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Forticrete roundtable: specifying green

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The experts at this AJ/Forticrete roundtable give their top tips on how to get contractors to take your green specifications seriously

When it comes to designing greener buildings, no task is more challenging than specifying materials. The general lack of transparent information and the proliferation of ‘greenwash’ is often bemoaned by specifiers, but the findings from this AJ/Forticrete roundtable suggest that things are changing. Here, our roundtable participants exchange views on current trends.


  • Andy Batterham, design and innovation manager, Ibstock Brick
  • Rory Bergin, partner, sustainable futures, HTA Design
  • Fran Bradshaw, partner, Anne Thorne Architects
  • John Fifield, technical advisor, CRH Group
  • Chris Halligan, director, Stephen George & Partners
  • John Lambert, director and general manager, Forticrete
  • Sarah Lewis, associate architect, Barron and Smith Architects, NPS Group
  • Paul Martin, senior technical architect, Levitt Bernstein
  • Sandy Patience, editor, GreenSpec
  • Guy Thompson, head of architecture, housing & sustainability, The Concrete Centre
  • Hattie Hartman (chair), sustainability editor, The Architects’ Journal

BREEAM and the need for statutory legislation

Chris Halligan: Using sustainable materials is incredibly important in reducing the carbon footprint of a building, but this isn’t covered in any UK statutory legislation. The only one that really comes to mind is possibly BREEAM. BREEAM isn’t statutory, although it is becoming almost a de facto requirement in many commercial specifications. BREEAM is a double-edged sword. It’s great because it ensures a sustainable agenda, but it is hard to dissuade people from cynicism with a system which rates expanded polystyrene higher than straw bales.

Guy Thompson: Embodied carbon is very difficult to legislate because no one has agreed how to measure it yet. A lot of direction is currently coming from Europe, such as CEN TC350 standards and environmental product declarations.

John Fifield: Another change is the UK moving from British Standards to European Standards, which means that most products are now performance-based. The old prescriptive minimum dimensions and cement contents are gone, so we are able to engineer the shape of a product much better these days. The move to the European Standard has reduced the amount of cement we’re using by up to 15 per cent.

Paul Martin: We need a stick as well as a carrot approach, whether it is just statutory regulation or whether it is BREEAM. The bulk of clients frankly aren’t that fussed. There has got to be a mandatory target beyond an architect saying ‘wouldn’t it be lovely?’

John Lambert: There are parallels with the food industry in terms of the drivers for a sustainable supply chain. Our equivalent of Tesco and Sainsbury’s is Travis Perkins and a Jewson outlet. They said to us several years ago, ‘we want you to prove to us that you are acting in a responsible manner. If you are not ISO 14001 by this date, you’re out.’ For specifiers, that could be a good starting point. Even on design and build projects, if you put an alternative forward, it should come from a supplier with 14001.

Innovation in concrete

JF: A huge amount is happening in the cement industry. The current approach is alternative fillers. People are also looking to polymers but they are still more expensive. Carbonation is another approach. People like Solidia in America are looking at a totally different kind of cement.

GT: If you look at precast blocks, something like 4 per cent is cement, and in ordinary concrete, it varies between 8 and 12. You get these magical figures about how one tonne of carbon equals one tonne of cement, but no one actually buys cement – they buy concrete, and they build with concrete. There is quite a lot of complexity. If you haven’t read this document [Specifying Sustainable Concrete, by The Concrete Centre], you should.


Sandy Patience: Conversations about materials are very quickly dominated by the carbon argument. We ought to be opening up about the other environmental and health impacts of materials.

Rory Bergin: From the housing perspective, there is very little connection between the desires and aspirations of the end user and the product. Whereas if you look at the food industry, there has been a huge growth in local food, organic food, Fairtrade food. Our industry needs to rethink its relationship with the market. People care deeply about toxicity.

