Carbon Counts
Carbon Counts
In Brief

In a 60 year cycle, a building’s carbon impact is made up of three parts: recurring embodied carbon, operational emissions and initial embodied carbon. Proportions vary, but the construction impacts of material choices do not.

FCBStudios’ response to the Architects Declare manifesto advocates an accelerated shift to low embodied carbon. 

The embodied carbon of a building is made up of the impacts from the extraction, processing, manufacture and packaging of the materials we use; the carbon emissions resulting from their transport and construction on site, maintenance over their lifespan and what happens after the building is demolished.

We have committed to interrogate the material choices in all our work. Here, we draw together key metrics for ten of the most common materials used in architecture today:  brick, aluminium, steel, copper, limestone, concrete, CLT, glass, PVC and bamboo.

By understanding the embodied and emitted carbon in the construction and life cycle of our designs, we will be able to make better informed choices to improve the impact of our work on the environment.

There will be difficult decisions to make; balancing longevity vs. embodied carbon/style vs. substance/perceptions vs. experience/tried and tested vs. new technologies. In doing so, we can continue to create spaces which are engaging, are sensitive to their external environments and which touch the planet lightly. By choosing the right materials we can emit less CO2 to reduce the impact of our work on the planet.

Our materials research is presented in the exhibition: Carbon Counts in our London gallery space between December 2019 and March 2020. 

1kg of CO2

It starts with the materials we use and how we use them...so we can emit less carbon.

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Aluminium

Carbon impact per m3 material
25,650 kgCO2e

Global production (2018) 
Primary Aluminium: 64 Mt

Associated emissions
1 % of direct global CO2 emissions

UK production
42000 t

Forecasted consumption
Quadruples by 2050

Bauxite is dug from the ground and purified into alumina, which is delivered to a processing plant where the alumina is dissolved in a bath of molten cryolite and aluminium is extracted via energy-intensive electrolysis. Carbon dioxide is released as a direct product of this reaction. Aluminium scrap can be included in the melt to recycle it. The resulting aluminium is cast into ingots, extruded or rolled, and delivered to manufacturers for fabrication into components.

The average global recycling rate is 63%: in the UK it is around 40%. Overseas emissions from UK aluminium demand are 3x higher than those from domestic aluminium production. The carbon intensity of aluminium is very dependent on the carbonisation of the electricity grid in its country of origin.

Environmental impacts

Anti-corrosion metals like aluminium have a high embodied carbon per kilogram but corrosion resistance means that carbon-intensive coatings (such as paint) may be avoided throughout the life of the product. Metals have a long lifetime, are durable and can easily be recovered for recycling.

We can reduce demand by considering alternative or hybrid products. Hybrid products are available – such as aluminium covered timber-framed windows, that provide some of the embodied carbon benefits of timber with some of the durability and low-maintenance characteristics of some metals. 

FCBStudios examples: St Mary Magdelene Academy, cast aluminium cladding panels at the University of Roehampton Library and Murrays' Mills.

Bamboo
The sequestration rate of bamboo is about 15.4 tons of carbon per hectare per year. This value includes carbon sequestered in long-lived bamboo products from harvested bamboo. The productive lifespan of a bamboo planting is 75-100 years.
Bamboo

Carbon impact per m3 material
230 kgCO2e

Global production 
It is estimated 31.3 million hectares of land is used for growing bamboo

Net imports
The EU is the largest global importer of  bamboo products 

Forecasted consumption
The total additional area determined suitable for bamboo is 122 million hectares, made up of degraded forest and grassland in humid climates, 4x the current output area.

For bamboo production, shoots or culms grown from resprouting underground rhizomes are typically harvested after 5 - 7 years. They are transported to processing where they are treated to protect against infestation and mould and seasoned. Depending on their end use: they may be left in their natural, whole culm form; split into sheets; pressed and glued into engineered sections; or even chemically reduced to their constituent fibres for conversion into strong fabrics.

Bamboo has the compressive strength of concrete and the tensile strength of steel. It reaches its full height in one growing season, at which time it can be harvested for pulp or allowed to grow to maturity over 4-6 more years. After being cut, bamboo re-sprouts and grows again.

Environmental impacts

Transport carbon can have large impacts where bamboo is specified at a distance from where it is grown. 

Bamboo could be used for structural members but transport-related emissions may increase embodied carbon.

Advanced curing treatments/surface treatments are required to protect against the primary longevity issues of whole culm bamboo: rot, infestation and UV degradation.

FCBStudios examples: Whole culm bamboo was used for structural frames in a stage and outdoor learning area for St George's Orphanage in Chennai. Processed bamboo is available for flooring, panelling, furniture, and matting: for example the entrance doormats to our London studio.

