Concerns raised by a panel of independent advisors about the government's heat in buildings proposals have been raised in Holyrood following a report in The Herald on Sunday.

MSPs from the Conservatives, the SNP and Labour quizzed Patrick Harvie on issues set out in a letter to Mairi McAllan by the chair of the regulatory review group (RRG) last week.

A consultation launched by Mr Harvie last year sets a target for all buildings in Scotland to be heated by green energy devices by 2045.

It also said private rented homes should meet minimum energy efficiency standards (MEES) by 2028, while owner occupied homes by 2033. It said these should be achieved by improving the insulation of walls, windows, roof, or floor – of a property.

Professor Russel Griggs, chair of the RRG, told the Cabinet Secretary for Wellbeing Economy, Net Zero and Energy, to warn that the panel of advisors he chairs had "significant concerns" over dates set out in consultation on a prospective Heat in Buildings Bill.

READ MORE: Heat pump proposals blasted by top ministerial advisors

He pointed out that the prospective bill along with the review of energy performance certification (EPC) "have the potential to be the most significant pieces of regulatory intervention since devolution affecting every individual and business in Scotland".

However, in a detailed letter he set out the advisors' range of concerns which included a lack of detail on the scope of the plans, the cost to the consumer, whether any buildings would be exempt and the lack of plans for a regulatory body to enforce future regulations.

The Herald: Mairi McAllanThe RRG wrote to Cabinet Secretary Mairi McAllan.  Photo PA.

Conservative MSP Edward Mountain pressed Mr Harvie on concerns in his proposals over "unrealistic deadlines", market readiness "and total incomprehension of costs to householders and businesses."

READ MORE: Ministers to delay plan for heat pumps to replace boilers from 2025

He told Mr Harvie that getting a two bedroom property to the necessary energy efficiency standard would cost £40,000 and asked him what government help would be available to households.

Mr Harvie said the government would keep "existing generous package of grants and loans under constant review" and added that ministers will "consider the option of a cost cap".

SNP MSP Ivan McKee asked how many buildings had been de-carbonized across the country Mr Harvie became a minister in August 2021 and for the timescale "to deliver net zero across the remainder of Scotland’s housing stock at that rate."

Mr Harvie replied: "The number of installations has been accelerating, but I am afraid that it would make no sense to project how long the process would take at the current rate. The whole point is to continue the acceleration of the installation of zero-emission heating systems." 

Conservative MSP Douglas Lumsden pressed Mr Harvie on the RRG's concerns that consumers will be vulnerable to rogue traders "if there is not sufficient capacity in the market to install new products". 

He asked:"What actions is the minister taking now to prevent rogue traders from entering the market?"

Mr Harvie replied: "The Scottish Government funded grant and loan schemes have a requirement with regard to the skills and qualifications of suppliers that people choose to use. We are also exploring the option of a supplier-led scheme instead of—or as well as—the consumer-led scheme that we have."

However, he added that the regulation of consumer protection rests with he UK Government. 

Labour MSP Sarah Boyack also pressed Mr Harvie on what the government was doing to ensure companies fitting clean energy systems were "reliable and trustworthy" following the concerns raised about rogue traders by the RRG.

She also pressed Mr Harvie on how the £33 billion proposals would be funded amid the current cost of living crisis.

Mr Harvie replied: "Under our powers, we ensure that the grant and loan schemes require people to use qualified and trusted installers. 

"We also work with UK-wide bodies, such as the microgeneration certification scheme, which will relaunch its criteria later this year, to reduce barriers to certification for small and independent contractors."

Scottish Greens MSP Mark Ruskell accused opposition parties of "playing political games" over the roll out of clean heat  and said businesses and households were "being fed a diet of misinformation by MSPs".

The Regulatory Review Group is a body re-established by the First Minister Humza Yousaf in October last year as part of the New Deal for Business to advise ministers on legislation.

It followed major criticisms from industry that the Scottish Government under former first minister Nicola Sturgeon did not take sufficient account of business interests when developing laws.

Clashes between ministers and the private sector had erupted over a range of policies including the deposit return scheme, measures to extend fishing restrictions and curbs on alcohol advertising. Ms Sturgeon's successor Humza Yousaf shelved all three.