Never ending code cycle: And a patchwork of high-powered proposals
With the 2006 edition of the international codes barely off the press, the 2006-07 International Code Council’s code-change cycle has already begun. Although at the time this was written the ICC had not posted the record-breaking 2,300 proposals submitted for this cycle on www.iccsafe.org, it is possible to get an idea what the “hot” topics for glass and glazing will be, based on the preliminary code-change proposals already circulating.
Energy conservation once again will be one of the biggest topics. Issues to be addressed will include:
• Developing appropriate requirements for residential buildings
• Recognizing daylighting benefits in the International Energy Conservation Code
• Setting provisions for glazing in commercial buildings.
Energy ratings to the fore
Several proposals to revise the prescriptive provisions of the 2006 IECC for exterior glazed assemblies in commercial construction will be considered during the 2006-07 cycle. The primary focus of these proposals will be revision to the infamous Table 802.2(2), now designated Table 502.3 in the 2006 IECC. The development of this table during the 2003-04 cycle was a drastic change to the previous prescriptive provisions of the IECC for commercial fenestration. In many applications, products currently on the market simply could not meet the requirements of the resulting table. In response, industry lobbyists rallied back and successfully won some relief from these stringent requirements during the 2004-05 cycle.
The relief was achieved, in part, by providing separate U-factor requirements for metal-framed entrance doors and other glazed assemblies, from those that are not metal framed. The reason for these different requirements: the higher structural values metal framing provides, paired with the inherent higher U-factors of metal framed glazed assemblies.
Table 502.3, as it appears in the 2006 IECC, is the version of the table approved during the 2004-05 ICC cycle. Although this version of the table received strong support from the commercial glazing community during the last code-change cycle, other parties were not as enthusiastic due to its reliance on framing material. We will likely see more than one proposal to remove this connection from the table.
Beacon on skylights
We will also see proposals addressing the skylight portion of the table. Different U-factor and solar heat-gain coefficient limits are currently given for glass skylights than for plastic skylights, but the area of both types is limited to 3 percent of the roof area. Proposal would:
• Permit increasing the roof area percentage to 6 percent when automatic lighting controls are provided
• Establish one set of requirements for skylights, regardless of the type of material used.
We’ll likely see more than one proposal introducing the concept of “daylighting.” This could benefit the commercial-glazing industry. At present, the IECC treats glazed openings in the building envelope as a negative or debit on the building envelope balance sheet. Introducing the concept of daylighting, with its associated benefits of reducing lighting load and use of electricity, can help turn that debit into an asset, encouraging the use of exterior glazing in designing and building energy-efficient buildings.
Alternate labeling schemes
Another proposal to be considered this cycle that could be beneficial to the commercial glazing industry, if approved, would permit the use of the American Architectural Manufacturers Association’s AAMA 507 to determine the U-factor and SHGC of fenestration in commercial buildings, instead of labeling in accordance with the National Fenestration Rating Council’s NFRC 100 and NFRC 200. AAMA 507 gives the designer and glazier greater flexibility than reliance on the NFRC standards, because it provides a method of determining the separate U-factors for framing and glass, and then combines those based on the actual size and framing configuration in the proposed glazed assembly; so an overall U-factor for the entire actual assembly can be calculated. This method also provides the mechanical engineer for the building with more realistic U-factors for designing the building’s heating, ventilating and air-conditioning systems.
Multifamily residential buildings
The energy conservation requirements for multifamily residential buildings might also generate discussion in this cycle. At present, apartments, condos and assisted-living facilities four stories or less must comply with IECC provisions applying to one- and two- family dwellings and townhouses. These provisions consist of relatively stringent requirements for building envelopes, coupled with fairly liberal requirements for the HVAC and lighting.
Once these buildings breach four stories, however, they become commercial buildings under the IECC. At that point, the requirements for the building envelope, including exterior glazed assemblies, become less stringent in most cases, while the requirements for the buildings’ mechanical systems—that may include smoke control systems as well as heating, venting and air conditioning—and lighting systems become more complex.
Some parties contend that if the mechanical and lighting systems in these buildings meet the more complex requirements for commercial buildings, the requirements for the building envelopes should be less stringent, even if they remain four stories or less in height. At least one proposal to this effect will be discussed during the next code- change cycle.
Other parties argue that the more stringent envelope requirements of the smaller buildings should be applied to all residential buildings, regardless of their height or requirements met by the mechanical and lighting systems. The basis for this thesis: the energy-use patterns for residential spaces have grown similar, regardless of the height of residential buildings. These spaces tend to be occupied during the evenings and overnight, so heating and lighting emerge as dominant factors in overall energy use. The cooling and heating load is affected by the use of cooking appliances, laundry equipment and so forth. Some also argue that comfort levels are more critical in these buildings than in other types of occupancies. Multiple proposals to make the building envelope requirements of these types of buildings more stringent, regardless of building height, became topics of discussion during the previous code-change cycle and may prove controversial again.
Although there will surely be proposals of interest to our industry on topics other than energy conservation, it’s clear that energy-related proposals will be a dominant factor in this cycle’s discussion. All 2,300 proposals will be presented during two weeks beginning Sept. 20 in the 2006-07 ICC Code Change Development Hearings in Lake Buena Vista, Fla. The hearings will be followed by public comments, and the fate of each and every proposal will be determined during the ICC Final Action Hearings May 22-25, 2007.