le-cerveau

I have build my own spreadsheet 40, tabs and counting. I tried one of the free SAP programmes but they came up with gibberish in one field of another. It has taken me a few weeks to work through the SAP2012 regulations and create my own formulas, but I got there. It was made easier by having all the details in PHPP to extract info from.

Has anyone ever done a manual SAP calculation? I have just finished it (lots or excel work that I can maintain and update) and want to make sure I have some sensible answers. Here are some key points: Total Floor Area: 414.29m2 Living Floor Area: 107.39m2 Dwelling Volume: 1077.88m3 Window Area: 50.5m2 U-values 0.8 – 1.04 (PHPP calculations) Door Area: 10.62m2 U-value 0.73 External Wall Area: 345.4m2 U-value 0.10-0.11 Roof Area: 355.8m2 U-value 0.11 Thermal Bridges: 7.85W Design 26.66W TFEE Design FEE TFEE Effective Air Change Rate: 0.15 10.23 10.52 Heat Loss Parameter: 0.508 W/m2K 9.162 W/m2K 9.563 W/m2K Water Heating required: 2837 kWh/year 2404 kWh/year 2837 kWh/year Internals and solar Gains: 1540-2711 W/month 1396-2423 W/month 1612-3322 W/month mean Internal temp: 20.22-20.49oC 13.59-14.97oC 17.76-19.02oC Space Heating required: 1.17 kWh/m2/year 11.64 kWh/m2/year 11.94 kWh/m2/year Space cooling required: 0.64 kWh/m2/year 0.06 kWh/m2/year 0.04 kWh/m2/year Giving a Fabric Energy Efficiency of: 1.81 kWh/m2/year Design 11.70 kWh/m2/year FEE 13.77 kWh/m2/year TFEE So my designed Fabric Energy Efficiency is far better than the notional Dwelling Fabric Energy Efficiency Rate let alone the Target Fabric Efficiency rate, so I am ok there. On CO2 emissions the Target Emission Rate is 7.37 and the Design is -1.11 or -1.89 depending on how I calculate the DHW, so again well under. So my calculated ratings are SAP A (100-102), CO2 A (101-103) and Primary Energy A (109-115). The variation is based on DHW higher figure for pure Gas DHW, the lower if is assume half provided by ASHP pre-heat (but I will have to get authorisation for that). Is this the sort of answers I should be getting?

I have a large pending order with my ICF supplier, foundations and wall from one company. Approximately 256m2 of raft and 430m2 of wall blocks, I went firm on the supply/design company around Brexit time so agreed with them a 2.5% deposit based on current prices, however the final quote will be decided at a mutually agreed time. I am hoping prices will recover some what from that point and agree for the contract price at that point. The gamble is mine but at the point of agreement the price was rubbish (just after Brexit result) so worth waiting. This is a good reminder to look at the current price and decide to lock in or not. The supply I snot until just after Easter 17 so I have some time.

I will be using the Izadom 2000 Polska system as supplied by Econekt. The main reason being that as I will not be able to be on site for the build, it will be done by a contractor, I wanted to select the simplest system and this system has both the raft foundation and walling and they interconnect, so one less thermal bridge to worry about.

It is not quick, you need the full details for the house, dimensions, windows location type, the works, so there is a lot of information you need or have to assume. Even if you paid someone to do it you would have to provide them with the info so it would take probably just as much time! I spend an hour or two a night for a couple of weeks, working through the book and filling in the details into the system and I had a lot of info to start with. As I say you will need to do a lot of work either way!

@jack just checked on PHPP it is 25oC and 10% of overall days, as you say quite hot in a Passive type house, you can adjust the temperature not the percentage. the 25/10 is for PHPP certification (I suspect), in reality I think 23oC is a more realistic target to aim for if you want a truly comfortable house and the PHPP software lets you play around. You can change MVHR unit which can have an effect (one thing I did), change the specifications of each individual window, all sorts or options.

