Concrete Block Association                            SBE0017

Written evidence from the Concrete Block Association

 

The Concrete Block Association Is the trade association for the UK  producers of aggregate concrete blocks and their suppliers.

We are responding to the enquiry as we feel some of the questions raised intimate a lack of awareness of the work that has been going on and the standards established in respect of sustainability in construction and the sustainability credentials of concrete masonry.

 

The Climate Change Committees recommendations seem to be centred on the misconception that the use of timber is the panacea for decarbonising the fabric of new homes. This is only true if looking selectively at part of the life cycle of timber products. The whole life cycle needs to be taken into account, including transport from source, in accordance with a recognised standard. At end of life sequestered carbon is released from timber but not from concrete which can continue to carbonate at end of life .Timber products such as CLT and Glulam are not recyclable and the only option at end of life is incineration with the consequent release of sequestered CO2. We believe that, in the report commissioned from the Bio-Composites Centre of Bangor University, the carbon footprint of concrete was overstated at the same time as that for timber was understated

This is the wrong question. One needs to make a whole building assessment rather than trying to identify specific products in this way. The methodology for making such assessments at building level exists in standards such as EN 15978 Sustainability of construction works - Assessment of environmental performance of buildings - Calculation method,. This allows a scientific whole building approach to be taken covering the combination of products used in a building.

A building constructed with masonry has a design life far in excess of the 50 years for one constructed of timber. The Environmental Product Declaration for our concrete blocks has a reference service life of 150 years.

Again this is the wrong question. All materials are nature-based to a greater or lesser extent. It is wrong to blithely assume that so-called nature-based, by which we assume timber-based products are meant, have net zero benefits. Such nature-based materials need to be transported significant distances between source and site. This adds significantly to their carbon footprint. A Danish report based on the analysis of 60 buildings found that the choice of materials made little difference to either embodied or operational carbon. This enquiry should follow the science.

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?

RIBA and LETI have targets which seem workable so no other system should be proposed or encouraged as this would add confusion to the marketplace.

Applying the standard EN 15978 Sustainability of construction works - Assessment of environmental performance of buildings - Calculation method, allows a full assessment of the environmental impact of a building design to be made based on scientific principles.

Taking emissions at end of life and transport distances into account, the much-talked about green credentials of timber are put into perspective. The RICS Professional Statement on Carbon could be taken into  account although the study needs to be updated to use more realistic wastage rates and to use up to date EPDs for concrete blocks.

Of course. The definition of embodied carbon in the process of being adopted by ISO is:total of all greenhouse gases emitted in the processes associated with the production, transportation to site, installation, use and disposal at end of life of materials and products’.

Thus, there is a need to take into account all emissions involved in the production and the transport of a resource/material from its source to the factory, through the manufacturing process, delivery to site, installation, during use and then disposal and emissions at end of life.

The carbon cost of every stage in the ISO definition needs to be taken into account otherwise a skewed assessment will result. We already see the need for this with the flawed thinking behind the importation of wood pellets from North America as a fuel for Drax power station.

If recognised methods of assessing sustainability such as EN 15978 and BREEAM are used then this is already being done. These are both established methods. BREEAM was developed by The Building Research Establishment (BRE) in 1990 and is used internationally.

 

May 2021