Brick
Bricks can have a thousand-year design life. Detailing should consider their later reclamation, and to ensure their longevity and easy reclamation lime mortar should be used.
Brick

Carbon impact per m3 material
320 kgCO2e

Global production 
1500 billion bricks

Associated emissions
< 1 % of direct global CO2 emissions

UK production
1.8 - 2 billion bricks

Net imports
0.3 billion in 2017

Forecasted consumption
Doubles by 2060

Bricks are made from clay and sand dug from the ground, crushed, mixed with water and squeezed into shape. They are air-dried and then vitrified in a kiln at around 1000 degrees celsius.

The majority of bricks are from Asia, where production is entirely unautomated and kilns burn dirty coal or biomass. Brick production in this part of the world causes aggressive deforestation and high levels of air pollution.

Environmental impacts

We can reduce demand by considering alternative load-bearing and cladding materials, and detail to maximise load-bearing capacity and/or visual impact of material used.

Alternatives include recycled bricks or those which use less energy-intensive firing: rammed earth, hemp-based products, geo-polymer stabilised soil or even unfired bricks.

To reduce transport it is possible to source locally, detail to reduce waste, reduce damage in construction and to use all bricks delivered. 

Bricks can have a thousand-year design life. Detailing should consider their later reclamation, and to ensure their longevity and easy reclamation lime mortar should be used.   

FCBStudios examples: Croft GardensUniversity of Roehampton LibraryKellogg College HubMurrays' MillsDrapers' Academy, and Mzuzu University Medical Centre.

Concrete

Carbon impact per m3 material
550 kgCO2e

Global production of cement (2018)
4100 Mt

Associated emissions
6-8% of direct global CO2 emissions

UK production (2017)
9.4 Mt

Net imports (2012)
1.4Mt

Forecasted consumption
Doubles by 2060

Limestone is dug from the quarry and crushed and ground to a fine powder, before being heated to 1450 degrees Celsius to make clinker, which is then cooled and ground to cement. Cement is mixed in various proportions with water and aggregate from a variety of possible sources, depending on the desired concrete properties. It is then poured into shaped containers, with or without reinforcement, and cured.

The UK cement industry produces about 90% of total consumption in the UK. To decrease the construction industry's reliance on concrete, alternative low carbon materials can be used, such as timber, low carbon concrete, stone or other materials useful in compression.

Environmental impacts

During design, it may be possible to reduce spans, design to suit structural loads on every member, avoid over design, use void formers to reduce weight and use arch and vault forms to reduce reinforcement, but factors of regulation and safety and code compliance issues may be leading to over design.

Where concrete is to be specified, it should be sourced locally, rather than imported, to reduce emissions from transport and waste reduced on-site. Cement replacement materials can be used alongside recycled steel reinforcement and aggregates.

At the end of its life, concrete is difficult to upcycle. 

FCBStudios examples: Precast concrete radiators are fixed to CLT at Woodland Trust Headquarters, the concrete structure of Southbank Centre has been renovated;  use of timber structure above a concrete structure at Washington Student Housing; exposed precast concrete at University of Roehampton Library, heavy concrete floors needed for best performance in complex acoustic separation structures: Royal Birmingham Conservatoire.

Copper

Carbon impact per m3 material
24,230 kgCO2e

Global production (2018)
21 Mt

Associated emissions
The proportion of embodied emissions of transport to Europe for virgin copper will be large

Copper ore is dug from the ground with a copper content of between 0.5 - 2.0%. This ore is heavily processed at high temperatures to remove imperfections and by-products such as iron, silver, lead and gold. Eventually, we arrive at blister copper, a 97 - 99% pure form of copper, which is then electrolyzed to produce market grade pure copper.

The vast majority of virgin copper is from South America or China. Chile has by far the largest global reserves. Transport of virgin copper makes up for a large proportion of its embodied carbon. 

Environmental impacts

Copper's largest use is in construction, which is dominated by building for residential purposes. Construction of an average modern house requires at least 200kg of copper metal.

Plastic or plastic coated aluminium is suggested as an alternative to copper water pipes and plumbing fixtures. Where copper is required, specifying recycled copper is likely to result in lower embodied transport (for that life cycle).

80% of all the copper that has ever been mined is still in use today, and it can be endlessly recycled without degradation of useful properties. Recycled copper requires 1/6th the energy to produce as virgin material. Over half of the copper used in the EU is recycled and retains a high value (95% of virgin material).

Copper with high recycled content could be an appropriate cladding material on a long-life building, detailed to allow for eventual recycling.

FCBStudios examples: The Hive and South Quay, Hayle.

