The most daft way of achieving compliance with Part L Renewables - but its valid

fclauson

Mods - please move to either BER or Renewables if you see fit

Moved - (mod note)

I have stated a new thread on this as this is a new angle

So you have spent €€€€€ on making you building super airtight and snug only to find you struggle to meet Part L as defined by TGD and DEAP specifically for the renewables

So should you
a) ask for exemption
b) review your renewables
or
c) wait for it - down grade you structure

take a look at the attached

Fundamentally the problem I have highlighted is with ANY building which comes in lower on the EPC and the CPC than regulation you have room to increase both by down grading your fabric and U-values which in turn will up your energy demand – which in turn ups your demand on renewables.

So ANY building which has a lower EPC or CPC can strive to achieve its renewable target by moving the fabric in the opposite direction to that which the legislation wants you to

Now the €64,000 questions - Part L1 is very explicit that CO2 is the objective and Part L3 is about how to achieve Part L1.If you achieve Part L1 by reducing your CO2 by say 50% from current regs does this mean you comply with Part L3

Your thoughts please

beyondpassive

I think option 3 is the best approach. I am going to have to do 2 airtightness tests, a full EN13829 test for the client and then one where the trapdoor is left uninstalled or a window left open, purely for the compliance DEAP calculation. We will use defaults for thermal bridging and MHRV rather than actual test data. The Deap methodology is not fit for purpose for Part L 2011, and discourages low demand house design.

just do it

The regulations are daft in this regard. You're penalised for reducing your heating demand. Ramping up building control and ensuring compliance with earlier regulations would have been more beneficial to the housing stock in the country than making the regs more demanding. And this was done in the knowledge that earlier regs weren't even being complied with. The government will be slow to rectify this though given the slack they're getting over septic tanks.

Any of the new builds I've seen in my locality in the last year still have the traditional 100mm cavity but now will have solar panels on the roof! Surely if all these were 150mm cavities that on the long term would be better?

Sorry for the rant fc and I know it doesn't answer your question. I'll be doing what BP outlines when the time comes.

sinnerboy

@ beyondpassive- Agreed.

I had my heart scalded with SEAI once trying to get them to accept non default windows U Values.

So for your PH being DEAP / BER assessed suppose you "misplace" the true window values and simply enter the DEAP default

And likewise with the Y factor. You will have to carefully read the following to see what I'm saying next - which is simply enter 0.15 for the Y factor .

( I do invite my smarter Boardies - you all know how you are - to verify or challenge my interpretation here )

TDGL 2011 - items

1.3.3.2 (iv)

(iv) use alternative details which limit the risk
of mould growth and surface
condensation to an acceptable level as
set out in paragraph D.2 of Appendix D
for all junctions.

then 1.3.3.3 paragraph 5

Where provision for thermal bridging is made
in accordance with option (iv) of paragraph
1.3.3.2, this multiplier (y) should be taken as
0.15.

then 1.3.3.3 paragraph 6

As an alternative to all of the above, the value
0.15 may be used for the multiplier (y)
providing the details used limit the risk of
mould growth and surface condensation to an
acceptable level as set out in paragraph D.2
of Appendix D for all junctions.

then Item D2

D.2 Mould growth and surface
condensation
The key factor used in assessing the risk of
mould growth or surface condensation in the
vicinity of thermal bridges is the temperature
factor (fRsi).
The temperature factor (fRsi) is defined as
follows: -
fRsi = (Tsi – Te) / (Ti – Te)
where: -
Tsi = minimum internal surface
temperature,
Te = external temperature, and
Ti = internal temperature.
For dwellings, the value of fRsi should be
greater than or equal to 0.75, so as to avoid
the risk of mould growth and surface
condensation. For three-dimensional corners
of ground floors this value may be reduced to
0.70, for all points within 10 mm of the point
of lowest fRsi.

