Imported Stone

[David OLIVIER]

Is it only me who wonders how imported stone slabs are profitably sold to us at the same price as UK concrete paving slabs? I'm not just thinking of sandstone and granite from the Far East - lots of Italian, Spanish and even German stone far undercuts the UK version.

Now, if I try to calculate embodied energy, I conclude that the energy cost of say sandstone from North Africa is about 50% lower than of concrete slabs made in the UK, largely because sea transport takes very little energy versus other forms of transport.

I did of course check the price of locally-quarried Hfds. sandstone and it's £50 per m2. Reclaimed slabs of the thickness or standard needed aren't available at present.

I seem to have two choices
1. Buy local, avoid 3,000 tonne-km of sea transport, an indeterminate amount of road transport & avoid emitting just over 60 kg of CO2 (similar to burning 25-30 litres of petrol).
2. Buy from distant shores and spend my saved £800 on other measures which will avoid the emission of far, far more than 60 kg of CO2.

I favour 2 but what do others think of the reality that cheap stone even from elsewhere in the EU undercuts UK stone? And what of the dilemma that quarrying and transporting stone from the relatively distant Mediterranean still emits less CO2 than; e.g., making concrete pavers or coping stones in the UK?

[Nick Grant]

We used some UK stone in our house for visual and emotional reasons  I can see why it costs more and didn't bedgrudge paying the premium.

Our sandstone windowcills are very locasl and it is all hand dug, split and cut to size with a handheld disk cutter. The resource is too small to warrent tooling up and the location in the Golden Valley would not be improved by a huge quarry even if the stone was there to justify it.

Our Caithness flag kitchen worktops are lovely but I am sure the road haulage from Caithness is far more than sea haulage for granite from China plus a shorter road trip.

Bathroom Travertine is from Turkey - we thought it was Italy but didnt delve as it was on special offer! We also had some cheap black slate from China for porch floor and loo walls.

Our biggest concerns are working conditions in Chinese quarries - not something we looked into but rumours and assumptions abound - and support for local economy. Embodied energy is probably a red herring as David demonstrates.

What is great about the rational accounting of carbon emissions for materials is that it puts things in some perspective and lets us focus effort where it does most good. It also frees us up to consider wider issues rather than getting fixated on embodied energy at the expense of lifetime energy, durability, quality, local economies, craft skills etc etc. A recurent argument through the forum.

[Tahir]

What is great about the rational accounting of carbon emissions for materials is that it puts things in some perspective and lets us focus effort where it does most good. It also frees us up to consider wider issues rather than getting fixated on embodied energy at the expense of lifetime energy, durability, quality, local economies, craft skills etc etc. A recurent argument through the forum.

I agree, and I'm glad that David has put forward the case for imported stone, I'm sure the average Joe Punter (me for instance) would have thought that it was a bad thing to use imported stone.

There are so many things to balance in the material selection process, maybe someone could come up with a computer programme to weigh up the plusses and minusses....

[Nick Grant]

The problem with such systems is that the programmer has to make the value judgements when weiging up say local landscape damage with energy cost, with creation of local employment with a country's human rights record etc etc. These assumptions are usually hidden.

I'm a fan of back of the envelope calcs for the stuff that can be measured (transport CO2 for example) then the rest can be done by the brain and body which is good at fuzzy logic and aesthetics but bad at intuiting about environmental impacts.

What I recon would be useful  is a ball park ready reconer table for say transport CO2 /kg.km and materials manufacture. I expect David has most of the figures to hand but is it already written up anywhere?

I have seen tables for embodied energy but often in Co2/kg rather than useful unit. Accuracy not critical unless the quantities are significant.

Anyone know of a definitive reconer?

[David OLIVIER]

I since checked reclaimed stone and this costs even more - £60 per m2 for local 20-30 km away (salvage yard) and £25-30/m2 for flagstones from South Wales (direct from the dealer who reclaimed them). But the lower rate still amounts to paying c£250 to save 30 litres of diesel = £250/30 = 8.30/litre which is extraordinarily expensive compared to other CO2 reduction measures (except perhaps PV!) I'm told that reclaimed stone now has scarcity value which is why the price is higher than Indian or North African imports of similar stone.

I don't know where this is written up concisely yet so maybe I should think about putting it in a book. You can get figures for sea transport energy with a quick Google, sticking to web sites of known organisations. The figure for UK concrete flags I got from 1990s UK government data (before BRE was privatised - newer data is secret but I doubt it's dropped or risen very significantly).

David.

[Tahir]

I don't know where this is written up concisely yet so maybe I should think about putting it in a book.

Excellent idea, an online resource would be good too, maybe subscription for professionals and free for consumers or something?

[Tahir]

BTW I'm working with a programmer to establish a free planting/yield database for the UK, a free to end user service, if he's any good (mySQL) he might be able to programme something to make it easier, and available online.

He's cheap (college leaver)

[Nick Grant]

Good on you Tahir! get the energy figures for materials and transport (David's and google). Sumarise in a table and stick on forum for comment.

Then get your mate to create a browser based application...

Go for it!

[Tahir]

The one that we're workinhg on is for trees (agroforestry/orchards etc), if he does OK on that then I'll definitely look at getting this done. It's not that expensive, the software (mySQL) is free, just programming time and hosting.

If he doesn't seem too good I've had another couple of programers offer their services.

Of course if any individual here or the AECB would like to do something like this I could pass you on their details, I wouldn't mind being a "consultant" on the project either.

It's shouldn't be that difficult as long as the data is available.