Design and build projects

PM: The single biggest barrier to greener specification is the disconnect between the architect and the end user of the building. The people living in the flats are not the people commissioning the flats. And the people commissioning the flats are not the people building it. It is probably a design and build job, so the contractor has final say over what we produce. We can write a really great spec, but we can’t guarantee it is going to be built.

Fran Bradshaw: Specification is especially critical in design and build, because it becomes a much weaker tool. The problem is that we have allowed ourselves to say, ‘build it like this, or similar’. Part of specifying for green buildings is specifying that ‘or similar’ very carefully, because often there isn’t something similar. That is where GreenSpec is very useful; when you are giving an option, you can check what those options actually are.

Green Guide to Specification

CH: People get really wound up about the BRE’s Green Guide to Specification. We have many projects where all that matters to the client is getting that Green Guide rating. There are serious financial implications from not attaining that level. That driver is the only thing actually working at the moment.

RB: I’d be surprised if anyone here said the Green Guide to Specification was among the top five places to look for guidance.

Risk and warranties

CH: Context is incredibly important. Just because a material has a low carbon footprint, it doesn’t mean it is going to be successful in a particular context. We developed a whole list of materials that we really wanted to use, and we quickly discovered that in the commercial sphere they were completely unsuitable. We couldn’t get anybody to take a risk on them, they weren’t available in the quantities we wanted, and there wasn’t the expertise in the country.

SL: When you work at a large scale, you need warranties. There are products that we need to educate warranty providers on, like timber-frame buildings. Specifying materials a contractor can guarantee will be on site when needed is also a challenge, as well as making sure that we don’t specify something that is going to come from only one provider, because if there is a problem with that one provider, then there is a problem across the site.

Transparency of information

SP: Our main challenge is that we are working with very little evidence. Until there is a good evidence base available through environmental product declarations (EPDs), there is no systematic way of assessing materials.

AB: Bricks are the first construction product to be verified under BRE Global’s recently launched EPD scheme.

JL: The difficulty is what criteria you put into the EPD; it is so broad. We got so brassed off when the Green Guide was released with all concrete roof tiles rated A+, and then John Fifield goes away and invents a product that is 40 per cent less carbon per roof, and it gets the same rating.

Calculating embodied carbon

GT: Designers need a generic figure when they are doing early design; they are not going to focus on whose concrete it is. Of course it then links with BIM because that is where the embodied bit is going to be counted.

RB: You can get into a very intricate numbers game, and you can spend quite a lot of time and effort comparing the number of trucks you might need to move a pile of aggregate from one canopy to the next. Somebody has got to pay for that – it is time-consuming and complex.

Specifying ‘process’ as well as materials

FB: I always think that it is not the point of specification to describe how to do something. But when you’re trying to encourage people to do something differently from how they have done it before, it can be useful. It is quite good to give people a chunk of text which says, ‘Look, this is the process I expect you to go through. If you allow for this, you might achieve the result I’m looking for.’ I’ve found that by including this, it has enabled the person pricing it to realise we are serious, and they can’t just come along later and say, ‘Oh, we didn’t quite read that bit of text’.


RB: Two positive things are happening. One is the growth of BIM. Architects who take BIM seriously and then look at the NBS and how you read the two together, suddenly have a powerful tool for describing a building in detail. They know how many cubic metres of concrete are going to be in there, how many cubic metres of block work. The second thing is the big focus on the performance gap. There is going to be a toughening on regulation in the residential sector to drive that gap down, so that buildings are being delivered which actually do what they say on the tin. That will mean tightening the specification.

PM: I’ve written a few specs in NBS Create which is compatible with BIM. The process isn’t quite there yet, but it has potential and could be very useful.

And finally…

SP: I am massively encouraged by everything I hear around the table. The heavy industries are getting on board really well. I am also impressed by the progress structural timber has made in this country. But overall I’d still like to see a lot more evidence.

Please click here for a full transcript of the Forticrete roundtable.




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