How Concrete Is Evolving for a Net-Zero Built Environment

REMIXED How concrete is evolving for a net-zero built environment

WHOLE-LIFE THINKING: HOW TO BALANCE THE RISE OF REUSE UNLEASHES EMBODIED AND OPERATIONAL CARBON A WAVE OF BRILLIANT BUILDINGS 2 CONCRETE FUTURES

CONTENTS WELCOME

Now and forever ��3 Designers understandably With their inherent durability, thermal efficiency have questions for the and adaptability, concrete buildings will have a concrete industry about vital role to play in a future circular economy what it is doing to minimise or eliminate its A life less ordinary �� 10 contribution to climate How architects and engineers are bringing change. We welcome existing concrete structures back into use – these questions: since often with a completely new identity 2008 we have been Welcome home �� 16 publishing detailed information about our Innovative systems are allowing concrete to give sustainability targets, back to nature – as a host to plants and a home to on materials, carbon, insects and animals waste, biodiversity, water No offsets required �� 20 and wellbeing, and our The concrete and cement industry is working progress towards them. The 12th annual performance report towards a carbon-negative built environment, on the Concrete Industry Sustainable Construction Strategy, without offsetting. Here’s how based on data up to 2018, shows that the embodied carbon of a standardised mix of concrete is 30% lower than in 1990. With most of our 2020 targets met, the industry is preparing to publish a new strategy to take us further towards net-zero carbon, without relying on offsetting. There’s much that we can and are doing in terms of fuel switching, investing in technologies such as carbon capture, use and storage, and developing low-carbon cements (see page 20). There is also much that can be done to reduce carbon in the way our products are used – for example, by project teams The Concrete Centre provides design guidance, seminars, courses, specifying low-carbon concrete and designing material- online resources and industry research to the design community. Our aim is to enable all those involved in the design, use and performance efficient structures that can be delivered. One problem is that of concrete to realise the potential of the material. sustainable choices are often stripped out before projects get to site. Contractors are driven by economics – understandably, The Concrete Centre is supported by industry to inform, educate given the number of firms that fail – so clients and investors and inspire. Our members are Aggregate Industries, Allen Newport, Breedon Aggregates, Brett Group, Britannia Aggregates, British Precast, must make sure that sustainability is economically viable for Cemex Materials, Deme Building, FM Conway, Gallagher Aggregates, every link in the chain. GRS Roadstone, Grundon Waste M’ment, Hanson Aggregates, The Concrete Centre was established to be the bridge Harleyford Aggregates, HH and HE Drew, Hills Minerals, Ingrebourne between materials suppliers and the designers and Valley Aggregates, J & J Franks, J Clubb, Marshalls Group, Moorhouse contractors who rely on their products. We want to facilitate Sand & Gravel Pits, Moreton C Cullimore, Morris & Perry, Myers Group, Quattro UK, Rotherham Sand & Gravel, Sea Aggregates, Smith & Sons, the conversations and collaborations that are essential to Springfield Farm, Tarmac, Tudor Griffiths, Volker Dredging. reaching a net-zero carbon built environment. We can’t do it alone – but I’m confident that we can do it together. The Concrete Centre is part of the Mineral Products Association, Claire Ackerman, director, The Concrete Centre the trade association for the aggregates, asphalt, cement, concrete, dimension stone, lime, mortar and silica sand industries. concretecentre.com @concretecentre THE INDUSTRY IS PREPARING TO

Edited and produced by Wordmule wordmule.co.uk PUBLISH A NEW STRATEGY TO TAKE Design by Nick Watts Design nickwattsdesign.co.uk US FURTHER TOWARDS NET-ZERO, Cover: Bioreceptive facade panel at The Bartlett School of Architecture, by Richard Beckett, Marcos Cruz and Javier Ruiz. Photo: Sarah Lever WITHOUT RELYING ON OFFSETTING WHOLE-LIFE CARBON 3

NOW AND FOREVER

The need to cut carbon is urgent, but we can’t lose sight of the net-zero future. Tom De Saulles explains why circular thinking is vital w 4 CONCRETE FUTURES

he UN declaration Views may have polarised carbon in mind, both at the outset made last year that somewhat between whole-life and in their ability to ensure IN A CIRCULAR only 11 years remain and upfront carbon reductions, the building remains energy ECONOMY, THE to limit catastrophic but a more pragmatic way forward efficient and in use for as long climate T change is a warning that combines both approaches as as possible, allowing maximum DESIGN STAGE IS seems to have resonated more far as practicable. This is perhaps value to be extracted before they THE ENTRY POINT than any other with the design best summarised in the World are repaired, repurposed and TO A CONTINUOUS community. Organisations Green Building Council’s definition ultimately recycled. CYCLE OF MORE such as the RIBA and RICS have of net-zero carbon, published So where does that leave announced net-zero carbon in August 2019 in Bringing concrete? As a material, it has SUSTAINABLE initiatives with ambitious Embodied Carbon Upfront, which several qualities that sit well CONSTRUCTION timelines – initiatives that acknowledges the immediacy of with the principles of a circular also place a strong emphasis the UN declaration by encouraging economy, provided they are on “saving carbon now” in designs that reduce initial carbon actively used in the design and respect of the embodied impact impacts as far as possible, with the operation of buildings. These of building materials and balance offset over a building’s include its longevity and ability construction activities. This can life through operational savings to help meet multiple design seem at odds with the principles and efficiencies. needs, namely structural, aesthetic, of a whole-life approach, also This approach also broadly acoustic, fire and thermal, without widely promoted and largely aligns with the principles of a reliance on additional materials Below and previous page: The Zayed Centre for Research into Rare Disease in focusing on longer-term carbon circular economy, in which the and treatments. A further Children, London. The exposed concrete performance. So, do they design stage is the entry point characteristic of many existing frame reduces heating and cooling needs conflict? At what stage in a to a continuous cycle of more concrete buildings is the long-term Right: The coffered ceiling at Bannetts building’s life cycle should the sustainable construction. This is serviceability of the frame and Associates’ Royal College of Pathologists greatest emphasis be placed on predicated on selecting and using foundations, which often makes HQ in London minimises the weight of saving carbon? materials with their embodied reuse a viable option (see page 10). concrete while maximising thermal mass WHOLE-LIFE CARBON 5

