ragg987

From what I understand you do need conditions that will allow moisture to be removed. Heat and airflow are the 2 main contributors to this. In our case I switched on the MVHR early and put it on a timer so that when people were working in the house it would be off (to avoid too much dust in the works, so i asked the builders to open windows and doors during the day and shut them all when they left), then come on overnight for approx 14hrs. I also used a large fan and heater in our basement as that was very damp from flooding during some core drilling through the ICF. I then changed the filters and washed the heat exchanger prior to moving in - they were filthy, and I think we still have a bit of dust in the ducts but we live with it. In all it took a bit longer than the 6-8 weeks (calculated) it should have to get a sensible reading on the meter. Also, suggest you scrape off the laitance sooner rather than later. It will be easier do remove if done early and will also improve drying. Tip from my screed company.

Can't help with this specific one, but our unit also has a heater built in and (if I have interpred the instructions correctly) it will come on only if the incoming air, post heat exchanger, would be below a set temperature. This is a user setting, I have set mine to 10C and it has not been used. One thing I would look out for is occupant behaviour. For instance, when the other half is cleaning / vacuuming etc she likes to open the windows "to let fresh air in". Then a couple of hours later she says the house is too cold! Aaargh. It has taken a lot of reminding that even with all windows closed we are constantly getting warmed fresh air in the house, and that opening the windows on a cold day means the poor little 7kW ASHP cannot cope and dump sufficient heat like a 25kW gas boiler did in our old house. Not sure if the message has fully got across yet...

Oh and if you need to transfer funds in a foreign currency, suggest you steer clear of banks, paypal and such as they take a big cut. Try the specialist companies like transfergo and transferwise. I use both and they are quick and fuss-free, I compare rates on the day and chose the cheapest. If you want to use these I can give you an introductory code, they will both give you some benefit (e.g. free transfer) as well as a small kickback to me (in the interests of full disclosure!)

Hi @jpinthehouse, some have been mentioned on here before. Bear in mind i purchased some 18 months or so ago, so things may well have changed by now (certainly EUR is stronger relative to GBP) megabad for all things sanitary taps etc. I used google chrome with auto-translation to navigate the German language site. Good prices with an auto-applied volume discount made the prices unbeatable as I was ordering enough to get the maximum discount. I also liked that they made sensible recommendations with an item, it made it a lot easier to get the right bits together in one order. A bit slow with responding to queries, and some items did take a long time to get in (e.g. my custom-drilled baths). Delivery was fine with nothing missing or damaged. Paid by BT. PVO for lighting. I emailed prior and they offered a discount code based on my volume. I only purchased SLV LED products, which seem to be solid and reasonable value, though they may not be to everyone's taste. I made my shopping list through CEL's catalogue and ordered on PVO. Fast delivery, one damaged item that was quickly rectified. Paid by BT. Milpe for rooflights. I did not order from the webshop direct as the windows I wanted were specific, but they were fast to respond by email and delivered quickly with no damages. Bear in mind leadtime for manufacture of products. Paid by BT. wagner-sicherheit for some very specific stainless door stops for external doors. Emailed and offered a good discount, quick delivery. Paid by BT. There were others e.g. for stainless external post box, rubber strips for internal doors (these give a luxurious feel to door closing - a nice touch!). Opportunistic purchases.

I found boards were going to be costly once shipping was added (was looking specifically at Fermacell), and managed to find a UK distributer who was cheaper than the internet sellers. In the end prices would have been about the same after shipping. Water softener look at waterclearlimited. Solid units at good prices. Boiling tap I got it cheaper from Germany as part of a volume discount with all my second fix plumbing, but the unit developed a leak and Grohe UK washed their hands from the warranty as it did not comply with UK regs. Got a good price for a replacement unit from appliancehouse - there was a cashback offer on at the time. But for sure purchasing from Europe is a good thing and quite safe. I ended up buying direct all bathroom / taps etc, LED light fittings, roofights and a bunch of minor bits and pieces. I also purchased European products like kitchens, engineered flooring and windows, but in the UK through a local distributor.

