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Green Building Bible, Fourth Edition
Green Building Bible, fourth edition (both books)
These two books are the perfect starting place to help you get to grips with one of the most vitally important aspects of our society - our homes and living environment.

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      CommentAuthordjh
    • CommentTimeOct 21st 2021
     
    From the abstract: "As frequency and type of data collection varies between sites, we adopt a pessimistic approach to the analysis by systematically over-estimating space heating demand in the presence of uncertain data. Results pooled across multiple years, show that mean observed space heating demand is 10.8 kWhm2a−1 (SD 9.1) with no statistically significant difference against predicted demand of 11.7 kWhm2a−1 (p = 0.43, d = −0.1). These results provide powerful evidence in favour of the Passivhaus standard as a reliable means of obtaining low-energy and low-carbon buildings"

    I can't access the article, or even the diagram you showed, but 'measured' heating would imply actual in-use data and not the calculated demand that PHPP predicts. So the differences may simply be in the way that people are using the buildings, rather than any errors in PHPP?
  1.  
    Sorry, thought it was public.

    If the mean is 10.8 and the st dev is 9.1 then the result is..... doubtful! Or rather , on average over a large number of houses, the average predictions were close to the average actuals, but there is a very wide distribution of results, some much better and some much worse than predicted. They tried to correct for some factors but overall the randomness probably is about how the occupants live in it.

    >>>>So a Standardised Assessment will not match reality and people shouldn't be led to expect that.
  2.  
    My PH scored a B on EPC (which I guess is the median between the other two on here!), but I logged on to point out that in the case of those PH results, it's worth pointing out that when the energy demand is so low already, being ­±100% of the prediction is less of a big deal...still worth investigating, but compared to SAP it fares so much better.
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      CommentAuthordjh
    • CommentTimeOct 21st 2021
     
    Posted By: WillInAberdeen>>>>So a Standardised Assessment will not match reality and people shouldn't be led to expect that.

    No indeed. But as has been pointed out by other researchers there are reasons of the way SAP is designed that account for some of its errors, so we should certainly hope that they can fix those.

    Did the paper that you extracted the diagram from attempt to measure and correct for the most basic of difference-causing factors, such as people running their houses warmer or cooler than the PH design temperature of 20°C?
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      CommentAuthordjh
    • CommentTimeOct 21st 2021
     
    Posted By: Doubting_Thomasin the case of those PH results, it's worth pointing out that when the energy demand is so low already, being ­±100% of the prediction is less of a big deal...still worth investigating, but compared to SAP it fares so much better.

    Indeed and as the average design demand in that group was 11.7 kWh/m²/a versus the PH design limit of 15 kWh/m²/a then there's absolutely nothing to worry about even for houses nearly 30% above the average.
    • CommentAuthorrevor
    • CommentTimeOct 21st 2021
     
    Can a dwelling that consumes less than 15Kwh/m²/a be considered a passive house ? If it has solar PV and exports then presumably it is the net consumption that counts and if it exports more than it uses can the excess be discounted against the total used by the dwelling.
  3.  
    •  
      CommentAuthordjh
    • CommentTimeOct 21st 2021
     
    Posted By: revorCan a dwelling that consumes less than 15Kwh/m²/a be considered a passive house ? If it has solar PV and exports then presumably it is the net consumption that counts and if it exports more than it uses can the excess be discounted against the total used by the dwelling.

    No, a document that has a PHPP model that says demand less than 15 kWh/m²/a or load less than 10 W/m² and **that also meets the various other requirements** and that is certified by an independent approved third-party certifier is a passivhaus. Note that these are heat demands, not electricity consumption. For a basic introduction see e.g.

    https://www.passivhaustrust.org.uk/what_is_passivhaus.php

    Solar PV is treated separately in passivhaus. It can't be 'netted off' and is treated separately. If there is enough, relative to the available roof area then the certification can be upgraded to 'Plus' level. There are also separate tests for overall primary energy used and suchlike in the basic spec.
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      CommentAuthordjh
    • CommentTimeOct 21st 2021
     
    @WillInAberdeen thanks for the researchgate link. :bigsmile: It didn't come up in my searches for some reason.
    •  
      CommentAuthordjh
    • CommentTimeOct 21st 2021
     
    So I've now skimmed the paper. It seems a pretty strong argument in favour of building every new dwelling using PH methods, and oversight etc even if not everything is built to PH standard itself (although I personally would support that too).
    • CommentAuthorgravelld
    • CommentTimeOct 21st 2021
     
    The HIBS is a disaster.

