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Author Topic: Just bought a new house...  (Read 12784 times)
brackwell
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« Reply #105 on: August 20, 2017, 08:27:57 AM »

PHP 40,000kWh/yr for the whole house must be incorrect.  This is a mistake surely - https://www.ofgem.gov.uk/gas/retail-market/monitoring-data-and-statistics/typical-domestic-consumption-values    Perhaps its 40,000 Wh/yr

My energy use is c8000kWh gas/leccy and charging EV in a EPC C/D and larger than yours.    Sorry but this sounds like rubbish in =rubbish out.  Sorry.

Ken
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djh
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« Reply #106 on: August 20, 2017, 11:02:39 AM »

FWIW, I believe PHPP internal temperature is 20C rather than 21C.
The report I was given stated that internal temperatures were assumed to be a constant 21C - I have no idea if this is the PHPP default though.

Hmm, the default is definitely 20C and PHPP says 'only change in justified cases'. Is it actually a PHPP report?

I also agree with Ken that 40,000 kWh seems exceptionally high as an annual heat demand. Something's definitely wrong there. What experience does your architect have with PHPP and PH design in general? I'd be wanting to see the actual PHPP spreadsheet.
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« Reply #107 on: August 20, 2017, 11:38:03 AM »

PHP 40,000kWh/yr for the whole house must be incorrect.  This is a mistake surely - https://www.ofgem.gov.uk/gas/retail-market/monitoring-data-and-statistics/typical-domestic-consumption-values    Perhaps its 40,000 Wh/yr

My energy use is c8000kWh gas/leccy and charging EV in a EPC C/D and larger than yours.    Sorry but this sounds like rubbish in =rubbish out.  Sorry.
Current place is EPC E and the EPC gives 17,000 kWh/year for space heating alone. The 40,000 kWh/year is assuming no changes made to the ground floor at all, the upper floor is to minimum building regulations standards, an air tightness of 8 ACH50 is achieved - and I think the 21C temperature is assumed to be maintained 24/7. Under those assumptions then I think 40,000 kWh/year is a reasonable assumption - but I'm well aware that they don't represent how I'm likely to live my life in the house. However, provided the assumptions are declared and understood then I'm just fine with this. Note that the base case is calculated on 255 kWh/m2/year and the SAP report has a primary energy calculated at 338 kWh/m2/year: it's somewhat apples to oranges but does highlight that the current situation is very poor - solid brick walls, uninsulated timber suspended floor and 200mm of mineral wool in half of the loft. Just putting what is essentially a new roof on top with similar levels of insulation (building regs minimum is what was modelled) won't fix the problems.

Hmm, the default is definitely 20C and PHPP says 'only change in justified cases'. Is it actually a PHPP report?
Good catch - I've checked the EnerPHit standard and it also states 20C so I've raised that with them. That's a significant error. The report is stated to be generated using PHPP but what I've been given is written up as a report rather than being sent the original spreadsheet.

What experience does your architect have with PHPP and PH design in general? I'd be wanting to see the actual PHPP spreadsheet.
The practice has got quite a lot, although I'm not sure if the particular architect has - she's done the exam to be a Certified European Passivhaus Designer, but is relatively young and is very recently back of maternity leave so may be quite rusty. The initial drawings she sent over included a couple of the sort of ideas I'd expect to see from a fairly junior engineer in them, but the quality has since improved markedly. I'll ask to see the PHPP spreadsheet.
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djh
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« Reply #108 on: August 20, 2017, 12:40:26 PM »

The initial drawings she sent over included a couple of the sort of ideas I'd expect to see from a fairly junior engineer in them, but the quality has since improved markedly. I'll ask to see the PHPP spreadsheet.

I found I had to check things fairly carefully but I think in general they were fine with an inquisitive client. I'd already bought PHPP and on that basis the architect was willing to share his working copy with me but the certifiers were only willing to give me a paper copy of their version.
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biff
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« Reply #109 on: August 20, 2017, 12:46:45 PM »

