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Light fields in climate-based daylight modeling for spatio-temporal glare assessment

Applicant Wittkopf Stephen
Number 179067
Funding scheme Project funding (Div. I-III)
Research institution Hochschule Technik+Architektur Luzern
Institution of higher education Lucerne University of Applied Sciences and Arts - HSLU
Main discipline Civil Engineering
Start/End 01.02.2019 - 31.01.2023
Approved amount 400'000.00
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Keywords (7)

Climate-Based Daylight Modeling; glare; light field; daylight simulation; visual comfort; building performance; Radiance

Lay Summary (German)

Lead
Methoden zur Bewertung von Blendung durch Tageslicht in Gebäuden sind unverzichtbar in der Planung leistungsfähiger Gebäude, die Energieeffizienz mit hoher Aufenthaltsqualität verbinden sollen. In der Gebäudesimulation nehmen sie eine Sonderrolle ein, da sie sich nicht auf räumlich und nutzungsabhängig definierte Zonen beziehen, sondern Wirkungen auf eine imaginäre Person mit bekannter Position und Blickrichtung auf der Grundlage von rechnerisch erzeugten oder photographisch aufgenommenen Bildern untersuchen. Die Blendungsbewertung anhand simulierter Lichtfelder verspricht ein umfassenderes Verständnis von Blendung als Funktion der räumlichen Variablen Position, Blickrichtung sowie der zeitlich variablen, äusseren Tageslichtbedingungen.
Lay summary

Inhalt und Ziele

Um eine Methodik zur räumlichen und zeitlichen Untersuchung von Blendung zu entwickeln, zielt das Projekt auf drei Herausforderungen:

1) Die rechnerische Erzeugung von Lichtfeldern unter wechselnden Tageslichtbedingungen als vollständiger Beschreibung von Licht in einer definierten Zone.
2) Die Entwicklung von effizienten, rechnerischen Methoden zur Anwendung von Blendungsmetriken wie Daylight Glare Probability auf Lichtfelder.
3) Die Identifizierung von Kombinationen aus Position, Blickrichtung und Zeitpunkt, die zu einem erhöhten Blendungsrisiko führen.

Die zu entwickelnden Methoden soll angewendet werden, um Blendung durch Tageslicht in exemplarischen Gebäuden zu untersuchen.

Wissenschaftlicher und gesellschaftlicher Kontext

Zahlreiche Studien zeigen auf, dass leuchtdichtebasierte Metriken zur Bewertung visuellen Komforts beleuchtungsstärkebasierten Verfahren überlegen sind. Das Projekt schafft Grundlagen, um leuchtdichtebasierte Metriken raumbezogen anzuwenden. Es soll zu einem besseres Verständnis der räumlichen und zeitlichen Abhängigkeiten von Blendung führen. Die Methode ist auf natürliche ebenso wie künstliche Lichtquellen anwendbar. Sie eröffnet Möglichkeiten zur Untersuchung von zeitlichen Effekten, wie der Adaption an wechselnde Lichtbedingungen, sowie zur immersive Erforschung von räumlichen Effekten.

Ein Verständnis von Blendung im Raum erlaubt quantitative Aussagen über die Auswirkungen von Planentscheidungen auf den visuellen Komfort. Eine derart geleitete Planung soll hohe Aufenthaltsqualtät mit durch Tageslichtnutzung optimierter Energieeffizienz verbinden. Die Bewertung von Gebäudezonen entspricht der Praxis in anderen Gebieten der Gebäudesimulation und lässt sich daher in Planungswerkzeuge ebenso wie in Richtlinien integrieren.

Direct link to Lay Summary Last update: 30.04.2018

Responsible applicant and co-applicants

Employees

Project partner

Publications

Publication
Photon mapping to accelerate daylight simulation with high-resolution, data-driven fenestration models
Grobe Lars Oliver (2019), Photon mapping to accelerate daylight simulation with high-resolution, data-driven fenestration models, in Journal of Physics: Conference Series, 1343(1), 012154-012154.
A critical literature review of spatio-temporal simulation methods for daylight glare assessment
Wasilewski Stephen, Grobe Lars Oliver, Wienold Jan, Andersen Marilyne (2019), A critical literature review of spatio-temporal simulation methods for daylight glare assessment, in SDAR Journal of Sustainable Design in Engineering of the Built Environment, 7(1), 4.

