2006 IECC vs. ASHRAE 90.1-2004

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Hello, all,

Does anyone know of a study that has compared the equivalency of the 2006 edition of the International Energy Conservation Code (IECC) compared to ASHRAE Standard 90.1-2004? It seems to me that they are roughly equivalent...The State of Wisconsin allows either one to show compliance with its energy code. Is there something credible I can refer to that states that they are essentially equivalent? An admittedly quick search I did came up with only some lighting comparisons.

Keith Swartz, P.E., LEED AP

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IECC 2006's Section 501.1Scope states
"...commercial buildings shall meet either the requirements of
ASHRAE/IESNA Standard 90.1, Energy Standard for Buildings Except for
Low-Rise Residential Buildings, or the requirements contained in this
chapter."

Therefore complying with ASHRAE 90.1-2004 is complying with IECC 2006.

Chris Baker, AIA, EIT, LEED(r) AP

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I would add a nuance to your conclusion Chris: ... "Therefore complying
with ASHRAE 90.1-2004 is one way of complying with IECC 2006."

The two publications do have their differences (notably with regard to
certain lighting controls and 90.1's space-by-space LPD table) that may
make one preferable over the other if and when you have the choice.

Here are a few differences that are fresh in my mind:

- A strict reading of IECC 2006 requires manual control in all
spaces, with exceptions to corridors and security concerns. 90.1-2004
however offers the flexibility to use just automatic controls (like a
ceiling occupancy sensor) in some spaces if manual control is not
desired.

- The two publications also diverge in regard to additional
controls required should you decide to have the interior lighting
automatically shut off via timeclock.

- 90.1-2004 has a lengthier list of situations where lighting
may be exempted when totaling the interior lighting power. Some are
significant depending on your project (i.e. "Casino Gaming Areas")!

The two are "roughly equivalent" in the sense that they have roughly
equal degrees of stringency, but if the systems' designer is given the
choice the best answer would be to become familiar with both to ensure
you're using the most appropriate standard during design. COMcheck may
be a useful tool mid-design to quickly generate two reports under the
two standards to identify some of the differences, though I would
caution that it may not pick up all the subtleties...

NICK CATON, E.I.T.

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