VIEWPOINT: SIMON STURGIS “Everyone has to up their game on whole-life carbon” Everyone wants to know what they need to do about whole- life carbon and how they can do it, and I’m having a lot of conversations with architects who recognise that now is a key moment. Investors are recognising that whole life carbon is a business issue, and are asking developers and clients the difficult questions. It took us 45 years to get our act together on operational energy. We have to do rather better with whole-life. Architects have an opportunity to reverse their marginalisation in the construction process by becoming the focal point for carbon assessment. To tackle whole-life carbon, architects and designers need to do the carbon assessments on their designs – there really is no substitute. But everyone needs to be on the same page. One of the problems is that different software gives different answers, so various organisations have put out target figures, and they are all different. I’m working with Cundall on Concrete can also contain recycled clinker content in cement with guidance for whole-life carbon assessment for the GLA’s draft content and itself be recycled. low-carbon cement formulations London Plan. This will hopefully provide a way forward by being There remains the question (see page 20). Progress towards more specific about what’s required in a carbon assessment. of upfront embodied carbon net-zero carbon will continue to be There is a parallel problem to do with professional indemnity impacts, and what the cement reported in the concrete industry’s insurance. Most buildings are significantly over-designed in and concrete industries are doing annual sustainability performance structural terms since structural engineers are concerned, not today to help meet the net-zero report, first published in 2009. unreasonably, about safety. Without this over-design, it could be carbon challenge. Cutting carbon possible to make savings in embodied carbon of as much as 20%. has been, and continues to be, Using environmental product Concrete has been fingered as a material of concern, and it an ongoing activity for the UK declarations does start at a disadvantage because of the carbon-intensive concrete sector, which to date At a more technical level, digging and heating involved in making cement. If you can use has reduced its emissions by 30% carbon reductions will also be cement substitutes that helps, along with sourcing locally to against a 1990 baseline. reflected in future updates to the reduce transportation. The industry also needs to make the case Reaching the ambition of sector’s environmental product for the whole-life benefits of thermal mass, longevity and ease of net-zero production by 2050 will declarations (EPDs) for concrete maintenance, and to address its suitability to the circular economy involve incremental cuts as cement products, which now cover a – precast flooring planks and other elements have the potential to production methods are reshaped, range of generic ready-mixed be re-used, but standardised sizes would make this easier. entailing technological challenges and precast concrete products. It’s easy to be glib about which materials are better for that will take time to develop and The environmental information embodied carbon, but the truth is that manufacturers in every implement commercially. The provided in these independently sector have to work harder, and architects need to know more cement sector is actively focusing verified EPDs offers a good starting about these materials and how to reduce carbon. Whatever the on fuel switching to zero-carbon point for early-stage design. For structure, you still have to get everything right when you build a fuels, including increased use of example, the generic ready-mixed building to benefit in carbon terms. Everyone has to look at the biomass for cement production, concrete EPD is based on the core of what they’re doing in order to up their game. on capturing the CO2 released commonly used mix strength Simon Sturgis is an expert on low-carbon design. He is the author of from the cement manufacturing (C30/37), making it suitable for all Targeting Zero: Embodied and Whole Life Carbon Explained process, and on reducing the foundations, floors and most u illustrations: Ben Southan Cook. Hufton + Crow; Potrait Photos: Peter

concretecentre.com 6 CONCRETE FUTURES

building structures. It contains a assessment at the building level, LCA tools such as One Click, level of cementitious additions which looks at the collective which is BS EN 15978 compliant, DESIGNING OUT (ground granulated blast-furnace life-cycle performance of the help to make this possible and SUSPENDED slag (GGBS) and fly ash) that structure, materials and building are increasingly used by engineers CEILINGS CAN SAVE reflects the current UK average. systems. The established method and designers throughout the Product-specific EPDs from for undertaking this type of construction sector. UP TO SIX TONNES manufacturers and suppliers can analysis is set out in BS EN 15978: Looking specifically at concrete in OF MATERIALS be used later in the design process, Sustainability of construction works LCA terms, it can offer a number of PER 1,000M2 when more specific concrete – Assessment of environmental building-level carbon efficiencies. performance requirements performance of buildings. Some of these are summarised are known and there has been Unsurprisingly, the European below, along with an indication of discussion with the concrete technical committee behind the carbon savings they offer. Designing out finishes supply chain. These can offer this standard is also responsible Where practicable, designing opportunities to further reduce for the development of the EPD Material-efficient structural out suspended ceilings and floor embodied carbon through a scheme that underpins it. The design finishes, through the use of visual greater use of cementitious standard brings together all the The upfront embodied carbon concrete for soffits and polished additions and other manufacturing elements needed for life-cycle of a concrete frame can be reduced concrete floors, can save around 2 efficiencies. Generic and product- assessment (LCA), enabling each not only through consideration 10 and 20kgCO2/m respectively, specific concrete EPDs are free to aspect of a material’s whole-life of the credentials of the concrete according to research by WRAP. download from: carbon performance to be properly itself, but the volume of concrete Additional longer-term savings l ibu-epd.com/en/published-epds evaluated at the building level, used. Structural design and from avoided maintenance and l greenbooklive.com where it matters most. different framing solutions replacement of finishing materials l concretecentre.com/EPD This is especially important for therefore have a role to play. are likely to be even more concrete, which increasingly fulfils For example, ribbed slabs can significant, as carpet has a typical Building-level carbon multiple design functions that can provide long spans while using life span of only 15 years and assessment help maximise the return on the less concrete, while pre- and suspended ceilings 24 years. It is tempting to use EPDs as a carbon investment. It also ensures post-tensioning reduce structural Designing out suspended standalone shortcut to material construction materials, systems and depths. The Concrete Centre’s ceilings can also provide a number selection, but their intended products are assessed in the round, tool, Concept, offers a simple of indirect savings: purpose is to inform a more with the ability to explore design means of assessing and comparing l Up to six tonnes of materials comprehensive environmental synergies and trade-offs. structural solutions. saved per 1,000m2 l Net saving per storey height of around 250mm l Improved effectiveness of natural ventilation from increased slab-to- slab height l Greater building adaptability from increased slab-to-slab height l Up to 5% less floor area needed for plant l 2 Around 50kgCO2/m saving if air-conditioning plant can be designed out completely (see overleaf). u

Left: At the Bullring shopping centre in Birmingham, a demand-side response system and thermal mass have combined to cut operating costs by £23,000 over a six-week trial period Opposite: At Sevenoaks School Science & Technology Centre, concrete soffits are integral to heating and cooling the naturally ventilated spaces WHOLE-LIFE CARBON 7

VIEWPOINT: HERO BENNETT “Clients should ask for a whole-life assessment at the start”

Embodied carbon thinking is We should be optimising carbon, by refining the embodied carbon rapidly changing. Last year assessment regularly over a project rather than just through rigid we had four times as much optioneering as required by BREEAM. Even small changes to finishes interest from architects and and metal supports, for example, can have an impact. Clients should clients as the year before. There understand that it takes time for designers to analyse the options is certainly an increased appetite and find the right solution, and they need to allow for that. for carbon literacy, which is The starting point has to be use of low-carbon materials but there important because without that isn’t just one design solution, or one right structural or material designers can’t interrogate the approach. We need to always strive for better and think beyond data and critique what they’re standard solutions. If we use a concrete structure, for example, being told. how can that be optimised? There are ways to slash the amount of But the industry has a long way to go and quite frankly, people concrete in a floor slab, for example, by using hollowcore. Also with still aren’t looking at whole-life emissions nearly enough. We are concrete, we need to stop patting ourselves on the back for using going through a period of transition, just as we did 12 or so years 50% GGBS cement replacement – we should be looking at how we ago with operational carbon. can go further. In terms of structure, the most important thing is to At Max Fordham, we’ve been shifting our thinking to whole- ensure that the floor-to-ceiling heights are of the right generosity life-carbon assessment for some time. And while traditionally this to allow a second life in a different use. If you get that right, you can is done over a 60-year period, we are increasingly focusing more be less concerned with being able to take the structure apart, and on the next 10-20 years in recognition of the fact that if we don’t more about the elements that need to regularly refitted such as address carbon reduction in that time, we’ll miss longer-term facades and finishes. targets. This focus raises the importance of reducing embodied We’re on the cusp of real change. Currently there isn’t enough carbon in the creation of the building as this represents a bigger incentive to optimise design in whole-life terms. But with investors proportion of the calculation. seeking clearer standards in relation to climate resilience for financial Clients have an important role to play in setting the brief and reporting, this will, hopefully, rapidly start to happen. asking for a whole-life assessment at the start so that there is no Hero Bennett is principal sustainability consultant and partner at dispute about the necessity, who will do it and how its paid for. Max Fordham Photos: Hélène Binet; Hammerson Photos:

