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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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    • CommentAuthorHarefield
    • CommentTimeMay 5th 2014
    I have hit an apparent bureaucratic wall and I wonder it anyone can help? I want to install a small pellet boiler in my SIPS construction new build project. The boiler I have chosen is on the MCS database and RHI approved but not on the SAP Product Characteristics Database (PCDB) owned by BRE (not surprising because there are only 20 on it at present). I have had some email correspondence with a friendly chap called Will via the email link associated with the PCDB. I asked how it was that a boiler could be on the MCS database of RHI purposes, but not on the PCDB. He stated that the only way for a boiler to get on the PCDB is for the manufacturer to apply. For whatever reason the MCS database appears well populated and the PCDB very badly populated. So at present, my only way forward if I want a small visually acceptable pellet boiler like the Pallazetti Anita 13kW is to accept the default efficiency of 65%. This seems to be bureaucratic stupidity as its efficiency is 88%, accepted as such in mainland Europe and also on our own UK MCS database. Any ideas please?:confused:
    Why do you give a shit about SAP? Accept the default efficiency and throw the SAP certificate in the only place that it's useful once the place is built. (in the fire...)

    Unless you're building a massive house or one with truly godawful fabric performance, that stove will be of no use to you anyhow. The minimum output will be too high to be useful.
    • CommentAuthorEd Davies
    • CommentTimeMay 5th 2014
    Posted By: markocosicWhy do you give a shit about SAP?
    My thought entirely. As long as you scrape through for building regulations purposes it's desirable to have the worst SAP rating possible if you ever want to grub around with RHI. Otherwise it really doesn't matter - what matters is how the house actually performs.
    • CommentAuthorHarefield
    • CommentTimeMay 5th 2014
    OK this is a useful new perspective for me. When you say scrape through the building regs, are you referring to a pass on the dwelling emissions rate (DER)?
    • CommentTimeMay 5th 2014
    I thought new builds were not eligible for RHI in which case it does not matter about the database.
    • CommentAuthorGotanewlife
    • CommentTimeMay 5th 2014 edited
    Posted By: HarefieldI want to install a small pellet boiler

    Posted By: Harefieldlike the Pallazetti Anita 13kW
    ????? As Mark says, that's going to chuck out a lot of heat into your room (speaking as the owner of a pellet boiler)
    • CommentAuthorEd Davies
    • CommentTimeMay 5th 2014 edited
    Posted By: HarefieldWhen you say scrape through the building regs, are you referring to a pass on the dwelling emissions rate (DER)?
    To be honest, I really don't know, having taken almost no interest in the subject, but yes, something like that. For my own rather-bizarre off-grid design the house designer will put in some plausible numbers to reflect aspects of the proposed house which fit with the SAP assumptions on house design. So long as there aren't outright lies and building control are happy that's all I care about.
    • CommentAuthorHarefield
    • CommentTimeMay 5th 2014
    Thanks for the feed-back. I'm not concerned about overheating as the house is built around a large central double height atrium which is also where the stove boiler will be. This will heat a 500l buffer tank which in turn feeds the UFH. Based on the provisional SAP calc, if I change the boiler efficiency from 88% to 65% then the DER will exceed the TER which I believe results in a 'fail'. I can understand the contempt that many feel for the SAP and the associated EPC rating, however I do need a 'pass' and I don't want to be forced into unnecessary additional expenditure on addition energy features such as solar panels just to get a 'pass'.
    I see!

    That says the fabric of the building is pretty abysmal. You've got one of the lowest (notional) CO2 outputs per kWh, even after the 65% emissions hit, and the emissions rate is still marginal. It'd be way over on gas or in reality for wood...

    (see Table 12 of SAP)

    Fixing the fabric is relatively cheap to address at design stage. It doesn't matter how you heat the thing if the base load is de-minimus, as it ought to be on a new build.

    If you want the lipstick on a pig approach of poor fabric plus play games with CO2 per kWh of heat then have a read of Appendix J. I think you can use manufacturer data for a solid fuel appliance to get an equivalent seasonal efficiency factor for the device that's >65%, no?

    • CommentAuthorTriassic
    • CommentTimeMay 6th 2014
    Harefield. Are you familiar with the fabric first approach? Insulation and air tightness is the key to any new build. If you need a large pellet boiler you have fallen at the first hurdle.
    • CommentAuthorJeremy S
    • CommentTimeSep 19th 2017 edited
    If you take a look at the forms http://www.ncm-pcdb.org.uk/sap/page.jsp?id=48" >here you'll get an idea of why there are so few items on the list...
    The SAP regulations for pellet boilers seem very poor "For efficiency, use product database if possible, otherwise use efficiency from this table" (SAP 2012 Table 4a). Particularly as open fires have a default efficiency of 63%. compared with 65% of pellet boilers. Normally you would assume an open fire has an efficiency of 15% to 25%. I presume manufacturers don't register their products with the BRE unless there is demand as I guess BRE charge for the service, and there probably aren't many pellet boilers which are the primary heating system in new builds?

