This article appears as part of the Unspun: Scottish Politics newsletter.

Patrick Harvie appeared in no mood to compromise in Holyrood when MSPs from across the political divide pressed him yesterday on the government's heat in buildings proposals.

Mr Harvie, the minister for zero carbon buildings, had been asked to respond to a question by the Conservatives' Edward Mountain.

It followed a report in the Herald on Sunday revealing significant concerns by a new body of ministerial independent advisors about the plans.

The Scottish Government's consultation, published in November, said private rented homes should meet minimum energy efficiency standards (MEES) by 2028, while owner occupied homes by 2033. It said the standards should be achieved by improving the insulation of walls, windows, roof, or floor of a property.

The consultation also proposed that by 2028 work would be required to be underway to remove gas and oil boilers from all buildings and that none should be heated with fossil fuels by 2045 – when Scotland is due to become net zero in law.

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But in a letter to Mr Harvie's boss Mairi McAllan, the cabinet secretary for net zero, and copied to her bosses First Minister Humza Yousaf and Deputy First Minister Shona Robison, the Regulatory Review Group chair Professor Russel Griggs expressed major worries about the details and delivery of the policy.

Professor Griggs did, as Mr Harvie noted in his response in parliament yesterday, underline the potential benefits of the policy to Scotland's economy.

But what he also argued in his letter to Ms McAllan was that to achieve that aim the proposals would have to be properly delivered.

And it was clear from the detailed contents of his letter Professor Griggs thought that to date there are considerable weaknesses and gaps in the policy.

The Herald: Regulatory Review Group chair Professor Russel Griggs stressed the potential benefits but expressed concern on its deliveryRegulatory Review Group chair Professor Russel Griggs stressed the potential benefits but expressed concern on its delivery (Image: Newsquest)
He said: "The RRG has significant concerns that the proposed dates for delivering a Heat in Buildings Standard across domestic and non-domestic buildings are unrealistic given that there is limited understanding of market preparedness and no formal identification of a suitable regulator."

He pressed Ms McAllan for detail on the rationale behind the key dates and what the Scottish Government was doing to assess the readiness of energy suppliers and households in making the switch from fossil fuel to clean energy heating systems.

READ MORE: MSPs quiz Harvie after advisors' concerns revealed

He warned that "consumers will be vulnerable to rogue traders" if there are not enough qualified suppliers able to install new products or repair existing ones.

Professor Griggs asked how the policy would be enforced "particularly as no regulator has yet been identified", sought precise numbers of the properties which would fall under the policy remit and for a list of any building type that would be exempt from the prospective law.

He also pointed out significant funds would in future years have to be spent on checking that householders and businesses were complying with the new rules.

"Monitoring compliance of retrofitted properties will require significant regulatory resource," he warned.

How Mr Harvie responds to Professor Grigg's list of concerns will be significant.

Professor Griggs is an independent voice in the debate, an expert appointed by government to identify potential weaknesses in its legislative plans in a bid to try and remove them early in the process.

The minister gave little away about what may happen to the plans, whether for example timescales will be pushed back, the scale of the scheme reduced and whether there will be some properties that will be exempt.

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It will also be important to see what the government's thinking is on how it will build a workforce equipped with sufficient skills to deliver the huge plans.

In parliament yesterday Mr Harvie gave no hints on what his response would be.

He stated: "We welcome the views of that independent group and all the submissions to our consultation, which closed on Friday.

"The group has highlighted the economic opportunity for Scotland in transitioning to clean heat and has identified the key issues of communication, the supply chain and phasing, on which we will continue to work as we develop the bill."

The Scottish Greens were bullish in a statement to the press after the topical question, accusing opposition parties of spreading "misinformation" over the bill.

Party backbencher Mark Ruskell accused opposition parties of "playing political games over the roll out of clean heat to Scotland’s homes" and that businesses and households are being fed "a diet of misinformation by MSPs".

It's not immediately evident what is behind such an attitude – one which could well be counterproductive.

Could the Greens be sensitive to previous legislation they championed which was halted?

Three of the big reforms the party pushed for – gender recognition, the deposit return scheme and the extra restrictions on coastal fishing under the planned highly protected marine areas – have all been shelved following intense resistance among some groups who would have been most affected by the policies.

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Could there be lessons for the government to learn in how it handled the shelved legislation so that similar missteps aren't repeated?

Part of this lesson, would be to take on board concerns early on, responding with more detail and suggesting an alternative timescale.

Such an responsive approach would in the end be ultimately better for the environment, for the Scottish economy, and for the consumer.

It would allow the proposals to survive, albeit in a modified fashion.

The risk of the government digging in and being reluctant to revise its strategy is that opposition intensifies, problems mount, and the heat in buildings strategy becomes another ambitious and well intentioned policy that simply falls by the wayside.