AN EVALUATION OF THE ENERGY AND THERMAL IMPACTS OF A TRANSITION TO LED LIGHTING IN CONTROLLED ENVIRONMENT GREENHOUSES

A large portion of greenhouse overhead costs are attributed to the energy it takes to maintain an ideal growing environment, especially in climates where heating and supplemental lighting are a necessity. A lack of research on this topic leaves uncertainty about which variables to consider when justifying a change in supplemental lighting type. Using Engineering Equation Solver, nightly heating requirements were determined for a range of outdoor temperatures. This data was used in a MATLAB solver to calculate annual nightly heating contributions from High-Pressure Sodium (HPS) and LED lighting arrangements for different locations. Computational Fluid Dynamic analysis was performed to compare steady-state internal air temperatures for HPS and LED arrangements. It was found that HPS lamps contributed the most heat energy to the greenhouses. A measurable penalty was found for using LED lamps. Regression analysis revealed that the total lighting hours correlated most with the significance of this LED penalty.