Hi Plee, welcome to the forum. "Offer too good to refuse" - we live in Aylesbury and some of the farmers are making a killing by selling their land for development! Mid-engine Audi's are a favorite plaything here. My feeling, having completed a build, is that yes the windows do matter, but probably more important is the service in fitting these. For some reason, the whole process was pretty problematic from window apertures being too big on site (timberframe supplier believed supplied dimensions were for windows not apertures), inconsistent levels with adjacent windows, fitting not being square, sticky doors, hinges out of alignment, poor sealing and the list goes on. It seems all issues in slab, timerframe, levels etc manifested themselves in the window and door fitting. For some reason the suppliers seem to outsource the fitting and the fitters are hit-and-miss, most turn up on site not having seen that particular hinge type before and so it is all a learning process. In our case, our supplier did see it through right to the end (though it was a painful process) and once I identified a fitter who was good, I asked for him to be allocated to all snags. So, I very much doubt a small difference in u-value is hugely material in the whole process, what is more important is you get the look, opening types and price right, plus ensure they are able to provide a good service. On GBS, I did look at them for windows but did not end up going to them for a quote, so no real experience. We ended up with inward opening Eastern European windows with a tilt and swing mechanism. Very practical and I now prefer this to the UK traditional outward opening swing.

In my experience there are 3 mains types of pricing. "high street chains" - inflate their prices then come up with massive sales so pull the punter in. My view is avoid, I found their bathrooms and kitchens to be extremely poor value even during their sales. Advantage is they offer a full design, supply and fit service - convenience. "discounted or specialist suppliers" - generally supply only but aiming a good value for money. e.g. IKEA or your local kitchen company, also covers internet merchants who are about shifting volume at lower margins e.g. Megabad. Some of these may have offers periodically (e.g. IKEA have 10% off all kitchens or interest free credit). "genuine discounters" - shifting stuff that does not sell well or may be seconds. eBay is one such source. Some great bargains to be had (I am selling some surplus stuff at around half price, for instance) but supply is hit and miss, suits opportunistic purchasing provided you have the time and can store the materials. I did most of my purchasing with the second group - googling for the best deals then getting on the phone and haggling where I could justify it - e.g. when I bought large quantities of oak floor, amtico, skirting etc. Most companies were happy to improve either the price or give free delivery. I supplemented that with opportunistic eBay purchases, but given the time constraints these were minimal. My biggest savings came from purchasing from Europe. I did this for bathrooms, rooflights, lighting as well as for some other bits and pieces. Google is your friend, but don't be afraid to ask for additional dscounts even when you find the best price, especially if you have some volume.

Rechargeable NiMH or similar? If you have kids these become essential. They also have much larger capacity than alkalines, so will need changing less often.

The way I did it was to start with outcomes. To give you an example of a bathroom (fairly obvious, but baby steps must...) Outcomes 1: water Location of bath, shower, sink, toilet >> initial layout of drains and water pipes, 1F. Type of taps and sanitaryware >> improves 1F e.g. because you want taps that are embedded in the wall and not on the sink. Communicate this to your plumber (in my case he marked positions and we went through it together and I had a big delivery from Megabad prior to 1F so they could rifle through the equipment) Outcomes 2: electrical What is needed, switches, towel rads, electric shower (please, no!), heated loo seat with a bum shower, etc >> initial location of wiring, 1F. Type of equipment >> improves 1F e.g. height of towel rad Additional stuff to think about, again based on outcomes "i want the lights to come on automatically" >> need to locate a PIR >> 1F wiring "I need a humidity sensor for MVHR" >> 1F wiring "I need a wall mirror with backlighting or demisting >> 1F wiring "I need a telephone by the toilet" >> 1F wiring Communicate these to your electrician (we marked switches, sockets and other things by a walk around) Outcomes 3: function based e.g. MVHR or ASHP, these need to be designed based on function and will have impact to both M & E. So not difficult, but you do need to go through it methodically. I do not know how to plumb or wire (nor do I care in reality, other than being able to wire a plug) but I knew what we wanted and communicating this was the key. And avoid too many changes. You're welcome Who ever said doing a self-build was going to be easy!

