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PHPP does account for energy from the occupants, but what were you asking for it to report with regards over-heating? It was a while ago I did mine, but from memory, by default, it reports percentage of time you can expect to experience 25°C or over, with not more than 10% (I think) being the target. Had you lowered the threshold temperature for "over-heating", and got that down to close to 0%? If not, then it wouldn't have reported out what you are experiencing. Have you got a cooling unit on your MVHR? Even with one, MVHR will only have a small cooling effect across the house, but without one you're unlikely to see sufficient delta between the inside and outside temperature to have any meaningful effect. The Heat Recovery works in Winter with a 20 degree delta temp and lots of energy in the high humidity exhausted air being transferred into the lower temp, lower humidity incoming air, but the reverse cannot happen in Summer, without a chiller unit. I don't personally experience rising temperatures in the bedrooms overnight, I mostly rely on stack ventilation to purge the heat out of the house overnight, so all rooms will see a small temp drop as long as the outside temp is lower than the inside temp.

I assumed that , just thought it was a bit subtle for a newbie unfamiliar with the chat on hear.

I think it's more about low heat loss and "correct" ventilation. Comfort to me is stable temperatures. Higher heat loss and "powerful" heating is more likely to lead to temperature gradients through the house (as you move away from the emitter) and cycling in time.

Hmm, Touchwood Homes are well known for offering this and did have a great website showing lots of examples, but I notice they've let their website expire. I think they are still active on Facebook, but that doesn't hold the same info, so you'd need to contact them. Cullen Timber Design (who design & engineer Touchwood's frames) have a little info. www.cullentimberdesign.com In short, CTD can prepare a cutting list of the frame and send it to James Jones I-Joists and the pre-cut frame then turns up on site on the back of an artic, ready to be assembled in line with the very comprehensive CTD drawings. A competent carpentry team could easily put the frame together. The benefit of Toucwood's involvement is if you are wanting to achieve extremely high air tightness (above PassivHaus), they have some processes, especially with the outer sheathing, that others would not be aware of.

Is this a property for yourself? How high on your priorities is low heat loss and comfort? I wouldn't personally use SIP without a masonry outer skin. While U vales on PU filled SIPs can be reasonable, the short decrement delay of PU insulation, without a masonry outer skin won't perform as well as say a cellulose fibre insulation. CPS could mean twin stud panels pre-filled with cellulose fibre. Out of the two options you have mentioned that would be my preferred option, but you could also consider an I Joist, stick built structure with cellulose fibre. Speed is similar, just the time for the CPS and SIPs is in a factory and not on site. CPS (as I understand what you mean by it) and I Joist are pretty similar in costs, performance and time, but for me I Joist just edges it (but I'm biased). Edited to add: I can't see any have a differing effect on value, all things being equal. Without a masonry skin each will have less lenders willing to lend against it, and less insurers willing to insure it, but that doesn't mean that lending or insurance will cost any more.

Yes but... depends when measurements are taken for the opening. The lintels are probably not fully loaded when the openings are measured so an additional gap should be allowed for worst case loads (1st floor loads, snow loading etc. etc.). Mine was ordered off drawing, so everything was "theoretical", but SE deflection calcs appear to have been accurate.

Will Olof not come and work on site now? He'd previously attend site and install the Foundation and UFH, directing a 2 - 3 labourers supplied by the self-buider.

I fear that will be a difficult ask if the terms "existing derelict/disused" have been used to describe the original building within the application for the new: It may well amount to abandonment. To apply for a Certificate of Lawful Existing Use or Development, the Use needs to be existing at the time of the application (although it can be dormant). It's likely it was previously immune from enforcement, but is its Use now "dormant", so still immune; or "abandoned", so no longer immune? Needs a knowledgeable planning consultant to go through the history. The additional structures around the caravan can't be considered as transportable, so the Use that may have been lawful would be as a permanent dwelling-house. To get that accepted as its lawful Use by the LPA would put the proposal for a replacement dwelling on a lot firmer ground.

Cited by you, but have the Council acknowledge that? I feel they are looking at this as a New Build, within the garden of your grand mother's Bungalow, so following their local rules for minimum spacing. If the existing caravan and sheds does not have planning permission you can't use it to justify breaking those local rules. You may need to make the existing "dwelling" lawful first, which may be difficult.

Does that dwelling have planning permission, for a fixed dwellinghouse, not a caravan? Could you leave some walls in place so that what you wish to do is an "extension" rather than a demolish & rebuild, or are the existing walls (attached to the caravan) not structural.

