As the world starts to contemplate what the ‘new normal’ looks like, it is clear, and perhaps more important than ever that the focus on sustainability and durability in construction starts to take centre stage. Welcome initiatives like Architects Declare and the RIBA’s 2030 Climate Challenge shift the footing of the debate from the theoretical to actual targeted delivery and we’re noticing this shift of emphasis in daily conversations.
The context
It is now quite well established that around 40% of the UK’s carbon footprint relates to the built environment and over half of that impact is from the energy used in buildings throughout their lifetime.
Also, research carried out by Constructing Excellence shows that for every £1m spent on construction, £5m is spent on operation and maintenance with energy as the single biggest contributor to ongoing costs.
These simple facts establish a compelling point: The efficiency of the building in operation has the biggest impact in reducing carbon and also reducing cost – see my Scaling PassivHaus article from 2015 for more on that!
But what about materials?
The graphic above from UKGBC research still shows that 55% of the carbon impact of the construction process is related to materials, so of course, it does matter as it equates to 8% of the overall Carbon Emissions in the UK. One of the big issues here is how to define and measure that impact. I’d like to break it down into 3 parts:
- Performance Characteristics: Insulation, Thermal Characteristics, Airtightness – See my article on Energy Efficiency originally written in 2009 for more on that…!
- Embodied Energy/Carbon: The amount of energy/carbon required to produce the material
- Lifetime: The expected lifetime of the product/building.
Having tackled performance in another article, it leaves the last two points to expand on.
Embodied Carbon
Embodied carbon is one of the easiest concepts to understand, although it is far from simple to measure, and because of that it was one of the first to be considered back in the early days of EcoHomes/Code for Sustainable Homes/BREEAM.
Embodied carbon normally encompasses both CO2 and other greenhouse gases, and includes emissions from all the extraction, transport of raw materials and manufacturing processes required before products are ready at the factory for delivery to the customer. Transport can also play a significant role – dried timber from the other side of the world may actually be more carbon intensive than cement from 5 miles away.
Relating this to bricks and ceramics, there is an obvious fact that there is a lot of energy required to fire at 1000+ degrees. Of course this varies hugely depending on the manufacturing process and efficiency. Some of the most modern brick & ceramic manufacturing plants can boast on-site renewable electricity generation and super-efficient kilns and dryers; at the other end of the spectrum it could have a product produced on the other side of the world in an open kiln!
The big point here is that it is fundamentally important to know about the exact product you are specifying. UK & European brick and ceramic producers have invested massively over the last 20 years in the efficiency of their processes both to minimise cost and carbon.
Lifetime
This is where brick and ceramic comes into its own. The oldest surviving buildings in the world are predominantly made using brick, ceramics and stone. It is relatively easy to prove a lifetime of 150 years with a masonry built building and much more difficult to do so with lightweight construction.
The beauty of the natural material also ages well. This image is one of my favourite demonstrations of this. The ancient city of Babylon, mentioned in the Old Testament, features glazed bricks which still bear the name of the ruler, Nebuchadnezzar, and are still bright in colour after more than 2500 years! Buildings with a brick or ceramic exterior, if detailed well, will remain looking beautiful for years to come with minimal maintenance.
Finally, when the building reaches the end of its life, brick and ceramic are both recyclable – either by reclamation and re-use; or by breaking up into an inert material which can be used again. It is also possible, with clay blocks like Porotherm and careful selection of finishes, to build buildings that have a natural, breathable external skin which creates a healthy living environment for the occupants.
For a building to be truly sustainable it must perform well in use, manage the carbon intensity of the construction process and be durable. The need to meet the challenge is now and maybe will characterise the ‘new normal’ we all crave.
About the Author:
John Cave has been involved in Sustainable construction for over 15 years including: Acting as a Government advisor for the Dept of Energy and Climate Change, Board Director of the British Photovoltaic Association, Non-Executive Director of the Midlands Environmental Business Council and EH Smith are 5 times winner of the Sustainability Award at the Annual Builders’ Merchants Awards.