I suspect most people here have done their own design, or used the tradesman to do so. In my case I did not pay for this piece, though architects details did cover locations of some items e.g. bathroom and kitchen. electrical 1F (first fix) - electrician designed it with my input e.g. location of stuff (oven, router, ASHP etc) and switches electrical 2F (second fix) - I selected the lighting and other equipment (electrical included mains as well as alarm, ethernet, telephone cabling) UFH, ASHP, DHW, stats - designed by combination of me and equipment supplier plumbing 1F - designd by plumber with my input plumbing 2F - I detailed the layouts, taps, sanitary etc alarm - I designed and commissioned, electrician did 1F detailing MVHR - designed by supplier, builder did the detail dicting runs as they went along What have i missed? I don't consider it to be difficult but it does require attention to detail - e.g. you have to think about all cable runs you will need and make sure they are planned in before you board it up. This means thinking about all switches, lights, PIRs, doorbell, ethernet (inc location on Node 0), thermostats, telephone points, aerial, satellite, alarm panels and detectors. Many hours of work here.

Not measured - I gave some numbers to illustrate a point. Your calculated values are probably right, but do they assume perfect conditions? What about the impact of boundary layer (transfer of heat from water to pipe) and non-contiguous materials (voids in screed, adhesive and flooring)? Our system is currently flowing at 29C with a return of 26C at 1050l per hour (as reported by the HP). I calculate the power to be 3.7kW. House is 330m2 (though only about 220m2 has UFH), so calculated UFH output is 17W/m2. We have 150mm pipe centres. Interestingly, whole ASHP system input power is 750W so we seem to be achieving a COP of nearly 5! Not sure I trust those numbers too much. The deltaT could be anywhere between 2 and 4 given the rounding inherent in displaying the flow and return (no decimals are displayed). This gives a range of 2.5 to 5kW heat output, and a COP of 3.3 to 6.7. Coming back to your original question of do low energy house need heating controls, my view is they do need something that either regulates the flow temperature or turns heat on and off. And to achieve these requires data on room temperature at a minimum. This sounds like a control system.

Our UFH is in approx 50mm of screed with insulation below and engineered wooden flooring stuck on with adhesive. The slab is not going to be a constant temperature all over, there are going to be heat gradients all over the place. So, in order to maintain room temperature of 21C for a particular heat demand, we could have the following scenario: Engineered floor at 22-23C Screed below flooring at 24-25C Screed at 30mm depth at 25-26C UFH flow at 26-27C The above are very simplified and do not take into account the impact of pipe spacing in the UFH. In reality there will be a compound temp gradient in 3 axes. So for your 75m2 of engineered floor to absorb said 1kWh, the room temperature would need to be 23.4-24.4C. Too late and much too warm already. Plus the ability of the slab to absorb heat would be limited as the temperature of the screed below the surface is already higher than the room temperature, nowhere for the heat to flow (apologies if my terminology is a bit casual). In any case, forgetting the theoretical aspects, we do find that a couple of hours of winter solar gain will raise our open plan room temperature by about 0.5C and that when we cook and have people over the temp will rise by up to 2C. The advantage of having a room thermostat and closed-loop control is that as room temp rises, so flow temp will be reduced by the controller so (in time) it should balance out. In our system, a flow of approx 29C is called for when external temperature is 0C according to the heat curve I have set. I have no means to measure the slab or floor temps.

