IanR

No, the insulated "slab" can't extend under and take the external wall loads (making it a raft) while sitting on PIR and without a suitable build up under the raft (see AFT examples at link I provided) What's missing in the AT's sketch is the pile capping/beam that joins the top of the piles for the dwarf wall to sit on. Giving the AT the benefit of the doubt, the rectangle they've drawn is intended to cover the piles and beams. What have you asked for with regards the floor/foundation. There appears an attempt to go above building regs regards insulation, but there are better ways of doing it.

That's not a raft foundation. Is the technician calling it a raft, or is that an assumption you have made. Yes, to be a raft, what is shown currently as a concrete slab needs to extend under the load bearing walls. If you are after an insulated raft and require it to be supported with piles due to ground conditions, that's quite niche. You'll need someone with proven experience. I'd recommend having a chat with Advanced Foundation Technology: https://www.advancedfoundationtechnologylimited.co.uk/our-products/timber-steel-icf-framed-building-foundation/

What have you based your opinion on? Are you aware of the NPPF Rules for Green Belt? Does the LPA have a policy in the Local Plan that says how they deal with development in the green belt? From https://www.gov.uk/guidance/national-planning-policy-framework/13-protecting-green-belt-land You need to be able to argue one of the exceptions, otherwise the LPA will refuse. If you have deep pockets with regards obtaining the planning permission, it's worth looking at "Para 80 e)" development. While it's not explicitly a green belt exception (it's regard development in the open countryside), on occasion it does get an Approval within the green belt.

I've got the KF410 Studio from 2017 in my Utility and Boot room, which looks to be halfway between the current KF520 and KF410 versions. For an opening sash, there's not enough frame on the inboard side to cover any more than around 5mm of the frame, before you'd be stopping the inward opening sash from being able to open. So, internally you'll be seeing nearly all the frame. Externally, you can cover the sides and top of the alu-clad frame with your cladding/render board, but not the bottom. On the sketch below the blue block at the bottom comes on the window and I've shown the internal cill level with the bottom of the frame, and the pink is a folded external cill. The hatched area is supposed to show cladding on the side of the rebate covering some of the frame. Edited to add: I have alu-clad timber across the rest of the house and while I'm very happy with them, if/when I do it again I'll think seriously about saving the money and going UPVC through out. The KF410 is a really solid, stable, well built window.

Ha - Not something I have direct experience of but I know of the "Probity in Planning" guidance document for councillors: https://www.local.gov.uk/sites/default/files/documents/34.2_Probity_in_Planning_04.pdf As per section 5 I believe the councillor in question would have to withdraw from the committee since if he's already given his view before committee he has a "closed mind" with regards the decision to be made.

I'm going to ignore your comments now, no idea why you choose to be argumentative, some of your input is of value. The ASHP will be on and off, the emitters are more constant. They are not balanced.

The gauge in the pocket 2/3 up looks close to me measuring at 35°C, although both the gauge and the laser temp gun will likely have a ±1°C tolerance so can't be relied on to compare between the two. You'll need to measure a few times to get a feel for what is going on, the temps are dynamic as the ASHP comes on and off and you're wanting 0.1° accuracy which isn't achievable with consumer devices. It would be nicer to see the temps across the top, and those at the bottom within 1° of each other. If after multiple readings, at different times, you are still seeing a similar result are you could try to slow the emitter pump down and are you able to limit the flow rate of the ASHP? Not sure if it's a setting available on all HPs, but I can turn mine down (on space heating only) to make it run slower for longer. I set mine up with a data logger and DS18B20 sensors and some times the traces would show the flow temp to the emitters higher than the flow from the ASHP, which isn't possible - the accuracy of the readings I need are not within the capability of the DS18B20's. After about 10 different sets of readings, each running for a couple of hours mine averaged out with the emitter side being within 0.5°C of the ASHP, except just as the ASHP stopped or started. Is it cold enough that the emitter circuit is running continuously (my own heating isn't on yet), are the measurements you have taken are at a reasonably steady state?

