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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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    • CommentAuthormarsaday
    • CommentTimeFeb 2nd 2020
     
    Is it easy to get EPC certs through at a higher spec than reality ?

    I ask because i am looking at buying an older solid walled house which is split into 7 flats. I have just checked all the certs done in June 2019 and 5 out of 7 are much higher than i would have estimated.

    2 x ground floor flats = C (73 points) and D (59 points)

    2 x mid floor flats = D (64 points) and D (63 points)

    3 x top floor flats = D (64 points) and E (53 points) and E (52 points).

    I would expect all the flats to come in at around a high E. I am very surprised by the C.

    On this property the walls are solid and the roof has no insulation (including any flat sections).

    The plus points are good modern combos with good controls.

    The glazing is single glazed big old sashes.

    I have got some older semis with insulated walls, 260mm loft insulation, d/g and good boilers and controls and get a C and 74 points)

    Another with the same set up got a D and 64 points and another a D and 63 points.

    Anyone know how this system really works ?
    • CommentAuthortony
    • CommentTimeFeb 2nd 2020
     
    Variable, tighter than it used to be a lot of anomalies still and totally dependant on the assessors view.
  1.  
    We laughed when we saw the EPC of the place that we subsequently bought.

    Solid uninsulated walls, solid and suspended uninsulated floors, botched loft insulation, oil boiler, reasonable DG.

    EPC 'C' - allegedly!

    Perhaps it's fortunate that nobody pays any attention to them, after all...

    The EPC is based on the cost to heat the house per unit of floor area, so lower floor flats should score better than semis, as less external area. Semis should score better than detached, etc. Gas heating should score better than oil or electric.

    The EPC is commissioned by the seller not the buyer (in Scotland, and I assume in England), so maybe some conflict of interest there.
    • CommentAuthormarsaday
    • CommentTimeFeb 2nd 2020
     
    Ok I see.

    They are big concerns for landlords.

    You cannot rent out anything less than an E now (which makes sense), but my worry is the requirements get tighter as time rolls on. Pretty sure D will be the eventual minimum. Most older houses with cavities are laughing. They can all now get to a C really (loft and walls insulated, d/g, good gas combi and LED lights.

    It is the solid walled houses which will have problems.
    • CommentAuthorArtiglio
    • CommentTimeFeb 3rd 2020
     
    It’s not that hard to get to a c in a terraced solid, i’ve an 1870 building, divided into 4 flats, one on each floor, all but one made a C rating ( but only by a couple of points) , the one that did’nt make it has’nt had the boiler or heating controls upgraded and the tenant was using incandescants in about half the lights.
    The front facade had had the upvc glazing replaced with timber dg sashes which were a big improvement in terms of comfort.
    The property has a rear addition, lining these rooms (as they become empty during voids)with 50mm of celotex again made a noticeable comfort gain and crucial extra points.
    Fairly confident i’ll be able to maintain a C by the time the epcs need doing again (2028) , but all the relatively easy gains have been made so achieving much more is unlikely.
    Completely unscientific but the tenants never mention high bills or trouble keeping warm, which given its a predominantly housing benefit/ lha area and money is tight is to me a good sign.
    • CommentAuthormarsaday
    • CommentTimeFeb 3rd 2020
     
    I have just seen it is a C rating by 2030, so wasn't aware of that.

    I need to look into a cost effective secondary DG solution for the sashes i might be buying. I think that will be the cheapest option to get these important points.
  2.  
    New version of SAP is due out soon (but has been for a while) - the previous updates shifted some properties up or down a few points, as the prices of different fuels have changed.

    https://www.bregroup.com/sap/sap10/
  3.  
    Finally got round to looking at the new version of SAP.

    Our house is allegedly scoring 75 points under 2012 SAP which is EPC "C" band.

    Under the new SAP it will improve to 81 points which is a low "B", because it has oil heating and the oil price has fallen.

    If it had gas heating it would degrade slightly to 74, still a "C"

    If it had electric heating, it would degrade from 75 to 68 points under the new SAP as the prices of electricity have gone up. That would push it down to an EPC "D".


