'Jonathan Ritson is a freelance sustainability consultant, please contact him for advice or help on green projects'
When you’re considering an eco-renovation there are some pretty clear criteria for what improvements to make and what technologies to use; how much energy will it save, will your bills be reduced, what is the payback time. And these are all valid questions; however what if you have, say, an option between insulation produced in the UK or some slightly better insulation that’s getting shipped over from China?.
At this point a lot of uncertainties come into play- what materials are being used and how are they sourced? What manufacturing processes were employed? Is the anthracite powered freighter going to destroy the environmental credentials of your new insulation?
These are the questions that Embodied Carbon (EC) aims to answer. It can be defined as the amount of carbon (or energy) that is used to in the creation of a product or service including extraction of raw materials, processing, transportation and disposal. This is quantified through a Life Cycle Assessment (LCA) where someone has the laborious task of finding out exactly where those materials are coming from, how much energy is used in to turn them into the finished product and counts up the air miles taken to get them over here.
Once you start to take these things into account life gets a bit more complicated.
The desk I’m writing at, for example.
It started life as a tree in a UK forest. During this time it absorbed a considerable amount of CO2 until someone came along with a chainsaw and hacked it down. It was then taken, probably by road, to a sawmill where it was processed into planks. Then a trip by lorry where it took shape and became a desk, another jaunt on the motorway to the retailer before finally being bought and taken to my house.
Sound easy to quantify? Well take a step back and it gets even more tricky.
Those screws holding it together, where did the steel come from- China? India? Australia? What about the paint? Where did the chemicals and processing occur to make some white gloss? And who exactly made the chainsaw that chopped the thing down in the first place?
Thankfully an entire industry has sprung up around answering these questions for us so now freely published data is available on most common types of building material (checkout the ICE database put together by the University of Bath). These sorts of tools allow people in the industry to asses which building material will give the lowest EC and so tinker with the overall carbon budget of a project by removing the most polluting materials
Applying these ideas to your own projects can be a little daunting considering the work involved and that the results are hard to visualise in any real sense. For the most part though, no one is going to expect you to perform a full LCA for a renovation- in this case common sense will normally prevail. Using local and sustainably sourced materials will ensure a low EC without having to do all the sums; try to find local suppliers and materials that have been accredited, such as FSC certified wood, or that have a significant proportion of recycled materials in them. Asking your suppliers if they know the EC of their materials will also help- there is a growing pressure to include this information with building products and by asking regularly you’re helping to bring about change in the industry.
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