concretecentre.com 8 CONCRETE FUTURES

and renewable energy would Left: Lifschutz Davidson Sandilands’ otherwise not be fully used. In Hoxton Southwark hotel and office building addition to lower running costs, in London is designed for future flexibility. this approach enhances the carbon The concrete frame enables clear spans and efficiency of grid-supplied power. adaptable floorplates, so hotel floors can become offices and vice versa An example of the use of DSR Opposite: For the refurbishment of the and thermal mass to cut operating Bartlett in London, Hawkins\Brown costs is the Bullring shopping convinced the client to retain the concrete centre in Birmingham, which frame because of the whole-life benefits delivered savings of £23,000 over a six-week trial period, according to owner Hammerson. The use End-of-life and beyond of DSR in this manner represents Moving finally to the end-of-life a significant development for stage, it is a little known fact that the future use of heavyweight the demolition and crushing of materials, even if it is something concrete results in a surprising

that LCA tools cannot necessarily amount of CO2 being absorbed take account of at present. into the newly formed concrete aggregate due to carbonation. What is old is new again This naturally occurring process Building refurbishment in is purposefully limited during preference to new-build has the in-use phase of the building become an increasingly pragmatic to prevent corrosion of any option, driven in part by the embedded steel reinforcement. principals of a circular economy There is, however, a much greater and carbon considerations. degree of carbonation during the Reuse can be the largest single end-of-life stage, when crushing means of maximising whole- greatly increases the concrete’s life carbon performance. The surface area, thereby enabling

savings realised from extending much more rapid CO2 absorption. a building’s life are of course Ultimately, the combination of largely project-specific, but for carbonation during the building concrete essentially equate to that life cycle and during its secondary Reducing energy demand demand and cost as fossil-fuel of a new concrete frame. As an life as a recycled aggregate can A visual concrete soffit unlocks use declines. For designers and indication of the upfront embodied reduce its initial carbon footprint the thermal mass provided by architects unfamiliar with the savings that can be achieved, by around a third, as outlined in the slab, enabling it to form a key use of exposed concrete soffits the initial embodied carbon in BS EN 16757:2017, Sustainability of element in the cooling strategy for cooling, refer to The Concrete the concrete superstructure of construction works. by using its passive performance Centre’s Concrete Floor Solutions an office is generally around The need to save carbon now 2 to help reduce or avoid the need for Passive and Active Cooling. 200-250kgCO2/ m , according to and achieve net zero in our built for air-conditioning. For office research by Arup (see Whole-life environment is a challenge that environments, this can cut the Demand-side response Carbon and Buildings, published the concrete sector takes seriously, average cooling load by 40-70% Looking to the future, thermal mass by The Concrete Centre, for more with work underway to produce (based on the typical cooling is also set to form a key element details) and provides a design life a roadmap for production, supply output of an exposed concrete in demand-side response (DSR) of 100 years or more. and use, building on the 30% soffit as a percentage of the control systems, which smooth out A “long life, loose fit” approach, cut in emissions that has already average office cooling load, cited power use in buildings to counter combining the use of durable been achieved. In the meantime, in BSRIA’s 2011 Rules of Thumb the intermittency of renewables materials and a format that is not there continues to be much guide), which over time will supplying the national grid. DSR tailored too tightly to the building’s that a whole-life approach to deliver sizeable savings. As the can be configured to use thermal primary function, aligns well design can do to demonstrate grid continues to decarbonise, this mass for storing and later releasing with circular-economy thinking. the contribution concrete makes saving will gradually switch from heat or coolth produced by heat Designing in this way today over its life cycle, including the carbon to energy – a commodity pumps or chillers at times of low provides valuable low-carbon aspiration of making a circular that will be subject to increasing grid demand, when power is cheap resources for future buildings. economy a reality. l WHOLE-LIFE CARBON 9

VIEWPOINT: JAKE ATTWOOD-HARRIS “You can’t just look at materials in isolation”

At Hawkins\Brown, we’re very H\B:ERT has produced surprising results, and that’s exactly why we much in favour of the whole- need it. Broadly, metals and plastics have the largest carbon impacts. life carbon approach to carbon A basic principle is that if a material is mined or smelted, its embodied calculations. By 2030, we want carbon will be huge due to high-temperature manufacturing every one of our projects to have processes – and will account for a lot more than involved in the capability to be zero carbon. transportation. This includes recycled steel and aluminium. There We’re moving towards that target are some high-performing wonder materials: earth-based materials using our open-source H\B:ERT like terracotta bricks; natural materials that have good thermal tool, which we’ve developed properties and can be net biogenic carbon stores such as hemp-lime; with University College London. cement fibreboard. But you can’t just look at materials in isolation. A It calculates the embodied carbon using the volume of modelled building with a timber or stone facade looks promising but it’s the construction materials and components in Revit. We are further substructure supporting it that has the highest carbon load. developing it to include energy in use to allow us to assess whole-life Sometimes thermal mass is more useful than insulation, especially carbon per square metre across all types of projects, balancing the with rising temperatures. When we refurbished Wates House for the contribution of each component. This fundamentally changes how Bartlett, for example, we convinced the client to retrofit by retaining we design, which is exciting, and allows us to value the retention of the concrete frame rather than rebuilding – not only is the thermal heritage buildings as well as take new design approaches. mass useful (and beautiful) but it saved the energy of demolition. It’s difficult to measure carbon in buildings. The industry has We see it as inevitable that the industry will move to using whole- historically focused entirely on energy in use, since operational life carbon calculations, leading to a fundamental reassessment of carbon used to be the major part of a building’s impact. But how we practise architecture. as energy efficiency improves, in many building types the Jake Attwood-Harris is sustainable design advisor at Hawkins\Brown embodied carbon is now the largest component. The problem is that the more you focus on operational carbon and ignore embodied carbon, you end up with what we call “spaceship”-type buildings. While many are incredibly well-sealed and insulated, this can come at considerable embodied carbon cost, since this is achieved with aluminium, steel, plastic insulation materials and a large amount of mastic. Working with H\B:ERT and our project engineers, we now calculate whole-life carbon figures for every new project. We’re also going through our back catalogue to learn from measured energy data. This knowledge is key during the briefing process, where we look at the largest embodied carbon impacts, which tend to be the structure and facade. Photos: Hawkins\Brown; Paul Riddle Hawkins\Brown; Paul Photos:

concretecentre.com 10 THIS IS CONCRETE

A LIFE LESS ORDINARY

Architects and engineers are showing how utilitarian structures can be reimagined as inspiring, future-flexible spaces. Nick Jones reports

