Decoding the New Minnesota Energy Code: Part 2

Kraus-Anderson construction professionals, architects and engineering firms learned about the 2015 Minnesota State Building Code through training developed by MEP Systems Coordinator Matt Stringfellow.

Stringfellow presented the AIA-accredited class at the Duluth Building Green Conference on September 14 and the Minnesota Educational Facilities Management Professionals Association 2016 Fall Conference in St. Cloud on September 29.

What Are the Highlights of the New Code?

Matt Stringfellow: The 2015 Minnesota Energy Code allows designers to choose a prescriptive or performance compliance path under the 2012 International Energy Conservation Code, or IECC, or the optional ASHRAE 90.1-2010 Energy Standard for Buildings Except Low-Rise Residential Buildings.

ASHRAE 90.1-2010 also includes a subcompliance option within its prescriptive path, called the Building Envelope Trade-Off Option. This option allows designers to vary the performance of building-envelope components within the rules of the standard.

The 2012 IECC prescriptive path limits vertical vision glass to 30% of gross above-grade wall area. The limit can increase to 40% when daylight controls are used across 50% of the building’s conditioned floor area.

The ASHRAE 90.1-2010 prescriptive path allows vertical vision glass up to 40% of gross wall area.

In addition to envelope requirements, both the 2012 IECC and ASHRAE 90.1-2010 include performance requirements for mechanical systems, service-water-heating equipment, electrical systems and other building equipment.

What Is the Difference Between Prescriptive and Performance Compliance Paths?

Stringfellow: The prescriptive compliance path tells the design team what performance criteria are acceptable for specific building components and systems. Examples include:

• R-values for wall insulation
• U-values and solar-heat-gain coefficients for windows
• Acceptable continuous air-barrier materials and assemblies
• Required mechanical-equipment efficiencies
• Allowable lighting loads in watts per square foot
• Other requirements that affect building energy performance

Many of these requirements vary by climate zone.

The performance compliance path allows the design team to vary architectural and engineering components in a proposed design, then compare the proposed building against a standard reference design defined by the code.

Under the performance path, the proposed building must have an annual energy cost equal to or lower than the reference building. The analysis must use an advanced energy-modeling program, such as DOE-2 or BLAST, and the results must be documented for the local code official.

Designers must select a compliance path that fits the goals of their particular building project.

The 2012 IECC was based on the ASHRAE 90.1-2010 Standard, so the documents include many similar requirements, along with some differences. The energy-code training includes a side-by-side comparison of prescriptive requirements under both options to help designers understand their choices.

What Was the Biggest Change From the Previous Code?

Stringfellow: The single largest change was the 30% vertical vision-glass limitation in the 2012 International Energy Conservation Code.

What Was KA University’s Role in the Training?

Stringfellow: KA University, led by Mike Smoczyk, identifies current educational needs, identifies instructors, provides a structure to support class development and delivery, and offers related support.

KA University also provided instruction on effective teaching methods.

What Feedback Did Participants Share?

Stringfellow: Feedback was consistently positive. The most useful elements were the outline of available compliance paths, the main steps required for each path and the side-by-side comparison of the two prescriptive paths.

Each participant received a desk reference based on the presentation.

What Did the Training Experience Demonstrate?

Stringfellow: The design and construction community is a relatively small, integrated group of professionals, regardless of location.

When a professional-education need arises within an organization, it can also provide an opportunity to share knowledge with others in the industry, add value and build new relationships.

Learn more about Minnesota Energy Code requirements, Part 1, Minnesota Energy Code requirements, Part 2, mechanical, electrical and plumbing services and building science services.