@PeterStarck +1. I also bought PHPP, after much soul searching, it is not that expensive in the grand scheme of thighs and I just followed the instruction book. I am sure what I have is not perfect but close enough to give me an idea, play with wall/roof insulation options etc. I don't have an overheating problem, no large glazing elements (stand fast one NW long and wide stair window) and in Cumbria so not exactly hot! It does however allow me to look at what will happen, if I drop the overheat temp from 25oC to 23oC then there is some overheating, not much, so I have made provision for slab cooling (as in JSH design) and heat redistribution (but that is another topic).

My house has a larger that standard ground floor 3.3m between ground and first floor! that is 2.75 ground floor, 150mm service void 250mm pre-stressed spans & 150mm screed (I will be less, but that is the planning figure). But I also have 8.7m spans so that doesn't fit in with the standard BC guidelines. The whole house is being specified by a SE (current work) in preparation for BC submission and my architect is not concerned.

This would appear to be the sensible way, ask searching questions, guide him in the right direction but be prepared to stand your ground.

Legally, you only have to make 'reasonable provision', do if you are prepared to stand your ground and prove that you have made 'reasonable provision' the go for it, but you would also be potentially alienating the BCO. It is up to you if you wish to fight them but in the eyes of the law there is very little that they can make you do! (Standby the lawyers)

I have been following but not contributing to this thread (it appears to have become a bit heated in a nice way), however this is my plan: I need 472.92 m3/h of vent for my house (yes it is large see my blog), so I am working on 495 m3/h as my working figure (for various reasons). I am looking at MVHR units in the range 675-945m3/h so that it is running at 50-70% capacity normally. I am also massively over specifying ducting, flow rates never to exceed 2m/s and most planned much less. This then gives me the following: The unit will be running slow so quiet and more efficiently (heat exchange efficency drops off towards the upper levels of capacity). If I have condensation/mold problems I have the capacity to increase flow rates relatively easily (some re-balancing required). But that is my design and I won't touch house builders and people designing to the minimum limit!

+1, in our design I have gone for a dedicated plant room (1st floor) next to the airing cupboard, so it can share the excess heat (minimized hopefully) but keep the clothes and equipment separate.

Whilst I am not having a stove (I have gas) I am also seriously considering an ASHP (so I can cool as well as heat) and future proof, likely, gas price increases. As you are having a stove a TS is a must (as I understand it) and you can quite easily mix down off the TS to whatever your UFH requires. How well insulated and leaky will your house be? As if it is near PassiveHaus standards then you are not going to require huge amounts of heat, as you are specifying 12kW stove, 9kW ASHP, either it is less efficient or you are looking at the DHW requirement also. As for running the ASHP for morning UFH, if the TS is up to heat, you won’t need it, you can just draw off the TS, but if you want hot water for a shower then that is different. I can’t see you needing a Buffer with a TS, it is the buffer, and the ASHP just feed the TS directly, provided your TS can cope with low grade heat as well as high grade, ie the top and bottom are separated (Akvaterm Geo style), ready to be shot down Nick! The plumbing of it all together shouldn’t be a major issue, I wait for Nick to say otherwise, the big issue will be control: What heat source is supplying what and when, and can you automate it? The question is, and I think others have said this, is UFH or DHW your biggest driver (mine is DHW)?

I would, For our build ENWL tried to charge us VAT on the whole lot (it is knock down and re-build) stating as there was an existing supply it wasn't a new build, but I pushed them on it and they relented in the disconnection of the existing supply was VAT enabled, but the re-connection was VAT free.

