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Do you have any other "systems" for heating, cooling, avoiding solar gain? For me it was an easier decision to have Loxone controlling the UFH as I also wanted to control the MVHR, roof vents and external blinds to ensure everything was working together to either heat, avoid heat or cool the house. Loxone decides whether the house is heating, cooling or taking passive measures using an average of all the temps from the Touch Pure light switches in each room AND comparing the temp of those rooms effected by solar gain with those that are not AND comparing the slab temp in those rooms effected by solar gain with those that are not. Loxone then decides whether to just circulate the UFH, without any heat/cool input in order to distribute solar gain, or to employ blinds and/or vents, or to heat/cool the buffer and distribute that heat/cool via UFH and MVHR. I have Loxone actuators on each loop of the UFH as well as relays to control the UFH pump, MVHR wet heat exchanger pump, DHW loop pump and a valve on the UFH splitter manifold that separates it from the buffer when it's just circulating the UFH to distribute solar gain.

Good news, that was the first concern, and you'd have needed to take a few steps before speaking to the local planning authority.

Hi and Welcome. Does the property currently have planning permission? Sounds like when it first appeared on the landscape it may not have had residential planning permission, if so has that ever been normalised?

Yep, rules changed at end of 2017. HP "water" cooling is now allowed on RHI

100l per person per day seems high for hot water usage. I thought 50l per person was considered high usage. But, perhaps that's a rule of thumb he uses for sizing cylinders. After all you're not going to heat the water once a day and then use it all, your heating system will be topping it up though out the day. Should you not be sizing for the capacity of the house, rather than your particular usage? Also, falling in line with the 2022 regs seems a good idea, ie. sizing the UVC for a low temp heating system, avoiding having to refit later. If 4 adults is the capacity of the house (3 Bed??), and a low temp heating system is allowed for, then your plumber's 400l tank sounds about right. Maybe you could go a bit smaller, but if there's space, bigger is better - just don't run it hotter than you need to.

My 12kW Nibe requires a minimum 80l buffer (or always open loop), and I believe the 8kW Nibe was the same. I've gone with a 200l buffer, but for cooling reasons. ie. I can cool the buffer and let the UFH work off of that for longer while the ASHP is heating the UVC.

Hi and welcome. What made you choose Baufritz? (not a loaded question, I know nothing about them). What are the "Eco" credentials? Good U Values and Airtightness? What Foundation/floor systems will you use?

Your M&E guys must be assuming the energy losses of the FF (and basement) are then being covered by another heat source. I can't imagine you want to use the electric UFH and towel rads to fully heat the FF, but rather to top up those rooms if the GF heat has not permeated sufficiently. Your ASHP needs to cover the total energy losses for the house and the GF UFH needs to emit sufficient heat for the whole house. This will then permeate to the 1st floor via convection, conduction and MVHR. In a well insulated and airtight house, DHW is more likely to be the energy requirement that drives ASHP sizing. What size UVC have you spec'd? I have a slightly lower energy loss than your calculation, and a 500l UVC. I went with an over-sized 12kW ASHP for a quick reheat time on the cylinder. I could probably have gone with 8kW ASHP and not noticed the difference as the DHW usage is not as big an issue as I expected, even when both space heating and hot water are being called for simultaneously. Over-sizing the ASHP does of course require a decent size buffer for space heating.

Apologies, in the very last calc., I've incorrectly used the the Thermaline's U Value and not its R Value. So, what I should have said is: And then to get the total U Value of the new wall build up: 1 / ( R of original wall + R of the Thermaline), so 1/ (0.51 + 1.96) = 0.405W/m².K Edited to add: ...and Ubakus roughly agrees

There is a bit of a mix up in the units. Typical units for U Value are W/m².K . the 1.9 figure you have looks "about right" for a 9" solid wall with some plasterboard on it, so that's probably 1.9W/m².K The value you have for the Gyproc Thermaline Super looks more like a λ (lambda) value ie. Thermal Conductivity of the phenolic foam part of the composite board. The typical units for an λ value are W/m.K. But the boards are made up of gyproc wall board (λ 0.19W/mK) + the phenolic foam (λ 0.020W/mK). If you wanted to workout the thermal resistance (R value) of the whole board thickness, you need to divide each material's thickness in meters, by its λ value to get its R value, and add the R values together. Typical units for R are m².K/W For the 50mm thick Gyproc Thermaline then, that's (0.012 / 0.19) + (0.038 / 0.020 ) = 1.96 m².K/W (I've assumed 12mm gyproc and therefore 38mm phenolic foam) To get to the U value, you need to 1 / (sum of the R values). For the Thermaline on it's own that means the U vlaue is 1/1.96 = 0.51 W/m².K But to see how this effects your wall if added on, then you need to revert the wall's U value to it's R value ie. 1/1.9 = 0.53 W/m².K And then to get the total U Value of the new wall build up: 1 / ( R of original wall + R of the Thermaline), so 1/ (0.51 + 0.53) = 0.96W/m².K Edited to add: There are online calculators to make this easier https://www.ubakus.com/

For someone looking for low energy losses, but not wishing to go as far as PassivHaus type measures then 3m³/m².H @50 Pa is the sweet spot. (I've changed units from ACH as "m³/m².H @50 Pa" this is what Building Regs uses) In England at least, if you drop below this level then Building Regs require you to provide mechanical ventilation, which you're not going to benefit from unless you go significantly below this threshold.

