Do you think you've offset the 50 tonnes of CO2 used to build the house yet? (
https://citu.co.uk/citu-live/what-is-the-carbon-footprint-of-a-house)
Hmm. several thoughts on this; not sure I'm awake enough to post them in a considered manner.
- Elephant in the room is - how does 50t of CO2 compare with av UK adult yearly footprint.
- Second is, how does that compare with what thr av uk adult can save without noticing **
- 3rd, is a comparison with the numbers I work with on projects - which is the bit I'd have to go away and look-up. It is a balance issue - for example, using a PVC roof membrane with a 40yr warranty is an outstanding choice for certain large projects, in terms of embodied energy, embodied carbon, total reliability and actually - min energy input to achieve those things. Since it is made from the scrapings of the bottom of the oil barrel, and salt - that to me is total win over 'oh - but pvc?!'. Those scrapings were getting burnt in ships otherwise - and at end of life that roof membrane can be recycled.
Now then:
Certainly on one job I completed 4yrs ago, we managed to save 45t of CO2 (just from the choice of
facing brick - from clay to concrete (!) (- and it
had to be a masonry construction for...other reasons (on 3300sq.m /3sto 'office'
(cough) building you cannot visit)
As an architect in a practice with Sustainability we hold a key concern for - this stuff is right at the forefront of what me, my colleague, consider. Small changes have to balanced over expected lifetime and other costs- and it remains a very interesting, and ever -shifting calculus!
For example: we'd love to do more med/large scale in timber frame, of course we would - but if the client's Insurers (and that's ALL of them post- Grenfell, pre- Grenfell Inquiry resolution) won't insure it, or demand a premium (oh yeah) - then the Lifecycle Cap-Ex & energy saving gets dwarfed by the annual Ins premium - e
ven if in Carbon/total lifecycle on energy terms it would be a better solution.
tl;dr: Approaching zero-carbon is a multi-dimensional problem. We've several such jobs in process to get to grips with, too.
footnotes:
**eta: since the UK electrical Grid has actually de-carbonised so fast - this is harder than it used to be.
10yrs ago I did a large civic facility, and the consideration for electrical consumption modelling was 450g CO2/KwH; owing to the mix of fuels used in the UK electrical grid then.***
Today, ten years later, that UK electrical average is close to 150 g CO2/KWh; simply owing to the loss of coal-fired input, and the massive rise in Wind & PV to the grid displacing even 'clean' gas.
It makes a unit of electricity at the point of consumption, much-lower -carbon, than burning a unit of gas locally at 100% efficiency for the same total useful, local output. And 2-3x better than the same unit of fossil fuel in a modern petrol/diesel car, quite apart from the fact electric cars are
already 2-3x more efficient/KM in input energy use for distance travelled than a petrol/diesel car. Think about that for a bit.
This decarbonisation of the UK Grid is an
immense change; and lies behind the recent push to electrical-everything - from VRF heatpump systems, at every scale, to electric vehicles. It dwarves lifetime materials choice, for many building types.
HTH.
*** That facility it still beat the NHS 'best-practise' benchmark for energy use in class by 30%, which I remain proud of.