Oz07 Posted February 2 Share Posted February 2 How hard is it nowadays to achieve an epc of A with a new build? I seem to remember it being discussed changes were made to stop people incorporating loads of solar pv to offset poor design. What kind of ratings is everyone here achieving? My place built a few years ago came to a B. Im trying to understand if it would be prohibitively expensive nowadays to achieve A or whether it is do able without going full on passive. Cheers Link to comment Share on other sites More sharing options...
Andehh Posted February 2 Share Posted February 2 Dead easy, just stick a lot of PV on the roof. We snuck in with our new build, above average insulation, 4kw solar array. Not sure we deserve it with windows and very in efficient floor plan (big sprawling bungalow with high ceilings) but I wasn't going to argue! 1 Link to comment Share on other sites More sharing options...
Alan Ambrose Posted February 2 Share Posted February 2 The problem afaik is that it is not clear how the epc number is calculated - the algorithm seems to be a total black box - which is properly dumb. In contrast to PHPP, for instance, - where if you take enough trouble you can see how every little bit is calculated. 1 Link to comment Share on other sites More sharing options...
Oz07 Posted February 2 Author Share Posted February 2 (edited) 33 minutes ago, Andehh said: Dead easy, just stick a lot of PV on the roof. We snuck in with our new build, above average insulation, 4kw solar array. Not sure we deserve it with windows and very in efficient floor plan (big sprawling bungalow with high ceilings) but I wasn't going to argue! I seem to remember it being discussed here years ago they did away with this loophole. When was your epc done? Cam DNO restrict size of pv? Edited February 2 by Oz07 Dno, pv Link to comment Share on other sites More sharing options...
Oz07 Posted February 2 Author Share Posted February 2 11 minutes ago, Alan Ambrose said: The problem afaik is that it is not clear how the epc number is calculated - the algorithm seems to be a total black box - which is properly dumb. In contrast to PHPP, for instance, - where if you take enough trouble you can see how every little bit is calculated. I suppose the assessor can play around with the figures in sap let you know what to aim for? Link to comment Share on other sites More sharing options...
nod Posted February 2 Share Posted February 2 (edited) Very easy We recently marketed our first build All viewers where professionals Only one asked or cared about the EPC Edited February 2 by nod Link to comment Share on other sites More sharing options...
SteamyTea Posted February 2 Share Posted February 2 1 hour ago, Oz07 said: Cam DNO restrict size of pv By default, all DNOs do, to 16 A/phase. I am sure of you applied for a larger system, as long as you met the critter, it would be granted. 28 minutes ago, nod said: We recently marketed our first build All viewers where professionals Only one asked or cared about the EPC Are we going back to the 1980s 'yuppies' with their conspicuous consumption and debt envy. Link to comment Share on other sites More sharing options...
ProDave Posted February 2 Share Posted February 2 You used to be able to download the SAP program and input all the details yourself. You could never produce an officially recognised EPC doing that but it is a good way to while away a lot of time. For a good EPC you need good levels of insulation, good probably triple glazed windows, good air tightness that probably means a proper air tight membrane everywhere with well taped joints and good detail at every penetration, An efficient heating system, probably ASHP and UFH, MVHR and possibly some solar PV. and an official air tightness test. When I sent all the final as built figures to my assessor, my instructions to him were that if it failed to get an EPC A, to not lodge the EPC instead come back and discuss what would be needed to achieve an A. It came back with an A94 which I was happy with. Link to comment Share on other sites More sharing options...
nod Posted February 2 Share Posted February 2 44 minutes ago, SteamyTea said: By default, all DNOs do, to 16 A/phase. I am sure of you applied for a larger system, as long as you met the critter, it would be granted. Are we going back to the 1980s 'yuppies' with their conspicuous consumption and debt envy. We are not far from a hospital So nearly all where doctors The ones that asked where computer bods Who also asked for the Wi-Fi speed 😁 Link to comment Share on other sites More sharing options...
