Our project is in the process of determining the exterior lighting power allowance for an ASHRAE 90.1-2010 Appendix G energy model. What qualifies within LEED as a surface that is “designed to be illuminated” per ASHRAE 90.1-2010 Section 9.4.3?
ASHRAE 90.1-2010 Interpretation 33 states: “It was the intent of the Standard that spaces, areas, or applications that claim Lighting Power Density for compliance or performance rating have been designed to some reasonable lighting design criteria that meets industry standards, good design practice, and client desires.” Aligning with this intent, the average illumination of a surface “designed to be illuminated” must meet or exceed published minimum recommended illumination levels for the surface type (such as the IESNA Handbook, Zumtobel – the Lighting Handbook, EN1264-2, local code regulations, etc.).