Daylighting through top lighting causes problems with respect to lighting design due to the unavailability of measured lumen output data and inherent problems of skylights, including solar heat gain/loss. The development of Tubular Daylighting Devices (TDDs) has made top lighting a viable component of the lighting design of a building.

Tubular daylighting devices are suitable for designers and energy managers seeking environmentally sustainable illumination alternatives for commercial buildings. Solatube Australia launched ENERGY STAR certified 750 DS daylighting system at the Form & Function/DesignEx 2009 exhibition.

The 750 DS daylighting system has been tested and certified for its solar heat gain and U-values. The tests provide quantifiable results that can be used by mechanical engineers. According to Solatube Australia, the 750 DS daylighting systems offer optimum light performance with minimal solar heat gain.

Solatube Australia have quantifiable lumen output data based on isometrics of various cities combined with the photometrics of each device, providing lumen output tables. This allows engineers to predict, with accuracy, the lowest/highest average light levels. IES data files are available for each device. Advanced optics in the dome are used for the 750 DS daylighting systems that allow for a consistent lighting level, maximising low level light and optimising high level light to reduce glare and heat.

The various options for TDDs include dimming functionality that controls the output of the device (or groups of devices) and also provide 0 to 10 volt inputs which allows for automation compatibility. These options dim artificial lights and the TDDs can meet the lux level requirements of the space.

The available range of sizes and configurations allow for TDDs to be considered in most building types including residential, education, retail, health, office, and industrial. Daylighting multiple floors is made possible with long tube runs and 0 to 90 degree bends, and the reflective tubing reduces losses and allows greater flexibility to reach areas within buildings. Diffuser options, called ‘designer choices,’ can incorporate effects lenses, which allow for softening or warming effect results (dropping colour temperature by up to 1000k). The tubing of TDDs also delivers a colour rendering factor of 100.