Hello all

I was wondering if anyone has any thoughts on the row that is erupting over the Green Guide?

I think that today there will be some major articles in the press as well as the full report - some rumors last week on the web already.

http://zerochampion.building.co.uk/ and http://www.bdonline.co.uk/story.asp?sectioncode=426&storycode=3129274&c=1&encCode=00000000018a35b9 , even the BRE are warning over using their own guide! : http://www.building.co.uk/sustain_story.asp?sectioncode=29&storycode=3129128&c=3

I have read the GHA ( http://www.goodhomes.org.uk/ ) report and it is very clear about the issues.

I agree with GHA, however I wonder what the BRE Green Guide will do? I cannot see them downgrading many major manufacturers products from 'A' to 'C' or worse, or indeed whole industries (such as uPVC).

When I look at their introduction - http://www.goodhomes.org.uk/news/111 I see it says "Please see below for the full report". But there's nothing below! Does anybody know where the report can be found?

I have same "see below" problem as Dave, (DJH)....


J

Thanks Mark

That document seems to criticise the operating methodology rather than the (scientific) methodology so I've no idea how valid the claims are

Anyone else got a view?

PaulT - I think that is my concern as well. I understand that there are people within BRE who think they have the Green Guide fundamentally wrong. I see the 'A' specification daily on projects (probably 80% of development/commercial projects I see these days). I see major industries and lobby groups advertising and promoting products / systems / generic materials as 'A' rated and therefore 'green' when clearly they are not. I have heard lobby groups deny a lot of the comparison issues (as it plays to their systems).

Are BRE really going to downgrade many major products / systems / generic materials and upset some major companies? It can only end up in court if they do...especially with such lack of clarity and transparency in the assessment process?

Do we need a 'Green Guide' - I understand that we are pretty much the only country to have attempted such a guide - products are rated in other countries by inclusion in a project, but they don't have a 'choose from this guide' system.

I also think it is a massive statement that BRE are now saying 'oh, don't use the green guide to help specify and design' when that was the idea in the first place....

Yes, but Carbon is only one factor - I think there is a good argument over a 'green guide' if it covers many other issues to do with materials - both in manufacture, in use and disposal.

There are plently of things in the Green Guide that I find very hard to explain to clients, if i had a shed I would consider heading there too Biff... I feel your pain

Biff, I think the BRE are basing that grading on LCA data that possibly mis-represents what is still an incomplete scientific study and understanding of the reaction between isoprene (a biogenic VOC) emissions from oak trees and NOx.

A good introductory text to this area is http://www.metoffice.gov.uk/research/hadleycentre/pubs/HCTN/HCTN_40.pdf which gives some basic background on the issues of isoprene and ozone.

As with all these things there will be differing results from different LCA studies and it depends where the BRE have decided to cherry-pick their data from. These results, in turn, will have depended upon which study or computer simulation model of ozone production efficiency was used in the specific LCA. See http://www.mpch-mainz.mpg.de/~kuhlmann/rvkdisshtml/node10.html for a quick discussion on some of the problems with these.

This report http://aspenface.mtu.edu/Monson%20et%20al%202007%20-%20Isoprene.pdf covers some of the complexities of the interaction between isoprene and NOx. It's clear that the concentration levels of NOx are crucial to the impact that the isoprenes have on ozone creation or depletion. NOx of course comes mainly from man-made pollution, the isoprene has been around for as long as trees have grown on the planet. So complaining that isoprene production is the cause of ozone problems is a bit off track when the root is the NOx emissions that they react with.

Also isoprene emissions vary massively based on many variables; species, leaf mass, sunlight, region. See the report downloadable from http://www.urbanforestrysouth.org/resources/library/Citation.2004-12-15.2727/view? So which figure is going to be 'right' for your oak? Well, you would've needed to study the tree before it was felled, too late now to make anything other than an educated guess and it is quite possible to rationalise almost any number you want.

As far as comparing PVC with wood windows in general is concerned:

A 2002 FAO report cited an earlier 1996 German report that POCP for PVC windows was 2.71 while wood was better at only 1.64. http://www.fao.org/docrep/004/y3609E/y3609e08.htm#P1050_57238

The Entec/Manchester report (comparing softwood, not oak, with PVC) states on p65: "For window profiles the depletion of the ozone layer is not considered to be a significant impact for either material."

I included links to some other PVC vs wood LCA reports in the other thread.

I've studied LCAs in some detail for about the past 4 years, with an emphasis on energy generation and building materials and my view is that, as with any set of statistics, they can be presented so as to produce whatever conclusion is desired by the author. My own conclusion after reading the various reports comparing PVC and wooden windows was that there is not enough difference to choose between them on any purely environmental grounds. Economics will always push you to PVC (for the time being at any rate) and socio-aesthetics towards local wood/craftsmen.

He who pays the piper etc... The closeness of commercial interests, politics and academia should not surprise us should it? Economic lies, damn economic lies and statistics, should we worry? Any source of data is always conditional anyway and a huge dollop of applied knowledge is required to adapt the data to fit the multi variables of each individual situation not just over one year in this case but over potentially 100 years of building and product operation. There will be another set of data along in a minute to confuse and distort the already muddy waters. I have direct experience of getting products through certification and as the joke about the prospective buyer of a racehorse goes, when the breeder is asked by the prospective purchaser, 'Who is the horse bred from', the breeder asks 'Who would you like him to be bred from'. Bring back common sense or remind folk about the emperors new clothes at every opportunity!