This is a good thread,
                  and quite an interesting one. I am sorry that I can offer little or no help, building has now evolved somewhat beyond my level of expertise. It is good to admit that and not shilly shally around and poke at it with a stick, just leave it to the people who have done the figures and hope the finished job is as good as expected. And yet I read and study and wonder about overkill and strength of construction, Anchoring the house to the ground, lack of weight for ballast. A lot of modern material does not allow for water damage.
 These unpredictable times, we need to remember to invest in foul drain technology that prevents sewerage from lifting the lids and spilling out into the nearby houses.
Then landscape the place in such a way as the water runs away from the house,rather than towards it. Some of the most simple oversights can have the most devastating consequences. Experience has taught me, that the posher and more awarded the Architects, the greater the scope for the foulest of cock-ups.
As an example,where I was not personally involved. I was asked to drive a friend up to the New hospital in l,kenny. She was feeling dizzy and a little worried, so i drove to the hospital and marveled at the new multi million extension that had just been built. The new casualty entrance was hard to find because it was around the back of the hospital, like almost driving into a quarry,there had been so much excavation, the place was totally changed. I hardly knew where I was. Now i owned property less than a 2 minute walk or a stones throw away and rented rooms to the staff in the hospital. i knew the area pretty well. There was something very wrong. There was a river missing. I kid you not. I used to walk this area with my old dog Bruno and cross a little plank bridge. So the patient was sitting in the all new waiting rooms, very modern, very spic and span and I went off to dander about, I have a real genuine interest in layouts and I pondered the fact that the casualties were having to drive across the front of the hospital along a road and round the back to a little cul-de-sac carpark, nicely marked out and tarmac like carpet..and that carpet came right up to the entrance door, Big sliding door that whispered back and forth. There were no steps none, the tarmac was level with the tiled floor of the new hospital wing. I had never seen such a thing. I looked for a slope or a fall to the grids in the center of the little car park, there was very little or none. L,kenny had the most wheelchair friendly Hospital in Europe, there was no doubt about it. But where did that burn go ?.
  Not long afterwards L,kenny made the headlines . The brand new wing costing multi millions was flooded. The missing burn had been piped under that little car park and under the hospital, backed up and then came barreling in the new entrance door. The water came up the corridors to a depth of 3ft. It was a genuine disaster.
 I have no idea what happened to the genius planners and architects. I never even enquired as to who they were. There were so many just like them and it was depressing to even talk about it.
 So the moral of the story is,,,,,,,,,Keep it simple,straightforward and comfortable.  Grin
                                                                                           Biff
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Ted
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« Reply #110 on: August 20, 2017, 01:40:27 PM »

On the subject of permitted development for ASHP. This is only applicable (in England) if the ASHP installation is in full compliance with MCS regs, i.e. both product and installer must be MCS certified. It would be much simpler if you included the ASHP in your planning permission.

See page 100 of The Town and Country Planning (General Permitted Development) (England) Order 2015 for all of the other terms that apply in addition to the MCS requirement.
http://www.legislation.gov.uk/uksi/2015/596/pdfs/uksi_20150596_en.pdf

and Section 3. of the MCS020 Planning Standards
http://www.microgenerationcertification.org/images/MCS_020_Planning_Standards_Issue_1.2.pdf

There are specific calculations involved to determine the dB figures, including any reduction if there is a 'solid barrier" between the ASHP and the neighbour. To fall under PD the net figure must not exceed 42dB.
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pdf27
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« Reply #111 on: August 21, 2017, 06:46:42 PM »

See page 100 of The Town and Country Planning (General Permitted Development) (England) Order 2015 for all of the other terms that apply in addition to the MCS requirement.
http://www.legislation.gov.uk/uksi/2015/596/pdfs/uksi_20150596_en.pdf
Thanks Ted. Condition G.3(a) states that the air source heat pump is used solely for heating purposes - so planning would be required and I suspect they'd be unsympathetic.
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djh
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« Reply #112 on: August 21, 2017, 07:39:59 PM »

Is using an air source heat pump, or anything else, for cooling something that planning departments are specifically worried about? What planning legislation gives them the backing for such concerns?
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pdf27
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« Reply #113 on: August 21, 2017, 08:13:14 PM »

Is using an air source heat pump, or anything else, for cooling something that planning departments are specifically worried about? What planning legislation gives them the backing for such concerns?
A mixture of nimbyism and noise, I suspect. I'm really not sure if it's something I want to fight them about or not - the PHPP calculations say overheating won't be a problem so it's just something that would be very nice to have for the week or two a year when the weather is oppressively hot. I'm leaning towards either caving in and not trying or going the GSHP route and stumping up the extra cash. Either way it isn't happening any time soon - the existing gas combi boiler will be adequate for some time to come, it's just ~12 years old and I need to at least plan for replacing it so we've got a sensible plan for when it does die.
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pdf27
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« Reply #114 on: September 03, 2017, 09:18:28 AM »

Clarified the 20/21C issue: all calculations were done for 20C in PHPP but there was a typo stating that they were at 21C. I think the main reason the heat consumption is so high is that the current building is essentially uninsulated (retrofit loft insulation over half the roof, rotten form factor and maybe some cavity insulation to part of it.

