Sir Patrick shuts up shop to allow everyone to get home after what's been a significant week at the RHI Inquiry.

Mrs Foster has spent a day-and-a-half in the hotseat but she'll have to come back for two more days next week.

Monday will see the return of her former ministerial adviser Dr Andrew Crawford, so join us the at 09:45.

Thanks for following our coverage today - have a great weekend!

BBC News Northern Ireland

The judge chairing the inquiry suggested to DUP leader Arlene Foster that she seemed to be heading up a "dysfunctional department".

Sir Patrick Coghlin said it appeared "incontrovertible" that her trust in two key people she had relied on had been "completely unfulfilled".

Image source, Pacemaker

The focus of Friday's evidence was on a key meeting in June 2011 at which the cash-for-ash scheme was selected.

Sir Patrick Coghlin said it should have been minuted and the lack of "notes or records of this" pointed "towards a dysfunctional department".

There was "very little conversation at all" about the need for cost controls to be added to the RHI scheme, says Mrs Foster, and she claims it's not fair to suggest the necessity passed her by.

She says she believed that there was a mechanism by which the scheme could be suspended in an emergency but that "turns out to be the wrong understanding".

Image source, RHI Inquiry

But the inquiry chair Sir Patrick Coghlin says the need for cost controls was raised in letters to her from the UK government's then energy minister Greg Barker, who was overseeing the similar RHI scheme that was in Great Britain.

When that's put to her, Mrs Foster accepts that Mr Barker - now Lord Barker of Battle - wrote to her and the department and alerted her to the issue of budget protection measures.

Mr Scoffield has been digging through old copies of the Belfast Telegraph and has turned up an article Mrs Foster wrote for the newspaper in December 2016 (below) when the RHI debacle erupted.

In it, she wrote that setting up the RHI scheme "was the right thing to do" and "supporters of renewable energy and others were telling me at that time it did not go far enough".

Asked who she meant by that, she says it relates to respondents to the consultation about the scheme in 2011 before it opened, who said that the subsidies on offer needed to be higher.

A key flaw in the RHI scheme was that the cost of the fuel used in biomass boilers was lower than the subsidy that was on offer to claimants, accepts Mrs Foster.

Dr Crawford has told the inquiry he knew that was the case.

Mr Scoffield queries whether he should've raised that with her or DETI officials, "given your reliance on him in some of these more technical matters".

Mrs Foster says it wasn't discussed and turns the attention to civil servants, saying she would've relied on their advice, saying she "would've taken it as read" and "at face value".

Mr Scoffield says the picture emerging from the evidence is that she was there to "take policy decisions and set policy direction".

"But when it comes to implementing the policy or comes to delivering on representations or assurances that have been given to you you're a very passive participant, if a participant at all," he adds.

Image source, RHI Inquiry

Asked if she was more actively engaged than that, she responds: "I don't think anybody would have described me as a passive minister."

"I certainly didn't see my role as interfering in which project management style you were using to monitor this particular scheme."

One reason why DETI rejected a vastly cheaper alternative for the RHI scheme was that the initial administration costs for it weren't thought to be affordable.

The ongoing subsidy scheme that was ultimately chosen was estimated to cost £329m more overall than a grants offer that was also considered.

The subsidy scheme's admin costs were put at £1.5m over the first four years while the grants offer would cost £5m to deliver, so DETI opted for the short-term £3.5m saving and plumped for the first of those.

Image source, Getty Images

Mr Scoffield says a point the inquiry wants to "grapple with" is why DETI chose to spend hundreds of millions of pounds more over 20 years in order to save a few million up front and he queries whether that was a "sensible way" handle public money.

Mrs Foster says £3.5m is "not a huge amount of money" in the wider context of the scheme and accepts that finding that money at the time "may have been difficult but it wouldn't have been impossible".

But she says it wasn't raised with her and if it had been she would've looked for a way to find the admin money in order to make the massive long-term saving.

Mrs Foster says she doesn't think "there was any malevolence intended" by civil servants in not providing her with a briefing in why one option for the RHI scheme was chosen over a much cheaper alternative.

