Daylight in Buildings

Completed (1995 - 1999)


his project was carried out in partnership with the IEA Solar Heating and Cooling Implementing Agreement (Task 21). The objective was to develop a scientific, engineering and architectural basis to support the effective and economical integration of daylighting concepts into the design of non residential buildings. The project sought to promote daylight-conscious building design, saving energy through greater utilisation of natural light, while at the same time improving visual comfort and control of solar gains.

The project focussed on those daylighting systems and strategies which could be applied in new and existing buildings with a high aggregate electricity saving potential, such as offices, schools, commercial and institutional buildings. Systems and strategies were tested and performance evaluated through studies in laboratory facilities, by computer simulations, as well as in case study buildings. The performance assessment sought to cover visual, architectural and environmental aspects, including user acceptance of the systems. The project was divided into four research areas:

Performance evaluation of daylighting systems

The objective here was to provide a Design Guide on the performance of both innovative and conventional daylighting systems. Systems were assessed according to energy saving potential, visual aspects and the control of solar radiation. The evaluation of systems was based not only on technical feasibility but also on architectural and environmental impacts.

Daylight responsive lighting control systems

The objectives here were to evaluate the performance of existing selected daylight responsive lighting control systems (in conjunction with selected daylighting systems) in terms of user acceptance of the systems. This will assist building owners, developers, architects and engineers to select and commission daylighting responsive systems, and to estimate the potential energy savings at an early stage of design.

Daylighting design tools

The objective here was to improve the capability, accuracy and ease-of-use of selected daylighting design and analysis tools for building design practitioners. The practitioners will be able to predict the performance of different daylighting systems and control strategies, and to evaluate the impact of the integration of daylighting in the overall building energy concept by using these design tools.

Case studies

The main objective here was to demonstrate the viability of daylighting buildings in various world climatic zones as a means of achieving significant improvements in building energy efficiency, while maintaining a satisfactory visual and thermal environment for occupants. Measured performance data included illumination, the luminance distribution of the interior space, electrical lighting consumption, the total building energy consumption, and user acceptance of the environmental conditions.


  • A system specific Design Guide on daylighting systems and control systems providing recommendations on systems integration and performance data on energy saving potentials.
  • A set of Daylighting Design Tools that markedly improve the designers' ability to predict the performance of daylighting systems and control strategies and to evaluate the impact of daylighting integration in the overall design concept.

Operating Agent

Dr. Kjeld Johnsen
Danish Building Research Institute
PO Box 119
2970 Hørsholm
Tel: +45 4586 5533


Australia, Austria, Belgium, Canada, Denmark, Finland, France, Germany, Italy, The Netherlands, Spain, Sweden, Switzerland, United Kingdom, and United States of America