    If we replaced a gas or oil boiler with a heat pump, we would save carbon on the EI score, but the EPC rating would actually get worse, as the price of electricity is so high in the new SAP.
    • CommentAuthorJeff B
    • CommentTimeFeb 13th 2020
     
    Our EPC is absurd. We have a D rating purely because we have a wood pellet boiler which the assessor has given a generic efficiency of 66% IIRC. If we reverted to oil we would achieve a B!

    The house is very well insulated and our carbon dioxide output is calculated to be 0.1 tonnes p.a. (average UK house = 6 tonnes p.a. according to the EPC). The CO2 rating is an A (score 99).

    We are in a 4 bed detached dormer bungalow (181 sq.m. floor area) in an exposed hill top position in windy west Wales and the annual space heating demand is 14,000 kWh; equivalent to 77 kWh per sq.m., compared to UK average of 133 kWh per sq.m.*, so not bad I think. (Still a million miles away from Passivhaus though at 15 kWh per sq.m.!)

    * source = https://www.ovoenergy.com/guides/energy-guides/how-much-heating-energy-do-you-use.html)
    • CommentAuthorgyrogear
    • CommentTimeFeb 14th 2020
     
    Thanks for the above, "How Much Heating Do You Use", but it does not state if the usage figures are as metered and/or billed, or whether they need adapting for primary energy.

    (Per SAP, in previous post, the factor seems to be 1.5 for electric).

    In France it is 2.58...

    I cannot understand why such a big difference...
    86% of our electric is nukular.

    for our all-electric house, we use 9000 kWh pa for 200 sq.m

    Corrected for PE, this comes to 23,200 kWh, or 116 kWh/m2/yr
    which puts me in band "C" for France

    I also burn logs - 2m3 at 2100 kWh, with a PE factor of 1
    So total energy load is 25,300 kWh, or 126 kWh/m2/yr
    so still band "C"

    (we are trying to improve...)
    gg
    •  
      CommentAuthordjh
    • CommentTimeFeb 14th 2020
     
    Posted By: gyrogearThanks for the above, "How Much Heating Do You Use", but it does not state if the usage figures are as metered and/or billed, or whether they need adapting for primary energy.

    I think in the absence of any statement, you can be fairly sure it's actual/metered energy that's discussed.

    In France it is 2.58...

    I cannot understand why such a big difference...
    86% of our electric is nukular.

    There's a rather old paper at http://go.leonardo-energy.org/rs/europeancopper/images/PEF-finalreport.pdf that says an appropriate factor for nuclear is 3.

    It also says: "...it is not clear what number is exactly used and their exact algorithm is not known. There are
    clear signals that the PEFs for France, the Netherlands, and Sweden do not arise from purely scientific arguments and a clear algorithm." and "The factor 2.58 is a political factor, but in practice not far off from what would be
    calculated based on the electricity mix and a coefficient of 3 for nuclear (more or less the internationally established standard). They do not want to change it every year. There are no documents explaining the algorithm, it is just stated in the RT2005 (this is for new buildings) and will be the same in the new version, the RT2012."
    • CommentAuthorgyrogear
    • CommentTimeFeb 14th 2020
     
    Thank you DJH for the detective work !

    so it looks like a mix of "politics, damn lies and statistics"
    :devil:
    gg
  4.  
    Hi Jeff, that is absurd, because the prices in current SAP 2012 for oil and wood pellets are pretty much the same! 5.44p Vs 5.26p/kWh. Given the low usage, the efficiency certainly shouldn't push you from D to B. Your low CO2 is partly because of the favourable emissions factor for wood pellets, but even so it's very good.

    Hi GG, the current UK version of SAP 2012 has PE factor for electricity of 3.07, to be reduced to 1.5 in the forthcoming update, reflecting the decarbonisation of UK electricity since 2012.
    The UK SAP EPC system is actually based on heating cost, not consumption or efficiency, which is confusing imho. Is that the same in France?
    •  
      CommentAuthordjh
    • CommentTimeFeb 14th 2020
     
    Posted By: Jeff Bsource =https://www.ovoenergy.com/guides/energy-guides/how-much-heating-energy-do-you-use.html

    I'm not very impressed by that guide.

    For starters it's going to give very wrong answers for anywhere that has solar panels fitted, and they don't give any kind of warning at all.