PNAmble Posted February 2 Share Posted February 2 Our as designed EPC was A95 - they also got the flow temperature wrong so we expect to beat that when we do the as built. Has a 4kw solar array. we got the full calculation sheets and they can be followed to a sense. The defaults are based upon an old fashioned view of heating systems ie zoned, timed, stepped back and people in and out of the house etc. The default thermal bridging values were also used as apparently using the approved details and Psi values is no longer allowed. Link to comment Share on other sites More sharing options...
Oz07 Posted February 2 Author Share Posted February 2 1 hour ago, nod said: Very easy We recently marketed our first build All viewers where professionals Only one asked or cared about the EPC Was the epc a? Link to comment Share on other sites More sharing options...
dnb Posted February 2 Share Posted February 2 (edited) 1 hour ago, SteamyTea said: I am sure of you applied for a larger system, as long as you met the critter, it would be granted. I did apply and was given permission for a 6.5kW array on a single phase but since it was Covid time they didn't send me a critter. As for EPC, this made it an easy A on the old scheme. Something like 105 to 112 depending on how the heating gets scored. Edited February 2 by dnb Link to comment Share on other sites More sharing options...
saveasteading Posted February 2 Share Posted February 2 3 hours ago, Alan Ambrose said: the algorithm seems to be a total black box That's correct. My business got the software when it was a brand new thing, and we played around with it. The only way to understand it was to do dozens of variations on each project. Some tick boxes were beyond anyone's understanding or logic and BRE were not at all keen to engage in discussion. In so doing we revealed lots of inconsistencies, but also the easy fixes and bad ideas for a good rating. For example some choices which everyone would think were an obvious good idea, might make the epc worse, so we simply didn't show it. It was interesting but not worth the annual cost' once we had established the principles. Link to comment Share on other sites More sharing options...
Oz07 Posted February 2 Author Share Posted February 2 2 minutes ago, saveasteading said: That's correct. My business got the software when it was a brand new thing, and we played around with it. The only way to understand it was to do dozens of variations on each project. Some tick boxes were beyond anyone's understanding or logic and BRE were not at all keen to engage in discussion. In so doing we revealed lots of inconsistencies, but also the easy fixes and bad ideas for a good rating. For example some choices which everyone would think were an obvious good idea, might make the epc worse, so we simply didn't show it. It was interesting but not worth the annual cost' once we had established the principles. Care to share any obvious ones Link to comment Share on other sites More sharing options...
Oz07 Posted February 2 Author Share Posted February 2 26 minutes ago, dnb said: I did apply and was given permission for a 6.5kW array on a single phase but since it was Covid time they didn't send me a critter. As for EPC, this made it an easy A on the old scheme. Something like 105 to 112 depending on how the heating gets scored. This is what i thought under the old scheme you could just load up on pv Link to comment Share on other sites More sharing options...
SteamyTea Posted February 2 Share Posted February 2 4 minutes ago, saveasteading said: BRE were not at all keen to engage in discussion. It is a real shame the the bodies we pay to develope this kind of service are not forced to open source the code, or at least the algorithm. I used to be able to get the BSI stuff from my local library, not anymore. Way I see it is that I paid for it to be created, then pay, through my council tax to have access to it, and now I can only see a copy if I pay full price. Link to comment Share on other sites More sharing options...
saveasteading Posted February 2 Share Posted February 2 Just now, Oz07 said: Care to share any obvious ones So long ago...and it was always vague anyway. We weren't cheating, simply trying to avoid nonsensical penalties within said black box. It also allowed us to design a building that we knew would pass, tweak insulation if necessary, and avoid shocks at the end. Our EPC assessor would discuss these things with us, and we could share our disdain, but they were very strict and professional: I think there are other types available. Solar panels to the roof that our client would fit...later. Boilers were rated wrongly...we reckoned they had inverted the adjustment factors from worst to best. Air source heating was assumed to be used for cooling in summer whether likely or not, greatly damaging the electricity use figure (which was considered to be bad energy by BRE at the time) Very dubious assessment of solar gain. If I remember more I'll come back. 1 Link to comment Share on other sites More sharing options...
