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I started off as a joiner then build a construction and civil engineering company from £300k to £10m in a past life. I have a lot of experience and knowledge. My main subject is retaining wall design and construction.

It wasn't a turn off when we sold our house last year. We had three people bidding against each other at significantly higher than the asking price. We had an EPC of A95 without renewables which is what people seemed more interested in.

Been there have the T. Block built passivehouse, cavity wall, EPS beads. Plug in rad for heating. Words of caution. 0.3 ACH is difficult. You'll probably need to do it yourself. I was pathological to get there. A true window install of 1.1w/m2k without overwapping external insulation is almost impossible. Windows are routinely 5 times worse than a wall for heat loss. Also EPS beads real life I suspect are closer to a k value of 0.04W/M/K.For a 200mm cavity work on a U value of 0.2. Passivhaus 20deg is not warm enough for everyone, in every room. Our house lives closer to 21/22 which will have an effect on your bills. With no central heating you rely on air-circulation to even up temps. If doors are closed ,ground floor rooms will cool down if the never get any sunlight. More so if you have windows. Equally, overheating, west windows are the worst as they're a pig to shade. A small room with a closed internal will get hot at any time of the year. Finally and most importantly you may or may not have to co-occupy with other humans. Passivhaus goes out the proverbial triple glazed window when you have a gale howling through the hallway for an hour a day as the front door is permanently open. Likewise if you open ever window for 24hrs a day in a heatwave you will have overheating. If I'm home alone the resistance rad on a timer with open internal doors works well. Kids+partner add so many variables in real life however......... you may want to spend £500 on UFH pipes just in case. TLDR. If you plan on having windows and/or non scientifically fundamentalist lodgers an active heating/cooling system might be prudent.

It looks like cooling will be more of an issue for you. Does the glass in the southern wall cover both floors? Once the heat is inside a well insulated house, it is very difficult to remove without A/C. My biggest takeaway from the forum when I first started my research was all these well insulated houses were overheating. A certified Passive House tries to balance the solar gain with window overhangs. I put in upstairs UFH purely as part of a summer cooling solution. I also went with solar cooling window coatings, because despite the reduction in solar gain, it is easier to add heat in winter, than cool in summer unless you have A/C.

We have a 192m2 floor area, UFH pipes on 300mm centres. But with a smaller area you have watch flow rates as they can easily be way to low for a heat pump. Ours is about 12-13l/m so ok for a 3to 5kW heat pump. If the floor area was smaller you need to looking at 100-150 spacing to ensure you have a suitable flow rate to keep the HP happy. Don't base any calc on having solar gain, as it may not be there. Couple of overcast days with no gain can make a big difference.

How will you be heating water? I'd still be tempted to go for some form of UFH if only for the cooling function in the warmer months.

