Dr Asif Din                            SBE0041

Written evidence from Dr Asif Din

 

CCC recommendations on decarbonising the structural fabric of new homes

The use of low embodied carbon materials needs to be placed in policy. The CCC have recommended the use of whole life carbon evaluations within the built environment and this has been reflected in government procurement but not to the wider market. These procurement rules need further definition to include targets rather than the process taking place with no end goal.

Current policies relate to operational carbon which has made an imbalance that needs addressing. with the reduction of operational carbon, the impact of embodied carbon has increased in significance and needs to be addressed.

The use of low embodied materials has been hampered by insurance and regulations particularly to fire. This has been clearly shown in the loss of momentum of the use of timber in buildings whilst other countries (US, Canada) have clear policies regarding fire issues particularly for higher buildings and apartments.

ONS data does not help in forming these arguments due to a lack of data regarding items such as timber construction which need to be revaluated. By this method a clear evaluation can be made of the impact of decarbonization within the construction sector.

Materials employed to reduce the carbon impact of new buildings

Materials impact on operational carbon to minimise heating and cooling. This is mainly in the form of insulation materials a particular emphasis should be placed on natural materials and those of low human impacts.

The evaluation of materials in terms of carbon. This is needs to be evaluated as part of a whole life cycle impact assessment to show how a systematic approach is taken to reduce the carbon impact. Particular importance needs to be placed on ‘cradle to gate’ impacts, the so called Carbon Burp within buildings, as most of the carbon impact is within the materials (CIBSE TM65) rather than the material processes. The sooner this carbon is mitigated the greater impact this has on new building impact of the immediate climate change crisis.

The evaluation should be at the earliest stage possible to have the greatest influence (the MacLeamy curve) with further evaluations taken at subsequent design stages to reduce the risk of specification creep. This would be mitigated by a target system to give the industry realistic carbon value for all building typologies.

Construction items such as foundations should have clear and viable low carbon alternatives. This could be done through the decarbonistaion of sectors such as concrete/ steel or materials added to these carbon hungry components such as 100% cement free concrete to reduce their impact within the construction industry.

Thinking in the long term materials as a minimum should be 100% recyclable to make sure materials can be used again and again. This feeds into the circular economy in increasing recycled content and durability to retain the value of materials.

Materials that sequester carbon should be incentivized as this reduces impact in both the short and the long term. Again, this should be done through clear regulations and guidance of when items such as timber are being used.

 

Nature-based materials for a net zero ambition

Nature-based materials tend to be more homogeneous in composition as a result requiring less energy to process and more compatible with circular economy processes. Many nature based materials lock up sequestered carbon, as CCC has indicated in new home construction out of timber both increasing growth in UK forests as well as providing building materials.

The CCC has reported this requires effort in forestry management. This can be further complimented by a range of crops the byproducts of which can be used in the construction industry. This includes straw, wood fibre, cork, hemp and sheep’s wool which can be used for insulation as well as other products such as cladding (Marget Farm) reducing reliance on traditional high carbon components.

 

The planning system, PDR and building regulations in delivering a sustainable built environment

For these elements to play a role the embodied carbon of projects requires assessment and has to be addressed in policy. The CCC (2019) has investigated mechanisms in which policy could act including monitoring and reporting, set limits and regulatory targets. The declaration of all products was recommended by Green construction board (2013) and would be a requirement of the CCC findings for mandatory reporting but not acted upon.

Although RICS have a database on carbon assessments this needs to be enlarged for any policy to be implemented and to be freely available through anonymisation. This would allow the checking of benchmarks and targets within a refined methodology allowing focused training (e.g. Finnish regulations).

 

Accounting for embodied carbon consistently in buildings

BS EN 15804:2012 provides the consistency of data for the carbon impact at product level, and is the basis of manufacturers providing Environmental Product Declarations (EPD).

