Relative spectral emission of 1) a high-pressure sodium (HPS) lamp (in this case : Sunlux ACE, NH-360 FLX; EYE Lighting, Wacol, Queensland, Australia) and 2) in this case : light-emitting diode (LED) 4000 K color temperature high bay lamp (LUXEON M, LXR7-SW40; Koninklijke Philips, Amsterdam, The Netherlands). Emission spectra are normalized to the spectrum with the maximum intensity and were kindly provided by each manufacturer.