Roger440

Thats what the internet suggests. What number do you think is realistic?

Yes, the barn has a 4000sqft roof. But siginificantly shaded and a shallow pitch, so not really much use. I do have a 4 acre field, the southern bounday of which has uninterrupted views of the sky. I we thinking more along the line of JohnMo's arrangement of vertical panels to maximise winter production. (glossing over any planning issues!) As said earlier, tons of power in summer is of little use to me, If i need to top up with the oil burner in the least productive periods, that not an much of an issue. It will be a massive oil consumption reduction either way. Heating parts of the barn is a seperate issue project. Though potentially stil linked. Just to make life more difficult. That currently on resistance heating and makes my meter spin rather quick! I should resuurect by barn heating thread.

I used 90% to allow for inefficency. On little basis other than that seems sort of right-ish. 20 would only apply with a HP of course. To get 20 in mid winter, even if mounted vertically is going to be a massive array. The numbers people seem to be getting are all over the place, so hard to know. Im keen to avoid batteries. Partly due to cost, but also moves me further away from DIY.

That would be nice. Not sure if thats achievable in my case without demolition.

Fortunately i dont, as i expected it. Its certainly not a surprise its high. Wasnt using much less in the last place, though that was nearly twice the size. Would be nice to be lower, but back to that payback issue. Just makes no sense. And im releatively confident the government will pay eventually, so no good spending my money. However, there are things i will do, because it will make it nicer, primarily the windows, and the (uninsulated) flat roofed part, which will need reroofing at some point.

Late into this one. But, yes, seems very high! Ive got a stone built cottage, with 70's extension and even worse 70's double glazing. In wales, halfway up a hill. ?So much colder overall. Im doing circa 70kWh. Fortunately im on oil so only paying 1/4 of the price per kWh that you are. As others have said, id be looking to reduce heat loss first. I would imagine with heat loss that bad theres going to be some easy wins there, especially with air leaks.

Sadly, a rough calculation suggests im dreaming. Based on my oil consumption, im currently munching circa 70kWh per day if my calcs are right. Though that may not be the case.. And ive got a barn to heat part of by some means too.

Nothing much i guess. I have no use for it.

Surely the invertor will manage the voltage situation? Yes, the start current might be an issue. But i could just use the mains for that. Someone posted a load divertor device a while back. Obviously the downside of the heat pump is, i need to be generating enough to run it. Whereas with immersion, i can use any solar power available. So on dull days ill still get something. That may not be the case with a heat pump. Just musing. Needs thinking through. The driver is, that i could, if i wanted to, put up a 50kw array, im not limited for space. Only money. The oil boiler would then be retained to heat same tank in the event of a shortfall in solar energy. Still need to avoid electronics as far as is possible, as they are, inevitably, the weak point.

I very much like the large tank idea. Ive been looking at this, as i have, effectively unimited space for solar panels, and more or less, unlimited indoor space in the barn. It much cheaper than batteries, And simpler. And no bunch of electronics to go wrong. The question then is, do you use a heatpump to heat that water? As it will be circa 3 times more efficient than immersion. Cost of solar panels at £100 a pop V the cost and complication of a heat pump. If it works well enough, then i can not bother destroying the house to try and insulate it. Idea needs proper numbers putting to it. Which is where i tend to fall down.

Can i ask why you used a private BCO in this instance?

Are you sure? When i built my insulated garage, it was cheaper than all of those.

No idea! Still seems like a quick, simple solution. And can arrive in kit form ready to be bolted together.

If its not airtight, what possible use will EWI be if there is ambient air circulating in the cavity?

Thats a good summary. To be honest, i couldnt evenfind a bargain I dont know why people rate them so highly.

Im not sure i understand the definition of a "small site". Is that 5 houses, one house, an extension? Sounds like another load of non jobs hsave been created. Who will no doubt charge £1000 a day for their services.

That makes no sense. With no DPC the wall is wicking water already to some extent. Where will it go if you stick EPS in front of it? If you stick a load of damp clothes in a plastic bag and hang it on the washing line, what do you think will happen?

Magic no. But damn good at stopping moisture. A french drain, in most cases will not solve this. Imporove? Maybe. Solve. No. Not unless you are building in a desert. Sadly, it rains here a fair bit. Ground is always damp.

I face a similar issue with my 70's extension. On a slightly diffrent point, if you go with EWI, then surely the cavity will need to be aitight. And thats not going to help if there is any moisture in there. Unless the cavity is 100% fill?

How will you stop the new (lime?) render cracking and allowing water in? I see Carrington Lime are running practical courses on insulating traditional walls.

The OP says wall has no DPC. So the wall will be damp/wet to some extent. EPS will trap that in the wall. As well as the acrylic render. With a DPC, sure.

Im not sure i understand why you think there will be aitr movement behind the VCL? Only if you leave air paths open to it. Surely the answe is not to. As per ProDaves suggestion? Ive just done similar in my workshop. 100mm PIR between batens, VCL over. But i sealed everthing before i started, which was onto bare block.

I took that to be the council have tasked him with this. Though i agree, it doesnt actually say that. As per toughbuttercups comments, why are the council involved? One struggles to imagine a scenario where the council getting involved is likely to have any positive or useful effect? Unless they employ directly. However, assuming stats are right, id suggest its because there are much easier ways to earn money. No amount of money could entice me into the building game, even though my skills and the trade have a useful amount of overlap. I dont really use most of my skills now, because selling stuff is easier and earns me more. And i get to sit in a warm office, not outside in the wind and the rain.

Yes i used the double sided. I may be misunderstanding, but why not put VCL UNDER the battens? Or, actually, why are you using a VCL as you have put a DPC in already. Or are you worried about condensation forming within the floor build up? Seems unlikely and thus overkill?

Yep. But the rule is, never mention canal walls or buildings built in rivers and canals. Because then you start questioning things.