We are evaluating several types of fixtures in the Utah State University Research Greenhouses. Our studies include upgrading older mogul-base HPS fixtures to double-ended HPS fixtures where broad, even distribution of photons is important, and installing LED fixtures where focused photons are important (plants on a single bench with wide spacing between benches). Diverse plant spacing among research projects mean that diverse fixtures types are useful.

Since the photon distribution from the Gavita DE-HPS fixture is considerably more focused than our older HPS fixtures from Sunlight Supply, in some applications we have achieved a 60 % reduction in electric power without a reduction in photon flux at plant level. http://cpl.usu.edu/files/...