhuset kindergarten (Hoersholm, Denmark)

Daylight factor simulation (0.85m above the ground)


Group room 2

Luminance and illuminance levels - 21/12 at 12 o’clock, with intermediate sky


Group room 2



Group room 2



Group room 6



Circulation area



Design iteration

Initial design

The daylight conditions in the initial design are evaluated using the daylight factor (DF) performance indicator.

The simulation shows the areas of the building where the light levels are not sufficient, such as the gymnastic room located in the central part and the dining room facing east (e.g. 5% DF instead of 2% DF). By contrast, it shows high light levels in certain areas which could be used better if re-distributed.

Revised design

A revised window layout is proposed based on the findings made in the first evaluation, aiming to reach adequate light levels in the central parts of the building. This new model also included angle openings of the window linings.

The light levels obtained in the central part of the building and the dining room are much higher than in the previous model, ensuring that all the activity rooms have sufficient daylight.

Final design

According to the architect, the number of windows and size of the window linings opening has been optimized in the final design to promote a more rational solution in terms of ceiling construction, while keeping a generous and good distribution of daylight inside the rooms.

The daylight factor simulation of the final design shows a significant improvement over the results obtained with the initial design.

ExampleGeneric house (France)

Daylight factor simulations – situation without roof windows


Daylight factor simulations – situation with roof windows


Staircase

Luminance renderings – situation without roof windows


Staircase

Luminance renderings – situation with roof windows

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