This page: Architecture Initiative’s Northampton International Academy – a derelict Royal Mail sorting office reborn as a 2,200-pupil school REUSE 11

o the casual observer, Serious structure last year’s Architects Adapting existing buildings is as Declare manifesto old as construction itself, but it appeared to offer the has been enjoying much greater unusual T spectacle of an entire prestige in recent years. The last profession shooting itself in two winners of the Mies van der the foot. The commitments Rohe Award, the EU’s top prize contained in the headline- for contemporary architecture, grabbing document – signed have involved the radical by many of the UK’s leading overhaul of postwar buildings: practices – sought to address Lacaton & Vassal’s transformation the construction industry’s of a 530-unit housing block in contribution to climate change: Bordeaux and NL Architects and awkward truths such as that it XVW’s reboot of Amsterdam’s produces about 40% of the UK’s brutalist Kleiburg development. total carbon emissions and uses Meanwhile, architects are 295 million tonnes of virgin discovering possibilities in existing materials per year. Among the utilitarian structures that would architects’ pledges was a vow to be inconceivable if built from “upgrade existing buildings for scratch: at the Zeitz MOCAA art extended use as a more carbon gallery in Cape Town, Thomas efficient alternative to demolition Heatherwick carved and sliced and new build whenever there an old grain silo into one of the is a viable choice”. The fact most instagrammable buildings that construction and disposal in the world; in London, Herzog contribute about half of a & de Meuron recast the brooding typical new building’s lifetime oil tanks beneath Tate Modern as carbon emissions can no longer one of the capital’s leading cultural be ignored: increasingly, we’re attractions, without even having to going to have to make do with clean the oil stains from the walls. the built environment we have. It is no coincidence that these “The reuse of our existing building buildings all have a reinforced stock is key to maximising the concrete structure. Concrete, carbon we’ve already spent, and perhaps more than any other fundamental if we’re ever going to material, is ripe for adaptation. get near to carbon neutral as an “Longevity has no chance without industry,” says Paul Hutter, a director serious Structure,” wrote the at engineering consultant AKT II, architectural theorist Stewart which has helped to revitalise a Brand, who in the 1970s did much series of existing buildings, from an to popularise the idea of designing 18th-century flax mill in Shrewsbury long-life, loose-fit buildings capable to the South Bank Tower, once the of adapting to new uses. Given that tallest building in south London. the predicted life of contemporary In pursuit of this goal, architects reinforced or prestressed concrete and engineers are showing that structural elements in an internal building types previously dismissed environment is 100 years, there as inflexible – from 1970s office is usually plenty of scope for a blocks to multistorey car parks – second lease of life. can be put to a range of new uses, It takes a lot to make an sustainably, economically and to existing concrete structure stunning effect. Far from sounding unviable. Architecture Initiative’s the death knell of the architectural Northampton International profession, the rise of reuse could Academy project, for example,

be its most exciting chapter yet. began with a derelict former u Will Photo: Scott

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Royal Mail sorting office that was little more than a frame blackened “WE NEED TO MAKE by arson attacks – an inauspicious SURE WE GIVE THIS starting point for a school. But the GIFT OF DATA TO THE material was in a surprisingly good condition, says design director Lee NEXT GENERATION. Mainwaring. “All of the concrete NOT THE SAME was covered in soot, but we gave DATA WE’VE USED it a sandblast, which brought up – WE NEED TO GIVE the nice raw finish, and that was basically it in terms of the structure.” THEM MORE” The fair-faced concrete is now PAUL HUTTER, AKT II one of the defining features of the interior (see box, opposite). It may sound obvious, but giving obviously a massive amount of concrete a good clean can be effort and money and time and revelatory. On London’s Euston craftsmanship. So we just cut these Road, Camden’s unloved, brutalist two long slots down the length former town hall annexe has been of the building, with the primary reborn as the very hip Standard school arranged around one hotel, but the precast concrete and the secondary school around facade is essentially the same. It the other. It was very simple.” has just been carefully cleaned The 3.6m-wide voids were with a mild water-pressure-based created between the main 10m abrasive system, revealing its near- x 10m structural grid lines on all white aggregate from beneath three floors by breaking through 45 years of London pollution. The the slabs with jack hammers. The intervention could barely be more rebar caging was then reset and light touch, but it has been vital to the in-situ concrete recast around the building’s reinvention. the edge of the slots. Daylight It’s also striking how little work is now washes through the spaces, often needed to make a concrete enhanced by 6.5m ceiling heights structure fit for a completely and the liberal use of white, glazed different use. A Royal Mail sorting and reflective surfaces. office is starkly different in terms Featherstone Young’s recent of function to a school: deep- award-winning conversion of the plan with very little daylight, lower levels of a Wrexham car park the Northampton building was into an arts centre and community built for storage and logistics space also involved less of a rather than the shaping of young structural overhaul than might minds. Mainwaring says that it be imagined. “There was a lot of would almost certainly have been discussion about how we could torn down if the local property work around what was already market had been more buoyant. there, and make smaller rather But they still tried to do as little than wholesale changes – partly as possible: “Every insertion is because that’s more sustainable, but partly because it’s more economical as well,” says architect Above left: AKT II’s forensic analysis of Sarah Featherstone. “Externally, the 30-storey South Bank Tower in London the brick facing and blue-painted allowed Kohn Pedersen Fox’s design to extend the existing structure by 11 floors ironwork weren’t the most Left: Lacaton & Vassal transformed three attractive, but inside it was actually social housing blocks in Bordeaux by a very beautiful precast concrete

Photos: MikePhotos: O’Dwyer; Ruault; Philippe adding a 3m-deep structural facade structure. It has these prestressed REUSE 13