She says there could have been good non-monetary reasons why the more costly option was chosen and it was an "oversight" that she wasn't made aware of them.

Image source, Getty Images

By that stage - March 2012 - the projected cost difference between the two options that were considered had increased from more than £200m to well over £300m and Mrs Foster argues that she wasn't told about that.

Dr MacLean says that was a lapse that had happened several times and wonders whether that meant there was "some intent behind it" to "push ahead and get the thing done as quickly as possible".

Mrs Foster replies: "I don't know what the intention was behind not bringing me the papers but it turned out to be very significant, no doubt about that."

Mrs Foster "put an enormous amount of trust" in her adviser and DETI's energy boss "that doesn't appear to be well-founded at all", says Sir Patrick Coghlin.

The inquiry chair says it appears that they didn't draw crucial material about the RHI scheme to her attention in order for her to make decisions on it.

Image source, RHI Inquiry

The DUP leader says that "as far as I was concerned I was working with two very professional people" and she expected to bring her what she needed.

"I know this panel has been all about 'expectations' and what have you but that certainly was my expectation," she adds.

Inquiry panellist Dr Keith McLean wants to know if civil servants were pressing ahead with the scheme without keeping Mrs Foster abreast of the issues because of a time pressure.

She expresses some frustration at how that played out when the debacle ultimately became public knowledge.

Image source, RHI Inquiry

"It wasn't the officials' place to take that decision - it should have been my place to take that decision," she tells him.

"I think that in all the furore around the scheme in December 2016 and '17 the whole attention was on my role on this issue because I was the policymaker and the decision maker but I wasn't given the option of taking the decisions."

Dr McLean says it appears there was something "structurally" wrong with the department "where procedure after procedure was being ignored".

Matters turn to turning now to a key part of the RHI scheme's approval process - its scrutiny by an internal DETI panel, known as a casework committee, in March 2012.

Mrs Foster describes it as a "peer review" process held before the business case for the scheme was forwarded to Stormont's finance department to be rubber-stamped.

Image source, Getty Images

DETI's departmental financial procedures of the time decreed that all projects over £1m required ministerial approval and specified that all documents from the casework committee should be sent to the minister's private office.

Mrs Foster confirms she didn't receive papers from the meeting and says that "chimes with me" because there was a similar situation with casework papers from the arms-length body Invest NI, Northern Ireland's economic development agency - she didn't get those either, it seems.

Image source, RHI Inquiry

Resuming after lunch, chair Sir Patrick Coghlin clears up the arrangements for next week's inquiry sessions.

Dr Andrew Crawford, Arlene Foster's former ministerial adviser, will be back on Monday and Tuesday.

And Mrs Foster will join us again on Wednesday and Thursday.

That was a busy first session of the day and the inquiry now breaks for lunch.

It'll be back at 14:00 and so will we - join us again for full coverage of the afternoon session.

In the meantime, you could have a listen to today's podcast from The Stephen Nolan Show.

Sam McBride - the political editor at the News Letter and a certified expert on all things RHI - discusses the significance of the evidence given to the inquiry by Arlene Foster and her adviser Dr Andrew Crawford.

Ofgem, which was eventually engaged by DETI to administer the RHI scheme carried out a legal review of the draft regulations for the Norther Ireland initiative, which were largely based on those for the similar scheme that was running in Great Britain.

It identified a log list of concerns, including something called "parasitic loads", which Mr Scoffield explains involves drying wood to be put back into a biomass boiler to be burned to dry more wood.

More importantly the review expressed considerable concerns about definitions of terms such as "useful heat" and concluded that it was "critical that these concerns are addressed by DETI".

Mrs Foster says that if the concerns had been brought to her by department officials she would've requested a submission detailing them - looking at the Ofgem review "for the first time today" she notes that there are "quite some considerable and lengthy difficulties."

"I think I should have been told that there were a range of difficulties being raised - and I wasn't," concludes the former minister.

David Sterling (below), the head of the Northern Ireland Civil Service, told the inquiry last month that Stormont always looked to get the "maximum amount" of money from the Treasury that they could.