    Unambitious, myopic, zero-sum.

    Still, pretty much what was expected.
    • CommentAuthorbhommels
    • CommentTimeOct 21st 2021
     
    Posted By: djhSo I've now skimmed the paper. It seems a pretty strong argument in favour of building every new dwelling using PH methods, and oversight etc even if not everything is built to PH standard itself (although I personally would support that too).

    Organisations that take a long term view because they have to consider the "total cost of ownership" over the entire lifetime of the building are doing just that: Norwich City Council and King's College Cambridge to name a couple.

    Builders or other tradesfolk build and install but don't have to consider the bills of running the thing. If this EPC idea takes off, perhaps this will change?
  4.  
    Posted By: bhommelsBuilders or other tradesfolk build and install but don't have to consider the bills of running the thing. If this EPC idea takes off, perhaps this will change?

    Only if there is an enforcible easy to use liability claims procedure.
    • CommentAuthorJonti
    • CommentTimeOct 22nd 2021
     
    Posted By: djhSo I've now skimmed the paper. It seems a pretty strong argument in favour of building every new dwelling using PH methods, and oversight etc even if not everything is built to PH standard itself (although I personally would support that too).


    I completely agree but we simply do not have the quality of trades people in sufficient quantity to do this. IMO there would have to be a drive to get more small and medium sized local builders started but this won't happen.
    •  
      CommentAuthordjh
    • CommentTimeOct 22nd 2021
     
    Posted By: JontiI completely agree but we simply do not have the quality of trades people in sufficient quantity to do this.

    It's not rocket science. Most tradespeople in my admittedly limited experience are more than willing and happy to do a good job if they are put in the right environment. Leadership and support and an emphasis on quality instead of maximum workrate. Clear instructions. Checking of work. Nobody on my project had designed or built a PH before. The architect had been on a course, I'd done a lot of reading, everybody else was willing to come along with us.

    It's happening in some places if I believe the stories. All public buildings in Frankfurt must be PH. All buildings in Brussels must be PH since 2015. Dublin keeps talking about it - I don't know whether they've actually done anything yet. The only way to get enough trained people is to start doing it and gradually expand the pool.
  5.  
    Posted By: bhommelsBuilders or other tradesfolk build and install but don't have to consider the bills of running the thing. If this EPC idea takes off, perhaps this will change?

    The only way things will change is if the big boys get on board with the improving standards and then do a quality build to those standards. IMO the only way that will happen is if not to do a quality build significantly hurts their profit line and of course the workers employed by the big boys have to work to a quality standard and not quantity demands. This will probably put up the price rather than reduce the profit line. The start could be made by doing an airtightness test on every house rather than batch testing, then comes thermal imaging for insulation tests.
    • CommentAuthorRobL
    • CommentTimeOct 22nd 2021
     
    Perhaps the CO2 emitted due to construction and ownership of a house should be logged? There's complexity with that, especially for PV and V2G/battery people and what the CO2 intensity of various energy sources is, but ultimately it is CO2 emissions that should be reduced - so somehow this should be actually measured and associated with the house rather than a proxy for it (EPC, inspections, etc).

