It took a while to warm up but today's session took a captivating turn this afternoon.

It'll be a while before Dr Crawford returns to the inquiry but he'll be back at some stage to face more questions on his role in the later stages of the RHI scheme.

Image source, AFP

As for tomorrow, the DUP leader Arlene Foster will be back in the Senate chamber for another evidence session - join us for the best seat in the house at 09:45.

We're off to make the most of that sunny evening...

BBC News Northern Ireland

Arlene Foster's former DUP ministerial adviser insisted he never understood the RHI scheme's "burn-to-earn" flaw.

Dr Andrew Crawford said he always assumed the tariffs were meant to incentivise firms to switch to more expensive biomass boilers.

Image source, Pacemaker

But he said he never realised tariffs allowed people to profit by running boilers unnecessarily.

"I didn't envisage that the scheme would be structured in such a way as to pay people to earn as you burn," he said.

Dr Crawford, who says he sold cattle for his father at farmers' marts, tells the inquiry that he didn't have any discussions about the RHI scheme with others in the agriculture industry.

He explains that his background and expertise would've been in "grass-based" farming, that his PhD was on dairy cows, and he emphasises that there's "not that great deal of an overlap" with the poultry industry, the main beneficiary of the scheme.

Image source, Getty Images

But inquiry chair Sir Patrick Coghlin tells him that the scheme was being heavily promoted at agricultural events and "everybody who was involved in farming of one kind or another" would have been aware of that.

But Dr Crawford insists he did not attend those events and he had no knowledge of how lucrative the scheme was.

It's put to Dr Crawford that one one interpretation of his decision to send the RHI scheme document to his cousin could be that he was engaged in a conflict of interest to help his family into an initiative that was "too good to be true".

The witness says his cousin's statement shows he didn't act in response to receiving the paper and it would be some period of time before he installed his biomass boilers through the scheme.

He says he had "no idea at this stage" whether or not the scheme was as lucrative as it turned out to be.

"I had no idea of the poultry industry, the heat requirements, the cost of pellets, the cost of an RHI boiler," he says.

Dr Crawford did not tell his minister Mrs Foster that he had shared the internal document about the RHI scheme with his cousin.

He accepts that "the minister wouldn't have been happy with me" if he had told her about what he'd done.

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"She knows I shouldn't have sent it out and she wouldn't have been happy because she known the various rules that there are regarding government documents," he adds.

Asked what would've happened if he'd admitted to Mrs Foster what he'd done, he says he would've expected some action to have been taken but he can't say what it would've been.

He says he still hasn't discussed it with her because "it's a matter for the inquiry" and it "wouldn't be appropriate" to talk to her about matters the inquiry is dealing with.

Image source, RHI Inquiry

Inquiry panel member Dame Una O'Brien asks Dr Crawford why he didn't just refer his cousin to information about the RHI scheme on the DETI website.

He says that in hindsight "I kick myself that I sent this out".

He accepts that he had other options, including "refer them to the website, refer them to officials - there's all sorts of things I could have done".

Dr Crawford denies that he was "in the habit" of sending internal documents to people outside the Northern Ireland Executive.

He says he doesn't believe he sent other documents out in relation to other aspects of DETI business.

Asked what made him "comfortable enough to hit send" on an confidential paper, he says he "can't answer that here today in terms of why my conscience didn't stop me".

"I suspect in this case, because it was my cousin, my guard was down, I shouldn't have done it."

It was "wrong" for Dr Crawford to email an internal document about the RHI scheme to his cousin, he admits.

He tells the inquiry that his cousin Richard Crawford had built poultry sheds and had asked him for information about the scheme that he had yet to subscribe to.

He explains that at the time uptake on the scheme was low and DETI had been trying to "encourage more people" into it.

Image source, Getty Images

"I shouldn't have sent it through to him - I want to apologise for it, it was wrong," he says.

He says his cousin installed biomass boilers in his poultry shed 12 months after the internal RHI scheme paper had been shared with him but "in no way did Richard in any way advantage through" receiving the information.

Richard Crawford has six biomass boilers that were installed through the RHI scheme.

Dr Crawford shared a key internal document about the RHI scheme with his poultry-farmer cousin - who became a claimant on the initiative - in the summer of 2013 before it had been made publicly available, the inquiry hears.

In his witness statement, Dr Crawford told the inquiry he was "not aware" of ever having breached any codes of conduct in terms of "making premature or unauthorised disclosures".

Image source, Getty Images

But evidence given to the inquiry shows that Dr Crawford sent a draft consultation document regarding changes to the RHI scheme to his cousin Richard Crawford in July 2013.

Asked why he didn't tell the inquiry about that, he said he had "no recollection of sending this email".

At the end of May 2013, the UK government's energy minister Greg Barker wrote to Mrs Foster in which he explained that his department was making major cost control changes to the Great Britain RHI scheme.

The letter was referred to the DETI officials who were dealing with Northern Ireland's RHI initiative.

They said it was "similar" to an earlier letter from Mr Barker and no action was therefore needed.

But that wasn't true - the earlier letter had referred to completely different matters - and the chance to tell Mrs Foster about the cost control changes wasn't taken.

Dr Crawford says neither he nor Mrs Foster received the letter but "the minister should've seen all the correspondence coming from a Westminster department".

Mr Aiken suggests that Mrs Foster not seeing the correspondence is proof that DETI was a "dysfunctional" department.