I've been interested in PV for a while but put off by the variance of estimated savings making it difficult to determine how useful it would be to my specific house. PVGIS is a fantastic tool, but how much of that generation could I actually use? "Around 50%" wasn't specific enough for me but fortunately, my smart meter was recently updated to connect to DCC, so it was time to go down that rabbit hole, results shared here to prompt debate and so others can point out errors and maybe explore a similar study on their own property. Firstly, hourly data for the proposed install location was downloaded from PVGIS and averaged over the 2005-2020 period available: https://re.jrc.ec.europa.eu/pvg_tools/en/. This average was then dumped into an InfluxDB database Next, half-hourly consumption data from my smart meter is available via a DCC connected company, with 13 months of data available. There are a number available, I chose Bright as they have API support: https://play.google.com/store/apps/details?id=uk.co.hildebrand.brightionic. This data was pulled down with a python library into the InfluxDB database: https://github.com/cybermaggedon/pyglowmarkt. Note I had to pull 10000 minutes at a time as there seems to be a limit on request size. Now I have all the data, there's a few options on what to do with it. Firstly, Grafana was used to support detailed interrogation of the data as well as an in-built method for summing timeseries data. Below pictures are for a 3kW system mounted vertically on a ~SSE facing house wall: Annual utilised PV is just the min of usage/generation for each hour in the time series. The result is... disappointing, suggesting if I'd had this system installed over the last year I'd only have used 40% of the generated power. As with most houses, the culprit is significant evening usage - computers, TVs, dishwasher etc. I can shift some of the usage to mid day, but not enough to make a significant enough impact. Inspecting a random day (6th September) confirms an increase in PV size would not solve the problem either: Area on this graph is kWh so it's easy to see a lot of wasted generation mid day (between the blue and orange lines) followed by significant grid usage in the evening (between the green and blue lines). Note that electicity consumption is quite low as my heating and hot water is from mains gas. Ideally this excess could be dumped into a hot water tank but we have a combi boiler and I'm struggling to make the sums add up once you factor in even more initial investment for a tank etc. Therefore I'm ignoring offsetting gas consumption and purely looking at the significantly more expensive unit rate electricity consumption. That aim then brings us to battery storage. I couldn't find a way to simulate state in Grafana so used the InfluxDB Python bindings to set up a basic charge/discharge simulation across the year. It does not factor in battery efficiency due to me being lazy which will slightly skew figures. This simulation takes three parameters: PV system power in kW, battery capacity in kWh and the unit electricity rate to calculate savings. Hard to predict for a long term investment so I just used the current 27.09p/kWh rate. It's then possible to experiment with proposed systems: $ ./battery_sim 0 0 0.2709 0.00kWh utilised and 0.00kWh stored out of 0.00kWh generated. Total 0.00kWh (0%). From grid: 2280.95kWh. Annual Saving £0.00 $ ./battery_sim 2 0 0.2709 750.32kWh utilised and 0.00kWh stored out of 1424.67kWh generated. Total 750.32kWh (53%). From grid: 1530.63kWh. Annual Saving £203.26 $ ./battery_sim 3 0 0.2709 863.03kWh utilised and 0.00kWh stored out of 2137.00kWh generated. Total 863.03kWh (40%). From grid: 1417.92kWh. Annual Saving £233.79 $ ./battery_sim 3 5 0.2709 863.03kWh utilised and 998.04kWh stored out of 2137.00kWh generated. Total 1861.07kWh (87%). From grid: 419.89kWh. Annual Saving £504.16 $ ./battery_sim 4 5 0.2709 930.05kWh utilised and 1102.64kWh stored out of 2849.34kWh generated. Total 2032.69kWh (71%). From grid: 248.26kWh. Annual Saving £550.66 $ ./battery_sim 4 9.5 0.2709 930.05kWh utilised and 1151.73kWh stored out of 2849.34kWh generated. Total 2081.78kWh (73%). From grid: 199.17kWh. Annual Saving £563.96 $ ./battery_sim 5 9.5 0.2709 970.84kWh utilised and 1211.10kWh stored out of 3561.67kWh generated. Total 2181.94kWh (61%). From grid: 99.01kWh. Annual Saving £591.09 $ ./battery_sim 5 13.5 0.2709 970.84kWh utilised and 1221.01kWh stored out of 3561.67kWh generated. Total 2191.85kWh (62%). From grid: 89.10kWh. Annual Saving £593.77 $ ./battery_sim 7 13.5 0.2709 1018.43kWh utilised and 1268.62kWh stored out of 4986.34kWh generated. Total 2287.04kWh (46%). From grid: 0.00kWh. Annual Saving £619.56 Quite easy to spot the return on investment of the PV and battery capacity is tightly coupled, no point having loads of generation you can't store or massive storage with no excess generation. This is where I've stopped for now, it'd be trivial to go one step further and optimise the system for most cost-effective setup but that would need a cost function for £/kW solar and £/kWh storage (installed) that I haven't bothered to put together yet. Note that the upgrade to a Tesla Powerwall (13.5kWh) is very cost-ineffective, but could technically provide 100% of my usage with a 7kW solar array. The 5kWh battery with 3kW PV seems a sweet spot for me and uses 87% of the generated power but I'm unsure on the costs of such a system yet. To go ahead I'd prefer a maximum 10 year ROI which sets pretty tight budgets, ~£2k for a 2kW system with no battery or ~£5k for a 3kW PV 5kWh battery system. This obviously rules out MCS, but has anyone got close to this with self installation and connection by an electrician? Comments and questions welcome, does this line up with actual performance people have seen from their installs?