T-beams which curve so you can Both projects hinged on see where the ramps lead up – it’s forensic analysis of the original not just a flat ceiling.” 1960s structural drawings, both Again, the main structural to understand the structure and interventions involved drawing to identify any spare capacity. more light into the deep-plan “We wanted to understand every building: larger openings were single bit of rebar and why it was made on the south and east there, what the original designer elevations and two deep voids was thinking. You have to start by were created by removing several putting their hat on,” says AKT II’s 10m-long concrete beams from Paul Hutter. The drawings were the first-floor slab. “We decided the most important thing on the to take them out in their entirety job, he adds: “If anyone went to rather than try to cut them, draw on my existing drawings which might have disturbed I slapped their hand away and IN PRACTICE the structure’s integrity,” says told them to get off. They were Featherstone. On the floor above precious to me – that pack of Northampton International Academy the voids, 30cm-wide slots were drawings drove the project, cut between the prestressed drove the architecture, drove the Four years ago, it would have been hard to imagine the beams of the roof slab – the thin structure, drove the programme. abandoned Royal Mail sorting office on Barrack Road as openings a necessary strategy to It enabled us to work out where the sort of place you would happily send your children on a avoid severing crucial tendons. the opportunity was and say daily basis. The near-windowless 1970s utilitarian structure Each pair of slots is straddled by a ‘let’s not just push it two or three had been vandalised, broken into, set on fire. “It had almost rooflight, casting light deep down floors, let’s go all the way’.” become a beacon of bad news. The only reason it hadn’t been into this previously back-of-house Combining the drawings demolished was that it would have been too expensive,” says area, now transformed into a with technology unavailable Architecture Initiative design director Lee Mainwaring. gallery space and open “people’s to the original engineers, AKT II Thanks to the practice, the sorting office is no longer an square” (see box, overleaf). modelled the entire history of the eyesore – and it’s turned out to be the answer to Northampton’s concrete frame to understand secondary school crisis too. With minimal interventions in the Added space the distribution of load, both as existing structure (see main story), the building has been reborn Another advantage of concrete materials aged and floors were as a 2,200-pupil school, covering primary to sixth-form. Two long structures is that they are often added. On Finsbury Tower, they voids cut into the floor plates of the two-storey, double-height strong enough to accommodate constructed finite element models, building wash the deep-plan interiors with daylight. In a nod to extra space, either in new storeys with over 200 construction stages, the building’s history, the concrete has been left exposed, with on top or new elements hung spanning from the 1960s through lighting and other services suspended from the 6m-high soffits. from them. For example, Lacaton to 2050. They also conducted Basing the spatial arrangement on the 900mm x 900mm & Vassal reinvigorated its Bordeaux extensive geothermal analysis, waffle slab structure, Architecture Initiative placed the housing block by adding a identifying the unused capacity classrooms around the building perimeter in a mezzanine level 3m-deep structural facade that of the piled foundations. “The u suspended via a system of steel clamps from the concrete coffers. provides generous winter gardens The teaching rooms are allowed maximum access to natural light to all the flats. through new window openings punctured through the existing Structural engineer AKT II has external walls. More specialist areas such as science labs and taken this search for spare capacity “THE CONCRETE WAS music and drama facilities are placed in the heart of the structure. to new levels. At the South Bank Mainwaring argues that in some ways it is better than a new- Tower in London, it collaborated COVERED IN SOOT, build school. At 22,250m2, it has a greater ratio of space to pupils with architect Kohn Pedersen Fox BUT WE GAVE IT A than the Department for Education would normally budget on a first-of-a-kind refurbishment, SANDBLAST, WHICH for. “There was no point demolishing or not using part of the adding a further 11 storeys to BROUGHT UP THE building, so we made the school more generous, and made use a 30-storey building. It is now of these double-height spaces.” The thermal mass of the concrete repeating the trick a couple of NICE RAW FINISH, structure also prevents overheating, he adds, and those mighty miles north in Islington, working AND THAT WAS floor slabs mean Northampton can teach subjects not normally with Horden Cherry Lee to add BASICALLY IT” on the curriculum: “On one side you can drive a car in, so they 12 new levels to Richard Seifert’s LEE MAINWARING, offer automotive engineering – not many schools can do that.” 16-storey Finsbury Tower. ARCHITECTURE INITIATIVE Will Photo: Scott

concretecentre.com 14 CONCRETE FUTURES

“AS ARCHITECTS, YOU HAVE TO CREATE A CLEAR FRAMEWORK, BUT YOU DO AS LITTLE AS YOU NEED TO DO” SARAH FEATHERSTONE, FEATHERSTONE YOUNG

advance in that type of analysis in the past 5-10 years has been quite profound, and it’s allowing us to push the boundaries more and more,” says Hutter. The upshot is that two tired London office buildings have become desirable mixed-use IN PRACTICE developments: on the South Bank Tower, the new storeys cantilever Ty Pawb, Wrexham concrete flagstones and employing a palette of from the core adding 67,000m2 utilitarian, everyday materials such as plywood of floor space; at Finsbury Tower, At Ty Pawb art centre, Featherstone Young has and exposed blockwork. The council client the new scheme adds 100% more shown how the reuse of an existing building team were initially nervous about the aesthetic: area within the footprint, replacing can give an architect the freedom to think “Celebrating the concrete paved floor, exposing the core but reusing the existing about a traditional function in an entirely new the concrete roof, using materials that were quite foundations and basement. It is light, and offer something that a new-build rough was difficult for them. But I think they the dramatic expansion of usable can’t. Within a 1990s multistorey car park and supported it in the end because of the concept area, says Hutter, that makes such market hall, Featherstone Young has inserted of the streetscape.” schemes commercially attractive. art galleries, market stalls, performance space, A light touch was taken with the structure (see “It’s more complicated work than a learning centre, cafes and bars. And in doing main story), with voids cut into the prestressed new-build, and you need a good so, it has radically reimagined what an arts roof and first-floor slab to bring light into the contractor, but the savings on centre can bring to a community. eastern side of the deep-plan building, and programme mean the construction The brief for the £4.5m project was originally openings cut into the east and south elevations. cost is substantially reduced.” to provide three gallery spaces for local arts This turned the former “back” of the building But more needs to be done organisation Oriel Wrecsam, but Featherstone into a welcoming new frontage, emphasising to build the commercial case Young successfully argued for a single dedicated the building’s role as a shortcut from the edge for refurbishment. As the gallery surrounded by looser, indeterminate of town to the centre. Where the new rooflights government’s Building Better, spaces, which would be more welcoming than have claimed space from the top-level parking, Building Beautiful commission typical “white cube” art centres. “These spaces there is now a bee garden – an example of user- highlighted in its final report in can lend themselves to a whole range of different led “baggy space” in action, says Featherstone. January, new-build construction is activities – workshops, concerts, recitals, open With cities including York and Birmingham zero-rated for VAT, but renovation mics. It resolved some of the tensions between considering a car-free future, could Ty Pawb is taxed at 20%. The reason often the art centre and the market hall: instead of the provide a template for the future of our parking cited for this anomaly is that the two never meeting, there’s this area where quite infrastructure? “We have had quite a few people construction industry, which different activities might come together.” ring up now with multistorey car parks they want constitutes more than 6% of the UK In keeping with this “baggy space” concept, to transform,” says Featherstone. “As soon as you economy and 7% of its jobs, relies Featherstone Young conceived the building as a take cars out of the equation, you have all this on the “planned obsolescence” continuation of the street, reusing the existing space you can potentially turn into public realm.” of buildings to keep the wheels turning. Such a position looks REUSE 15