There was lots of chat on this 10 years ago or so. iirc the consensus then was to use silver-lined pipes to avoid health issues related to mould growth. Not sure what the current thinking is, but do your research, it could be a breeding ground for mould.

ASHP cooling is allowed on RHI. Rules changed at the end of 2017. Although many installers seem to be unaware.

You have to submit your paperwork by midnight 31.03.2022. To get all the paperwork together the system will need to have been commissioned and the invoice paid.

Heading to auction. Perhaps someone is in a rush to sell. https://auctioneertemplates.eigroup.co.uk/auctioneers/ded/lot-details.html?lid=149337&ClientID=33&lad=Stebbing-Road-CM6-3LG

You've put 20mm for plaster, so perhaps there is a plaster board? If it's foil backed it resolves the condensation 100%. If not foil-backed it helps a little and pushes the surface condensation to only when it is below 0°C outside, and with an 8.5 hour decrement delay it's got to stay below 0 for 8.5 hours before the inner surface drops below the dew point. You may also have the inside temp lower than the 20°C I've shown and generally have a lower RHI than shown, which will all help avoid surface condensation. Plasterboard also brings the U Value down to just under 2 W/m²K

You've not mentioned a plasterboard, so I have assumed a rough coat straight on the brick then a finish coat on top. U= 2.222 W/m²K - It's not looking great for condensation (surface & interstitial ) at low outside temperatures. It's surprising how much improvement on the U Value a relatively thin insulated plasterboard achieves, and removes any condensation risk. U = 0.672 W/m²K Calcs from https://www.ubakus.com/en/r-value-calculator/?

I feel the Planning officer has a romantic notion of the "open countryside" and does not appreciate that in private ownership it needs to metaphorically earn its crust. It is unreasonable to expect a paddock to be open to an access track - there are 101 reasons why that wouldn't be acceptable, and it is unreasonable to categorise the open countryside as absent of fences and suggest that they are contrary to the intrinsic character and beauty of the countryside. It is also unreasonable to label post and rail fencing as "ranch type" suggesting it is alien to the UK countryside, being of a type only used on large North American horse and cattle ranches. I'd include the agriculturally typical post and rail in your Reserved Matters application and set your argument out. I can't imagine they'll refuse on that basis as I don't feel their position is defensible on appeal. Maybe an approach on the garden is to split what you currently have proposed into a smaller garden, close to the house and then the rest as an area of amenity land. It still allows you a residential use, but restricts the area that is considered as residential curtiledge, so from the LPA perspective it keeps the residential paraphernalia (sheds, rubbish bins, clothes lines, hard landscaping etc.) closer to the dwellinghouse.

Congratulations! There's a sniff of over-reach there. They will have given a justification for this in the Officer's report. This may be able to be challenged if they do not have a good justification. Yes, the conditions only cover the planning unit defined by the red boundary on your application. If the red boundary defined the track, then that does suggest there is nothing stopping you fencing the neighbouring field, from the track.

@Robw85 Thought this may be of interest, if you've not seen it already. A little North of Lower Barn Farm, and under the Uttlesford LPA, which by all accounts are a lot more relaxed on Change of Use PD/Applications. https://www.rightmove.co.uk/properties/113649239#/?channel=RES_BUY https://publicaccess.uttlesford.gov.uk/online-applications/applicationDetails.do?activeTab=summary&keyVal=QUPD1TQN01O00

I'll add a mention for an Insulated Raft foundation. Most "manufacturer's" of these will claim they are cost effective compared to traditional foundations due to the shallower dig, less concrete used and no need for a separate screed. I can't vouch for those claims as I never costed a traditional foundation, but went this route for my build due to the higher thermal performance. They are suitable for most ground conditions, down to quite low bearing capacity. An insulated raft for a timber structure is the simplest (cheapest) of the options, and gives the best opportunity for removing all floor to ground cold bridges. Having a masonry outer skin, or ICF build adds a little complication and cost to an insulated raft due to the likely need for a second, separated ring beam around the periphery of the raft to take the extra weight.

I like the wide door option, but what angle can you open them too? Ie. Is the frame set flush with the outer face of the wall so you can almost get them to 180. With the side lights you should be able to open them right up even if recessed into the reveal.

3G shouldn't be double the price of 2G, if all else is equal. I'd recommend 3G, if aspiring to PH levels of energy loss, ideally with triple air seals to assist in air tightness. Alu-clad will help the durability of the frames (giving a 60 - 80 year life), and certainly shouldn't be failing after 10 years.

Yes, definitely chase to get an indication of what issues, if any, they have with you application. Might give you an opportunity to make minor changes and avoid a rejection.

Couldn't agree more. There's no need for the additional complication, standing charge, service costs. I personally wouldn't consider keeping the Gas Boiler, based on what you have said. Your Gas boiler didn't require a backup system in case of failure, so neither would an ASHP. That brings RHI back in to play, if you can get the property to an EPC C. Victorian or not, as long as not listed, there has to be options. ASHP generally range from 2.5 to 5.0 SCOP. To get towards the upper level you'll need a space heating flow temp of 35 degrees. I think having a huge thermal store works against the ASHP. Trying to fill it up in 9 hours at 15kW, rather than heat the house directly at 5.4kWh makes for an inefficient (higher temps and large standing losses) and an unnecessarily large system.