Navigating the Energy Code for Steel Framing

Many Paths to Acceptance

The State of Hawaii has adopted the 2015 International Energy Conservation Code (IECC) with amendments (Hawaii Energy Code). Currently, the four counties in the State are going through the adoption process with their own local amendments, and soon all will have to comply with this newer version of the Energy Code. With the adoption of every new code, there usually is some confusion as to what the new requirements are, and the requirements for steel framed construction is no exception. Fortunately, the Hawaii Steel Alliance participated in the committee meetings of the State Building Code Council to make sure that steel framing remains on a level playing field with other building materials. 

One of the disadvantages of the 2015 IECC is that Hawaii is considered located in Climate Zone 1, a category also shared with South Florida, Guam, Puerto Rico, and the Virgin Islands. We all know here in Hawaii that our climate is not the same as the other regions, that is why we worked aggressively to help develop amendments to the 2015 IECC to take advantage of the unique characteristics of Hawaii’s climate. Based on our efforts, it is not difficult for steel framing to comply with the Hawaii Energy Code.

If you follow the basic path to compliance in the Energy Code (Sections 401.3 through R404) steel frame wall assemblies need to comply with Table R402.2.6 that requires, in addition to walls needing R13 insulation between the studs, a minimum of R4.2 continuous foam on the outside of the wall (about one inch). Contractors that have already built homes using continuous foam in Hawaii have found an increase in cost from framing thicker walls, door frames, thresholds and window openings. They have increased the amount of waste on the jobsite resulting from cutting foamboard insulation on the project. Also, there is a long payback in savings in Hawaii resulting from this additional insulation of approximately 40 years when you run models comparing energy bills versus the cost of construction. Fortunately, there are ways to avoid installing continuous foam, and still comply with the Hawaii Energy Code.

One alternative path is by using the Tropical Zone provisions (R401.2.1). In order for a home to be considered in a Tropical Zone, not more than one-half of the dwelling unit can be air-conditioned. Ceiling fans or ceiling fan rough-ins must be provided for the bedrooms, and the largest space that is not used as a bedroom. Air leakage for the air-conditioned space must be considered, and other provisions addressing glazing, lighting, and skylights must be met. The Tropical Zone only applies to residential buildings at elevations below 2,400 feet.

 A second alternative path is using simulated performance analysis software (Section R405). Software such as Rescheck will almost always pass steel frame structures in Hawaii by concentrating on trading off the fenestration U-factor. The maximum U in the 2015 prescriptive table is 0.50. Most windows on the market today will be at least half that so one may get enough out of the windows to effectively trade off the continuous foam insulation. 

Perhaps the easiest way to satisfy the Hawaii Energy Code is by using the third alternative, or the Points Option in Section R407 of the amended code. Using this method there are a list of options that one can choose from to allow the home to comply. Using the Points Option, you need to have total cumulated points equal to or exceeding zero points. For steel framed walls you start off with -1 points, but you can trade that off by adding points for using high efficacy lighting and Energy Star Appliances (e.g. refrigerators, washing machines, and dishwashers), installing ductless air conditioners,  using SEER 15 AC equipment, building tiny houses (smaller than 1,000 SF, installing energy star fans, or using solar PV. As long as you come up with a total of zero points or above, the design will satisfy the Hawaii Energy Code.

Look for notices on upcoming seminars that will be conducted by the Hawaii Steel Alliance that will further explain how steel frame structures can easily satisfy the 2015 Hawaii Energy Code.