I heard that the ASHRAE/IESNA 90.1-2001 standard was amended to adopt the lighting power densities in the 90-1-2004 standard, which are stricter. How is this addressed by the Commercial Buildings tax deduction program?

It is true that Addendum g is the 90-1-2001 standard changed the lighting power densities (watts/sq. ft.) to values that are now adopted in the 90.1-2004 standard, but the Commercial Buildings tax deduction provision recognizes the version of the 90.1-2001 standard that was in effect on April 2, 2003. This means the original published lighting power densities in Tables 9.3.1.1 and 9.3.1.2 are in effect as far as the tax deduction provision is concerned and not the vales in Addendum g and the 2004 version of 90.1. However, be sure to comply with all local and state codes, in addition to the applicable sections of the 90.1-2001 standard, if your project triggers the application of these local and state codes. (Source: http://www.lightingtaxdeduction.  more