 

CLT
Through innovative parametric modelling, we were able to remove 250 tonnes of steel in the roof by replacing it with cross-laminated timber. This saved 2,000 tonnes of CO2 compared with a concrete or steel alternative.
The Hive
Cross Laminated Timber

Carbon impact per m3 material
-600 kgCO2e

Global production 
European production volume estimated to be around 610,000m3 in 2015

Associated emissions
Carbon sequestering during the life of the tree makes CLT carbon positive

Cross Laminated Timber (CLT) can be made from a variety of species of tree. Most are grown for around 40 years in a managed forest before being harvested and transported to a timber mill and cut into boards, which are dried in a kiln and graded for strength. Boards are pressed together with adhesive and then cut to size.

CLT offers high strength and structural simplicity, as well as significantly smaller embodied carbon than concrete or steel. Other benefits include quicker installation, reduced waste, improved thermal performance and design versatility.

Environmental impacts

Demand may start to outstrip supply, even with huge increases in production in Northern Europe. Currently, the restricted number of manufacturers can result in high transport impacts.

However, demand could be frustrated by regulations, fire and acoustic performance issues and further research is needed to establish sole CLT use in buildings above eight floors. 

There is good potential for off-site manufacture and waste reduction. Timber and adhesive specifications alter embodied carbon impact.

Exposing CLT internally can reduce internal finishes costs and maintenance. Contribution to external thermal performance and airtightness can help reduce operational energy use.

FCBStudios examples: Woodland Trust Headquarters, the Dyson Centre for Neonatal CareCroft Gardens, King's College Cambridge and William Perkin High School.

Glass

Carbon impact per m3 material
3590 kgCO2e

Global production 
Flat glass accounts for only 16% of the global glass manufacture.
6% glass fibre, 45% containers and 33% speciality.
Western Europe produces 9% of global flat glass, Asia over 66% 

UK production
The UK glass industry produces around 4 million tonnes of glass per year.

To make glass, sand, limestone and dolomite are dug from the ground and transported to a kiln where they are melted at 1500 degrees Celsius. The molten glass is either floated to produce flat sheet glass or blown to shape, before being cut to its final size.

Architectural glass, glass fibre insulation, optical fibres, blown light fittings  all contribute to glass consumption.

Environmental impacts

We should reconsider the glass-façade office typology and the use of floor to ceiling windows - are we using the properties of glass efficiently (introducing light and views where they are appreciated)?  The embodied carbon impacts of smart glass technologies to allow better control of daylight, overheating and heat loss in the future will need to be judged against operational carbon saving.

Some coatings and finishes being added to glass façade products make them difficult to recycle or make them suitable only for downcycling: is their operational benefit offset by their end of life emissions? Are current building standards requiring the use of these products?  Is it possible to specify wool or cellulose fibre insulation rather then glass fibre? 

Glass should be sourced locally to reduce transport emissions.

The lifetime of glass-based components can be dominated by less durable elements, such as polymer seals on double and triple glazing units. Many glass products are entirely recyclable, including window frames. Is it possible to set up reclamation contracts with suppliers at the construction stage? Incentives and frameworks to properly reclaim and process architectural glass could be used to improve recycling rates. In the EU, proper recycling of building glass waste could avoid 925,000 tons of landfill and save 1.23 million tonnes of raw materials annually. Re-melting waste glass uses 25% less energy than making glass from raw materials.

FCBStudios examples: Rooflights at Hayward Gallery and glass cladding at Manchester Metropolitan University Business School

Limestone

Carbon impact per m3 material
250 kgCO2e

Global production 
The total market for natural stone for building is of the order of 1 million tonnes a year (including sandstone, slate etc) which is in sharp contrast to the 220 million tonnes of natural aggregates used each year.

UK production
Of the limestone produced in the UK, around 80% is used in construction

Net imports
The UK is a net exporter of limestone

Limestone is cut from the ground and graded, and then cut to shape or ground to varying fineness depending on its end use - of which there are many, from building stones to whitening agents.

Environmental impacts

The benefits of the use of heavy stone are reduced if transport emissions are high - local sources should be prioritised, movement by ship has the lowest impact. 

The embodied carbon content of limestone per kg is of comparable magnitude to unreinforced concrete, but it is far stronger, and far less of it is used.

Stones need to be chosen carefully, and installed correctly to weather without damage. Construction grade stone can be reused. Poor quality stone can be transformed into aggregate or processed into further products. 

FCBStudios examples: Local limestone (from the Forest of Dean) was used at The Hive for cladding and paving. Limestone has been specified for cladding at Trinity E3, Dublin. 