It is in his blog part 32

I have done a bit more digging into 7, 9 & 12kW ASHP performance (I am looking at the Panasonic range). WHSDC07H3E5 Water Out (oC) 35 40 Outdoor Air (oC) Capicity (W) Input Power (W) CoP Capicity (W) Input Power (W) CoP -15 4600 1980 2.32 4600 2190 2.10 -7 5150 1920 2.68 5076 2140 2.37 2 6550 1960 3.34 6575 2290 2.87 7 7000 1570 4.46 7000 1835 3.81 25 7000 970 7.22 6740 1140 5.91 WHSDC09H3E5 Water Out (oC) 35 40 Outdoor Air (oC) Capicity (W) Input Power (W) CoP Capicity (W) Input Power (W) CoP -15 5900 2660 2.22 5650 2820 2.00 -7 5900 2340 2.52 5850 2610 2.24 2 6700 2140 3.13 6650 2380 2.79 7 9000 2180 4.13 9000 2485 3.62 25 9000 1260 7.14 8660 1475 5.87 WHSDC12F6E5 Water Out (oC) 35 40 Outdoor Air (oC) Capicity (W) Input Power (W) CoP Capicity (W) Input Power (W) CoP -15 8900 3620 2.46 8500 3790 2.24 -7 10000 3660 2.73 9600 3950 2.43 2 11400 3310 3.44 11000 3530 3.12 7 12000 2530 4.74 12000 2960 4.05 25 12000 1660 7.23 11800 1940 6.08 These figures are taken from the service manual + the CoP calculation. Assuming I take the water at 35oC with my house load (max) of 4401W this gives me a comparison of: Option % required CoP 7kW @ -7 85.46% 2.68 9kW @ -7 74.59% 2.52 12kW @ -7 44.01% 2.73 7kW @ 2 67.19% 3.34 9kW @ 2 65.69% 3.13 12kW @ 2 38.61% 3.44 7kW @ 7 62.87% 4.46 9kW @ 7 48.90% 4.13 12kW @ 7 36.68% 4.74 This would suggest I discount the 9kW model due to poor performance at 2oC and lower CoP, so then it is down to 7kW or 12kW. The 7kW machine is running at 63-85% capacity from 7oC to -7oC, whilst the 12kW machine is at 36-44% capacity with a better CoP. So in theory the12kW machine can modulate down (30%) quite happily though at 7oC the load will start dropping. All this is ignoring less that ideal build (higher heat load) and DHW preheat. So is a 7kW machine working reasonably hard a better bet than the 12kW machine that is idling but with a greater DHW reserve? The pain continues.

Ok, to answer the question, why not just stick with gas: doing the calculations based on average Gas and Electricity prices in the NW (0.039 £/kWh and 0.136 £/kWh) (Gov 2015 figures), taking into account boiler efficiency (91%), boiler electricity consumption (37W), the breakeven point for an ASHP is 2.84 (Assuming the circulation pump is in the CoP calculation). If the circulation pump is excluded (68W) then it is CoP of 3.52 (can't find a definitive answer). There will be extensive PV on the property and in the long run gas prices will inevitably rise faster than electricity. As to size, working on Stones theory of absolute worst case 4401W (PHPP largest figure) then a 9kW ASHP would be operating at 49% capacity and a 7kW one at 63% capacity (CoP 4.13 & 4.46), however looking at the performance chart (A2/W35) the 9kW machine will only produce 6.7kW and the 7kW machine still produce 6.55kW so 66% and 67% capacity with CoP's of (3.13 and 3.34). So logic would say go for the 7kW machine as it produces almost as much heat, when you need the most, and is slightly more efficient, my head hurts.

