

Published in 2015, this document is an update to the previous RP-33 and RP-28 standards specifically regarding exterior environments. The Illuminating Engineering Society (IES) is the recognized technical authority on illumination. Their "Recommended Practices" (RP) are not merely suggestions; they are often adopted by building codes, insurance requirements, and municipal ordinances.
If you are an experienced designer, you might remember the old standard, IES RP-33-99 (Lighting for Exterior Environments) . The shift from RP-33 to RP-37 in 2015 was significant. ies rp-37-15 pdf