PVC

Carbon impact per m3 material
4790 kgCO2e

Polyvinyl-chloride (PVC) is made from crude oil and salt extracted from the ground. Oil is distilled to naphtha, which is then cracked to ethylene. Salt is ground to industrialised salt and then electrolyzed to chlorine. These reactants are combined to produce a monomer which is then heated to form a slurry and polymerised. The resulting PVC is spun into a powder and then transported to manufacturing facilities where it is melted and extruded or moulded into products.

Production of uPVC is associated with the release of organochlorides and, in particular, dioxins with associated health risks and accumulation in ecosystems. 

Environmental impacts

Demand for use in windows and doors should be reduced as these products come from oil. However, recent façade fires in the UK are making specifiers nervous over the use of flammable materials in building elevations. 

For windows, timber with water-based natural stains, and timber/aluminium composite windows offer lower carbon solutions and better performance over time than uPVC.  Polyethylene, PEX, or other non-chlorinated plastic products offer better environmental impact than PVC.

As a lightweight material transport of PVC is often lower impact than substitute materials. 

Because uPVC degrades over time and because there are so many different formulations in use, the material is not easily recyclable. In the UK only 10% of recycled content is allowed in new uPVC. This means that the bulk of the uPVC now being used will have to be treated as waste at the end of its life, and this presents difficulties in relation to the final disposal.

FCBStudios examples: Contractors selected PVC windows for University of Washington Student Housing

Steel

Carbon impact per m3 material
12,170kg CO2e

Global production (2018)
1809 Mt

Associated emissions
7-9% of direct global CO2 emissions

UK production (2018)
7.7 Mt

Net imports (2017)
3.1Mt

Forecasted consumption
Doubles by 2060

Iron ore is dug from the ground and heated to high temperatures with coke (itself produced from the kiln treatment of coal) to produce brittle, high-carbon pig iron. This pig iron is smelted with other alloying elements, mixed with a proportion of scrap, and treated with oxygen to reduce carbon content and produce varying properties. Once impurities have been separated off, the resulting steel is cast into ingots, extruded or rolled, and delivered to manufacturers for fabrication into components.

Environmental impacts

To reduce our demand for structural steel we can: explore alternative materials where steel is not required, reduce spans, design to suit structural loads on every member, avoid over design and challenge design load assumptions. Factors of safety and code compliance issues may be leading to over design. 

Timber, low carbon concrete, or stone and other materials useful in compression can be used as alternatives.

Stainless steel and corten steel may have a high embodied carbon per kilogram but corrosion resistance means that carbon-intensive coatings (such as paint) can be avoided throughout the life of the product, giving a long lifetime, and greater potential for recovery for recycling.  Future reuse can be encouraged by labelling and designing for deconstruction (particularly at connections). Recycled steel with some impurities can be used in construction: from scrap steel through electric arc furnace/process can reduce C02 emissions to 33% of new steel. 

FCBStudios examples: Broadcasting PlaceRoyal Birmingham Conservatoire, Kellogg College HubMurrays' Mills,

It starts with the materials

We can make different choices.

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Carbon Counts

With Carbon Counts, we are aiming to spark a conversation around the nature of materials, with this exhibition providing a framework to debate the good, bad, and ugly side of materials.

The exhibition itself has been designed to have a low environmental impact, while ensuring strong visual presence and longevity. Each material used represents what we feel is the best balance, with a particular focus on how we can use each most efficiently.

 

 

 

 

For this exhibition we have focused on carbon, as the most immediate consideration affecting climate change, but pollution, water use, biodegradation of extraction sites, and working conditions all have impacts.
Valchromat

The totems are made from Valchromat, an MDF board made from waste woodchips and poorer quality timber from sustainable sources (FSC or PEFC) providing value to what would otherwise be a waste stream.

By using organic dye throughout the material, we avoided using any finishes that would increase the environmental impact of the exhibition. This also increases the longevity of the product, with scuffs simply buffed out rather than requiring touching-up.

Each totem face has been sized to match standard sheet sizes of Valchromat, with the only wastage arising from the cutting lines and the cut out circles (which are to be reused as plinths).

After the exhibition, the totems can be unscrewed to be upcycled into models, cupboards, and potentially even benches.

Perspex

To achieve the light-edge effect on the circle cut out hoops we chose to use Perspex, a product made from crude oil. This was a tough decision, so we have worked to reduce the impact as far as possible while maintaining the visual performance.  

The light refracting properties of the material allowed us to achieve the desired visual effect using very low energy LED light sources for the exhibit.

Each letter of the text on the totems is made up from separate short cut parts to reduce the amount of wastage, saving over 2.5 m2, a total of 64%, compared to using full letters.

Each hoop is left loose in position, allowing them to be recycled as part of our next exhibition, increasing their value beyond just this display. At the end of their life, the Perspex will be recycled through the original supplier who will be able to make new raw material for others to use.