The RHI scheme had been set up to help Northern Ireland hit a target of producing 10% of its heat through renewable sources by 2020.

But in report about the scheme in June 2013, drawn up at DETI's request by external energy consultants CEPA, said that by that stage nothing the department could do would allow it to meet the target.

A submission sent to the minister Mrs Foster at the time, regarding a consultation on the next phase of the scheme, did not tell her that CEPA believed the 10% target could not be achieved.

CEPA's 132-page report was not attached to the submission - instead, there was simply a comment that it was "available if you want to see it".

Dr Crawford says he didn't "request the detailed technical document" but he believes he met officials to discuss the consultation document and what was in it.

Image source, The RHI Inquiry

The inquiry returns after the lunch break for the last of Dr Crawford's scheduled evidence session for now.

We'l be running until 16:45 today, with Arlene Foster returning to the inquiry chamber tomorrow morning.

Image source, Pacemaker

We're breaking for lunch now.

But we'll be back in the senate chamber when proceedings kick off again at 14:00

Off the back of the REM letter, Dr Crawford queried what would happen if two boilers on the RHI scheme were installed by a single applicant at different times, rather than both at once.

He raised the issue when he read a submission to the minister from DETI's energy team concerning the response to the REM letter.

He was told by the energy officials that it depended on the length of time between the installations.

They also said that the scheme regulations "prevents scenarios where applicants could install a number of smaller boilers in attempt to receive higher incentive payments".

Asked if that was accurate, Dr Crawford says: "Clearly we know differently now than what we knew then."

Inquiry chair Sir Patrick Coghlin says that "nobody understood" the question from REM and nor did they "pick up on the implication on a number of separate boilers being used".

A renewable energy firm noticed the RHI scheme's "perverse incentive" for poultry farmers within a few weeks of the initiative initiative opening.

Renewable Energy Manufacturing Ltd (REM) wrote to Stormont's Department of the Environment (DoE) in January 2013 to say that the GB RHI scheme encouraging the use of poultry manure to produce renewable heat but the Northern Ireland initiative had the "directly opposite effect".

Image source, Getty Images

It also drew attention to the NI scheme's "perverse incentive for farmers" to install several small boilers rather than one large unit in order to obtain a higher tariff that was on offer for smaller systems.

DoE passed the letter to DETI three months later, and a response to REM was put together in Mrs Foster's name, rejecting that "perverse incentive" claim and saying: "I can assure that this is not the case."

"Under the regulations, where two or more plants are using the same energy source and form part of the same heating system, they are treated as a component plant and the total capacity is assessed," it went on.

DETI officials did not tell Mrs Foster or her adviser that the department had insufficient resources to further develop the RHI scheme in autumn 2012, says Dr Crawford.

Just two people were working directly on the scheme and one of those was employed part-time, whereas a total of 77 were developing the similar initiative that was running in Great Britain.

Image source, RHI Inquiry

Asked if there was a "misunderstanding" about what the department could "reasonably do" with the resources it had, Dr Crawford says that DETI's energy team boss should have told the department's permanent secretary that the demands were too great.

"We certainly would've looked at were there other ways to deliver this particular project," he adds.

The RHI scheme opened in November 2012 and DETI immediately began to plan developing the initiative to extend it to domestic users.

The intention was to have that done by summer or autumn of the following year and it was said that the process "goes ahead as soon as possible".

Image source, Getty Images

Emails from the time show that Dr Crawford had asked if there was "any way to reduce the cost of this work".

He tells the inquiry that he had probably had concerns that the expert consultants at Cambridge Economic Policy Associates (CEPA) who had worked on the scheme up until that point "had already received significant money" .

"At that time there was pressure on the amount of money we were spending on consultants - that was across the whole of the Northern Ireland Executive."

Arlene Foster "would've been much more cautious" if she had been told of the unique way the RHI scheme was being funded, says her former adviser.

Officials at Department of Enterprise, Trade and Investment (DETI) had been told by the Treasury that Stormont would have to foot the bill any overspend on the initiative and there would effectively be a penalty imposed of about 5% in the case of going over budget.

Image source, Getty Images

That information wasn't reflected in a submission to the minister from senior DETI finance official Trevor Cooper.

Dr Crawford says that "at no stage did anybody flag up to us that I can remember" that there was a need for caution regarding the scheme's spend.

Special ministerial advisers are supposed to bring "real-world experience" to government, says inquiry panellist Dame Una O'Brien, who presses Dr Crawford on why he didn't ask more questions about the subsidy on offer through the RHI scheme.

Dr Crawford tells her that he "didn't envisage that the scheme would be structured in such a way that it would pay people to... earn as you burn".

"I just assumed - wrongly now - that there'd be checks in the system that would stop that from happening", he adds.

He says he took "reassurance" that civil servants had compared the scheme with a similar initiative running in Great Britain and he believed they had "thought through a process to stop somebody from taking advantage" of it.

"Did I understand exactly what that meant or how that would work? No, I didn't."

Image source, PA

Dr Crawford says it wasn't his job to ask questions about the details of the subsidies on offer through the RHI scheme.

He "had no knowledge" of the key factors - such as the cost of fuel, heating system installation and service costs, etc - that were considered when drawing up the tariffs that the scheme was providing to its claimants.

"I didn't see myself getting into that low-level detail... when I was looking at this scheme it was not controversial," he says.