I am looking at the same conundrum at the moment as I firm up the final specifications so my quandary is: I have a heat load of 4057W (last PHPP calculation worst case) so call it 4kW in the depths of winter 5kW if we don’t get the house quite as up to spec as I put in PHPP. I will have a TS for DHW and UFH buffer, the ones I am looking at are split 60/40 (bottom/top) with a baffle plate so the lower is heated by the ASHP and the upper by a conventional gas boiler. The TS has coils in both the lower and upper parts for DHW production. I have 5½ bathrooms (2 baths (large) with separate showers, 3 showers + toilet) so potentially massive DHW call, however over previous discussions have whittled it down to max 3 simultaneous showers (or 2 showers and a bath). The showers will be low flow 9-12 L/min so about 30L/min max. (I will have a cold water accumulator to provide flow). I intend to run the lower part of the TS at around 35oC, good for the COP of the ASHP (a la JSH setup) and heat the top to around 50-60oC depending on anticipated DHW load (how many people are home). I am playing with the following variables: ASHP power: 7, 9, 11 kW. Boiler Power: 12-30 kW. TS size: 500, 750, 1000L. Number of concurrent Showers: 2, 3 (or a bath). Follow on Showers: 0, 1, 2. I have tried to do some calculations but TS’s are notoriously hard to model so I am working on simple tank methodology to give me some approximations. And have come up with the following: The boiler will be a simple 12kW heat only affair, anything more is overkill because of the TS. The TS will be 750L. I could go for a 500L TS but could not sustain a bath and 2 showers, so would require domestic management (doable), it easily supports 5 simultaneous showers with follow-ons. To go for the 500L that I would need to go larger on the ASHP definitely 9 and probably 11 and 30kW on the boiler to be safe for the bath load. With the 750L TS a 12kW boiler is sufficient to do the bath and 2 showers with the TS at 35/55 (bottom/top). The ultimate question is 7kW or 9kW ASHP, the 7kW is enough (I reckon), but the 9kW gives me more spare capacity, more power in to the lower part of the TS so less gas used for DHW, or just go with the 7kW?

When I spoke to the Panasonic team they said that the lowest modulation was 30% so that agrees. So there is always going to be a point where the heat demand is les than the 30% so put in a large enough thermal store/buffer to reduce the short cycling to an acceptable level yet to have sufficient spare capacity.

Yes, if you are prepared to stand your ground, the building regs are not legally enforceable! the statute (legal bit) is M4(1) which states Reasonable (a word that is imprecise and open to interpretation) and should (ie please do it but if you don't there is not a lot I can do), if it said shall then that is an absolute in law.

Remember the Building Regulations are guidelines only and not enforceable statutes. M4(1). Reasonable provision should be made for people to— (a) gain access to; and (b) use, the dwelling and its facilities. So it is reasonable and should (not shall). WC facilities 1.17 To enable easy access to a WC, a dwelling should comply with all of the following. a. A room (which may be a WC/cloakroom or a bathroom) containing a WC is provided on the entrance storey or, where there are no habitable rooms on the entrance storey, on the principal storey or the entrance storey. b. There is clear space to access the WC in accordance with Diagram 1.3. c. Any basin is positioned to avoid impeding access. d. The door to the room opens outwards and has a clear opening width in accordance with Table 1.1. Again it says should. The issue is your door if opening inwards would impinge the 750mm clear space so it would be difficult to argue for it. However, if the toilet was on the left side or corner and the shower a wet room so you could use that as part of the 750mm access you probably could argue that the door did not impinge on the 750mm access and therefore you have made reasonable provision.

As for the building regs bit remember the enforceable bit is: M1. Reasonable provision shall be made for people to: (a) gain access to; and (b) use the building and its facilities. Section 8 (accessible switches and sockets outlets in the dwellings) is all advisory (should) so at your discretion, as long as you provide some at the appropriate height you can argue with any inspector reminding him that the only legally enforceable bit (the statute) say that reasonable provision shall be made!

Agree with IanR, I have a similar TIA and 437m2 and building regs gives me a rate 472.8m3/h. the DV110 may say 414 m3/h but is only PH certified for 63-256 m3/h so would be running virtually flat out and increase your noise. The Renovent says 300m3/h but PH of 59-235 m3/h so again flat out. My suppliers recommendations and all advice from the collection on this and the previous forum have been to have the unit (s) running at approximately 50% maximum and the simple economies of scale tells you that one larger unit will be more efficient than 2 smaller units. You may find that most suppliers will push you towards what they carry as standard rather that what is best for you. For you ducting also consider being able adjust the flow control at the manifold as if you adjust at the inlet/exhaust valve that is where the noise will be generated. If you are looking for an install company then may I suggest look at the Irish market, they have a more advanced base than the UK. (I can PM you who I am looking at)

The answer is in your question, you say 'they would prefer'. So they can prefer all they like and just ignore them, unless they have any enforceable powers.