Your logic of temperature differentials reflects my own case. The slab being maintained at a stable temperature is key, the temperature would need to be adjusted with heat demand. The complexity comes with how do you measure heat demand, given your low energy build? A major factor will be external and internal temperatures, however solar gain and internal activity have a strong bearing on the demand. Apart from the "50 people" scenario, cooking, appliances etc add heat and drying clothes, fabric losses, MVHR or air leaks removes it. Most of these aspects vary minute-by-minute in a busy household. I decided to use the logic built into the ASHP compensation controller to simplify this. So we have a room thermostat and external probe as 3 key inputs - i.e. internal temperature, temperature set point and external temperature. These inputs then drive all the logic to calculate optimal flow temperature and the system, essentially, self-balances. I currently leave it on 24x7 and let it do it's stuff. I experimented with using a timer on for 12 hours, but I found the COP of the ASHP took a massive hit when load was high compared to a smaller load over 24 hrs. The only aspect that can catch it out is sudden swings in conditions, e.g. massive solar gain or lots of cooking, I don't think this is just a controller issue, the slab temperature simply cannot be adjusted quickly given the energy it holds. You would need to devise some form of predictive logic to pre-empt your optimal slab temperature. Not worth it IMO, you are chasing diminishing returns given your starting point is a low energy build.

I used self build zone for combined BC and warranty. The final sign off was quick and easy once they had the documentation. Slight delay as my inspector left them just prior. Only thing I had was they started asking for additional "Warts and all" warranty along the way for roofing and render. I pushed back on the basis that these were not in the agreement and asking at a late stage caused a material change in our procurement. They backed off.

Insulation under slab is your primary defense against heat loss to the ground. ICF gives insulation inside and outside, but much less inside than out so it still allows the slab to absorb the heat and this will create a stable temperature with minimal need for additional heat. The key here is getting the right level of insulation in which case your heating requirement is very small. Ground temp is generally quite stable at about 8-10C, so heat loss will be much smaller than above ground. Unless you have moving water. For lightwells, you may not need a sump - maybe drain it to a small soakaway which can be catered for during the basement dig, you would not expect much water ingress into a small opening.

My feeling exactly. Three lines of defense which adds expense and assumes one or the other will fail. Our approach was similar, apart from using ICF formers to insulate inside and out, plus we had a beam and block roof over which MBC build their structure.

Kryton video, it keeps the fish out! https://www.youtube.com/watch?v=iwp7Xe1wW9U&feature=youtu.be

"Air-tight sash" (no experience with these, random google search) https://www.greenbuildingstore.co.uk/products/triple-glazed-timber-sliding-sash/ We used Kryton waterproofing for the basement. The theory is that any water ingress through small cracks will activate the Kryton and it will expand to fill the crack. Self-healing. The installation was inspected, certified and warranted by Kryton. 6200 sq ft should be doable with a single commercial-oriented MVHR, though if your house is long and thin it could well be more efficient to get 2 separate units to avoid long runs of duct. Suggest you speak to BPC, knowledgable and great prices. A single large gas-boiler should also suffice, depending on number of occupants and hot water demands a single large DHW cylinder might suffice, maybe add a pump to circulate hot water around. Hope you have planed for a plant room for all this stuff!

Hi there, welcome and seems you have an interesting project here. There are others here who will chip in with more experience - I can only come at it based on our own build so a little "one-dimensional". Basement - we looked at various options and decided to go ICF with waterproof concrete and joints. The slab of the basement sits on polystyrene. I kept all wet services out of our basement to keep it simple - hence no need for secondary water-related considerations like pumps, tanking etc, just a small drain in the lightwell for rainwater. For the main house, do take a look at MBC timberframe, especially if your objective is a low-cost thermally efficient house. I was advised against SIPS by my architect and project manager for reasons I do not recall. If going ICF I suggest you (or your builders) think about attending some courses that the specialists can provide. I feel MVHR is essential - it will save energy as well as keep the interior well ventilated. The key is to ensure you have built as air-tight a box as you can by using membranes, attention to detail with sealing doors, windows and other service holes. If you have mains gas then I think use that rather than ASHP. Cheaper to fit and not much difference in running cost.

