A rule proposed by the Department of Energy (DOE) that would require residential natural gas furnaces to operate at 92% annual fuel utilization efficiency would have “numerous unintended consequences,” according to the American Gas Association (AGA), which has taken the unusual step of filing a Freedom of Information Act (FOIA) request to obtain government documents in the case.

“While the rule might appear to be a positive step toward achieving greater energy efficiency, a closer examination reveals numerous unintended consequences including an unreasonable economic burden on consumers, wasted energy and higher greenhouse gas emissions,” AGA said. “Even according to the department’s own analysis, 66% of affected households would see no benefit — or bear higher net costs — under the proposed rule.”

AGA plans to file comments in the case, but has already submitted a FOIA request in an effort to obtain documents that would lift the curtain on DOE’s process for developing the NOPR. According to the FOIA request, the NOPR “references and relies on, but does not provide, documents that would disclose methodologies, models and/or conclusions used in the rulemaking and which would explain what DOE considered and why it did or did not take particular actions. Their absence from the public record prevents meaningful public participation in the rulemaking.” Previously submitted questions “have gone almost completely unanswered,” according to AGA.

Energy conservation standards included in the 271-page NOPR, which was released by the agency earlier this year, would have significant environmental benefits, according to DOE, including cumulative emission reductions from non-weatherized (indoor) gas furnaces (NWGF) and mobile home gas furnaces of 137 million metric tons of carbon dioxide, 3.4 million tons of methane and 816,000 tons of nitrogen oxides during the first 30 years of compliance.

DOE also expects the rule to result in increases of 203,000 tons of sulfur dioxide, 2,600 tons of nitrous oxide and 0.63 tons of mercury “due to projected switching from NWGF to electric heat pumps and electric furnaces under the proposed standards.”

But the downside of the proposed rule could go much further than that, according to AGA.

“We’re trying to figure out how they came to these conclusions,” AGA spokesman Jake Rubin told NGI’s Daily GPI. “There’s consultants that they used and there are documents that are not available. As you look through, there are pieces of information that we’re not able to see, and until we have that information we can’t really fully understand the rule.” From the information that has been made available, DOE’s “math does not add up,” he said.

The emissions standards included in the NOPR would be more stringent than those already in place for other furnace product classes. The minimum annual fuel utilization efficiency for electric and weatherized (outdoor) oil-fired furnaces, which went into effect in 1992, is 78%; mobile home oil-fired (1990) is 75%; non-weatherized oil-fired (2013) is 83%; and weatherized gas-fired (Jan. 1, 2015) is 81%, according to DOE.

A June 2011 rule for the non-weatherized and mobile home gas furnaces was remanded to DOE for further rulemaking following a lawsuit by AGA and subsequent settlement negotiations. A minimum annual fuel utilization efficiency of 80%, which had been set in a November 2007 final rule, is scheduled to go into effect Nov. 19.