    I do agree thermal cameras should be used, but I fear basing pass/fail building inspections using them will result in unintended consequences. For example, pre-EWI we had PVC cladding on part of our house, and my (ok, the day-jobs) thermal camera indicated that part of the house was cold hence very well insulated - in reality the air blowing around the cladding prevented the unsealed cladding from warming up. So if IR cameras alone determined pass/fail I predict we would see more houses with cladding and highly ventilated cold roofs...
    • CommentAuthorlineweight
    • CommentTimeOct 22nd 2021
     
    It would be more reliable to do IR camera tests from the inside would it not?
    •  
      CommentAuthordjh
    • CommentTimeOct 22nd 2021
     
    EPCs do record the predicted carbon emissions, but don't make recommendations based on trying to reduce them. Emissions during building is a much bigger and more difficult subject, even publication of numbers for individual buildings is still pretty much a research project.

    A key part of the PH methodology is the continuous quality control and the gathering of evidence such as PHPP, design drawings, photographs to prove it was constructed as designed, signed statements/certificates about e.g. airtightness, ventilation testing, quantity of insulation installed (for blown-in types), etc. All inspected by an independent certifier afterwards. The knowledge that that is what is going to happen and seeing the photographs etc being taken is one thing that makes the project culture focus on quality. Plus toolbox talks etc etc.

    You hear of cases where rolls of insulation are left in the loft and I've actually seen cases where cavity insulation was simply not installed. My brother, who is an architect, once had to stand in a foundation trench to get them to stop pouring the concrete, which was the wrong mix. It's environments in which those behaviours are acceptable or even encouraged that need to be changed.
    • CommentAuthorgravelld
    • CommentTimeOct 23rd 2021
     
    Posted By: djh
    Posted By: JontiI completely agree but we simply do not have the quality of trades people in sufficient quantity to do this.

    It's not rocket science. Most tradespeople in my admittedly limited experience are more than willing and happy to do a good job if they are put in the right environment. Leadership and support and an emphasis on quality instead of maximum workrate. Clear instructions. Checking of work. Nobody on my project had designed or built a PH before. The architect had been on a course, I'd done a lot of reading, everybody else was willing to come along with us.

    Isn't this a self selecting sample though?

    There seems to me to be an inherent misalignment of incentives. Trades are services workers; if they can sell something for the same price but spend less time doing it, that's what they'll do.

    I'm sure there are also a number of virtuous crafts people who are prepared to learn though, too, like you found.
    •  
      CommentAuthordjh
    • CommentTimeOct 23rd 2021
     
    Posted By: gravelldIsn't this a self selecting sample though?

    Not sure what you mean - it's my project so obviously self-selected?

    There seems to me to be an inherent misalignment of incentives. Trades are services workers; if they can sell something for the same price but spend less time doing it, that's what they'll do.

    There's truth in that I believe. In my case all the tradespeople were on hourly rates, not piecework, so if something took longer than they or I expected it didn't cost them anything. I think that was key, along with a regular supply of tea and cakes from my wife.

    I suspect that the vast majority of tradespeople will learn and do good work if the incentives are properly aligned.
    • CommentAuthorgravelld
    • CommentTimeOct 24th 2021
     
    The trades that appear happy to work on your project were also the trades that decided up front they would be happy doing this type of work.

    Therefore it's (possibly) unsurprising that they were "willing and happy to do a good job" and successfully completed the project.

    But this might only account for 5%, say, of trades.

    Agree with working on time and materials, but too many clients demand fixed price to the extent that it's the default pricing approach for most trades.
    •  
      CommentAuthordjh
    • CommentTimeOct 24th 2021 edited
     
    Posted By: gravelldThe trades that appear happy to work on your project were also the trades that decided up front they would be happy doing this type of work.

    TBH I didn't find anybody who wouldn't work on it. Well, except for all the main contractors I asked to quote for the whole job! But then my project was pretty niche.
  6.  
    I see that the long-awaited new building regulations for England have now 'gone live' on gov.uk and will come into force from June 2022

    Approved documents https://www.gov.uk/government/collections/approved-documents

    Part L Energy conservation (introduces SAP 10.2)
    Part F ventilation
    Part O overheating
    Part S vehicle charging
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