Radiation data are needed for solar resource assessment, design and evaluation of solar systems and buildings, and solar collector testing. As the performance of certain types of solar systems, building components and solar collectors depends on the spectral distribution in the ultraviolet, visible and infrared spectral range of the incoming solar radiation and on longwave thermal radiation exchange as well, a need was identified for improving the quantity and quality of spectral radiation data, both broad-band and narrow-band.

Task 17, which ran from 1 September 1991 until 31 August 1994, addressed this need by focusing research on three types of spectral radiation data:

• Narrow-band spectral radiation data for applications to solar and building materials;
• Broad-band spectral radiation data in the visible range (that is, visible light) for applications to natural illumination in buildings;
• Broad-band spectral radiation data in the infrared range (that is, long-wave radiation) for applications to the energy balance of solar systems and buildings.