Energy Minister Glenn Thibeault won't order the Ontario Energy Board to break out the costs of cap and trade on natural gas bills.

The Liberal government's plan to have companies buy and sell pollution credits to reduce Ontario's greenhouse gas emissions is expected to add about $5 a month to home heating costs starting Jan. 1. But those increases will be buried in the "delivery" line on natural gas bills.

The OEB announced earlier this year that cap and trade won't be a separate line item because the regulator considers them a cost of doing business.

The auditor general commissioned a survey that found that 89 per cent of natural gas ratepayers want the cap-and-trade costs clearly displayed, which has renewed calls for the OEB to reverse its decision.

But the regulator has so far stood firm, and the energy minister said he won't intervene.

"I am OK with the decision of the OEB," Thibeault said. "They're our regulator, the one that I trust to ensure that they have the best interests of our ratepayers at heart."

The Progressive Conservatives noted the government has issued many directives to the OEB in the past, and said Thibeault should do so on this issue.

"It's inconsistent," said PC Leader Patrick Brown. "It's only when it's convenient they seem to take a (step) back."

The Ontario Energy Board Act gives the government the power to issue directives in a number of areas, including steps "to promote energy conservation" and "the marketing of gas and the retailing of electricity in Ontario."

But Thibeault said while he has the power to ask the board to do a study, he doesn't have the power to overturn its decision as a "quasi-judicial and arm's-length" body.

"They did their consultations, they did the review, they met with stakeholders and this is the decision they've come up with," he said.

Those consultations involved 80 stakeholder groups -- and 75 of them wanted to see costs broken out on consumers' bills, the auditor noted. That includes the Independent Electricity System Operator and the gas companies themselves.

The auditor herself called for the costs to be broken out, for transparency and it could help prompt ratepayers to switch to an energy source, such as electricity, that produces less greenhouse gas. The Ontario Chamber of Commerce has made similar comments, also calling for the cap-and-trade charges to be shown separately on bills.

Even though the government has said cap and trade is expected to add $5 a month to the average natural gas bill, NDP Leader Andrea Horwath said customers will want to know exactly what they're paying.

"It seems to me very clear that not only do consumers want that transparency, but even the gas companies want that transparency," she said. "Everybody wants the transparency except for the government, who claims to be the most transparent government that we've ever had in the province of Ontario."

The OEB said it "makes sense" to include cap-and-trade costs in the delivery line, with the other natural gas business costs, and that the most important driver of consumer behaviour is total price.