The historic Shaheen-Portman energy bill making its way through the U.S. Senate enjoys rare and broad bipartisan backing, with the likes of Earthjustice and the Vinyl Siding Institute both announcing full-throated support. But the American Institute of Architects (AIA) and more than 350 other organizations have warned that they will fight Shaheen-Portman (a.k.a. the Energy Savings and Industrial Competitiveness Act of 2013) if a certain amendment is adopted.

Thanks in part to a handful of energy-efficiency advocates, that amendment may very well pass. The proposed amendment guts a hard-won provision of the 2007 Energy Independence and Security Act (EISA)—a few paragraphs in Section 433 targeting the eventual phase-out of fossil-fuel-generated energy in federal new construction and major renovations by 2030. Dubbed “The All-of-the-Above Federal Building Energy Conservation Act of 2013” by its cosponsors John Hoeven (R–North Dakota) and Joe Manchin (D-West Virginia), the proposed amendment is currently under committee review as a standalone bill and has strong support from the American Gas Association (AGA).

EISA “is all about advancing efficiency in federal buildings, and we are all for that,” explains Paula Gant, vice president of regulatory affairs at AGA. “We feel strongly that natural gas is a part of that.” The Hoeven-Manchin bill proposes three major changes to EISA. First, it redefines “major renovation,” shifting away from a cost-based definition to one based on energy performance. Second, the proposal focuses on efficiency instead of fuels, requiring new construction and major renovations to be designed for a 30 percent reduction in energy use compared with current ASHRAE 90.1 or International Energy Conservation Code (IECC) standards. Third, it extends the timeline for reducing actual energy consumption in federal buildings, requiring a 45 percent decrease in energy use intensity (EUI) by 2020.

“Section 433, because of the way it’s structured, doesn’t really save much energy until 2025,” argues Steven Nadel of the American Council for an Energy-Efficient Economy (ACEEE). The group recently published an analysis of all the potential amendments to Shaheen-Portman, concluding that “as currently written, Section 433 is not workable” and that the Hoeven-Manchin amendment “would result in larger energy savings than repeal of Section 433 would lose.”

In a technical review, though, Architecture 2030 points out what it views as flaws in ACEEE’s analysis. First, says the group, the EUI reductions are likely to be extended beyond 2015 anyway. And second, claims the paper, tying modeled energy reductions to codes would not require the kind of deep fossil-fuel-energy cuts mandated by Section 433.

Founder and CEO Ed Mazria, FAIA, gave the example of an existing building that’s due for a major energy retrofit in 2015. Under Section 433, that building would have to be designed to cut fossil-fuel consumption 65 percent compared with average national building performance in 2003. Under the Hoeven-Manchin plan, Mazria argues, the building would only have to be designed to reduce its consumption 57.5 percent. He claims that performance gap will widen as time goes on because codes do not change as quickly as the 2030 targets do.

Mazria also argues that buildings designed for net-zero energy use would meet the 2030 requirements, but the natural gas industry isn’t so sure. Gant said the law was “inartfully” written since it didn’t explicitly state that net-zero fossil-fuel use would be acceptable; AGA refers to Section 433 as a “ban” on fossil fuels. “A lot of people can agree that this could have been done in a variety of ways that could have been workable,” she said.

Many sources suggest that AGA remains adamant, however, about completely removing the fuel-related provisions rather than revising the wording to be clearer. Nadel at ACEEE readily concedes that “there are other potential solutions to these problems beyond repeal,” but he argues that a compromise with the fossil-fuel industry was necessary for the bill to move forward at all. “Some people are trying to thread a needle,” he said.

The AIA and the Sierra Club are currently conducting a letter-writing campaign among architecture firms and environmental organizations to fight the Hoeven-Manchin proposal.