increasingly untenable in the light Right: The facade of the Standard hotel in of challenging emissions targets. London was carefully cleaned with a mild Planning regulations could also water-pressure-based abrasive system be more pragmatic, says Hutter, Below right: At the Zeitz MOCAA gallery in Cape Town, Heatherwick Studio carved a pointing out that any unused stunning atrium from a grain silo capacity in existing structures is a wasted resource. “We need planning authorities to perhaps break their own rules and allow Her practice recently completed the correct amount of mass to be Bay 20, a community centre and added. With the South Bank Tower, boxing club under the Westway we argued we weren’t maximising in London: “It’s a shared space for the building, so they allowed us to two different activities, with the go to 11 storeys. The construction community centre as loose as industry needs to put these possible and this in-between space arguments forward before a new- between the two buildings, which build is on the table.” people can spill into and use in different ways.” An adaptable future The distinction between new- Recent conversions hold valuable build and refurbishment may insights for the design of new become increasingly blurred. buildings – what could we do now Building elements are already to encourage future reuse? For being designed to be demounted Hutter, the key lesson is to share for reassembly elsewhere: the drawings and data forward. “We precast-concrete top tiers of need to make sure we give this the 2012 Olympic Stadium, for gift of data to the next generation. example. This semi-permanent It’s not just about giving them the approach to construction could be same data that we’ve used – we coupled with material passports, need to give them more, so they now being pioneered in the can understand the buildings Netherlands by an organisation better than we do now. Then, in called Madaster that logs data 50 years’ time when they hopefully on all the materials in its library have more technology, they can of buildings. In the near future, push the boundaries yet again.” a Madaster-registered building A flexible, loose-fit approach scheduled for disassembly or often seems to characterise the demolition could be scanned new-build work of many architects by project teams for parts to be who’ve undertaken major reused elsewhere. refurbishments. Jean-Philippe The industry has a long way to go Vassal, the architect behind the if it is to make more than a token Bordeaux housing project, intends dent in the 295 million tonnes that every one of the practice’s of virgin materials it consumes new projects should contain equal every year. But architects and amounts of programmed space engineers are already coming up and “undefined space”. with ingenious responses, using Similarly, Sarah Featherstone is a the rich history of buildings and proponent of what she calls “baggy their component materials to space”: “It is about exploring how create new and reimagined spaces. much we as architects need to do, The Building Better, Building before other people can come in Beautiful commission may well be so it can grow and adapt. You have right when it says: “The beautiful to create a clear framework but building is one that outlives its

you do as little as you need to do.” original use.” l Soar;Tim Iwan James Morris; Baan Photos:

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ince 1950 the UK hedgehog population has shrunk by 96%. Tree WELCOME sparrow numbers are down S 95%. Many other birds, including starlings, swifts and songthrushes have also suffered HOME depressing declines, along with bees, butterflies and even earthworms. Concrete can support plant and animal All of this adds up to a steep decrease in Britain’s biodiversity. life in surprising and often beautiful ways, Everything from climate change finds Tony Whitehead to wind farms to modern farming practice has been blamed, and insensitive building too has played its part. From later this year, however, the construction sector will, by law, become part of the solution. With few exceptions, planning permission will be withheld from all development in England that cannot demonstrate a 10% net gain in biodiversity. The new regulations are set to become law this autumn and will apply fully by 2022 (see box, overleaf). Many planning authorities already impose net gain conditions on schemes, so the new rules should not prove too much of a hardship for developers who have adopted advanced environmental policies. But the changes will certainly serve to raise the profile of urban wildlife, not least as a focus for innovation in construction materials and techniques. Beyond biodiversity, the myriad benefits of nature in cities are well rehearsed and often intuitive. From mitigating air pollution, overheating and flooding to improving psychological wellbeing, we clearly stand to gain a lot by welcoming in the wild. It turns out that concrete can be a very good way to do this. Far from being grey and inert, it can support plant and animal life in surprising and often beautiful ways. Researchers are using it as durable substrate, robust shelter, BIODIVERSITY 17

even a source of nutrients for A test wall of Gilligan’s panels where they can do most good, as many different creatures from the is already in place at Queen’s “IT’S A HYPER- they can be relatively expensive smallest to the most useful to the University, Belfast and performing POROUS CONCRETE and may require some irrigation most endangered. well: “The bees, butterflies and and maintenance. If that puts off Take the work of concrete other bugs love it.” But the panels WITH A VERY OPEN some building owners, they might scientist Dr Elizabeth Gilligan. do more than just support local CELL STRUCTURE prefer a new sort of concrete panel Her company, Material Evolution, biodiversity: “The concrete TO ALLOW FOR created by two academics at the is developing concrete panels carbonates, reabsorbing CO2 Bartlett School of Architecture at that are specially adapted to host relatively quickly. The sedums PLANT AND WATER University College London. INGRESSION. IT sedums, the low-maintenance also absorb CO2 and are good at Professor Marcos Cruz and succulent plants used extensively trapping pollution particulates. HOLDS WATER LIKE lecturer Richard Beckett have been on green roofs. “The panels have They could be particularly effective A SPONGE” researching how concrete can be deep indents in which sedums lining an urban canyon – we have made more bioreceptive, and have DR ELIZABETH GILLIGAN, can take root,” she explains. measured local improvements in MATERIAL EVOLUTION developed facade panels specially “This happens with the panels air quality of up to 60%.” designed to encourage the growth horizontal, but after a few days, The panels must be irrigated to of cryptogams – organisms such u when the plants are established, protect the plants from drought, the panels can be made vertical to and grey water can be used for form a building facade.” this: “The panels can form part of Much of Gilligan’s research has a filtration system, cleaning the focused on developing a plant- water and then returning it to friendly concrete mix. “It’s a hyper- the building.” porous concrete with a very open Of course, not all green walls cell structure to allow for plant require specialist concrete. Precast and water ingression,” she says. “It panels are routinely shaped to hold holds water like a sponge, so its various systems of planters, with qualities are exactly what most the concrete simply providing a precast panel manufacturers tough, root-resistant background would try to avoid. However, the against which plants can thrive. concrete still forms a protection Dr Eleanor Atkins, lead researcher for waterproof membranes and at Staffordshire University’s insulation behind it.” Green Walls Centre, addresses The mix comprises 90% recycled the potential concern that plants material, as well as nutrients for will damage a building: “Plants the plants, along with elastic can damage buildings, but roots fibres which help the concrete tend to find existing cracks – so cross-knit back together if it starts if the facade is new and sound, it to crack under the influence of shouldn’t be a problem.” roots. The exact details remain In fact, a covering of plants secret, pending patent approval, can be a shield against local but Gilligan says it can be adapted environmental conditions: “As well to recycle local waste streams: as boosting biodiversity, green “For example, a lot of seafood gets walls can protect a building by eaten in the San Francisco area. providing insulation and reducing We have done some experimental weathering, including frost work there using crushed oyster shattering. They can also keep shells as a nutrient source.” a building cool in summer by providing shade, and if the plants are deciduous, this shade will be Opposite: Green and Blue’s bee homes are reduced in winter to let the sun all made from concrete with a 70% recycled mix using local china clay waste through – particularly useful for Right: Material Evolution’s concrete mix seasonal window shading.” contains 90% recycled material as well as Atkins advises that green walls nutrients for the plants should be selectively placed and Blue; Elizabeth Gilligan / Material Evolution Green Photos:

concretecentre.com 18 CONCRETE FUTURES

as moss, algae and lichens – which develops. This gives you plants that turned his attention to the role require no irrigation. are well adapted to the location, “WE ENCOURAGE of biodiversity in improving the The aesthetic effect has been but obviously takes longer and MOSSES AND indoor micro biome. “This is the a major focus of their work, says gives less control over aesthetics.” population of bacteria that inhabit Beckett. “After all, a green stain The panels’ benefits are wide LICHENS TO GROW your building,“ he says. “The more on a white building can look ranging: mosses and lichens IN A WAY THAT IS cleaned and sealed our buildings terrible. It often marks some absorb CO and punch above their become, the less diverse the 2 PLEASING TO THE point of failure like a leak. So we weight when it comes to purifying bacteria. You end up with too many have experimented with ways to air by trapping particulates. They EYE AS WELL AS human-related bacteria, which can encourage mosses and lichens to also provide a habitat for micro BENEFICIAL TO THE be unhealthy.” grow in a way that is pleasing to fauna and small insects on which ENVIRONMENT” A rich diversity of plant and the eye as well as beneficial to the birds can feed. RICHARD BECKETT, THE BARTLETT animal life outside a building can environment.” This has involved None of these benefits will improve the bacterial diversity designing a range of mixes – be realised, however, unless the most of which result in a slightly panels look attractive enough porous concrete that allows the to be specified. “We have tried rhizoids (root structures) to get a various patterns and the ones foothold. “We have also altered the with more flowing shapes tend to pH so that it is more conducive look best,” says Beckett. He points to the plants,“ says Beckett. “The out that lichen-covered statues in concrete is perhaps a little weaker churchyards develop a pleasingly than standard mixes, but we are romantic aspect: “You’ll often proposing it for facade panels pay more at auction for a garden rather than structural purposes.” statue with patina than for a new, The surface can either be unweathered one.” “seeded” with spores, or cultivated There are plans to install the cryptogams can be transplanted panels at two sites in London – a onto the panels. “Alternatively school and an underground