? The emitters are not on, the Buffer is at flow temp, possibly fully charged. You can't draw any conclusions, unless you have a biased view. A 4P buffer removes the inefficiencies and warranty concerns of short cycling, at the cost of minor standing losses and powering a second circulation pump that would not otherwise be required in most cases. ? The ASHP will switch off when the buffer is fully charged at flow temp.

That's not correct. A 4P buffer is to allow hydraulic separation, allowing the emitter circuit to take energy at a different/slower rate than the ASHP adds energy, reducing short cycling. Thermocline/stratification is a robust phenomena that does not require balanced flow rates - it occurs in HWCs that do not have balanced flow rates, and have no baffles or features to promote stratification.

You'll be losing a lot of temp from the uninsulated pipe work. Can you measure the temp on the pipe into the buffer from the ASHP, just at the joint to the tank.

Keep an eye on the temp gauge, there's no circumstance where it should stay at 30°C. At 2/3 up the tank then when the ASHP is on it should mostly be showing a temp around the flow temp, and when the ASHP switches off, if the UFH is still running it will, after a while, drop to return temp, shortly before the ASHP switches back on. Flow temp is water temp coming away from the ASHP. The flow rates either side of the buffer do not need to balance, a 4 port buffer is there to allow the exact opposite, ie, the UFH to take energy from the buffer at a different rate to what the ASHP supplies it, it's what protects the system from short cycling. The biggest improvement you could make is some insulation on those pipes.

It would mean 0.714m³/m².h, rather than ACH, natural ventilation. For total ventilation you'd then need to add the MVHR ventilation (converting your 0.5ACH to m³/h). Or you need to convert the air permeability target units to ACH and add to the 0.5 ACH of the MVHR. Apologies, I shouldn't have included the "@50PA" on the MVHR figure, it would be just the m³/h. The *10% is to account for the 90% heat recovery of a PH certified MVHR. If we're keeping everything in ACH, and the target is 2 ACH, then total house loses from air flow is the 0.2 ACH (from natural ventilation) + (0.5 ACH * 10% (from MVHR)). If the heating engineers don't consider MVHR then then I'd give them this value. [physical air permeability testing (blower door test) in the UK tends to provide results in the m³/m².h@50Pa units, as that's what building regs uses, so you need to work out how to convert between them and ACH for your property] I'd ignore natural ventilation for the MVHR figures. The building regs airflow requirements are a minimum, so base those on MVHR only. I'd only consider natural ventilation figure within the total house losses, when sizing the heating system.

Is it a 4 port buffer? What size is it? What height is the temp sensor? Assuming 4 port (or 3 port) I'd go with flow temp control running off a weather compensation curve.

It's actually 8m³/m².h@50Pa rather than ACH. Each house has a different relationship between the two so you'd need to calculate the ratio for your house. (PH is 0.6 ACH as you say) Supposedly, the Building Regs change due 2025 (if Labour continues with the plan) for the future homes standard will drop to 5m³/m².h@50Pa. 20 is used for an unexposed area, 14 tends to be used for an exposed area. I'd keep it, but use the "rule of 14". But, infiltration losses should be based upon: (air permeability (m³/m².h@50Pa) / 14) + (MVHR flow rate (m³/m².h@50Pa) * 10%) The higher insulation and air permeability you target the greater the proportion of losses due to thermal bridging. Have you attempted to account for thermal bridge losses for your construction type? Most heat loss calculators include a "standard" psi value for typical construction methods, if you are mitigating thermal bridges you should adjust for this.

Hello and welcome, Sounds like your LPA is taking a pragmatic approach, which is as much as you can hope for. Look forward to seeing your plans once you are ready to share. Hopefully keeping the portal frame has not put you off the passive slab, depending on finished floor level versus the height of the pads under the columns there's a bit of extra detailing to do, but it is all "doable". I worked through mine with Advanced Foundation Technology Ltd and came up with a neat solution dove tailing the two together so they have some previous experience which may be useful to you if you've not already settled on a supplier. Have you thought of construction method for the timber frame? While the existing portal frame is quite an open structure, keeping the purlings in place (to keep teh LPA happy that it's a conversion) does make it awkward to crane a panelised system into place. I settled on a stick built solution but went with an I-Joist structure to allow lots of insulation. Good luck with your planning app.