A comprehensive detailed formula for LED degradation and lifetime estimation leading to reduce CO2 emissions

Abstract

Recently as global warming and (green-house gases) GHG emissions topics have become hot, many countries have pledged for decreasing their carbon footprint in a reasonable time. Since a substantial part of carbon footprint is coupled with electric energy consumption and in turn, a considerable part of consumed electrical energy around the world is related to the lighting, as energy efficient light sources LEDs have attracted notices to themselves. According to long lasting LEDs as semiconductor light sources, they face a great amount of lumen depreciation during their lifetime. Since, besides environmental impact, economic aspects are also of great interest for users, it is important to be able to anticipate the LEDs lifetime as exact as possible. This enables users not only to select the correct LED luminaires by cost-benefit analysis, but also to schedule for renewing them in the right time. As mentioned in former researches LEDs can show better lumen maintenance than what is estimated by prevalent TM 21 standard method. This paper proposes a comprehensive detailed formula for finding LEDs’ more accurate lifetime. The novelty of the research methodology is breaking up the LED to its major parts and by finding each part degradation model and combining them, coming up with the ultimate accurate formula. The proposed formula anticipates longer lifetime than what estimated by TM 21 method especially for low currents and temperatures stresses. Also, constant lumen output drivers (CLOs) are designed based on proposed comprehensive formula and TM 21 lumen maintenance projection method and their efficacies are compared. According to lower lumen depreciation anticipation, less energy delivery to LED for compensating depreciation is needed for CLOs designed based on proposed formula. By less energy consumption, using proposed comprehensive formula can lead to less CO 2 emissions.