you can just wait and see what station. Meanwhile, Beckett has Richard Beckett, Ruiz Sarah Lever; Cruz and Javier Marcos Photos: BIODIVERSITY 19

Opposite: The Bartlett’s facade panels are specially designed to encourage the growth of organisms such as moss and lichens Right: Green and Blue’s bee homes can be built into the fabric of a house without compromising its structure inside, says Beckett. He is looking to boost this further – again by using concrete. “We have found that by seeding specially adapted concrete with healthy bacillus we can encourage good bacteria at the expense of the bad, and end up with panels that are resistant to MRSA, the bacteria that causes infections in hospitals.” Working on an altogether larger scale, a company in Cornwall is using concrete to provide builders with an easy way of making their developments more friendly to local fauna. Green and Blue’s range of small animal homes are all made from concrete with a 70% recycled mix using local china clay waste. “We chose concrete because it is a material builders are familiar with,” Biodiversity net gain explained says founder Gavin Christman. “It’s long-lasting and structural, The requirement for developers to achieve a will have to do more and possibly add off-site so our homes for bats, swifts and biodiversity net gain of 10% is expected to improvements.” bees can be built into the fabric become law in autumn this year, which will While in most cases it is best to achieve the of a house without compromising mark the start of a two-year transition period. net gain on the site concerned, where this its structure. And being integral To begin with, biodiversity will probably be proves impossible developers can offset by to the building, they are there for measured using the Biodiversity Metric, an improving nearby sites or purchasing sites that good, whereas wooden boxes can online tool published by Natural England. have been improved by others. “For example, we decay over time through lack of Developers will comply first by minimising have worked closely with the Mineral Products maintenance.” any destruction of habitat and then by adding Association as their members are typically good Initially interest in the products improvements. at achieving net gain from quarries that have came mainly from developers “Currently different local planning authorities stopped operating. Many of them restore sites specialising in building with use different metrics and require different to a standard beyond what is required, and this nature, but Christman says that levels of mitigation or improvement,” says Dr gives them the potential to make surplus gain it is receiving more enquiries Nick White, Natural England’s principal net gain available to others. This would in effect create a from mainstream companies, adviser. “The new rules should make it easier for market in biodiversity.” thanks to the biodiversity net gain developers to know where they stand.” To avoid having to purchase off-site rules. Formalising biodiversity The metric includes a range of things that improvements, White recommends architects requirements within the planning could count as a credit, such as green roofs, green and developers consider the biodiversity target system also chimes with a wider walls or urban trees. “What’s required will vary at an early stage. “Too often the site is designed, change in public awareness, he according to what you start with,” says White. “If and then handed to ecologists to green,” he says. suggests: “We have ambitious you are building on an relatively uninteresting “It is much easier and better to look to integrate housebuilding targets in the UK, so brownfield site, then an area of community green infrastructure early on. Ideally this can I think there is an understanding grassland or a sustainable drainage scheme may be done in a way that delivers wider functional that the more we build, the more be all you need to do to achieve a 10% gain. But benefits such as mitigating flood risk and important it is that every house if you are building in an area rich in wildlife you improving air quality.” gives something back to nature.” l Photo: Green and Blue Green Photo: concretecentre.com 20 CONCRETE FUTURES

NO OFFSETS REQUIRED

The concrete industry is developing a roadmap to net-zero carbon – and there will be no grey areas, writes Claire Ackerman

ecarbonising concrete some of the key components of has been a focus of the solution. the industry for 30 The first challenge in reaching years. It has been net-zero carbon is to understand reporting D on its efforts since the what puzzle you are trying to Kyoto protocol in 1990 – which solve. Are you looking at carbon is why 1990 is the benchmark at a product level, or carbon at a for the carbon indicators in the building or structure level? They Concrete Industry Sustainable obviously work together, but Construction Strategy. First the levers for change are very ABOVE Team Zopherus’ expandable community of hexagonal pods would be launched in 2008, the strategy different, so they are best explained 3D-printed inside the landing vehicle represents a commitment from separately. Then there is the carbon 10 different sub-sectors to comparison for the first life of a work to an agreed reporting building versus its many potential framework. The latest report, the uses over a whole lifetime, which is 12th, is based on performance covered on pages 3-9. data from 2008 to 2018 and the headline statistic is that Decarbonising cement and the embodied carbon of a concrete standardised mix of concrete is The majority of the embodied now 72kg per tonne, a reduction carbon in concrete comes from of 30% from the 1990 baseline. cement, an ingredient that plays The original strategy set a range an important role in properties of targets for 2012, which were such as fire resistance and subsequently updated with new durability. For over 20 years, ones for 2020. As we reach that the UK cement industry has milestone, the concrete industry been replacing fossil fuels with will set out a revised strategy for renewable, low-carbon sources. beyond 2020, with the aim of Through fuel switching and achieving net-zero carbon. At the use of by-products from The Concrete Centre, we want other industries, carbon dioxide to make the journey as easy as emissions per tonne of cement possible for designers, but – let’s have fallen by 29% since 1990. be honest – it is complex. So the A 2019 study by the University next four pages don’t contain all of Cambridge Institute for the answers, but they do explain Sustainability Leadership (CISL), u ROAD TO NET ZERO 21

INNOVATION IN ACTION “YOU DON’T REALLY THINK ABOUT IT Low-carbon cements BUT EVEN SAND In 2018, the Mineral Products Association (MPA) initiated a IS DIFFERENT ON project to develop new low-carbon multi-component cements for UK concrete applications, forming a partnership with Hanson, MARS. IT’S GOING BRE and Bison Precast with the aim of saving carbon through the TO BE SHARPER” increased and more efficient use of low-carbon cement. Recent TREY LANE, TEAM ZOPHERUS research has shown that materials such as ground granulated blast-furnace slag (GGBS), fly ash, calcined clay and powdered limestone can work together effectively in a multi-component cement. Combinations such as cement-GGBS-limestone, cement- fly ash-limestone and cement-calcined clay-limestone potentially enable greater rates of cement replacement – in current tests, 65% has been achieved. The project is testing the performance of a range of concretes (22 new cements in 50 concrete mixes) and the results will be used to support standardisation of low- carbon multi-component cements in British standard BS 8500. The project is due to be completed in 2021 with the new materials available to the market soon after. The research and demonstration are part-funded by the government under the Department for Business, Energy and Industrial Strategy’s (BEIS) £9.2m Industrial Energy Efficiency Accelerator programme, which is managed by the Carbon Trust assisted by Jacobs. Industrial fuel switching Switching from fossil fuels to hydrogen and plasma energy could also reduce carbon emissions in cement and lime production. In 2019, a BEIS-funded feasibility study found that a combination of 70% biomass, 20% hydrogen and 10% plasma energy could eliminate fossil fuel CO₂ emissions from cement manufacturing. Now BEIS has awarded £6.2m to the MPA to test that theory. The groundbreaking project will involve trials at sites operated by Tarmac and Hanson Cement, one focusing on electrical plasma energy with biomass, the other on hydrogen and biomass.