It has been a while since I posted and things are progressing, so expect a flurry of posts in the next few months as things are decided before we go to contract, however I have been working on some minor detailing. I have decided that I want to extract toilet smells directly from the pan (see JSHarris blog part 32) I have 6 toilets in the house, in 3 pairs (see the plans on blog 02-The Planning Saga) so can use 3 extract runs, one to each pair, the simple bit. I then need to work out how to connect to the MVHR system and the toilet cistern. The MVHR ducting will be Hybalans+, thought the design/supply/install is still be to sorted out. So I have 3 issues to work out: 1 connecting to the cistern, 2 connecting to the MVHR, 3 connecting the two together. Connecting to the cistern. After much research looking at low flush toilets and attempting to get information from suppliers (as soon as you go for non-standard ideas they all clam up) I discovered the Geberit Duofresh with build in odour extraction and started enquiring with Geberit about getting the connecting pipe from cistern to pan and using it on a standard cistern. Trying to get this bit. The issue being that the bit I want is not available as a part and is solvent welded to the cistern, however after much toing and froing of e-mails and finally a call from the technical department it was agreed that by using the Duofresh cistern (available without the filter and fan unit) I could cut through the pipe and connect it to the MVHR system. The plan is to cut the vent pipe (it is 50mm) and put on a solvent weld joint with reducer and 40mm push fit adaptor (reason for 40mm push fit later). I was also planning to seal up the feed into the cistern (vertical pipe) however this is square post the transition bend so not going to be so easy (can’t use a 50mm plug) so I may end up just filling it with expanding foam to seal it. I have decided on the Geberit cistern as the ability to service them once installed appeals and the Duofresh cistern is only about £10 dearer than the standard cistern. Connecting to the MVHR. I then needed to work out how to connect the pipe to the MVHR system, the pipe coming from the manifold will be either 92/75 or 75/62 (external/internal dimension) and connect it to two 40mm pipes. I then realised that soil pipes are 110mm standard and the vent terminals are between 100 &125mm so there was some potential there. My solution (still to be tested) is to use a vent terminal adaptor onto a solvent weld pipe, my reasoning as follows: The 110mm soil pipe has an outside diameter of approximately 110mm and the solvent weld socket has an outside diameter of 121mm. The straight vent connector has a diameter of 125mm, the 900 one 118mm, however the vent inserts show a diameter of 114mm, so I suspect the 125mm is an external and the 118mm internal. The straight vent connector has a diameter of 125mm, the 900 one 118mm, however the vent inserts show a diameter of 114mm, so I suspect the 125mm is an external and the 118mm internal. I should be able to connect the vent terminal adaptor over the plain pipe with a push fit sealing ring on it and solvent weld a plug into the other end. Then insert two 40mm push fit boss adaptors into the bosses on the pipe. I should now have an adaptor that connects the 92/75 MVHR pipe to (1-4) 40mm push fit waste pipes. Connect the MVHR adaptor to the cistern connector. With 40mm push fit sockets on both ends it is a simple job to connect up the two ends either with flexible 40mm pipe or rigid with a length of flexible 40mm pipe at each end: So now I have a plan to connect the toilets to the MVHR. The Geberit parts number is: 111.353.00.5 (Geberit Duofix frame for wall-hung WC, 112 cm, with Sigma concealed cistern 12 cm, for odour extraction with recirculating air) The normal cistern is: 111.383.005 (Geberit Duofix frame for wall-hung WC, 112 cm, with Sigma concealed cistern 12 cm, wall anchoring and connection bend)