Doing so would have an "economic impact" on Northern Ireland.

Mr Sterling was the top civil servant at DETI when Mrs Foster was the minister at the department.

Image source, RHI Inquiry

Asked about those remarks, Mrs Foster agrees that Stormont departments want to get "the maximum benefit for Northern Ireland" but not "regardless of the cost".

"I don't think it's the way to deal with public money," she adds, referencing her experience as a former Stormont finance minister.

"I don't accept that we would've just said: 'Well, this is going to cost £200m more but what about it - it's coming from Treasury.'"

Inquiry panellist Dr Keith MacLean asks if Mrs Foster's civil servants might've thought she wouldn't have been too interested in what they were telling her and therefore didn't raise the cost increase.

He queries the relationship between the minister and her officials that resulted in them not mentioning the £200m cost increase in her chosen option for the RHI scheme.

Image source, Getty Images

Responding, Mrs Foster says: "I don't think any official would make the assumption that £200m was not of interest to the minister.

"My goodness, if something's going to cost £200m more but 'we'll not bother telling the minister' is quite a significant thing to do."

Dame Una O'Brien (below) - a highly experienced former civil servant who headed Whitehall's Department of Health - asks whether Mrs Foster could've "asked more questions" about the RHI scheme.

Dame Una recalls Mrs Foster's evidence yesterday when she said energy wasn't her favourite topic when she was enterprise minister, and the inquiry panelist wonders if she should've been "more curious".

Image source, RHI Inquiry

Looking with hindsight, Mrs Foster says "one wishes one had asked more questions".

But she says that because major cost increases weren't drawn to her attention by civil servants at the time then "I don't think it's unfair to think there hasn't been any huge change and that's clearly is what I thought at the time".

It "wasn't in my mind" to go for a scheme that maximise the amount of money that Northern Ireland would receive from the Treasury, says Mrs Foster.

"At the end of the day its still public money and it has to come from somewhere."

Image source, Getty Images

She says that if she'd been aware that the option she had chosen for the RHI scheme was hundreds of millions of pounds more expensive than the one she rejected, she would've "certainly stopped and had a discussion as to why we were going ahead" with it.

"You don't try and deliver a policy at the highest possible cost - you try and deliver it at the lowest cost to the public purse."

Mrs Foster would've expected civil servants "to draw any significant changes" affecting her decision to go ahead with the RHI scheme "directly to my attention", she says in her witness statement.

"This was not done," she adds.

She says that remark relates to a major upward shift of more than £200m in the projected cost of the scheme, as assessed by expert consultants at CEPA in June 2011.

Image source, RHI Inquiry

The original decision to go ahead with the scheme was based on a draft report by the consultants and they sent their final report, external to DETI about two weeks later.

In it, the projected cost on the option Mrs Foster had chosen went up by £200m and a rejected option was estimated to be much cheaper - CEPA described the change as "pretty stark".

Mrs Foster says "there's nothing... to suggest" that was to her attention, neither from civil servants or her adviser Dr Crawford, who she believes should have at least read a summary of the expert report, but it should've been done.

A former president of the Ulster Farmers' Union "was particularly forthright about the need for incentivisation" of renewable heat production and "sought to influence" Mrs Foster, she says in her written statement.

She describes Dr John Gilliland (below), who has a farm in County Londonderry, as a "pioneer" in the renewable energy sector whose view was widely valued.

He wrote to her in May 2011 - a couple of weeks before she decided on what type of RHI scheme to opt for - saying that matter was his "favourite bugbear".

Asked if Dr Gilliland or others in the industry made a "push" for an ongoing subsidy scheme rather than an up-front grants offer, Mrs Foster says "they probably did have a preference" for that.

It "may well have been in my thinking" when she was deciding on what option to choose, says Mrs Foster, but it wouldn't have "overruled" any expert advice that may have suggested that was not the best option.

She points out that "it's not unusual" for interested individuals to write to her about their wants and needs but it "doesn't mean that we're going to go in that direction".