D.4 Calculation procedures
The calculation procedure to establish both
temperature factor (fRsi) and the linear
thermal transmittance () is outlined in BRE
IP 1/06. Details should be assessed in
accordance with the methods described in
I.S. EN ISO 10211. These calculations of
two dimensional or three dimensional heat
flow require the use of numerical modeling
software. To be acceptable, numerical
modeling software should model the
validation examples in I.S. EN ISO 10211
with results that agree with the stated values
of temperature and heat flow within the
tolerance indicated in the standard for these
examples. Several packages are available
that meet this requirement.
Detailed guidance on decisions regarding
specific input to the modeling software and
the determination of certain quantities from
the output of the software is contained in
BRE Report BR 497 Conventions for
calculating linear thermal transmittance and
temperature factors. This guidance should
be followed in carrying out modeling work so
that different users of the same software
package and users of different software
packages can obtain correct and consistent
results.

then D5 (a)

(a) Heat loss through thermal bridging can
be accounted for in terms of a fraction (y)
multiplied by the exposed surface area of
the building. Where Acceptable
Construction Details for sections 1 to 6 in
the 2011 edition of the document
“Limiting Thermal Bridging and Air
Infiltration – Acceptable Construction
Details” are used for all key junctions the
value of (y) can be taken as 0.08. Where
this is not the case, but this method of
accounting for thermal bridging is used,
the default value of (y) is taken to be
0.15.

Translation - assemble your building ONLY using the DOE published details and you may either

1. enter a global y factor of 0.8 or
2. using tables D1-D6 you may calculate a measured y factor based on the give psi values X actual lengths of the relevant junctions on your build

BUT , BUT , BUT ...

If you build using details other then the DOE published details and you find a professional to trained to use Therm to calculate psi values and Frsi factors ( i.e. in accordance to TGDL 11 - D4) you must use y of 0.15 !!

In the context of the credibility of DEAP and it's lamentable failure to credit good innovative detailing in DEAP (and by extension- the BER rating ) calculations , this is bad news.

However in the context of this thread - good news.

fclauson

sinnerboy - thanks as always for your knowledge

so just changing my psi from 0.01 (calculated assuming using ACDs) to 0.15 as per your note - and bingo - 4.8Kwh -> 10.1 - perfect (where did that heat go to)

I am now worried about any other value I might have to drop back to "default" will make me miss CPC/EPC

I agree with BP - not fit for purpose

fclauson

sinnerboy
I have now read the above and Part L (I was bored !!)

I think it would take a team of legal folk to untangle this - but I think your assumption is right in that 0.15 can be used if you fail to prove you can calculate anything better

this is good news for the low energy crowd (who are not interested in a A1 rating) but makes a nonsense of DEAP

thanks for you insight -

I and I beleive others have been worrying about meeting Part L against the right choice of technology & building fabric - this helps anull that - specifically fo Heat Pumps but may be for other techs - you can manipulate translate the numbers to get you over the line

thanks once again

sydthebeat

just a quick post....

doing a prov BER at the moment... A3 rated geo HP standard build...

Using DG 1.2 windows the Heat Pump alone meets the renewable requirement at 10.14

If i suggested an upgrade to triple glazed 0.8 windows the renewable requirement, for whatever mental reason, drops to 9.07 and thus doesnt comply.

Now that means DEAP is somehow telling me that, by installing TG windows, the Heat Pump is somehow offering less energy to the dwelling.... which is plainly incorrect.

I suggest that DEAP is not fit for purpose and needs to be seriously overhauled immediately. There is some formulae or algorithim that links renewable input on a per sq m basis to a percentage of primary energy demand. I suggest that this link should be broken and that the renewable requirement should be solely based on a per sq m basis of the notional dwelling (which cant change) OR on a percentage of primary energy demand....


but definitely not both!!!!!!!!!!!

because when you reduce your demand (which is what everyone wants) but yet still link it to a per sq m then you have this serious anomaly.

No6

Perhaps we should report this to SEAI, it should be amusing if nothing else!!:D

fclauson

Guys and girls

look at my graph a few post back

its very simple - renewables is a % of demand - demand drops, renewables usage drops (specifically on the heating side)

not fit for purpose

I am happy to articulate this to SEAI but I suspect as I am not a BER person they would say pahhh - so happy to help anybody who can articulate this

I am thinking of writing to the minister - its backwards logic

MY VIEW:
I think the renewables element in its current form should be dropped completely and the following put in place.

