ICC Code-change Proposals
The 2013 International Code Council Group B Code Development Hearings recently took place in Dallas, where code officials reviewed numerous proposals for changes to the 2015 International Energy Conservation Code, 2015 International Existing Building Code and 2015 International Residential Code, among others. Following is a report on the more significant results of these hearings, with regards to commercial construction.
Proposal: Increase threshold for mandatory daylighting
Effect: Increases the number of overall buildings where mandatory daylighting would apply and creates an incentive for building designers to provide daylighting by way of vertical glazing
The 2012 IECC requires toplighting, combined with automatic lighting controls, in public spaces greater than 10,000 square feet in area, with ceilings that are 15 feet or higher. Multiple studies, including one commissioned by the American Architectural Manufacturers Association in 2005-2006, show that energy savings of as much as 30 percent to 40 percent can be achieved by combining skylights with automatic lighting controls that reduce the amount of artificial lighting provided when not needed.
During the current codechange cycle, multiple proposals recommended decreasing the size of the space to which these toplighting requirements would apply. AAMA supported a proposal that not only reduced the threshold from 10,000 square feet to 2,500 square feet, but that also added an exception for spaces whose total area, minus the area sidelited by vertical fenestration, is less than 2,500 square feet. This proposal not only increases the number of overall buildings where mandatory daylighting would apply, it also creates an incentive for building designers to provide daylighting by way of vertical glazing. This proposal was approved by the IECC Commercial Committee during the code development hearings.
Proposal: Adjust calculation for maximum-permitted solar heat gain coefficient in commercial buildings
Effect: Eliminates the 2012 IECC calculation anomaly in which a higher maximum SHGC can occur in eastern, southern and western orientations than in northern orientations
The provisions of the 2012 IECC contained somewhat of an anomaly with regards to determining the maximum solar heat gain coefficient permitted for fenestration in commercial buildings. Due to the manner in which the maximum was to be calculated, a higher maximum SHGC could actually be permitted in eastern, southern and western orientations than in northern orientations.
Two proposals were submitted to address this. One proposal removed consideration of glazing orientation entirely from the calculation of maximum-permitted SHGC. The other proposal, which AAMA supported, kept consideration of orientation and projection factor in the calculation, but adjusted the base SHGC as needed to remove the anomaly. Consideration of both orientation and projection factor is appropriate in determining maximum-permitted SHGC, since both affect the amount of solar energy to which the glazing is exposed. The latter proposal was approved.
Proposal: Revise the criteria for the evaluation of dynamic glazing in commercial construction
Effect: Creates a range of solar heat gain coefficients that allows for a low SHGC on hot summer days when it is desirable to block the sun’s heat and light, in addition to allowing for more heat and light transmission on bright winter days when appropriate
Another proposal that was supported by AAMA, and approved at the CDH, revised the criteria for the evaluation of dynamic glazing in commercial construction. The 2012 IECC states that in order to comply with the prescriptive requirements for maximum SHGC in commercial buildings, the SHGC of dynamic glazing shall be the manufacturer’s lowest rated SHGC, and the Visible Transmittance /SHGC ratio shall be the ratio of the maximum rated VT to maximum rated SHGC. The 2012 IECC does not have any criteria for VT/SHGC ratio, so this text basically just evaluated dynamic glazing based upon its lowest SHGC rating.
The approved proposal states that dynamic glazing will satisfy the prescriptive maximum SHGC requirements of the IECC for commercial construction if the ratio of highest SHGC rating to lowest SHGC rating is at least 3, and the dynamic glazing is automatically controlled to modulate the amount of solar gain into the space, in multiple steps. This range of solar heat gain coefficients allows for a low SHGC on hot summer days when it is desirable to block the sun’s heat and light, in addition to allowing for more heat and light transmission on bright winter days when appropriate. In order for this type of glazing to contribute to the energy efficiency of the building in a passive manner that does not depend upon the building occupants, it must be automatically controlled, as required by the approved proposal.
Proposal: Require building designers to designate which areas of a building are in daylight zones
Effect: Assists the lighting designer and code official in ensuring lightingcontrol requirements are met
A proposal that requires the building designer to designate which areas of a building are in daylight zones was approved. The 2015 IECC will require separate lighting controls for daylight zones and non-daylight zones. Having these areas designated on the building plans will assist the lighting designer and code official in ensuring this requirement is met.
At this point, anyone who would like to challenge the results of the 2013 CDH can do so via public comment. Public comments are due, July 15, and will be heard during the Final Action Hearings, October 2-9, in Atlantic City, N.J. AAMA members will be meeting to discuss possible public comments from the association over the course of the next few months.