Hi John,

Thank you for your question.

The benefit is up to $1.80 if the building addition as a whole is 50% more efficient than the baseline (ASHRAE 90.1-2001).

If two systems get you to 50% you can get the $1.80.

In general, you need a little help from the 3rd system, in this case the envelope, to get to that $1.80 so the $1.20 is more likely.

Also, if we are just looking at heating, as opposed to heating and cooling, the threshold is a little more difficult to outperform.

If the lighting is changed in the existing building the $.60 could be extended to the entire facility which would increase the amount of the deduction.

The interim rules for lighting would be the most economical but does have an extra requirement of bi-level switching. Bi-level is the ability to dim either via a dimmer or fixtures on different switches so you have something between all the way on and all the way off.

Let me know if you have any other questions.

Related Advice:

• Exceeding ASHRAE 90.1: Challenges to Deductions for Subsystems in 179d?



• LED Lighting and Section 179d Tax Deductions: Everything You Need to Know



• Section 179D Analysis: Where Can I Find a Qualified Entity?



• Section 179d: Green Building Tax Deduction Contractors



• Section 179d: What About Exterior Lighting Retrofits?



• Tax Returns for 179d EPAct: Taking Advantage of Energy Efficiency in Prior Years



• Section 179d Qualified PE Engineers: Where do I Find Them?