Task 31
Task 31
SHC Task 31

Daylighting Buildings in the 21st Century



User Perspectives and Requirements

Subtask Leader: Christoph Reinhart, Canada

Interior space with glaze

Interior space without glaze

People spend more and more time indoors. Lighting conditions in buildings are among the important factors that affect their well-being and comfort. While it is commonly agreed that daylighting strategies have significant potential to reduce energy consumption and produce better quality work environments, there exists little fundamental knowledge about the behaviour of occupants in the control of integrated daylighting users with respect to new integrated daylighting systems. Without reliable data on user behaviour and preferences, the potential energy savings may be difficult to realize. Interior space with glare.


The members of Subtask A will investigate current knowledge on human response to the application of daylighting systems and control strategies. It is the aim to develop a reliable understanding of the role of user perceptions of visual and thermal comfort in the control of daylighting strategies aimed at energy conservation. The overall intent is to provide benchmarks, performance metrics and improved simulation and design tools to effectively optimize daylighting solutions to reduce energy consumption in buildings while at the same time maximizing the benefits of daylighting for their occupants. The work of Subtask A will include the development of databases of important literature on the topic and appropriate case study buildings. In addition, human subject studies in daylit buildings in various countries are planned to complement and expand existing knowledge.

Subtask A is comprised of the following projects:

  • Project A1: Literature survey 
    (Project Leader: Michael Donn, NZ)
  • Project A2: Methods for the assessment of visual comfort 
    (Project Leader: Anna Pellegrino, ITAL)
  • Project A3: Application of user assessment methods for visual comfort 
    (Project Leader: Anna Pellegrino, ITAL)
  • Project A4: Modelling 
    (Project Leader: Christoph Reinhart, CAN)
  • Project A5: Guidance 
    (Project Leader: Christoph Reinhart, CAN)


  • Practical methods to assess visual and thermal indoor environment comfort systems. Few tools are available to help designers meet the need of building in daylit spaces
  • Descriptions on daylighting requirements for inclusion in standards and codes
  • Rules of thumb for daylighting office spaces
  • Algorithms for computer software to predict user response for designing daylit environments and their lighting, and shading control systems
  • Guidelines on the use of these algorithms in daylighting and energy simulation software

The work resulting from Subtask A will directly support designers and manufacturers by improving their understanding of user perspectives or requirements. It will also support the goal of achieving the potential energy savings predicted by providing architects, designers, lighting professionals and energy simulation specialists with more reliable data, guidelines and tools. Governments, building code authorities, standards boards, and professional bodies will be able to update existing documents to further enhance building occupant well-being and comfort while at the same time contributing to a more sustainable future.

Back to Top


Integration and Optimisation of Daylighting Systems

Subtask Leader: Stephen Selkowitz, USA

Test rooms at EPFL, Switzerland

Test room in Oakland, USA

Energy efficiency strategies based on substitution of more efficient components, have helped many countries achieve reductions in building energy use. But much larger energy savings with greater cost effectiveness can be achieved when systems integration strategies such as daylighting, are skillfully designed and deployed. Successful daylighting solutions are beyond the grasp of most design professionals. They require a high level of expertise and familiarity with new design and evaluation tools and the understanding of design approaches that will lead to successful solutions. They also require the integration of diverse technologies encompassing glazing, shading and electric lighting as well as smart controls in a manner that optimizes overall performance including human factors. These are essential challenges if daylighting is to become the preferred option in buildings in the 21st century.


The objective of this Subtask is to enable building designers to successfully address system performance and integration issues in the design and evaluation of daylighting concepts. The aim is economical design solutions that minimize energy use and electric demand for lighting and HVAC (using only 30% of the lighting energy required in non-daylighted buildings). The overall effort will be applicable to different building types and different locations and climates.

In order to meet this need, a review project and three research projects will be carried out in this Subtask. Although the intent of the work is to be broadly applicable to any building type, the Subtask will initially focus its efforts on two common building types represented in every member country: office buildings and educational facilities. Within these building types a range of building sizes and space functions will be addressed.

Subtask B is comprised of the following projects:

  • Project B1: State of the Art Review 
    (Project leaders: Steve Coyne, AU; Steve Selkowitz, USA)
  • Project B2: Design Solutions Roadmap 
    (Project Leader: Mark Luther, AUS)
  • Project B3: Optimizing Control and Operation of Daylighting Systems in Buildings 
    (Project Leader: Nicolas Morel, SUI)
  • Project B4: Field Studies
    (Project Leader: Lars Bylund, Nils Svendenius, SWE)


  • A simplified design process roadmap that identifies key issues to be addressed by the design team
  • Database of performance benchmarks that quantify potential savings with daylighting strategies
  • Procedures to calibrate and commission key daylighting control systems
  • Measured control system operational data that will enhance confidence in control system performance
  • Measured total system performance data to increase building owner confidence in system performance
  • Test room and building performance data for tool validation.
  • Building performance data to improve optimization hardware and software.

Subtask B work will advance daylighting implementation. As there is no critical mass of R & D currently underway in any one country, this collaborative work will accelerate development of new design approaches, control algorithms and performance data. It will provide designers with performance targets for use in the design process and a roadmap to achieve better results quickly and at a lower cost. It will give manufacturers a clearer sense of the improvements needed in existing products and a vision of how new products might provide new market opportunities. It will also provide building owners with quantifiable expectations for systems performance and reduce the perceived and real risk of undertaking a daylighted building.