EPC and CPC gives you the maximum amount of energy and C02 your building may produce. You have a choice
a) Reduce them via insulation and better fabric
b) Or reduce by using renewables to meet you demand

But to give you an example via my build

Reference building for my size building –
primary energy 53,900 Kwh
C02 11,473 Kg
EPC limits the amount of energy I may consume to 0.4 * reference build = 0.4 * 53900 = 21561 Kwh/annum
CPC limits the amount of C02 I may produce to 0.46 * 11.473 = 5,277 Kg

Now I have a choice – reduce via renewables or reduce via fabric – if we use the standard of 10Kwh/m2 for my build I would have to reduce primary energy by 3590 Kwh/annum – which I have done by fabric (my current primary energy is around 12391)

So I comply if you use my method – and I believe I comply with Part L TGD 0.1.2.1 (a) which specifically calls out CO2 as being the prime driver of Part L

I could have not bothered with the better insulation etc and created my renewables via solar thermal or PV and got the 3590 that way (I still need to work out the C02 component for all this maths)

This is the rough outline of a concept – but we could develop this to propose a much better approach to energy management than we currently have.

fclauson

sydthebeat wrote: »

..... by installing TG windows, the Heat Pump is somehow offering less energy to the dwelling....

Syd - this is true - its offering less because supprise supprise - you need less (you are better insulated)

sydthebeat

fclauson wrote: »

Syd - this is true - its offering less because supprise supprise - you need less (you are better insulated)

I agree with what you are saying, but my point is that the energy 'offered' doesnt change.

similarly with solar collectors... just because you upgrade from DG to TG (or whatever upgrade you make) that in no way reduces the ability of the solar collectors to provide energy. If anything, the ability of the collectors to provide energy actually increases pro rata..... this is not recognised in DEAP, its actually penalised.

creedp

sinnerboy wrote: »

@ beyondpassive- Agreed.

I had my heart scalded with SEAI once trying to get them to accept non default windows U Values.

So for your PH being DEAP / BER assessed suppose you "misplace" the true window values and simply enter the DEAP default

And likewise with the Y factor. You will have to carefully read the following to see what I'm saying next - which is simply enter 0.15 for the Y factor .


If you build using details other then the DOE published details and you find a professional to trained to use Therm to calculate psi values and Frsi factors ( i.e. in accordance to TGDL 11 - D4) you must use y of 0.15 !!

In the context of the credibility of DEAP and it's lamentable failure to credit good innovative detailing in DEAP (and by extension- the BER rating ) calculations , this is bad news.

However in the context of this thread - good news.

Even though I don't have a passive std build I had to use default window values and a y value of 0.15. Otherwise wouldn't have had a hope with Part L compliance unless I installed a large area of solar panels for which I couldn't justify the additional cost.

fclauson

sydthebeat wrote: »

I agree with what you are saying, but my point is that the energy 'offered' doesnt change.

similarly with solar collectors... just because you upgrade from DG to TG (or whatever upgrade you make) that in no way reduces the ability of the solar collectors to provide energy. If anything, the ability of the collectors to provide energy actually increases pro rata..... this is not recognised in DEAP, its actually penalised.

Syd - I am interested where you are seeing solar as being less efficient in a low energy build. Can you give details (unless its where you are using Solar for space heating)

I have found that is specifically heat pumps which have this issue.

On you comment about the offered energy - this does vary if you think about it - if you HP provides 10Kw then say 5Kw is renewables - but if you only need 5Kw heat - then you only get 2.5 Hw renewables (all numbers are for example)

sydthebeat

yeah you are correct actually, just checked again....

i notice that the renewable requirement dropped and i assumed it was from the solar, but it was actually from the wood stove. Thats interesting.
So its not only heat pumps but any renewable energy source whether primary or secondary, apart from solar.

I think a lot of assessments under part L 2011 will serious look at the ability of solar to provide extra space heating. If you try to meet regs with solar alone on a, say, 250 sq m dwelling, DEAP may actually tell you that your solar system is oversized... even though you may consider this as a means to meet renewables.

so my initial point still applies, and i think we are both referring to the same thing in a roundabout kind of way.
The renewable requirement should be either directly linked to a percentage of the notional dwelling energy value (which would only change based on the sq meterage factor) or be directly linked to a percentage of the primary energy demand only.... not both as it appears to be.

........be directly linked to a percentage of the primary energy demand only......

just to expand on this... say you are in the region of B1... 22,000 kwhr/yr..... you can meet renewables by providing approx 11-13% of this primary energy value.

however if you are at A3 level, say 16,000 kwhr/yr, you need to provide 16-18% of this value to meet renewable requirement.
and from what ive seen this percentage rises pro rata on the primary energy value.

