Simon R

Thanks. No sound issues, a very quiet location. So I'll chalk that up as a vote for double...confirmation bias creeping in already...?

We get that problem on the boat! yes we will be highly insulated, I had hoped that having an MVHR would alleviate that problem. How much of a problem do you find it and are you running an MVHR system.

We are facing the dreaded windows selection conundrum and are trying to be objective, which is proving far harder than I would have expected. We have a glazing element that includes a roof area for which we need curtain wall glazing. However it's only available in double glazing and has a U value of 1.5. It fits well aesthetically with the Velfac windows we are planning of using for all the other glazing. The company (Rhino) who supply the curtain glazing also do windows and were keen to quote. Now comes the big but...they can only provide double glazing and the U values are on the average 0.6 worse than the Velfac triple glazed windows. This is mainly due to them using aluminium frames while the Velfac are aluminium clad wood. The price delta between the the two quotes is considerable, indeed it is enough to pretty much cover our PV installation. Looking at it from an energy value point of view using the standard HDD figure of 15 it's going to take a very long time for the additional energy required for heating to make up for the additional cost of triple glazing (about 30 years at current energy costs). Given we are very happy with the build quality and look of both products it comes down to comfort. Some thoughts on the experience of living with double glazing with U 1.5 and triple glazing with a U 0.9 would be very welcome. Simon

Thanks I'll take a look. We're only off grid while on our boat but it does change the way you live and think about energy. We're still looking at the battery store options we have and think we should be able to survive on 5kwh, but would prefer to double that. I'll read the blog you pointed me to and see what solution they have found works for them.

Regarding time scales, we are still getting the plans sorted, but I'll add it to the work that needs to be done so I don't forget....the list is getting somewhat interesting...

Thank you, I'll do that now

Point taken, despite my background I'm a bit of luddite when it comes to social media..despite my reservations I'll look at doing a blog. Tried several times to get a discount, as you say there should be some benefit to being a guinea pig. Not sure how much hand holding we'll get and it's me doing the PM... lets see now, first build using the bricks, first self build...what could possibly go wrong.

Indeed, hope we don't live to regret it! always referred to it as the "bleeding edge" in software, I should have learnt by now. No discount on offer, perhaps I've not tried hard enough, I'm told there's no margin? What I do hope we will get it's lots of support. And yes, should be lots of additions to this topic as we progress.

Just noticed I failed to respond to your post regarding Velfac. I would like to know what the issues were. Please would you add links/urls to the review you mentioned. I know they have what is considered a low tolerance to variations in opening size, but other than that the quality and performance look good.

We've decided to use the JUB ICF block system for our build, it's looking as though it's going to be the first build using the system in the UK. The JUB ICF approach is a little different from most of its competitors in so far as there is no block cutting done on site. This was a major factor in our choice as it should eliminate opening size errors and also the need to infill when cuts are not quite as perfect as they should be. The down side is that it makes the drawing up of plans an iterative process. Our architect is in the process of amending our plans to reflect the JUB ICF wall thickness of 390mm once this is done the plans will get optimized by JUB. The structural calculations will then get done which may result in further changes before we can get a set of plans for building controls. JUB also offer raft and roof solutions. The raft system has a quoted U value of 0.2w/m2K and is quite expensive compared to say "raft therm" from Castle Forms which has a U value of 0.1w/m2K. The JUB roof system looks good with a U value of 0.09w/m2K, again it's relatively costly and we have not decided to go this route or a cheaper more conventional rafter and spray foam option. JUB also do rendering, which appears to be there main business in the UK. The render system and ICF systems have been tested together and is covered by a single warranty. Hopefully not a feature we will need to call on. Being a first will no doubt result in a few issues along the way but it looks as though JUB are keen to get a build under way and will provide support. I've attached the plans for which we have planning permission, these have already changed a little to provide greater strength in the north east corner which has a big glazing area. I'll update this thread as we progress. Build plans JUB-ICF.pdf

Probably where we should have started. The 185 LS has capacity to spare even in the worst winter we are likely to get on the south coast, it's rarely below zero for more than a couple of days at a time in winter. Assuming the unit lasts 15 years, factoring in running costs it may just be simpler just to use PV and a couple of electrically heated towel rails. The RHI payments are not much of an incentive when you start getting close to passive house standards, at least that's my take on it.

My rather rudimentary calcs have given me a whole house value of 51w/K, arrived at by totalling all areas * material U values. What I'm finding hard to evaluate is the solar gain we are going to get. I've modelled the house in sketchup to see the way the sun and shadows fall, it looks reasonably good in so far as we protect the windows from sun in the summer. It looks as though the 185 should do the job, but I'll revisit my calculations. We will have solar (PV) and intended to configure the unit only to heat when PV failed to heat the water. Also only intending a small area of wet underfloor heating, just 6m2. Lots still to figure out.

Good morning gentlemen. Just got to love this forum?, first post and already stirring the pot. The house is low energy, and we are used to living off grid on a boat so tend to be carefully with our energy and water. I'll start a thread in the ICF section to address the JUB aspects and other ICF items such as structural calculations and building controls. Incidently JUB tell me they are the manufacturer of the ICF. Looking at sourcing the heat pump from Denmark as others on the forum have. In the mean time, thank you all again for your interest and input. Simon

Hi and thank you to all forum members for creating a very useful resource. Having managed to get planning permission my wife and I are about to start on our first self build. We intend to do as much work on the project as we can, we done several projects in the past but nothing on this scale After a lot of looking at various build systems we have opted to use the JUB ICF sytem. Our intent is to get as low energy build as we can with our budget. A little bit about the project: The house is in the region of 200M2 over two floors. The MVHR we are looking at the Genvex 185 unit which also gives us an integrated air source heat pump. We have not made a decision on windows yet but have Velfac on the short list.