Back to Top


Daylighting Design Tools

Subtask Leader: Hans Erhorn, Germany

Light transmittance of sun directing class

RADIANCE simulation of interior and exterior simultaneously

Daylighting design tools like ADELINE, developed in international collaboration within the last decade, helped designer to quantify the energy saving potential by using natural lighting resources. A wide range of different graphical, analytical and simple computer-aided tools, useful in the early and the detailed design phase, are available for practical use. However the use of these tools has mainly been restricted in the past by a lack of algorithms for new technologies and new research results e.g. visual comfort classification. There is a continuing need for algorithm and tool development and extensions that reflect these new technologies such as performance prediction methods, new sky models and user-friendly interfaces. New methods and updated design tools also have to be continuously validated to ensure correct results and give practitioners confidence in tool application. In this Subtask new developments will make available modular plug-ins to be used in multiple tools thereby reaching a larger number of users.


The objective of this Subtask is to improve the knowledge and quality of lighting tools to enable building designers to predict the energy performance and visual comfort conditions of complex fenestration systems in their daily working process. This Subtask will make a link between industry, designers and software developers and promote the tools to the practitioners. The research work in this subtask concentrated on four topics:

  • Evaluation on tool users expectations of daylighting design tools.
  • Development of new algorithms for complex fenestration systems and their implementation in different design tools.
  • Web based and target group oriented information and promotion platform for tool and engines.
  • Validation of new functionalities and benchmarking procedures of daylighting design tools.

Subtask C is comprised of the following projects:

  • Project C1: User Interactions (Joint Project Subtasks B and C)
    (Project Leader: Fawaz Maamari, FRA).
  • Project C2: Algorithms and Plug-Ins 
    (Project Leader: Jan de Boer, GER)
  • Project C3: Promotion of Tools & Engines 
    (Project Leader: Bill Carroll, USA)
  • Project C4: Validation
    (Project Leader: Fawaz Maamari, FRA)


  • Concepts for improved user expected interfaces and data bases
  • Models and libraries for complex fenestration systems
  • New Algorithms for sky models
  • Plug-in specifications for advanced visual comfort and user behaviour algortihms
  • Enhanced validated tools and engines, e.g. ADELINE 4.0
  • Plug - Ins for complex fenestration systems and sky models to extend the capability for use in standard lighting tools
  • Internet based catalogue of known tools and their capabilities
  • New data sets for integrated systems
  • Extended validation data sets
  • Online CIE approved benchmark procedure for tools and engines.

Subtask C work will advance acceptance of daylighting tools in the design process. It will emphasize improved tool quality and integration aspects, occupant response and the use of plug-ins to enable their use in a standard way with multiple tools. It will create a platform as a link between industry, designers and software developers by using the Internet.

Back to Top


Performance Tracking Network and Design Support Groups

Subtask Leader: Marc Fontoynont, France

College La Vanoise, Modane Savoy. France

Technical Museum, Berlin

This Subtask has the responsibility to disseminate the results of Subtasks A, B and C in a manner that facilitates widespread use of daylighted buildings in IEA member countries. Subtask D has three primary audiences: Building owners and others that make critical decisions about the nature of new investments in buildings, building design teams, their consultants and suppliers who provide the solutions and window component manufacturers or installers who sell and develop solutions to meet the demand of the market.


The main objective is to record benefits of daylighting techniques by providing the necessary facts and figures demonstrating all possible gains related to the use of efficient daylighting strategies. The performances concern energy savings in buildings as well as improved well-being, comfort, and building value.

These will be accomplished by the following activities:

  • Project D1: Development of a Web Server Structure
    (Project Leader: Michael Donn, NZ)
  • Project D2: Content of Data Base #1 - Record Benefits of Daylighting Techniques
    (Project Leader: Marc Fontoynont, FRA)
  • Project D3: Content of Data Base #2: Noteworthy Examples
    (Project Leader: Pascale Avouac -Bastie, FRA)
  • Project D4: Material for Support Groups
    (Project Leader: Marc Fontoynont, FRA)


  • The development of a web server in Wellington NZ. The site has restriction of access to participants and sponsors for the duration of the Task.
  • The establishment of databases demonstrating the benefits of daylighting techniques and noteworthy examples fully documented and accessible through the web.
  • The benefits of daylighting techniques which will include; financial benefits of investing in daylighting systems, added value of building, cost of daylighting options, electrical energy saved, daylighting and productivity and optimisation of solutions and monitoring results (from Subtask B).
  • The database on noteworthy examples will provide access to case study buildings (real and virtual) and long-term performance data over a decentralised network identifying noteworthy buildings worldwide.
  • The establishment of an international network of daylight design support groups that provide guidance on appropriate levels of design assistance. It will assist local and regional groups to effectively utilise the results of Subtasks A, B and C.
  • PowerPoint presentations for support groups

Since owners and designers are risk averse, the greatest need is for convincing documentation on successful daylighted buildings to be available for inspection by owners. The most powerful argument to support daylighting in buildings is to be able to walk through a well daylighted space and to compare to other similar buildings. In Subtask D, a network of buildings with measured performance data will be created that will be available for direct inspection or available to others as a virtual building on the World Wide Web. IEA SHC Task 31 will develop the tools to put these buildings on line.