saveasteading Posted February 2 Share Posted February 2 3 minutes ago, saveasteading said: If I remember more I'll come back. We designed and built our own office building, thinking of it for value, comfort, future proofing, running cost and also as an advert for sustainable design. That all worked because we got awards for it, but not necessarily the right things were appreciated. It was rated D, 15 years ago (which was considered great at the time). We had it reassessed last year and it got a good B without any modification. Most of that was because ashp is now 'good', whereas then it was 'bad', such was the knowledge level at BRE. I assume a lot has been improved but equivalent nonsense is still likely to be in the box. 1 Link to comment Share on other sites More sharing options...
Gone West Posted February 2 Share Posted February 2 5 hours ago, Oz07 said: How hard is it nowadays to achieve an epc of A with a new build? I seem to remember it being discussed changes were made to stop people incorporating loads of solar pv to offset poor design. What kind of ratings is everyone here achieving? My place built a few years ago came to a B. Im trying to understand if it would be prohibitively expensive nowadays to achieve A or whether it is do able without going full on passive. In 2018 our house achieved an A95 without any renewables, but we did design it to better than PH standards using PHPP. 1 Link to comment Share on other sites More sharing options...
Russdl Posted February 2 Share Posted February 2 We got an A103 with direct electric for heating (Willis) and DHW (Sunamp). 7.5kW of solar on the roof no doubt helps as does building to Passive standard. Link to comment Share on other sites More sharing options...
Alan Ambrose Posted February 2 Share Posted February 2 Of course, the 'Home Energy Model' is coming along in 2025 to 'replace epc'...probably another black box. Personally I would be happy for us to all adopt PHPP as it is auditable and I believe the background calcs and assumptions are all in proper research papers (but the ones I've seen are in German). Maybe the 'Home Energy Model' will correct some of the more daft epc quirks - but the targets are not at all ambitious (see below). I think BuildHub needs a political wing . I would like to see the algorithms published with rationale and research data - instead of some hidden professor's ramblings under a tiny consultancy's control then watered down by the big housebuilders. Then some for-profit software vendors with software put though an opaque 'validation process'. I'm having a bit of a grumpy day today - but if you check into Part O, that's exactly what you'll find. 1 Link to comment Share on other sites More sharing options...
Oz07 Posted February 2 Author Share Posted February 2 Interesting comments. Atleast you can play around with the design post planning. Altering windows for part O seems a bit arse about tit. Im not interested in cheating the system or getting away with bare bones. Im considering an application in the "countryside" and trying to at least make the physical dwelling be as sustainable as possible even if the location isn't! Link to comment Share on other sites More sharing options...
nod Posted February 2 Share Posted February 2 4 hours ago, Oz07 said: Was the epc a? It was solid build an 89 on a B If we had of added solar like the planning stated it would have taken us up to 91 A If we would have added MVRH That would have taken us back down to 89 Such nonsense 1 Link to comment Share on other sites More sharing options...
Oz07 Posted February 2 Author Share Posted February 2 46 minutes ago, nod said: It was solid build an 89 on a B If we had of added solar like the planning stated it would have taken us up to 91 A If we would have added MVRH That would have taken us back down to 89 Such nonsense Cheers does it matter on size of solar or would any of got you an a? I suspect solar would have got my current place to an a too. Assuming the sap system is logical which it sounds like it isnt!? Did you go triple glazed? Link to comment Share on other sites More sharing options...
saveasteading Posted February 2 Share Posted February 2 57 minutes ago, nod said: Such nonsense BRE was privatised. Then it changed from being a national service to a business. They introduced air testing but only they could do the tests. Then along came epc and it was again very restricted. I met loads of their staff on both occasions. They were nice pr people with no tech knowledge. So we can only assume that back at hq they don't know a lot either. I was so constantly critical but few people accepted that BRE could be wrong, so I passed one of their exams.....which they charged a lot for. Multiple choice., mostly obvious. 4 hours study as compared to the many days they suggested. Link to comment Share on other sites More sharing options...
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