The architects have also suggested we start looking at windows since they'll form a significant part of the total cost. I've got no idea where to start - requirements are triple glazed tilt & turn style, and Ug/g target values from PHPP are both about 0.5 (there is probably a little room for manoeuvre here). Any suggestions? Cost is rather more important than super-duper amazingness here, since you're unlikely to find anybody selling cheap & nasty UPVC in this performance bracket.
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djh
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« Reply #115 on: September 03, 2017, 12:34:06 PM »

The architects have also suggested we start looking at windows since they'll form a significant part of the total cost. I've got no idea where to start - requirements are triple glazed tilt & turn style, and Ug/g target values from PHPP are both about 0.5 (there is probably a little room for manoeuvre here). Any suggestions? Cost is rather more important than super-duper amazingness here, since you're unlikely to find anybody selling cheap & nasty UPVC in this performance bracket.

Glad to hear the temperature thing was just a typo.

Uw is more important than Ug (i.e. the combination of Uf and Ug) and the installed value is the critical one. Be aware that it can be quite a struggle getting accurate manufacturer's numbers for PHPP if you're taking it seriously and especially if you need to give pukka certificates to the certifier. They only supply the Uw of the window itself, of course, only the architect can supply the installed value once they have the basic data. It can also take quite a while to get an accurate quote - we took twelve revisions and that's not the worst I know of. Oh, and note that most ali-cladding makes a nonsense of wrapping the outside of the window with extra insulation, although I think some now stop short of the edge of the frame for this purpose.

Glazing is basically three layers of 4 mm glass with 16 mm of argon between layers and low-emissivity coatings in the cavity. Warm-edge spacers. Though the new Part Q might complicate things a bit.

Frames are may be timber, usually of laminated construction with an insulating material as the centre of the sandwich, and optionally with aluminium on the outside to reduce maintenance. Otherwise they can be UPVC with attention to detail in number of chambers and insulation filling etc. Note that some windows use UPVC in the centre with timber on the inside and aluminium on the outside - I suppose it's reasonable but they're advertised as timber and aluminium so get detailed cross-sections to check what you're paying for. Beware some windows that are glued together around the glazing such that it is not possible to replace the glazing if it breaks, you have to replace the entire sash.

Most of the lower-priced windows come from modern factories in eastern Europe but can have inflexible scheduling and problematic communication with the local agents so starting the process early is very good advice. Their hardware should be from one of a few good brands. There's a number of threads with peoples' experience with different suppliers on the green building forum.
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pdf27
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« Reply #116 on: November 11, 2017, 11:23:56 AM »

Just got the quantity surveyor's report back and it's fairly painful reading, although I get the feeling he hasn't quite grasped the concept of a Passivhaus sometimes (e.g. he's allocated 45/m2 for radiators in a building with a design heating load of 15W/m2 - total 7,500 to provide 2300W of heat!). The big number is about twice the insurance value of the current building, however, which is what is known as a big problem. Having said that the bit we want the most - fitting a new second floor - isn't totally outlandish so we may have some wriggle room to make this work, and some assumptions (e.g. plasterboard to all the ground floor walls when 90% of them will be unaffected and just need skimming).

Windows are assumed to be 550/m2 for 3g - does this look plausible given people's experience? I'm guessing it's a high-side estimate but it would be good to get an idea of how that feels to people.
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Countrypaul
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« Reply #117 on: November 11, 2017, 04:26:27 PM »

THis might give you some idea, but the windows were not to passihuis standard.

2 years ago I got some tripple glazed wooden windows made by a local joinery company, the prices were as follows

3m x 1.5m softwood with hardwood (Iroko cills) opening each side of a central section (about 50%) 1275 ex VAT, U 1.1
0.6 x 1.5m single fixed pane 275 U 1.2
0.9 x 1.5m two fixed panes 410 U1.2

Total for all the windows and doors 22.5K including fitting (ex VAT) think it was just over 60m2 with 10 tripple glazed windows (3 with floating mullions), one door window combination (tripple glazed) two sets of french doors (double glazed) and a further 11 windows all double glazed (5 with floating mullions) two of which were 1.8 x 1.8 and 1.2 x 2.0. There were also 3 oriel windows and one triangular bay window all double glazed). I only put the tripple glazed ones on the North side.

Unfortunately the joinery company got completely flooded out during the following winter and eventually went bust as they lost al their stock and much of their equipment.
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dhaslam
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« Reply #118 on: November 11, 2017, 04:49:08 PM »

Good double glazing may be good enough.   I have mostly lnon opening single panel  widows.    The heat load is about 3kW.   It depens a lot on the position of the widows.     There are four glazed outside doors but two are in porches.  One thing to watch is thermal bridging around windows because cavities are almost closed at window and door openings.
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eabadger
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« Reply #119 on: November 11, 2017, 05:45:59 PM »

i am just in process of fitting roller shutters on all the windows, first few are working great! made a huge difference to how the room feels even though we had high efficiency double glazed windows already.
i know not normal in the uk, but maybe in the future?
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1kw wind turbine.
26kw wood stove back boiler to underfloor heating and dhw
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