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Tips For Better Understanding Commercial Energy Codes For Metal Buildings

By Bill Beals, Therm-All Inc.

1. Understand the basics.

I’m sure you’ve heard of ASHRAE 90.1 and IECC, but what exactly are these requirements? Well, for starters, ASHRAE, or the American Society of Heating, Refrigerating and Air-Conditioning Engineers, mandates a minimum energy standard, not a code. The International Energy Conservation Code, or IECC, on the other hand, is just that – a code.

The author, Bill Beals, is a frequent presenter on energy codes in a variety of venues.

So, what’s most important to know when it comes to these two? First, the IECC adopts the latest ASHRAE standard plus any addendums and new data, so ASHRAE 2013 = IECC 2015. The IECC also increases the envelope performance values, ultimately making it a more stringent requirement than the ASHRAE standard. Keep in mind that IECC 2015 has yet to be mandated for any state; the most common standard is still ASHRAE 2010/IECC 2012. Last, it’s key to remember that ASHRAE and IECC follow different three-year cycles, which explains the constant adoption changes across the country.

When it comes to what’s contained in any energy code requirement, there are three major sections: Lighting, HVAC and Envelope. As insulation specialists, we’re predominantly concerned with the building envelope. There are several elements within the building envelope that are subject to energy code regulation, including opaque roof and wall assemblies, windows, skylights, doors, foundation and floor.

2. Find the information you need.

Finding the specific thermal performance values of roof and wall assemblies can be difficult. Do you start with ASHRAE, the U.S. Department of Energy (DOE), or just resort to Google? Well, search no more. You can locate U-Factor information in the following sections of the 2009 IECC:

Commercial Energy Efficiency – Section 502.1.2

Commercial Energy Efficiency – Section 502.2(1)

The following footnote, which can be found in Section 502 (Building Envelope Requirements – General), is important to bear in mind when calculating your building’s code requirements:

502.1.2 – U-Factor Alternative: “An assembly with a U-Factor equal or less than that specified in Table 502.1.2 shall be permitted as an alternative to the R-Value in Table 502.2(1)”.

3. Know the key to compliance.

This is probably the single most frequently asked question I receive. “What is the most important thing I need to know in order to meet the codes?” When it comes to insulation, the key to compliance is in the roof and wall assemblies.

Zone 4 walls = R13 ci (Board/Thermax) + R13 Fiberglass OR U-Factor of 0.052 (installed R-Value of 19.2)

Other options:

1. OptiLiner™ (Liner System) R30 (9” fiberglass) and foam tape = U-Factor of 0.049

2. Insulation board (thickness dependent on R-Value per inch)

3. Insulated panel (thickness dependent on R-value per inch)

Zone 4 Roof = R19 + R11 Liner System with thermal block OR U-Factor of 0.035 (Installed R-Value of 28.6)

Other options:

1. High-R Banding (Filled Cavity) R25 + R19 with thermal block = U-Factor of 0.029

2. Insulation board or insulated panels (thickness dependent on R-Value per inch)

Now that we’ve covered where to find the prescriptive assemblies, let’s take a closer look at the most common systems used to the meet them.

Liner System: Walls

NOTE: Liner System wall testing performed by Owens Corning and can be used for code compliance. Values are NOT found in ASHRAE tables.

It’s important to understand that the wall values as described in the IECC 2012 code are suggested methods to meet the U-Value for that climate zone (i.e. R-13 plus R-13 Continuous). The overall U-Value for this combination is U-0.052. Most builders do not realize that any system Hot Box tested with a U-Value equal to or better than any climate zone U-Value is also allowed. This information can be found in Chapter 4 section C402.1.2 of the IECC 2012 Code.

Liner System: Roof


My most frequently stated tip for better understanding prescriptive roof assemblies is to remember that the assemblies assume a standing seam roof with a thermal block is used. Though it’s fairly straightforward, builders often forget about this underlying assumption.

4. Understand COMcheck™.

COMcheck is the U.S. Department of Energy (DOE)’s commercial energy compliance tool that essentially tells a user whether or not a building meets the requirements of the International Energy Conservation Code (IECC) and ASHRAE 90.1, as well as state-specific codes. COMcheck is a software that can be downloaded for Windows® and Mac® and it supports the 2006, 2009 and 2012 IECC as well as ASHRAE Standard 90.1: 2004, 2007 and 2010, and various state codes.

COMcheck is a performance method, which means that it provides the building’s overall performance requirement and replaces the individual prescriptive requirements for building envelopes and assemblies. It is also known as the “trade-off” method. Builders often prefer the performance method over the prescriptive, as it allows more flexibility with the building envelope.

Although this may seem obvious, it’s important to remember that a building must be constructed exactly to what’s specified in the COMcheck report, as there may be a final inspection of the building after the report has been issued. If there are discrepancies between the report and what has been installed, you may be required to fully redo the install.

COMcheck is an extremely useful tool for metal building construction industry professionals. While it is helpful, it can also be overwhelming. Therm-All representatives undergo extensive training in COMcheck and are able to provide you with a custom COMcheck-based solution for your next job. Call 888-2-INSUL8 to reach the closest Therm-All representative.

About The Author

Bill Beals, District Manager of Therm-All Insulation, is a 28-year veteran of the metal building industry. He is a contributing member of several committees, including the Metal Building Manufacturers Association (MBMA) Energy Committee and the National Insulation Association (NIA) Laminators Committee. Beals also belongs to the International Code Council (ICC) and often makes presentations at industry conferences, including The 45th Annual Metal Building Contractors and Erectors (MBCEA) Conference. He has contributed to many articles and reference guides, and authors Therm-All’s bi-monthly commercial energy codes blog called “The Code Man”; click here to subscribe to the blog.

About Therm-All

Therm_All_logoTherm-All offers a full line of custom fiberglass and rigid insulation systems, reflective insulation, door and window systems, vapor retarders, OSHA-compliant safety systems, metal building accessories, insulation retrofit and more. To learn more, visit www.therm-all.com.

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