EPAct 179D Envelope Credit

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Dear List-
I am researching the EPAct ?179D Energy Efficient Commercial Buildings Tax
Deduction, specifically the segment for $.60 per square foot building floor
area for building envelopes that contribute to %50 better than ASHRAE 2001.
The main question I am attempting to figure out is if Phase Change
Materials could be used in conjunction with ASHRAE 90.1 2007 or 2010
prescriptive insulation and fenestration requirements (or better) to
achieve the tax credit. The projects that this would apply to are currently
going for LEED but may not be going for EPAct. I am trying to figure out
how the envelope contribution to the %50 better than ASHRAE 2001
requirement is segmented to understand if these projects could be
applicable for the credit due to the advanced Phase Change Material

I understand that the procedure to follow is ASHRAE 90.1 2004, and the
baseline to be 50% above is ASHRAE 90.1 2001.

- Question 1: Is the calculation for %50 reduction similar to the LEED
% of cost approach or if it is a % of energy basis?

The part I do not know is the multipliers to segment the envelope only
portion and associated modeling procedures. If this is based on minimum R
values and maximum U values than our product would not contribute to the
%50, while if it is based on %50 energy reduction from the baseline
envelope energy use than phase change materials could contribute to the
credit and receive the $.60 per square foot building area.

- Question 2: How is the envelope segmented from the HVAC and lighting
systems when applying for envelope only EPAct?

I have a budget to buy any required literature, but do not want to misuse
funds by buying unnecessary publications.

- Question 3: Should I get ASHRAE 90.1 2001 and ASHRAE 90.1 2004, or can
I find this info in the ASHRAE 2010 version I already own?
- Question 4: Is there any other reference materials that are advised
(free or purchased) to better understand EPAct rules and requirements?

Thank you in advance to anyone who shares their insights..

CleanTech Analytics's picture
Joined: 2012-02-09
Reputation: -1

1. i would recommend obtaining 90.1-2001 and 2004 as the requirements
of 2001 and the methodologies of 2004 differ from 2010.
2. don't forget 179d requirements over-ride requirements of 90.1.
3. do you have the 179d energy simulation guide? this one is free from
the nrel website. 40467.pdf is the name of it.
4. the irs bulletins on the revisions for partially qualifying have
changed over the years. most recently (02/12) with an option to use two
different percentage sets if the building is not fully qualifying until
12/31/2013. i.e. 10% building, 15% hvac/swh, 25% lighting OR 10%
building, 20% hvac/swh, 20% lighting. the old 16-2/3% for each
discipline expired at the end of 2008.
5. and if you're looking at partially qualifying don't forget a
partially qualifying is each discipline by itself so you can't have a
partially qualifying hvac/lighting only or hvac/arch. it would be one
simulation partially hvac, another partially bldg, or lighting. and in
the case of lighting you can use the interim lighting rules which
doesn't require simulation.
6. can't help you with the use of phase change materials.
7. the simulations start the same between leed and epact but a) you'll
see more savings with epact, b) the baseline requirements are different
(see the 179d simulation guide), and MOST importantly the 179d
certification is a certification of what is installed on the project.
i.e. who is field verifying what is there? you are. and you're
certifying this to the irs. this can make a large difference as far as
hvac due to your having field measure fan flow, motor volts, and motor
amps used. as these should be less than nameplate data you'll see more
energy savings. yes, i realize some of the language in 179d reads
equipment "that will be installed" but if you're using only catalog data
(which can differ from nameplate) due to trying to certify before the
building is constructed you won't see as much 179d savings. don't
forget you're also certifying building envelope installation and field
measured lighting levels (there are lighting contractors that can
provide this) per the 179d requirements.
8. the 179d savings are an energy cost savings basis. you have to
break out the percent cost of energy used by each discipline from the
total cost of the building based on the percentage energy used by each
discipline. see page 9 of the 40467.pdf from nrel.

9. remember you're only comparing energy for building envelope,
hvac/swh, and lighting. as misc/other energies are energy neutral they
don't impact your savings directly (unlike in leed).
10. solar pv savings do not apply to 179d, and neither does external
lighting (it's all internal lighting). we could have a lot higher
savings where i'm at if we could include external lighting due to
stringent site lighting reductions trying to keep our skies dark and
federally funded telescopes having great views. solar thermal (swh)
does apply.


Patrick J. O'Leary, Jr.'s picture
Joined: 2011-09-30
Reputation: 0