Even state-of-the-art horticultural LED fixtures operating at high photosynthetic photon efficacy ($\ge 3.2\ \mu\text{mol/J}$) convert over $50–55\%$ of input electrical power directly into waste thermal energy. Unlike legacy High-Pressure Sodium (HPS) fixtures that radiate heat via infrared photons, LEDs dissipate thermal energy almost entirely via conduction to the rear aluminum heat sink.
1. The 1D Thermal Resistance Network
T_j = T_{amb} + P_{heat} \times (R_{th,j-c} + R_{th,c-s} + R_{th,s-a})
Operating diodes above $T_j > 85^\circ\text{C}$ accelerates phosphor degradation, causes red/far-red wavelength drift, and triggers irreversible semiconductor lattice degradation, slashing L90 lifetime from 65,000 hours down to under 28,000 hours.
2. Interactive Thermal Optimizer
Calculate junction temperatures and fixture derating using our online tool: