Green Codes for Low-Rise Residential Construction Up for Debate

Julie Ruth
May 23, 2014
COLUMN : Code Arena | Codes & Standards

While more than 1,200 codechange proposals were submitted for the 2012 International Green Construction Code, fewer than 600 were submitted for the 2015 IgCC. However, some of these proposals are challenging the code’s basic parameters.

Among them is the relationship between the 2015 IgCC and the International Code Council 700/National Association of Home Builders National Green Building Standard, ICC 700/NAHB NGBS. The scope of ICC 700/NAHB NGBS is the residential portion of any building that is not classified for institutional use. It addresses the building itself, as well as the building site and subdivisions, if applicable.

The scope of the 2012 IgCC, on the other hand, is all buildings and their sites. An exception is provided for single-family homes, duplexes and townhouses that are three stories or less in height, as well as residential care facilities and apartment buildings that are four stories or less in height. But the exception only applies if the adopting jurisdiction chooses ICC 700/NAHB NGBS instead of the IgCC for these types of buildings. If the adopting jurisdiction does not specifically make this choice, then the IgCC applies to all types of residential and commercial buildings.

Proposals to remove these provisions from the IgCC were under consideration at the ICC Group C Code Development Hearings in Memphis as this issue went to press. If these provisions are removed, then the scope of the IgCC will be limited to high-rise residential and commercial buildings, and will not address low-rise residential construction. In that case, the choice to adopt a green code or standard for low-rise residential construction will need to be separate from the adoption of the IgCC for commercial construction. If the provisions are retained and an adopting jurisdiction does not choose to use ICC 700/NAHB NGBS for low-rise residential construction, then the provisions of the IgCC will apply.

The latter would include IgCC provisions such as those under discussion at the current hearings. These include the status of Life Cycle Assessment and the various components that go into performing that type of analysis, prescriptive and performance design for energy efficiency, electives available to an adopting jurisdiction and to the building designer, dynamic glazing, shading devices on fenestration, automatic glare control of glazing, bird-impact reduction and the building envelope’s acoustical performance.

The code change committees that hear the proposals can vote to approve them as submitted, approve them as modified, or disapprove them. Interested parties are able to offer suggested floor modifications for the committee’s consideration. If an assembly action is called for after the committee votes, that motion will be tabled for one week. During that one-week time period, all registered members of the ICC will be able to vote on that action online. If the assembly action is successful, a public comment on the committee action will be automatically included on the agenda for the public comment hearings in the fall.

Code Arena is brought to you by the America Architectural Manufacturers Association. Julie Ruth may be reached through AAMA at 847/303-5664 or via e-mail at julruth@aol.com.

  • State Code Amendments

    While the development of the 2015 IgCC proceeds this year, more widespread adoption of the 2012 I-codes is occurring. Some jusridictions amend them quite extensively. Among them, Florida and California.
     
    Florida recently completed the adoption process for the 2012 International Codes, which resulted in the 2014 Florida Building Codes. Among the more significant amendments is revision of the design wind speed model used in the 2012 IRC. As a result, both the 2014 FBC and 2014 Florida Residential Code will use Strength Design to determine the required design pressure rating for components of the building’s exterior envelope. This means that the required design pressure ratings in both the 2014 FBC and the 2014 FRC will need to be multiplied by 0.6 for the purposes of comparison to the AAMA/WDMA/CSA 101/I.S.2/A440 label. AAMA, WDMA and DASMA have written a joint technical paper on this topic, available here: www.aamanet.org/general/1/447/design-wind-loads.
     
    The targeted implementation date for enforcement of the 2014 FBC is December, 2014. California has completed its adoption process for the 2012 IC, resulting in the 2013 California Building Code.
     
    The most significant California amendments to the 2012 IC are those made to the 2012 International Energy Conservation Code. California previously relied on its own energy code and didn’t adopt the IECC.
     
    The primary impact of California’s fenestration amendments is that one prescriptive U-factor or SHGC is applied throughout all or most of the state, rather than varying by climate zone. In many cases, the more stringent value from Climate Zone 3 or 4 is used, e.g., the prescriptive maximum U-factor for residential fenestration is 0.32. This is consistent with the prescriptive maximum U-factor for residential fenestration in Climate Zone 4 in the 2012 IECC. But the prescriptive maximum residential SHGC for most of the state is 0.25. This is consistent with the prescriptive maximum SHGC for residential fenestration in Climate Zone 3 of the 2012 IECC.
     
    California has retained the performance path for both residential and commercial construction. This path permits a building owner to make tradeoffs between building envelope components such as fenestration vs. wall or roof insulation.