Yes. For a Monobloc, it's preferred to have the ASHP within 10m of the cylinder. Mine is 14m, so I uprated the insulated twin duct between the two. If you have to go significantly further apart you could consider a split system which are good for 30m between them. But this does reduce your options on ASHP you can use.

Is it a new build? If so, then including the garage in the planning with get you the VAT back. Building it as PD will require you to pay the VAT. I'd go option 3, amend the existing planning, and carry on building what you currently have planning for, only starting the garage if they pass your amended plans. Yes, if they refuse planning on the garage, you can go the PD route - assuming no conditions on the planning that remove PD.

I would believe you could read this how it best suits you, so if you want to install a small treatment plant, it would not be unreasonable to assume property means the Title Deed for the house, which I assume is the house, its curtilage, and adjacent 15m of driveway. I expect the next section of driveway in shared ownership, so is on a different Title. If you are able to work within the General Binding Rules, then you have no need to contact the EA, so no one will be involved to question it.

If you include the hot water a heat pump provides, it may make more sense. Based on compressor time, HW production is two thirds of the work my ASHP does. Also, COP for space heating would rarely drop below 4.0 on my HP, average for space heating would be above 4.0. Not quite, but in theory it brings the space heating down to what could be provided by an in duct MVHR electric heater. A solution for DHW is still required though.

Does their land not rise at all in the corner of their plot, adjacent to you? The way they've stepped the decking up suggests it does lift a little, otherwise it would have been much easier for them to have built the decking flat. If their garden remains at the lower level there must be a retaining wall holding "up" your higher garden. Is the fence sitting on top of a retaining wall, in the corner? Unfortunately, if their garden is also a little higher in that corner then the height of the eaves is measured from that higher ground.

Yes, if the roof has not previously been increased in volume from what was first built, then you have 50m³ of PD volume increase for your loft conversion, I believe.

The property has previously been extended: While not done under PD, this counts towards the PD for the property. PD is based on the original dwellinghouse, or what was there in 1948 if built earlier.

The builder must charge you 0% VAT on his work and on the goods he supplies/installs on your build. (He'll be able to recover the VAT on the goods he purchases for your build) If you get anyone else to work on your build, and that work is covered by the planning permission, then they must also zero rate the labour and goods supplied. If you buy any qualifying goods for your build and install yourself or by someone else charging labour only, you can recover the 20% VAT you have paid, at the end of your build.

Agreed, heat pumps require a hot water cylinder to provide sufficient hot water. My concern is the mood music from the government is changing from carrot (RHI) to stick (Building Regs) with regards zero carbon heating systems, and the stated annual target of 600,000 HP installs by 2028 will only be achieved with a large stick in the retro-fit sector. If you need to replace a boiler after 2028 I feel you will be strongly encouraged not to go with gas or oil. Having to retrofit a HW cylinder, UFH, larger rads etc. etc. will require a more significant tear up.

If it's not been extended already, since it was first built, doesn't have a condition disallowing PD (unlikely from 40 years a go), and is not listed, then it will have PD.

Septic tanks are not allowed to discharge to a water course, they must now have a suitably sized leach field, but small treatment plants can, if you work within the general binding rules.

Hi and welcome. I'd suggest looking at an ASHP. I assume you will be addressing insulation and air tightness, so have the opportunity to reduce heat loss. ASHP require lower capital than GSHP and are fairly similar in performance. RHI is running until next March, so you'll need to be quick if you wish to take advantage of it. Are you aware of the possible reduced VAT rate for renovating empty properties? It's worth looking in to it if you are not. You should also be aware of changes to Building Regs for next year that require the heating and hot water system to be designed for "low temp". Even if you start this year, it's definitely worth considering a system boiler and hot water cylinder to future proof your home.

You may not be able to use the hardcore you crush in areas that the SE has specified what needs to be used, since yours will not be "certified", but if you've got enough pathways and driveway to use it all then I'd say crush it on site.

Yes that's a possible argument the LPA would accept. Have you used up all permitted development on the house? Beyond PD you generally have to argue exceptional circumstances to enlarge further within green belt. Trading off other outbuildings is one of those arguments, but it's a case-by-case consideration. If the outbuilding is associated to the (farm???) house, and sets up a typical scene of an agricultural unit, then they may argue that even though you are reducing developed volume your proposed extension has greater visual impact (residential volume in lieu of agricultural). Would be a shame to have to remove a large outbuilding unless it's unacceptably close to the house, but 50m doesn't sound too close. If you have PD available I'd try and extend without offering the removal of the other building, and then see what they are willing to trade.