Scientific events

Active participation

Title Type of contribution Title of article or contribution Date Place Persons involved
5th Velux Academic Forum Talk given at a conference Traversing time dependent light fields for daylight glare evaluation: Method 08.10.2019 Paris, France Wasilewski Stephen William;
5th Velux Academic Forum Talk given at a conference Traversing time dependent light fields for daylight glare evaluation: Introduction 08.10.2019 Paris, France Wasilewski Stephen William;
18th International Radiance Workshop Talk given at a conference A variable resolution approach for zonal glare assessment 21.08.2019 New York, United States of America Wasilewski Stephen William;


Associated projects

Number Title Start Funding scheme
147053 Modeling and Simulation of Daylight Redirecting Systems 01.06.2013 Project funding (Div. I-III)
153849 ACTIVE INTERFACES - Holistic strategy to simplify standards, assessments and certifications for building integrated photovoltaics 01.11.2014 NRP 70 Energy Turnaround

Abstract

PROBLEM STATEMENTDaylight glare is a critical factor for the successful planning and operation of high performance buildings. It affects the visual comfort of occupants and triggers responses such as the operation of shading devices. Therefore, effective glare control is essential to leverage the beneficial effects of daylight in buildings.Daylight glare depends on luminance distributions in the field of view under continuously changing sky conditions. Computational simulation provides such images, which are evaluated by a combination of metrics to arrive at quantitative predictions. Since the employed simulation techniques are view-dependent and computationally demanding, current methods to evaluate glare are bound to pre-selected, specific viewer positions, directions and points in time. Such selections may be arbitrary and contradict representative, zone-based evaluations. Consequently, performance- driven design aiming for visual comfort is either agnostic to glare, or relies on simplifications. Punctual assessment of glare can miss critical conditions and is not robust, since it cannot account for potential glare mitigation e.g. by head movement, or predict such occupant response. In the planning phase, when counter-measures are most effective, areas of increased risk cannot be identified to guide in-depth analysis and modifications of the design. The lack of an efficient simulation method to compute imagery for building zones therefore hinders the understanding of glare as a crucial aspect of visual comfort, and thereby the successful utilization of daylight in high performance buildings.OBJECTIVESMethods shall be developed for the evaluation of the different aspects of daylight glare by multiple metrics1. the computation of light fields under varying sky conditions as a general description of light in a building zone;2. their rapid evaluation employing combined metrics for different aspects of glare; and3. solving for locations, directions and sky conditions with enhanced risk of glare in occupied zones of non- residential buildings.These methods shall be applied in the comparative evaluation of glare in building zones. 90 cases shall be assessed, defined by combination of 6 plan layouts in non-residential buildings with 5 exemplary technical means for glare control at 3 locations.TECHNOLOGICAL REALISATIONFor the rapid generation of imagery in spatial assessments of daylight glare, we propose to fuse scene-based ren- dering of Daylight Coefficients (DCs) with image-based light field rendering. Therefore, the concept of the light field as a complete description of the light distribution in a given space under static illumination shall be extended for Climate-Based Daylight Modeling (CBDM). Rather than computing DCs for pre-defined sensor points or views, the pre-computed Daylight Coefficient Field (DCF) relates radiance along any vector passing through a building zone to regions on the sky hemisphere. From the DCF and local weather data, light fields under any sky condition can be generated that carry all information of luminance distributions or different formulations of illuminance for any location and direction . The DCF shall extend the static holodeck light field representation in RADIANCE.A method for the computational evaluation of glare metrics as function of location, direction and time shall be developed that can directly access the spatial information in the light field. The implementation can be based on EVALGLARE. The direct interface between the evaluation software and the light field data-structure shall enable iterative refinement in the spatial assessment and thereby allow to identify regions of enhanced glare risk in the six-dimensional parameter space position (x, y, z), direction (?, f), and time (t).The method shall be applied in the spatial assessment of glare in non-residential buildings selected based on an analysis of building regulations, guide-lines and built examples. These cases shall be combined with technical means for glare control that are represented by geometric and data-driven models. For the resulting cases, positions, directions and sky conditions leading to enhanced glare risk shall be identified employing CBDM with RADIANCE.
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