Rammed Earth Consulting CIC SBE0120
Written evidence from Rammed Earth Consulting CIC
Rammed Earth Consulting CIC (REC) have been working in the field Sustainability in the Built Environment since 1998. REC have a portfolio of built projects ranging from the Eden Project in Cornwall to the WISE Centre at the Centre for Alternative Technology at Machynlleth, Wales. As well as a range of high profile public building projects incorporating earth into high performance buildings REC are involved in research and development, policy writing and publishing and advocacy.
In 2001 REC and partners won a contract from DTI to write Guidelines on Rammed Earth, generally seen as the unofficial UK standard. This has subsequently led to a BREEAM standard and a National Building Specification. REC also co-wrote a Code of Practice for Rammed Earth Construction funded by DfID which REC subsequently published as an African Regional Standard Organisation standard, peer reviewed an ASTM standard on Earth Wall Building Design and co-founded Earth Building UK and Ireland, a national association for all earth building.
REC consult in the UK, in Europe, Africa and the Middle East, focussing on public buildings. Recent projects include mixed use housing and business developments incorporating construction waste and natural materials.
1. To what extent have the Climate Change Committee’s recommendations on decarbonising the structural fabric of new homes been met?
We have a long way to go to meet the targets set which includes the need for:
New build standards: Implement a strong set of standards –with robust enforcement –that ensure buildings are designed for a changing climate and deliver high levels of energy efficiency, alongside low carbon heat1.
We are not aware of any work on such standards in our sector other than that which we have developed ourselves. Until a comprehensive standards program is undertaken then clearly robust enforcement remains a long way off.
1 The Sixth Carbon BudgetBuildings, https://www.theccc.org.uk/wp-content/uploads/2020/12/Sector-summary-Buildings.pdf page 55
2. How can materials be employed to reduce the carbon impact of new buildings, including
efficient heating and cooling, and which materials are most effective at reducing embodied
Insulation and buffering are two key tools to increase efficiency in heating and cooling buildings, this includes buffering of humidity and temperature, two linked issues. Materials commonly manufactured for structures and insulation perform poorly once ‘real world’ issues like humidity are introduced, structures are not vapour permeable and insulation performance falls rapidly where it is. In both instances reliance on active heating and cooling as well as ventilation become inevitable increasing not only the high embodied energy of the materials but also the long term energy running costs of buildings.
Rammed earth by it’s nature is both a load bearing structure and vapour permeable and temperature buffering. Added to this they are safe, do not emit toxic gases when they burn or emit other volatile organic compounds, VOCs, in use. Indeed clay bound structures and finishes have been shown to buffer humidity better than any other plaster or wall type and to sequester VOCs bringing health and well-being into the very fabric of the building, reducing the need for active ventilation, heating and cooling. In addition natural materials are either inherently low carbon in production, often on site or extremely local and or carbon sequestering, around 70% of REC builds use site material, saving on waste from excavation and emissions from imported manufactured products.
3. What role can nature-based materials play in achieving the Government’s net zero ambition?
Rammed earth is a load bearing technology used in the UK for more than 200 years producing buildings up to 5 storeys with materials dug at or close to site. Rammed earth is high in mass meaning that it can both buffer heat and cool and prove a measured structural load.
Clay as a binder lends itself to high mass load bearing structures and low mas thermal insulators and buffers. Materials such as chalk, often seen as unsuitable for use has been shown to be a useful admixture to a range of clay products as well as producing five storey load bearing structures on their own. REC have built two storey public buildings with pure chalk1.
Very low energy to extract and process, very low energy in transportation both make earth local and affordable and in terms of mass materials as low can be found anywhere.
Rammed earth has been used in a number of very low energy buildings as part of their Passivhaus design strategy including local authority classrooms2.
4. What role can the planning system, permitted development and building regulations play in
delivering a sustainable built environment? How can these policies incentivise developers to use low carbon materials and sustainable design?
We have worked hard to deliver a range of codes and guidelines to inform the planners and building control of the properties of rammed earth. We have developed robust systems for testing and compliance of the technology which has allowed a number of public buildings to be built1.
The use of site materials has allowed planning permission to be granted on SSI sites and other ‘hard to reach’ permissions which has incentivised developers to choose rammed earth. This use of local materials and the obligation to use them even on less contentious sites would be a further strong incentive for developers to choose local and low emission materials and technologies.
5. What methods account for embodied carbon in buildings and how can this be consistently
applied across the sector?
While existing British and Euro norms and standards including BS EN 15804:2012, EN 15804, EN 15804, BS EN 15978:2011, EN 15804 are well established, as well as mechanisms such as BREEAM to quantify products and processes. However it is clear that the emissions from materials such as cement and steel are consistently higher in production than a swathe of natural materials and agricultural ‘waste’, sequester no carbon and furthermore cannot fit the description of ‘circular economy’, a target which few commercial standards attempt to measure. In other words although there are a slew of existing standards they are written by and large to measure an existing industry and largely fail to compare the overall properties found in natural fibres and binders.
6. Should the embodied carbon impact of alternative building materials take into account the
carbon cost of manufacture and delivery to site, enabling customers to assess the relative impact of imported versus domestically sourced materials?
Naturally the embodied carbon in all building materials should be measured and added to the calculated emissions from transportation to site where relevant. Where site materials are used the savings should also be added to the carbon budget and the savings noted.
7. How well is green infrastructure being incorporated into building design and developments to achieve climate resilience and other benefits?
The resistance in changing standards, in education, in training, in the development of learning outcomes and curriculum and in the continued shielding of high emitters from paying the true cost of cleaning their pollution the incentives to change are low. Tax the polluters, train the designers and builders of tomorrow and invest in clean manufacturing if you want to increase green infrastructure.
8. How should we take into account the use of materials to minimise carbon footprint, such as use of water harvesting from the roof, grey water circulation, porous surfaces for hardstanding, energy generation systems such as solar panels?
Currently we are working on a dense urban site where the demolished buildings are being crushed at site and combined with clay extracted for the SUDS tanks to produce fire and sound-proof load bearing walls. By re-arranging the elements found on site we are able to ensure the lowest possible material movements, the increase in circular economy use of materials and the savings on high cost, high emission single use masonry. Any further additions of designed elements should build from this foundation and not be simply ‘added on’ to otherwise high emitting, low efficiency, high embodied energy ‘conventional’ buildings.
9. How should re-use and refurbishment of buildings be balanced with new developments?
As shown above we are doing both of these things, re-using demolished materials on site to create new developments. The balance between between re-use, refurbishment and new build should be calculated, measured and controlled against criteria and not simply left to the market.
10. What can the Government do to incentivise more repair, maintenance and retrofit of existing buildings?
Tax polluting industries like cement and steel and require a higher standard of proof for the need to demolish existing buildings in both public and private ownership.
Clay bound materials need skills and knowledge to turn the raw materials into mix and then apply it. Incentivising training, bringing skills and jobs in the sector would certainly be a big help. Finding people with the skills is often a block to their use. Educate students and designers to specify these materials. Many of the materials and processes exist but until they are specified don’t get used. Educate the public on the dangers of insulating materials which harbour moisture and produce moulds, and on insulation materials which burn and produce toxic gases. Build and retrofit government buildings including housing stock with low carbon natural materials, setting a target for both carbon sequestration and emissions reductions.