See page 20 and 21 of the installation manual. Looks possible if there aren't any openings nearby (I mean if the slope is ok).. https://mediacdn.baxi.co.uk/-/media/websites/baxiuk/files/product-literature/baxi-platinum-combi/baxi_platinum_combi_installation_and_service_manual.pdf

It is odd as I have heard on the radio (I don't have a TV) several times recently, that turning down the temperature at the boiler will save energy. Some people may be in for a shock, especially ones on quarterly billing, the period between October 1st and January 1st could be painful.

S'alright, they're stuck in with solvent weld, it'll come apart easily...and leak. Proper job here:

I just paid £250 for airtest, MVHR commissioning done at same time for £200.

If this is a combi I have found the same. I upped my temp to 65 and have a significant drop in gas usage. Tried at 48 and up, so 65 has been the best for gas usage.

It would be local ground level as you have to account for any slopes. E.g. if you have a fall of 500mm over the length and used the existing floor level as the datum, then your trench would only be 600mm deep. So you use the local ground level and introduce steps so you maintain a consistent depth. Of you've a fall of 100mm, I wouldn't worry too much. The whole point is to ensure you are down to firm, undisturbed ground and to allow enough depth for the concrete. It'll all change once you start digging!!!

We put 12mm2 in. Doing water pump treatment plant compressor, and discharge pump. Since installing have taken a power supply to garage, and will possibly have a small ASHP connected also.

I would check your solar gains at this time of the year. As said once the heat is in its difficult to get it out with out Aircon. Have you thought about a split Aircon system, high does heating and cold very efficiently.

The recent energy crisis will help change people’s attitudes towards heating with gay abandon because it used to cost buttons to better understanding that reducing the need to heat your house in the first place makes more sense.

Do you think you'll ever sell the house? Do you think a house with no central heating will be a turn off for potential buyers? That's why we stuck in UFH and an ASHP. May not be used, but no way somebody is going to pay market rate for a 300m2 house with no heating. £10k well spent. When we first moved in, three 1.5kW fan heaters on for 12hrs at a time kept the house at 18-20c when it was 8c outside and the house still drying out. So I'm certain we could live comfortably without the ASHP and UFH... But it's in and will be used.

IIRC we calculated a heating requirement of 1.14kW for a 30C temperature difference in our PH. We designed the house so we wouldn't need a conventional central heating system with UFH and ASHP. We heated the house with three electric towel rails in the bathrooms and a 585W EASHP providing warm air heating through the MVHR system when required. We heated the whole house to 23C. In order to compare what level of comfort you would like it is necessary to know the temperatures others have in their properties.

In 2017 I paid £200 for a half day which included finding leaks and doing the test.

It’s even more complicated than that. What about folk that pay a combined amount for rent and utilities. Most student accommodation is organised like that and they already get stiffed from my son’s experience. Same with folk that live in caravan type parks etc. This isn’t an easy nut to crack.

Almost exactly the same heat input requirement as us, just over 2kW when delta T is 30 degrees. A 5Kw ASHP is doing the job nicely, heating the house and the DHW (in a 300L UVC) Are you doing much of the build DIY? If so when you shop around, the cost of UFH parts is not a great deal so not much extra cost if you were having the ASHP anyway for water heating? We also have a 5kW wood burning stove that is also more than capable of heating the whole house. One thing is pretty certain from our own experience and others is you won't need heating upstairs, so that simplifies the heating to a few loops downstairs.

Or find a better plumber to patch up the old one so it will last?

Think the strength will depend mostly on the screw, how secure it is in the wood and how many along the bottom. The plastic is just to protect the glass edge from the screw. Tiny stress cracks can cause toughened glass to shatter. For same reason never stand toughened glass on concrete, tiles or stone.

Just replace with similar gas combi.