This is completely skewed in my opinion. There should be a carrot for upgrading the spec... not a penalty.
If there was a blanket percentage on primary energy required, say 12.5% or something, it would tip the balance in favour of the higher spec houses.

fclauson

I think the renewable is a complete red herring

We should be pushing for better performing buildings

If as a separeate issue we want people to invest in renewables then that is different but joing the two together does not make sense

why if I have reduce my build 50% in performance below the Part L should I then have to additionally add on renewables


remember Part L is about Co2 and not renewables

sydthebeat

I think the renewable requirement should definitely stay, its a justified policy, it just happens to be introduced with the finesse of using a sledgehammer to crack a walnut.

It stems from european policy and is ingrained in legislation currently.

Interestingly the easiest way to meet all Part L is by using biomass (wood) boilers.

fclauson

sydthebeat wrote: »

I think the renewable requirement should definitely stay, its a justified policy, it just happens to be introduced with the finesse of using a sledgehammer to crack a walnut.

It stems from european policy and is ingrained in legislation currently.

Interestingly the easiest way to meet all Part L is by using biomass (wood) boilers.

Don;t start me on biomass - its worse than the rest of them
see http://www.aecb.net/UserFiles/File/Biomass%20-%20A%20Burning%20Issue%20-%20published%20September%2020101.pdf

Conclusion : By incorrectly defining biomass as a low carbon fuel we are actually increasing global carbon emissions.

sydthebeat

fclauson wrote: »

Don;t start me on biomass - its worse than the rest of them
see http://www.aecb.net/UserFiles/File/Biomass%20-%20A%20Burning%20Issue%20-%20published%20September%2020101.pdf

Conclusion : By incorrectly defining biomass as a low carbon fuel we are actually increasing global carbon emissions.

Thats an argument for another day, and one we wont go into here....

but from the point of view of DEAP, biomass is acceptable.

creedp

sydthebeat wrote: »

I think the renewable requirement should definitely stay, its a justified policy, it just happens to be introduced with the finesse of using a sledgehammer to crack a walnut.

It stems from european policy and is ingrained in legislation currently.

Interestingly the easiest way to meet all Part L is by using biomass (wood) boilers.

Im all for encouraging the use of renewables but as you say Part L is dsyfunctional. Its counter intuitive to sanction someone when they improve their build standard from a space heating demand perspective. Its also hard to take that a new build it forced to spend on SPs simply to obtain a paper cert while existing builds get significant grant aid to achieve a must lower std of build. If Part L is so NB then put money where mouth is and incentivise it or else forget about it and let people build low demand houses without being crucified by bureaucracy gone mad.

sinnerboy

fclauson wrote: »

I think the renewable is a complete red herring

We should be pushing for better performing buildings

If as a separeate issue we want people to invest in renewables then that is different but joing the two together does not make sense

why if I have reduce my build 50% in performance below the Part L should I then have to additionally add on renewables


remember Part L is about Co2 and not renewables

E. Renewable Technologies
(Section 1.2). The RIAI propose that the requirement for on-site renewables be altered from an absolute figure to a proportional one, i.e. that 10% of the energy demand of a dwelling is supplied by renewables.
This policy has been very successful in the UK (The Merton Rile) as it encourages a developer to construct to a standard in excess of the regulations as a means of reducing the quantity of renewables required. As it is proposed to further increase energy efficiencies of Part L in 2013, and as retrofitting is expensive and of variable success, there should exist an incentive to construct to the highest possible standards. Take the example of a Passive House: it has a maximum Energy demand of 15kWh/m2/yr without resorting to additional renewable heating measures. The principle being – reduce the heating demand through the fabric of the building, and maximize the heat gains through solar radiation and internal heat gains.
Additionally micro renewables are an expensive abatement technology and regulations which would encourage their installation in non-optimal locations should be avoided. We would recommend that renewables be required in 'all reasonable circumstances'.
Finally we would recommend that following the logic applied to solid-fuel stoves and heat pumps. They should be excluded from the list of renewable technologies because both are only partially renewable, dependent on circumstance, and therefore should be treated the same.

SOURCE

just do it

SB

What an sensible proposition to DOE from RIAI. Where did it all go wrong?

A cynic might postulate the renewable energy sector are a persuasive lobbying group and probably talked up the number of jobs that would be created:rolleyes:

sydthebeat

Another example of this madness.

Doing a prov BER in a house which is using wood pellets as its main heat source.

renewables = 71 per sq m

introduce a 30 tube solar system and renewables drop to 68 per sq m

stupidly and plainly incorrect.