Carbon capture “Direct separation” is a new type of carbon-capture technology,

in which the pure CO2 released from limestone as it is heated is collected separately from the furnace exhaust gases. In a five-year, EU-funded programme that began in 2016, the LEILAC (Low Emissions Intensity Lime And Cement) project has been testing its application to the cement and lime industries at the HeidelbergCement plant in Lixhe, Belgium. The pilot unit has undergone two years of extensive testing in a standard operational environment, in order to demonstrate that the technology can work at scale across the industry. LEILAC will also deliver a techno-economic roadmap for implementation and share knowledge with industry partners.

LEFT All of the in-situ concrete at Nicholas Hare Architects’ University College London

Student Centre includes 50% GGBS Photo: Alan Williams

concretecentre.com 22 CONCRETE FUTURES

published by Material Economics, Concrete is a local material so the found that it was possible for overall travel distances are small. the cement sector to be net- As the automotive industry deploys zero carbon by 2050, although it low-carbon vehicles, the costs also estimated that zero-carbon and emissions profiles for transport production will cost more than will change. current practice. The next energy use category is The report identifies four routes direct emissions, the energy use for cement and concrete to that is in the control of the cement decarbonise: and concrete manufacturer – l Materials efficiency and circular combustion and process emissions. business models A cement kiln reaches high l Materials recirculation and temperatures, and that requires substitution energy. Here fuel switching is one l New low-emissions processes answer: the industry has already l Carbon capture and storage/use. replaced 34% of its fossil fuel Not all of these activities are use with renewable, low-carbon related to cement and concrete sources, which include biomass production – some fall under the as well as materials from other scope of the designer. industries and processes that could otherwise go to landfill. But to Cement and concrete reach net zero, a zero-carbon fuel production mix is needed, and this will require The simplest place to start is with new technologies. The cement energy use and indirect emissions. sector has recently been awarded As the electricity grid decarbonises, funding by the Department for the energy used to produce Business, Energy and Industrial materials will be less carbon- Strategy to test emerging intensive, reducing the embodied technologies such as hydrogen- carbon of cement and concrete. based fuels (see box, page 21). The decarbonisation of delivery Some emissions are difficult to transport will also have an impact. abate, and this is true of the process

Sustainable concrete: Progress to 2020 targets based on 2018 performance data The graph below summarises the 12th progress report on standard BES 6001, to which 96% of concrete is certiﬁed. The the Concrete Industry Sustainable Construction Strategy. The concrete industry is a net user of waste and by-products from other strategy is underpinned by the international standards ISO 14001 industries, using 271 times more than it produces. The graph is based on environmental management and ISO 9001 for quality and on a 2008 baseline year for all targets, other than carbon targets, performance, and the industry has met its target on both of these, which are based on a 1990 baseline year. For the latest updates on with 100% of sites now certified. It also uses the responsible sourcing the data, visit sustainableconcrete.org.uk

Environmental management systems to ISO 14001 100% Quality management systems to ISO 9001 100% Responsible sourcing to BES 6001 96% CO emissions production (normalised mix) 99% Waste to landll 100% Replacement of fossil fuels 67% Biodiversity 95% Emissions (excluding CO ) 100% ROAD TO NET ZERO 23

technologies. Implementation of these technologies is not all within THROUGH FUEL the control of the industry, though SWITCHING AND we want to collaborate to accelerate THE USE OF progress. One thing that the industry can control is the first principle BY-PRODUCTS FROM of the roadmap: it will not rely OTHER INDUSTRIES, on offsetting. CO2 EMISSIONS PER TONNE OF UK Concrete and carbon in the built environment CEMENT HAVE The other group of enablers that are FALLEN BY 29% vital to achieving net-zero carbon SINCE 1990 concrete and a net-zero carbon built environment are designers and the wider construction industry, l use the thermal mass of concrete through material specification, to save energy design, use and reuse of buildings. l optimise the whole-life carbon The construction industry represents investment of concrete buildings. 7% of the UK’s economy yet 10% We are also working to share

of its CO2 emissions, and it directly lessons learned and new influences 47% of the total when innovations on: the operational emissions from the l reuse and refurbishment of built environment are included. existing structures If buildings were designed to use l new cements less material, be more energy- l carbonation, the process by efficient in use, last longer, be which concrete absorbs carbon more easily repurposed, and then naturally, and new carbon-cured were recycled at end of life, the UK products in which this natural could reduce its carbon emissions process is accelerated. considerably. There are many It should not be forgotten that ways in which this can be tackled this is just part of the story. No using concrete. other product offers so much

ABOVE The LEILAC project has been testing the application of “direct separation” technology to Designers can use concrete in terms of strength, durability, the cement and lime industries at the HeidelbergCement plant in Lixhe, Belgium in myriad ways in the built thermal mass, fire resistance environment, and each application and resilience, all of which will emissions related to the physical cement and lime sectors, there can be specified with a different be essential for adapting to the transformation of limestone to is a live demonstration project balance between performance and climate change that is already Portland cement. One option is in Belgium (see box, page 21). carbon. There are material-efficient unavoidable. The Concrete Centre lower-carbon clinkers – already There are obviously considerable design solutions, there are energy is committed to working with other minerals are added to costs associated with such strategies that can use concrete’s industry, designers, contractors reduce the use of Portland cement transformative technology, and thermal mass, and there are flexible and clients to achieve the best clinker and produce lower-carbon collaborative European projects design choices that enable buildings carbon result now and to support cements. New technologies are also are currently leading the way. The to be used and adapted in many investment in new technologies to in development. UK cement sector is encouraging ways over their lifetime, to make the deliver a carbon-negative future. l Alternative clinkers can help to the government to support similar most of concrete’s durability. More information about the reduce process emissions, but projects for the local manufacture Guidance from The Concrete Concrete Industry Sustainable adoption of carbon capture, use of net-zero carbon cement. Centre is available to enable Construction Strategy is available and storage (CCUS) is needed to The cement and concrete designers to: at sustainableconcrete.org.uk. eliminate them entirely. CCUS industry is developing a l specify low-carbon concrete A range of guidance documents will enable the transition to roadmap to net-zero carbon, l design using material-efficient on low-carbon design published net-zero carbon of not only the which will include the potential design solutions such as post- by The Concrete Centre can be cement and concrete industry, application and associated tensioned concrete, ribbed slabs and downloaded from concretecentre. but the steel industry too. For the costs of a number of enabling offsite construction com/publications Photo: Carbon Trust

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