Something like this? https://www.omegabuild.com/shop/shop.php?category=secondary-glazing-fittings-easyfix-edging https://www.amazon.co.uk/s?k=secondary+glazing+fixings&adgrpid=126785493076&gclid=Cj0KCQjwyOuYBhCGARIsAIdGQROLktcHw02jG1vgMCeVkQrLrjesB6eIJsXgyeUmyD3Fgjd2tuwMySkaAm7iEALw_wcB&hvadid=543083316377&hvdev=t&hvlocphy=1006818&hvnetw=g&hvqmt=e&hvrand=7320255020270910883&hvtargid=kwd-360730112349&hydadcr=28181_1821134&tag=googhydr-21&ref=pd_sl_56z4dawksr_e

Just a heads up on earthing.. In many cases you shouldn't export the earth from the house to an outbuilding. There should be an earth rod at the outbuilding instead. A common set up involves: A MCB is fitted in the House CU. Rating depends on the cable. The cable braid is connected to earth at the house CU end only. At the outbuilding a "Garage CU" is installed. These are typically supplied with an RCD and two MCB (lighting and power). The Earth in the Garage CU is connected to an Earth rod hammered in the ground near the outbuilding. Edit: Your water pump could be plugged into a 13A socket on the power ring in the outbuilding. I think it may also be possible/better to wire it into an FSU.

Calculator here.. https://www.tlc-direct.co.uk/Technical/Charts/VoltageDrop.html Suggests 4mm^2 SWA underground is OK for about 7KW and 6mm^2 about 9kW. Main thing to check is the exact cable length. It's easy to forget you might need 4-5m each end.

Yep £300 here Gloucestershire. Mine was here for a good couple of hours.

I would go for a 4 or even 6mm cable, very little difference in price so might as well be over spec. To allow for extra sockets/lights etc to be added on later. assuming you don’t have big machines in the workshop in which case 10mm.

Oh yes! 1st fix electrics aren’t too bad on I’s but pozi’s make plumbing or conduit (protected fire alarm cables) runs so much easier

Good luck 🤞

Quick update. We have our Design Review Panel meeting this morning. Fingers crossed.

I am in complete agreement, it's a logical easy enough plan to follow. Only thing I would add is to take all the timers off the central heating, set the thermostats to around 24 and trvs fully open. Start the testing at a weekend when you home for a couple of days.

Your 11.2kW PUHZ version uses R410 coolant and a twin rotary compressor. The latest 11.2kW PUZ version uses R32 coolant and a scroll compressor. The good news is that the quoted overall performance ratings are similar between these two models so, as others have suggested, your PUHZ setup just needs more effort to find the efficiency sweet spot. If you haven't already, I would strongly recommend an inspection/service to ensure no faults.

dMEV are silent also, not the same as a normal bathroom fan. A few watts to run each.

Don't tell them that hospital have them. I think it is about time that everyone realised that power is not delivered from just one source. All countries need a mix of sources, it is just the fraction of each that seems to be misunderstood. I can play with figures and create a number of different scenarios to achieve the same end i.e. adequate power 99.9% of the time. I could show prices and delivery based on historic data (it's all there for anyone to look at). I could even throw in environmental issues. But it will make not one jot of difference to most people as they take no interest in it, and even less willing to learn about it. The best thing would be to let the National Grid sort out the size and location of generation installations (they know how to manage what they have incredibly well), then invite tenders from the generation companies. So planning rules will have to be overturned, but it is about time individuals realised they don't, through a fluke of wealth and location, have the right to deny others what they can easily afford. To show, in an odd way how fickle people are, the tourist figures for August came out yesterday. Allowing for rounding, Cornwall had 1 million less visitor trips. So about 20% down. Cornwall has not changed, except we had very little rain this summer, prices have not changed much, no travel restrictions and the people down here still hate the Emmets. Where did they all go, abroad or stayed at home?

I must fit some sort of active shutter to an extractor fan in our downstairs loo. I was puzzling over a uniform layer of dark grey dust on the lid of the toilet cistern when it dawned on me that the day before I'd been in the garden sanding a painted picnic table!

Plasterboard saw. Cut it big and rough then just foam around.

... I don't think the first link works? This should: https://flic.kr/p/2nJMkws

Anyone else been stung? Paid 90% with installation meant to start in a few weeks time and have just found out they went into liquidation yesterday. Been to the yard and there is barely a thing there. So despite one of my payments being entitled "Materials" and another "Manufacture" they have neither got my materials nor have they manufactured anything of my house. Anyone else been in a similar position? The more I speak to other trades and my architect the web of people they have let down is getting ever larger. The liquidator has informed me it'll be a week or more to get letters to all the creditors and then maybe a month or more before they know if there are any assets to liquidate. Feeling more than a little disappointed and have no recourse against them. More than that I now have foundations for a house I cannot afford to build.

@Onoff you’ve been busy again