PHPP and the downrating of Lamda values

[Michael George]

Hi all, hoping this is the right category for this...

Firstly I have no experience of PHPP,  though I am needing to research a little of it for a paper I am working on.

I have been advised that although the software accepts any inputted lamda values for insulation,  those required for passive house certification must be downrated from published UK values which are themselves based on UK and European calculation methodology. The values which need to be used are based on a German calculation methodolgy.

Putting aside the rights and wrongs and reasons for this alleged downrating is what I have said above accurate? and if so is there a published list of accepted lamda values for insulation?

Also can anyone [briefly] explain the difference between the German calculation method and that used in the UK?

[Nick Grant]

Mike

Someone else may have more time for fuller answer but quick answer is that in the UK it is now acceptable to use EN 90/90 values but in Germany the more pessimistic DIN test is used and not just for Passivhaus.

This is a pragmatic compromise.

Nick

[Michael George]

Thank you Nick.

[Dave Howorth]

The PHPP manual says that the values comply with ISO 6946 and makes no mention of DIN that I can see. It even provides factors to convert R-value-per-inch to a U-value for use in PHPP (lambda = 0.1442/R).

The criteria for residential use - http://www.passiv.de/07_eng/phpp/Criteria_Residential-Use.pdf - says that the PHPP handbook is subordinate to the criteria on www.passiv.de (and is unfortunately password-protected to not allow copying of the exact wording). Does anybody know exactly where "the most recent certification criteria" are? And do they cover this question?

[Michael George]

Hi Dave, I maybe being naive here but I wonder why they don't want the exact wording to be copied? If the standard is to be universally adopted then surely there must be greater transparency?

[Nick Grant]

I have asked Pete Warm to answer the lambda question. All totally transparent Mike. Pdfs often locked to prevent changes etc, nothing un-transparent or about not wanting it to be quoted.

This is an issue outside Germany only and I believe related mainly to production testing. I'm resisting saying more as my partial knowledge will confuse.

Nick

[Michael George]

Anyone found anything further on this? Or prepared to comment?

I've been reading some of the other PHPP threads regarding the accuracy of the software. (that it is good I mean)

Obviously the input of lambda values is very important in this context. Without having the knowledge of if/why this is done, and to what level, it is easy to think that this is a fudge in the software, used to compensate for something else. What? I don't know.

I say this as I have seen such fudges used [and others] to compensate for modelling deficiencies in other software.

I accept that it is wise to lock pdf's. Nick. Though not that they cannot be universally viewed - all that does is create suspicion as to motives.

[Mark Siddall]

Mike,
Downrating exists in Germany as this accords with a national DIN standard. PHI have confirmed that national standards apply and that if a country does not have a standard that down rates the performance of the insulation then this is acceptable providing that the insulation is tested in accordance with the relevant EN standard for that insulation type. If it is CE marked then all is well. In the UK we do not have a standard that down rates performance - so EN tested, CE marked products are suitable.

HTH
Mark

[Michael George]

Thanks Mark.

So if I'm reading what you are saying right,  down-rating of UK manufactured insulation lambda values is not required for input into PHPP, as long as these have been derived via the CE compliant hot plate test, I.E. - BR443?

[Mark Siddall]

Mike
What's BR443 got to do with it? Relevant EN standards govern CE marking.

Mark

[Michael George]

What am i misundertanding here Mark? I was under the impression that u-value calculations in the UK must be derived according to thermal conductivities measured via Hot plate testing. BR443 sets this out doesnt it?

This implies [to me] that since Part L is the UK mechanism for European Compliance [with the EPBD] that the conductivities measured via the subordinant BR443 referred to in Part L are compliant.

Like I said, I may be missing something here, which, is really the point of my original qusetion, ie better understanding.

[Mark Siddall]

Mike I'm probably being a stickler. BR 443 refers to a range of EN standards and adds a few additional tweaks (additional supporting data). The EN standards, for testing rather than calculation, are to use to establish the Declared Thermal Values i.e. the expected value of a thermal property of a building material or product. The Declared Thermal Value is establised:

• when assessed from measured data at reference conditions of temperature and humidity
• for a stated fraction and confidence level
• when corresponding to a reasonable expected service lifetime under normal conditions [EN ISO 10456]

All insulation materials are to comply with the Construction Products Directive through CE marking. CE marking is achieved through compliance with the European product standard. The standards according to PD 6680: 2002 are (Guidance on the new European Standards for thermal insulation materials)

• BS EN 13172: Thermal insulating products. Evaluation of conformity
• BS EN 13162: Factory made mineral wool (MW) products
• BS EN 13163: Factory made products of expanded polystyrene (EPS)
• BS EN 13164: Factory made products of extruded polystyrene foam (XPS)
• BS EN 13165: Factory made rigid polyurethane foam (PUR) products
• BS EN 13166: Factory made products of phenolic foam (PF)
• BS EN 13167: Factory made cellular glass (CG) products
• BS EN 13168: Factory made products of wood wool (WW
• BS EN 13169: Factory made products of expanded perlite (EPB)
• BS EN 13170: Factory made products of expanded cork (ICB)
• BS EN 13171: Factory made wood fibre (WF) products

For instance when using BS EN 13162 to “establish a typical requirement” it can be surmised that all the standards require that:

• Initial type testing of the products (establishing the thermal conductivity – Lambda classes at an approved lab (in the UK most UKAS labs) before being place on the market.)
• 6 monthly audit surveillance by a notified body (say by BSI) that the standard is being met.
• Defined marking and labelling of the product to show performance and compliance with the standard.
• The standard defines the rules for performance declaration and for thermal performance this is based on a “Lambda 90:90” statistical analysis of QC results carried out on each product. Lambda group and means that 90% of the production is within 90% of the declared value.

It is only on this basis CE marking could be considered proof that the Delcared Thermal Value is reliable. In essence there is a whole QA proceedure for testing and maintaining the thermal performance of the insulation. This is much more than 'simple' hot box testing.

HTH,
Mark

[Michael George]

Yes, that does help. Thank You Mark, I get it now.