    They give figures for heating only, and don't consider cooling load. I think that is likely to flatter Portugal particularly, and also Greece, Spain, Italy. And ooh - which countries appear to use least energy?

    And then they make statements like "Places like Denmark and Germany actually use less heating energy than most, once you have accounted for their colder climates and the differences in dwelling size." immediately below a chart illustrating that no, Denmark and especially Germany are still at the high end of the distribution, even after making the allowances.
    • CommentAuthorgyrogear
    • CommentTimeFeb 15th 2020 edited
     
    Posted By: WillInAberdeenThe UK SAP EPC system is actually based on heating cost, not consumption or efficiency, which is confusing imho. Is that the same in France?


    FWIW, here is the situation in France:
    https://fr.wikipedia.org/wiki/Diagnostic_de_performance_%C3%A9nerg%C3%A9tique

    A diagnostic is obligatory when changing owner or tenant.

    Comprises four parts :
    yearly consumption expressed in kWh and in Euro's,
    primary energy band (A to G) based on kWh per sq. m per year,
    greenhouse gas emissions per sq. m per year,
    bldg description (types of walls, windows, doors, ceilings & floors); systems (heating, DHW, ventilation & cooling).
    Recommendations for energy improvments.

    A sq.m. is not necessarily a "square meter" - as in basements or loft areas etc. For example, in a house, any floor area having a ceiling height of less than 2.3 m is not counted as habitable space

    gg
  5.  
    Thanks GG! So the A-G rating in France sounds similarly controversial as in the UK..

    Interesting that you can establish your A-G rating by producing actual energy bills, rather than by calculation.

    Also that the A-G rating is based on 'primary’ rather than actual energy consumption, whereas in the UK it is based on heating costs. In both countries the conversion (from actual energy consumption to primary or cost) causes oddities..
    • CommentAuthorJeff B
    • CommentTimeFeb 15th 2020
     
    In reply to djh: to be honest I was only interested in comparing my energy usage with other properties in the UK rather than elsewhere in Europe.

    In reply to WillinAberdeen: I don't understand how the relative cost of oil vs wood pellets should have any bearing on the matter? Isn't it all down to the efficiency of the boiler and the calorific value of the fuel used?
  6.  
    Hi Jeff, yes that would make more sense to me too, but oddly that's not how the SAP/EPC system works...

    The SAP rating is based on the floor area and the calculated cost of heating (and dhw and lights). If you swap to a cheaper fuel (gas) then the SAP and EPC get better.

    If you swap to a boiler that is registered as being more efficient, then the cost of heating goes down, so the EPC gets better. I wouldn't expect that to get you from a D to a B in the current version of SAP if your house doesn't use much fuel anyway, though obvs that depends on specifics of your house. I don't do this for a living so maybe there's some tricks that an expert could pull!

    Having said that, once they introduce the new version of SAP, oil will then be considered cheaper than wood pellets, so switching to oil would improve your EPC while pushing your CO2 right up.... Weird system!
    • CommentAuthorJeff B
    • CommentTime7 days ago
     
    <blockquote><cite>Posted By: WillInAberdeen</cite>Hi Jeff, yes that would make more sense to me too, but oddly that's not how the SAP/EPC system works...

    The SAP rating is based on the floor area and the calculated cost of heating (and dhw and lights). If you swap to a cheaper fuel (gas) then the SAP and EPC get better.

    If you swap to a boiler that is registered as being more efficient, then the cost of heating goes down, so the EPC gets better. I wouldn't expect that to get you from a D to a B in the current version of SAP if your house doesn't use much fuel anyway, though obvs that depends on specifics of your house. I don't do this for a living so maybe there's some tricks that an expert could pull!

    Having said that, once they introduce the new version of SAP, oil will then be considered cheaper than wood pellets, so switching to oil would improve your EPC while pushing your CO2 right up.... Weird system!</blockquote>

    As I said above, the EPC assessor gave my boiler a generic efficiency figure of 66% as it was never given a proper SEDBUK rating. I believe this was because the manufacturer (Ekopower) sold so few boilers in the UK it was not worth their while doing the testing required. In reality the efficiency according to the boiler spec for the rest of the EU was >90%!
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