Energy Code Information for Builders and Contractors

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The new Montana Energy Code came into effect on November 7, 2014. Local code jurisdictions begin phase-in periods starting November 7, 2014, which ranged up to 90 days. Outside of code jurisdictions, provisions of the Energy Code become effective as of November 7, 2014.

This updated Energy Code essentially is the state's adoption of the 2012 International Energy Conservation Code (IECC) with amendments specific to our region and climate. As in the past, the code continues to provide minimum requirements for the efficient design and construction of new and renovated homes. The Montana Residential Energy Code Handbook is a guide to complying with the statewide energy code. Or, visit the Montana Residential Energy Code Summary Booklet.

What's New for Builders

A major code change is the requirement for air tightness testing for all new homes. The one-year delay for testing the integrity of the building envelope for air leakage (blower door testing) ended on November 7, 2015. Some jurisdictions may allow projects that had plans submitted before the adoption date to be exempt from the requirement. For a listing of people available to perform blower door tests and local building industry association offices that have a blower door, duct testing, and infrared cameras, visit the Blower Door Test page.

Blower door equipment are available to builders through local building industry associations.

Builders and contractors are encouraged to contact their local association to learn the details of using these blower door testing devices. Some associations may require training in the use of the test kits before they can be checked out for specific projects. This manufacturer's video is a good introduction to blower doors with a second part that offers data interpretation.

Contact information for the local associations is available at the Montana Building Industry Association (MBIA) website.

Within code jurisdictions, testing may be required to be performed by an approved third party.

Builders and contractors who self-certify:

A 16-component visual Air Barrier and Insulation Installation Checklist is available to review the integrity of the envelope, including: ceilings and attic; walls; windows; rim joists; crawl spaces; and envelope penetrations (plumbing, lighting, electrical boxes, etc.).

The building tightness standard is targeted at 4 air changes per hour (measured at 50 Pascals pressure control), or 4 ACH50. This is a Montana amendment to the 2012 IECC, which recommended 3 ACH50.

In certain instances, builders must perform ductwork sealing tests.

When part of the heating ductwork is located in unheated/unconditioned space, such as in a garage or attic, the entire ducting system must be tested for tightness. Further, the new code requires that all ducts be sealed with code-accepted mastic or UL listed tapes. Manufacturer recommendation for mastic application is 1/16th-inch thick, about the thickness of a nickel. Testing, when required, may be at rough-in, or at post-construction.

Ductwork does not have to be seal-tested when the ducts and air handler are entirely within the building thermal envelope. A Montana amendment to the code allows building cavities to serve as return ductwork. Supply ductwork must be a discrete system separate from the building cavity.

Whole-house mechanical ventilation is new and constitutes one of the more significant changes to the Energy Code.

Functionally, efficient exhaust ventilation is required at a rate appropriate to dwelling square footage. For example, a 2,500-square foot, 3-bedroom home would require 60 cubic feet per minute (CFM) of continuous ventilation. Homes that rely on intermittent ventilation must feature greater ventilation capacity.

Other significant changes with the new energy code (2012 IECC) include:

  • More efficient windows and skylights;
  • Additional air sealing, air barriers, and insulation requirements;
  • At least 75 percent of permanent light fixtures must have high efficiency bulbs, such as CFSs and LEDs.
  • Testing requirement for heating system ductwork located outside of the conditioned (heated) part of the house is more stringent.
  • Whole-house mechanical ventilation required for all new houses.

Minimum local exhaust capability in kitchens and bathrooms is also called for in the new code. A balanced ventilation system that neither positively pressurizes nor negatively pressurizes the living space is most preferable, since such systems may recover some heat from exhausted air. These centralized heat recovery systems are more costly, however.

While this is a brief summary of major code changes, it should be noted that heating and cooling equipment must be sized according to a code-acceptable procedure. While not a code change, proper mechanical sizing is an important consideration in residential construction. Consult the ACCA Manual J Brochure for more details on heating plant efficiency.

For more information on the residential Energy Code, please review this training presentation.