Iceverge

Very similar detail to ours but we filled the cavity completely EPS beads which was super easy to do.

Something simpler would do me. Is it any good for detail drawings?

More blasphemy from you @saveasteading!!! I would very much go the other direction. It's not a "I spent less cash that you" competition. Nobody buys a Rolls Royce because it's cheap to run. But because it comfortably, quiet, and (maybe not these days) well built and reliable. Passivhaus is super cheap to run but it's the comfort, the ability to retain heat, the lack of drafts, the fresh air, the quietness that make it worth the extra effort. Also if done properly you can ditch complex central heating and it's actually quite economical. Back to the build, strip foundations perform excellently if done right. I would go to the local builders merchants and attempt to only build my house from stock items. The only exception being blown cellulose I think.

Can you not get precast concrete lintels easily in the UK?

Ok. Just to be sure. Tile. Tile batten, Membrane Counter battens running along the line for the rafters. 150mm PIR. 200mm Rafters with 200mm mineral wool in between? Any further layers of OSB or membranes in there?

I was always of the impression that in a horizontal "I* beam that the top and bottom sections did all the work. It's how in my head I explained this. The bid in the top was being squashed together, the bit at the bottom was being pulled apart and the bit in the middle was just making sure they stayed put. Without knowing the different yield strength of metals in compression and tension I do wonder why beams aren't built asymmetrically to gain maximum strength for minimal material.

Congratulations on your purchase. Perhaps consider baking a few cupcakes and knocking on the door of your farmers neighbours and saying hello. Us country folk can be very suspicious of newcomers but if we're assured you're reasonable and kind we will bend over backwards to help you and happily turn a blind eye to any minor planning infringements etc!

Carpenters are second only to joiners in particular-ness. It's probably the reason that almost all ultra low energy houses are made from timber. If money were no object I'd get joiners to build me a house. If I actually wanted to get it finished this century though I'd settle for carpenters.

Only if you raise the flow temp. You wouldn't need to do this if you just tripled or quadrupled the amount of radiators. Roughly 50m² of rads at a flow temp of 70 degrees would deliver the same amount of energy per second (power) as about 170m² of radiators at a flow temp of 35deg. This is what I mean by increasing the power of the emitters. And higher power emitters will always allow for a lower flow temperature.

Unless you had appropriately powerful heat emitters that could ensure a low enough return temperature. Like very closely spaced UFH in a highly conductive screed or multiple fan coils or giant radiators.

To beat the same drum again. How about ditching the idea of MVHR and using a couple of dDCV fans instead. They're cheap enough that you could buy them and give it a go to see if it helps.

This sentence feels likes it's only a slight spelling mistake from @Pocster levels of innuendo. Back to the door. The simplest thing I can think of is to buy some more adhesive backed cork tiles and fit them as neatly as you can. Or a far greater concern would be and draughts so make sure it seals excellently.

I would argue this only a consequence of the power output you can buy them in. If someone made a 40kW ASHP as accessable as a 40kW gas boiler people would probably use them in the same way. (Lots of technical and cost roadblocks with that approach I know). Most houses don't need heating 24/7 as people go to school, work, the pub etc and even a very low energy demand house will use less energy if it'a one heated intermittently. To allow for this you need high power heat generators and emitters to get up to temperature quickly and this is where a 5kW ASHP with widely spaced UFH pipes just doesn't cut the mustard. However get the biggest A2A unit you can fit with a appropriate fan coils and I don't see why it wouldn't work.

I normally use Sketchup on my laptop for drawing but would like something for my iPad when travelling. It doesn't need to be 3d. Just something that I can accurately draw dimensioned plans and details in 2d as well as handwrite notes on the page etc. Basically the technological equivalent of T square, ruler, paper and a pencil. Also I'm debating an Apple pencil to compliment it. Any pros/cons.

Define this please, especially where the insulation is. What is the buildup exactly from top to bottom.

That would work fine with oil. Have you considered air to air heat pumps?

A monoblock ASHP outside and a 300 l cylinder inside?

The only way I would consider straw bales as suitable for building a maintainable and mortgageable house would be as an infill to a timber frame. Here's my idea. Dig a standard strip foundation and build rising walls with 150mm blocks. Add a chunk of EPS perimeter insulation inboard and on the ground and pour a concrete slab as per normal. Build a 140*38mm stud frame on the 150mm rising blockwork at 450mm centres with 11mm OSB sheathing. Include ply gussets say 340mm long to connect later to an inner stud. Roof the house conventionally to ensure construction could continue inside in the dry. Add a sole and top plate for the inner stud too. Insert the bales "on end" in between the studs and push them tight against the outer sheathing. Use ratchet straps to compress them slightly and to compress any smaller segments that are needed at the top of the wall to take up any slack. Add the inner stud in a bay by bay fashion toe nailing it to the plates and screwing to the gussets. Take out the ratchet straps to allow the bales expand into the gaps. Finally add a good membrane inboard for airtighess and 38*50 horizontal battens to create a service cavity. Plasterboard and skim. Should have a U value of about 0.16W/m²K. With the double stud and large perimeter upstand it would have a very good thermal bridging characteristics and apart from the bales everything should be off the shelf from a merchant which is vitally important building in a more remote area.

Don't tell anyone who made their house from ICF......

Similar to passivhaus. It uses external surface area which tends to overestimate heat loss. It's one of the reasons that smaller houses struggle to meet the standard. Back to straw. I can see almost zero people advocating for structural straw bale houses but rather as an infill for a timber frame as insulation. The issues isn't the straw. Straw is fine. I've already linked lots of examples. It's the bales. They were designed to be able to package, transport and store a useful farm material and are full of compromise for any other purpose. Building a house out of them makes little more sense than making a house out of these just because they're made from polystyrene.

Get rid of the blown in mineral wool in the cavity and replace with EPS blown beads. Create an airtight layer by parging or applying a membrane to the external walls. Seal every penetration, windows doors, joist ends, wires and pipes to this layer with tape or airtight paint. Seal the walls to the floor also and ceiling. You'll need to return your airtight layer to the internal abutting walls too to prevent air leaks passing through them. Batten out the walls for a service cavity. Once all your wires are in place install 50mm mineral wool and then plasterboard and skim. Ensure you have some mechanical ventilation somewhere. MVHR is the best but often impractical in retrofits. Something like dDCV might be preferable.

We used Stuff like this from outside to the unit. These from the unit to the manifolds and To the rooms. If doing it again the only thing I would change would be to include some of these.

I know the feeling. Mind yourself. If you need to get in the door just tank the bathroom well and put off the tiling. It'll work perfectly well. In fact it is often a rather appealing swimming pool blue colour that reminds me of holidays brochures.

With everything in life start at the cheapest and work your way up until you get to an acceptable level of quality. If you've handballed the slates and they appear exactly the same just pick the cheapest one. We opted for slightly fancier textured fiber cement slates over plain jane ones. It was only €150 extra for the roof. Shouldn't have bothered.