Research on Energy Saving Analysis of Tubular Daylight Devices

Daylight represents a free source of illumination of building's internal spaces. Tubular daylight devices (TDDs) are simple means of directing daylight (diffuse and direct light) into interior spaces and underground spaces. Many predict models of TDDs have been developed during the past years, but most of them were established based on only a few experiment results of TDDs with no generality. In this paper, a new mathematic model on the basis of daylight coefficient method for TDDs’ light transfer characteristic was presented, which makes it feasible to calculate the time series of efficiency of TDD, and an energy saving analysis of an underground garage using TDDs was introduced in this paper based on Beijing daylight climate data, from which the huge energy saving potential of TDD was clearly shown.