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IECC compliance paths

QuestionThat

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Mar 26, 2019
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Greenville
Are there in reality 3 different compliance paths to meet IECC requirements?
1. Prescriptive method
2. Total building performance method. Meet minimum "prescriptive" requirements for each component then demonstrate compliance through energy model. Would comcheck generally be accepted as demonstrating compliance?
3. Alternative compliance path. Demonstrate through energy model that ASHRAE 90.1 is satisfied. Would comcheck generally be accepted as demonstrating compliance?
 

RLGA

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Oct 18, 2009
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Phoenix, AZ
Per the 2018 IECC, Section C401.2:
  1. Using the requirements of ASHRAE 90.1-2016.
  2. Using Sections C402 through C405, which include prescriptive requirements using one of the following for building envelope:
    1. R-value-based method
    2. Assembly U-factor, C-factor, or F-factor-based method
    3. Component performance alternative
  3. Complying with air leakage, some mechanical, and all of the requirements for water heating, electrical and lighting, total building performance, and commissioning, provided the energy cost will be 85% or less of the standard reference design building.
For 1, 2.3, and 3 you could possibly use ComCheck. For 2.1 and 2.2, there is no need for ComCheck in determining building envelope compliance, but you may need it for the mechanical, water heating, electrical and lighting compliance, which your consultants could use.

To my knowledge, my clients have never had a problem using a ComCheck report for showing compliance during a plan review.
 

QuestionThat

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Mar 26, 2019
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61
Location
Greenville
Thanks Ron. I appreciate this info as it will definitely be helpful going forward but I should have clarified that for this project I'm working with 2009 IECC and ASHRAE 90.1- 2007.

Here's where I am with this.....
I have been approached by our mechanical engineer that we should consider utilizing the ASRAE 90.1-2007 compliance path rather than IECC 2009 prescriptive (and I'm assuming the total building performance method option....).
The rationale is that by doing so we can eliminate the airside economizer in RTU's requirement that he is not recommending for this project.
What I'm trying to assess is how making this decision affects me as to the documentation we will need to provide.

As I look through ASHRAE 90.1-2007 it appears to me that a lot of what is contained there has for all practical purposes been copied into the IECC 2009. Haven't been through this with a fine tooth comb but betting that the tables & data align closely..... and thinking that they are basically describing (notes and all) options to prescriptive path, total building performance and ultimately the ASHRAE 90.1-2007 compliance path described in the IECC.
I believe that what I need to be looking into to use the ASHRAE 90.1-2007 compliance path that will ultimately get our engineer away from the airside economizer is near the back of 90.1, Section 11 "Energy Cost Method" but not sure. Do I need to be looking elsewhere? Could the ASHRAE specific prescriptive path (or total building performance method) get him there as well..... maybe because an older code (ASHRAE 2007 vs IECC 2009). What else could I be missing?

If we choose to go ASHRAE 90.1 to give our engineer what he requests, what are we up against?
Any specific coordination going to be required with/ between our engineering consultants?
Does taking this approach lend itself to comcheck with the separate disciplines using their separate analysis?

Can you help me to get my head wrapped around some of this?

Thanks!
 

RLGA

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Oct 18, 2009
Messages
2,662
Location
Phoenix, AZ
Section 501.2 (2009 IECC) allows two alternatives:
  1. Comply with Sections 502, 503, 504, and 505 in their entirety. Section 502 provides two approaches for building envelope:
    1. R-value method per 502.1.1.
    2. U-factor alternative.
  2. Comply with ASHRAE 90.1-2007 in its entirety.
I don't have a copy of the 2007 ASHRAE 90.1, but the 2013 edition does have requirements, but I'm not sure if they're been added or modified since 2007. It appears the use of economizers depends on the Climate Zone for both, but there are differences. What Climate Zone is the project located in? Also, the IECC breaks things down into "Simple HVAC Systems and Equipment" and "Complex HVAC Systems and Equipment." The RTUs would appear to fall into the "Simple" category.
 

QuestionThat

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Mar 26, 2019
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Greenville
Zone 3.
Can't speak to simple vs complex HVAC systems.
Any understanding about how ASHRAE 90.1-2007 Chapter 11 factors in to all of this.
I think this is a separate topic so going to post as such....
 
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