The building level assessment standard, BS EN 15978:2011, provides the framework of life cycle carbon measurement with the RICS Professional Statement on Whole Life Carbon provides guidance on how to assess embodied carbon in the UK context according to BS 15978. Other organisations such as BRE have their own methodologies

There are tools available to assess the carbon impact buildings but there is no standard industry tool for the UK. The variation between tools can be large (due to methodologies, data inputs amongst other factors) and a greater consistency is required for results to be meaningful. In the Netherlands, France, Switzerland and Sweden where there is regulation at building level a national methodology (similar to other national methodology such as SAP in the UK) is provided in line with EN 15978.

 

Embodied carbon impact of building materials accounting for the carbon cost of manufacture and delivery to site

The impacts of manufacture and delivery to site are geographically based and should be assessed for all building materials in line with current BS EN standards. Previous studies have shown that manufacturing inputs have a larger impact than transportation, but both should be assessed. A good example why both require assessment are the exceptions like steel transported by ship which will have a lower impact from an EAF process then UK manufactured steel.

Although imported goods are not part of our national carbon budget (Kyoto protocol) UK produced materials will have a lower carbon content overall especially for heavy items such as brick and should be properly assessed as a true value including carbon at all manufacturing and transportation stages internationally

 

Green infrastructure incorporation into building design

Green infrastructure is not fully considered within individual building design. More up front guidance and relationships need to be established. Some examples include battery technology used instead of strain put on the national grid, green/blue roofs to alleviate pressure on drainage systems. Now items such as green roofs are within planning policy (LB Islington) but is not communicated well on infrastructure impacts. This is not only restricted to the building features but also to material specification which reduces health impacts for building users and indirectly the NHS.

 

Materials use to minimise carbon footprint- water and energy generation systems

There is currently a lack of information on the impacts of water and energy systems. Water traditionally has a low environmental impact a greater incentivization of the reuse of water is required rather than just through building certification systems such as BREEAM. I am unaware studies in the area of water and is more about material and ecological flows rather than carbon.

Energy league tables should be put in place not only on a carbon basis but also for the health of materials and social impact to the supply chain. Most UK energy generation systems are imported and again a proper account of the carbon input of the products should be assessed and measured against other benefits such as distributed generation and resilience of infrastructure systems.

 

Re-use and refurbishment of buildings evaluation against new developments

The re-use and refurbishment of buildings has to be seen as a major tool to reduce the embodied carbon in the built environment. There should be a policy based on proving buildings are unable to be fit for purpose before demolition takes place. To meet current LETI and RIBA carbon targets reuse and refurbishment is the only realistic method to currently achieve the values given.

Buildings are generally over engineered and demolished a good number of years before the end of useful life. An understanding of the material commitment in a building needs to be a requirement and is shown in GLA circular economy statement but needs a wider application across all projects.

The cost implications for a refurb is investigation costs and the method the construction industry in which there is a preference of processes for new build. This needs to be resolved by two main aspects that of a register of building information to reduce investigation time and to incentivize the reduction of carbon in buildings through a whole life carbon analysis. This needs a reduction of hurdles and resistance to reuse and retrofits against business as usual across the whole supply chain from owners, agents and management companies.

 

Incentivisation of prolonged use of existing buildings

The main inventive that would make a difference is financial. There have been many calls to change VAT rates on repair and retrofit and should be incentivized against a new development. Through the measurement of carbon and reduction in offset tariffs could further incentivize retrofit. Planning policy could also be modified for the relaxation of external appearances for the fitting of insulation and the addition of stories compared to new build blocks.

A recommended pallet of materials should be available to ensure retrofit meets the three main drivers of reducing carbon in terms of material transparency, circular economy and durability. There is a clear link between robustness and reduction of carbon over the whole life cycle from Danish studies particularly when components are designed for disassembly. The use of natural materials has an inherent breathable quality that can specifically help in retrofitting older buildings without causing moisture issues. These could have a considerable impact in the reduction of the carbon impact of the construction sector within the UK.

 

May 2021