    The Stroma FSAP 2012 tool, does allow you to select 'Manufacturers Declaration' and then manually type in the boilers efficiency, which appears to have a direct impact on the EPC rating - so I am guessing there is no 65% default. I am not sure whether an assessor would accept a manufacturers declaration given the regulations, but some can be more flexible than others - chose your assessor carefully!
    • CommentAuthorDarylP
    • CommentTimeSep 21st 2017
    ... careful, while the SAP calc may allow the manufacturer's claimed efficiency, the EPC will not allow this.:shocked:
    The EPC has a choice; (tested) PCDF value or SAP default.
    These are the rules.

    fyi Open fires are taken to be 37% efficient at best; from SAP2012 Table 4a:
    Open fire in grate C 37 32
    • CommentAuthorSigaldry
    • CommentTimeSep 21st 2017
    SAP 2012 notes that:

    BS EN 14785:2006 'Residential space heating appliances fired by wood pellets – Requirements and test methods' covers efficiency of pellet boilers.

    Efficiency test results are normally calculated using the net calorific value of fuel. Before a declaration can be
    made, conversion to gross must be carried out by multiplying the efficiency by the appropriate conversion factor (0.91 for pellets according to table E4), So check with the supplier if its a net or gross efficiency value.

    It notes in section E2 of SAP that "Manufacturers’ declarations so calculated should be accompanied by the following form of words: "The net efficiency of this appliance has been measured as specified in [insert appropriate entry from Table E1, Table E2 or Table E3] and the result after conversion to gross using the appropriate factor from Table E4 of SAP 2009 is [x]%. The test data have been certified by [insert name and/or identification of Notified Body]. The gross efficiency value may be used in the UK Government’s Standard Assessment Procedure (SAP) for energy rating of dwellings."

    So it appears that you definitely can use manufacturers declared efficiencies. From an audit point of view for production of EPC, you'd need to ensure that suitably thorough evidence of performance is available.
    • CommentTimeSep 21st 2017
    I had exactly this issue when trying to get an EPC for my FIT application, I used two assessors and they both used the default despite the product being on the MCS database, in both cases it give us a very low EPC so we could not claim the FIT.

    In the end I had to wait for 18 months until the product was eventually added to the PCDB list otherwise I would still be waiting.
    • CommentAuthorDarylP
    • CommentTimeSep 21st 2017
    @nigel, the MCS 'list' is not the same as the Product Characteristics Data File (PCDF), as you have discovered
    ..... a bit like having a list of every car model in the market, but only being able to use the ones that have certified MPG figures...?:confused:
    • CommentAuthorSigaldry
    • CommentTimeSep 21st 2017 edited
    The PCDB isn't everything though, it's a primary source of information, but not the only.

    SAP (and EPC production) allows for suitably evidenced alternatives.

    There's a whole catalogue of tested performance information available from HETAS for solid fuel boilers, cookers and secondary heating appliances that can be used available at https://www.hetas.co.uk/find-appliance/ (although as noted previously, you do need to ensure you are quoting the correct efficiency and must keep evidence for audit).

    The MCS list is one list of efficiencies, with links to evidence that could be used.

    Similarly there's data out there from various industry sites for PV, Solar hot water, loss factors for cylinders, windows and a lot more - or direct from manufacturers.

    You just need to ensure that the evidence is there to support what goes into an EPC - which is why there is accreditation, auditing, conventions and qualifications.

    PCDF doesn't include a lot of older ventilation systems, or ones that won't perform as well, there's a lot of heat pumps missing - what it does do is include most gas boilers (because that's kind of where it started). There's nothing to force a manufacturer to apply for their data to be included. They generally will only choose to do so if their tested efficiency or energy demand is reasonably good.

    (edited typoes)
    • CommentAuthorDarylP
    • CommentTimeSep 21st 2017 edited
    @Sigaldry, Elmhurst will not allow anything but PCDF or SAP defaults for EPCs, and I think STROMA may be the same?
    I agree the PCDF is not the 'be all and end all' of information repositories, but for EPCs it seems to be? :shamed:
    • CommentAuthorSigaldry
    • CommentTimeSep 21st 2017
    For gas, oil or LPG boilers, ventilation systems and heat pumps, I agree - PCDF or SAP defaults is the correct approach. SAP states that either the PCDF values or the defaults should be used for these.

    For wood / pellet systems - there's not enough of them in the PCDF. Although the conventions do also note that the most recent version of the PCDF should always be used.

    If you look at latest SAP conventions section 1.01 notes:

    "SAP provides default values for many items, such as window U-values and boiler efficiency.

    Whenever specific product information is available, that should be used rather than default values.

    However when using any specific values there needs to be documentary evidence to support them, and such evidence should be made available to building control on request.

    For items using the database, the evidence required is that the specific named product, e.g. boiler, is the one being used."

    Convention 4.02 specifically notes for ventilation, it's PCDF or default value.

    Convention 6.01 specifically notes for Micro-CHP, it's PCDF or default value.

    For room heaters, SAP Section 10 notes: If declared efficiency is available (see Appendix E) use instead of value from table.

    SAP does note for Solid fuel boilers "For efficiency, use product database if possible, otherwise use efficiency from this table." So I guess Elmhurst could be right, but then convention 1.01 does seem to counter that as does the note in Section 10 for room heaters.

    I'd try and make an argument in those circumstances if there is sufficient test data available, but the selected device were not in the PCDF. Ultimately though, it's down to what the accreditation scheme will accept.
    • CommentAuthorDarylP
    • CommentTimeSep 21st 2017
    I agree, i have argued my clients' cases twice with Elmhurst now, to no avail...
    It makes a well designed new house look a lot worse on the EPC than on the DS SAP calc....so I have to go back to the clients to explain my AB...:cry:
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