Conservative rank and file will hear high-profile pitches at this week's Vancouver convention calling for the federal party to broaden its appeal to Canadian voters by putting greater effort into offering solutions to environmental problems such as climate change.

The proposals come as more than 2,100 Conservative delegates gather in Vancouver on Thursday to begin a makeover and reboot of their party that readies the political machine for life after Stephen Harper. The former prime minister, who quit as party leader when he was ousted from office in last October's election, is preparing to resign his parliamentary seat by the fall.

In a Friday presentation called Green Conservatism, former Harper-era cabinet minister Stockwell Day will discuss an effort to build a petroleum refinery on British Columbia's west coast – one that Pacific Future Energy is billing as nearly emissions free. The company counts Shawn Atleo, former national chief of the Assembly of First Nations, as a director, and another ex-AFN head, Ovide Mercredi, as an adviser.

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Along with Mr. Day, Ontario Progressive Conservative Leader Patrick Brown will talk about how Tories need to offer a more positive message on the environment. Mr. Brown has promised a revenue-neutral carbon tax as a solution to climate change. This would mean putting a levy on carbon-based fuels such as gasoline or natural gas, but rebating any revenue generated in the form of cuts to income taxes or other taxes.

This is a departure from the federal Conservative Party's historical opposition to a carbon tax under Mr. Harper – who called it a job-killing measure – but it's in line with the approach British Columbia's Liberal government followed in 2008, when it enacted a carbon tax in an effort to encourage a reduction in emissions.

Mr. Day and Mr. Brown are teaming up with Canadians for Clean Prosperity for this event at the Tory convention. The non-governmental organization – backed by business people such as Greg Kiessling, the founder of Bullfrog Power – promotes market-based solutions to environmental problems. Its executive director is Mark Cameron, a former senior policy adviser to Mr. Harper.

Mr. Cameron's group sponsored a voter study of the 2015 federal election, conducted by data scientists Vox Pop Labs, that looked at the evolution of the Conservative vote. It concluded that the Tories lost more than 20 per cent of their 2011 voters four years later – even as they picked up more support in places such as Quebec – and of those who abandoned the party, a significant number were Canadians who supported action on climate change.

"The voters [that the Conservatives] lost were disproportionately environment voters," Mr. Cameron said. "It's clear Conservatives have to have an answer when it comes to climate change."

There's a growing chorus of calls for the Tories to offer more to Canadians on matters other than just fiscal probity and a hawkish approach to defence and security. Senior Tories aren't calling for their party to emulate their Liberal or New Democrat rivals, but instead be more assertive in promoting conservative-minded solutions to challenges such as climate change.

This heralds what could be a potentially important shift in the party because the former Harper government was widely seen as a reluctant participant in efforts to fight climate change.

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Both former Treasury Board president Tony Clement, a potential leadership contender, and ex-Harper aide Nigel Wright have spoken publicly in recent months of the need for the Tories to expand their appeal to Canadians by offering bold proposals that address a broader range of challenges, from aboriginal affairs to homelessness.

Conservative leadership contender Michael Chong has also called for assigning a price to carbon emissions as a way to fight climate change.

Mr. Clement said that in the former Conservative government, Tories were stuck in a "straitjacket of only talking economy, generally, and security," and "we couldn't talk about those [other] issues because it was off message."

"We didn't have anything to say to city-dwellers, we didn't have anything to say to millennials – these things racked up huge disadvantages for us."

Mr. Day said Conservatives have to be enthusiastic and upfront in delivering a message that their party can find way to create jobs in an "environmentally sustainable, First Nations-friendly" manner.

"There are intelligent, sustainable solutions to prosperity and protecting the environment," he said. "There are ways to extract [resources] and ways to distribute these resources that are actually going to reduce climate change."

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He said he doesn't think a carbon tax is absolutely necessary, but if a government is going to enact one, it needs to ensure the money will be spent very carefully, such as through tax cuts. "It does make sense in some ways to tax the people who are apparently causing some of the problem."