Agree - else you might end up thinking "if only we had...". Also, what directon are the drawing room windows facing? If that wall is blocking your evening sun then your extension makes more sense. Have you thought of putting something interesting to make a feature of that wall - maybe some hanging plants, or a planter on the ground with tall feature plants? (I do like prairie grasses).

If your floors are cold I would expect the return to be a few degrees lower than flow at 30C, else heat is not transferring to the floor. You probably need a few hours for the floor to warm up so patientience is called for. If floor is not warming then maybe check for airlocks in the UFH? In terms of warming the rooms, heating the floor is just the first part, the whole structure needs to warm up to really feel the full effect.

On your diverter comment, a 2-lever affair will deliver this. One lever that controls flow and which shower head (e.g. left to hand-held and right to wall-mounted) and another to control the temperature. Or you can add a separate diverter downstream from the main mixer valve.

Hansgrohe and Grohe are indeed different brands. We went with Hansgrohe Uno 2 range across all taps, showers, baths etc (apart from kitchen). The Hansgrohe has a similar iBox which is the thermostatic mixer - it simplifies first fix and boarding and wall tiling happens with the iBox in place, then simply attach the tap and rose to finish. Have a look at this link - they show compatible items with the product, it shows a different model of mixer than the one you have linked to. Best to cross-check with the Grohe site before you purchase. https://www.megabad.com/hersteller-grohe-eurosmart-neu-brause-einhand-a-262221.htm On single lever, this is a personal thing, but I do not like having to juggle flow and temperature like this, it is more fiddly than having 2 separate knobs or levers.

I cannot help re the dry part, but the low wattage is not really an advantage imo. A higher power unit with a thermostat that can be dialled low enough will, on average, behave like a low wattage rail but has the advantage of faster heat up times. Our glycol filled electric rail has a 5 step thermostat. I keep it on 24 hours for 2 to 3 months at the lowest setting, I estimate approx 1kWh per day which keeps the bathroom comfortable and towels warm and dry. Rest of the year we turn it on with a countdown timer as required. £10ish per year.

Hi @ProDave, sorry to hear about your situation. Funding our build was the single most stressful aspect for me - we had to sell 2 houses as well as juggle a self-build mortgage and a family loan. It was major relief once our mortgage finally came through - despite the fact that I was borrowing to the hilt as our houses had not sold, the pressure lifted massively and we could get on with the dream. Once our build was completed and we sold the others I ratonalised everything into a small and affordable mortgage. It seems you have some assets in the form of a mortgage-free house and and pension available, question is what is the most sensible way to use these to unblock the jam. My thoughts are: in the end this is "just money" and is the means to realise your dream treat it like a business transaction - based on costs and outcomes potentially your DC pension is growing at 4-10% p.a. and is free of any tax (provided total pension pot remains below £1m) potentially a mortgage on your house will cost no more than 2% plus an upfront application fees It seems to me that the best option would be to mortgage the house to fund the remainder of the build plus keep some in reserve for monthly mortgage repayments. Yes you are in debt but you have a potential house sale to back that plus you can move out of the caravan sooner. If your house does sell in 2 years then you can release the mortgage and cash in on the balance (there may be a capital tax liability if that is considered a second home). Plus it might be possible to offset some of the interest on the mortgage against your rental income. In terms of pension, yes you have access to 25% tax-free but by using that to fund the build you have stopped it growing by said 4-10%. Mortgage is cheaper. Another note - you do not have to start drawing down on the balance 75% of the DC - you can defer it and it could keep growing. If you are working at the same time then it is most tax-efficient to not take a monthly income else you will pay tax at the marginal rate on the whole pension (e.g. 25% or 40% depending on your income). Delay the pension income until you stop working, if possible, to take advantage of the annual tax-free allowances. On an aside, it may be worth getting a valuation on your DB pensions with a view of transferring it to a DC. Transfer values are extremely high, though it means you increase the risk. http://www.telegraph.co.uk/pensions-retirement/financial-planning/now-time-cash-final-salary-pension/