Sounds crazy but it’s true.
Here’s a graph I put together showing the number of houses of various ages up to 2050. It clearly shows that, using current demolition rates, the vast majority of the homes in use in 2050 have already been built. Details on how I put the graph together can be found in a previous post.
Something interesting happens if you take that same graph but look at it in terms of carbon emissions: the disproportional effect of existing stock becomes even more pronounced. The graph below shows that nearly 100% of the emissions from the domestic sector in 2050 come from stock that already exists today.
Furthermore, it shows that if you want to achieve an 80% reduction in emissions from this sector, you have to turn every house built after 1917 into a zero carbon home. How’s that for a titanic challenge? But it’s exactly this challenge that we’re now legally committed to tackling.
So it doesn’t actually matter if your planners are asking for Code 3 or Code 4. It doesn’t matter whether the Merton rule is currently 10% or 20%. All new schemes will all have to be made zero carbon in the next 40 years. And the same goes for just about every other house you see as well.
carbon limited 
Great post. Concisely illustrates the challenges we face.
One small comment: I’m a little worried that some folks might take your post too literally and walk away with the impression that we can ignore the majority of solid-walled houses. i.e. the second graph implies that the route to an 80% reduction in CO2 emissions is to reduce to zero the carbon emissions of all houses built after 1917 and leave all older houses untouched.
Retrofit all homes since 1917 to be zero carbon necessary…
Casey Cole has posted an interesting analysis of the task needed to meet the Government’s recently announced target to cut carbon emissions by 80% by 2050 on his blog, Carbon Limited, which concludes……
Great post
I live in a grade II listed building, what proportion do heritage buildings form of the above graphs?
Buildings probably will compensate for other sectors, transport and manufacturing for example, so the figure of 90% carbon emission reductions could be talked around.
Have you done a similar exercise looking at commercial stock? Is there a breakdown of carbon emissions related to heat and power rather than together?
Scary stuff. Nothing underlines the gulf between committing to targets and then actually delivering them than this one.
I would consider it a near impossibility to upgrade every old leaky house without some massively radical action. How could we finance the upgrades for starters then manage the usage of energy in them, as well as control any alterations made to the properties? Carbon taxation? Community energy systems?
Its a huge task, but its what we face. The Germans have committed to doing almost precisely this over the next ten years. The UK now has a distinctly underemployed construction industry and a fair amount of unemployed sustainability consultants/experts.
It doesnt take a genius to see that one lot could train the other. Green New Deal, anybody?
Am adding this v. belatedly but haven’t you all realised that solid-walled homes are far easier to upgrade than these cavity-walled dwellings that are full of thermal bridges, one-piece steel lintels and trussed rafters. External insulation needs doing but you’re not limited in thickness and you can re-slate the roof and at the time add 400 mm of roof insulation on the outside as one 1870 house near the centre of Hereford has done.
Energy Expert – Do you have more information on the Hereford house? As an owner of a solid wall house about to commission a new roof I’d be really interested to here the detail of what they did.
Energy Expert,
You make a very good point and certainly addressing solid wall houses is a necessity. However, it’s cost that is the main barrier. At something like £100+ per m2, external insulation is certainly nowhere near as cheap as filling a cavity wall.
More importantly, insulation only has an effect on the carbon emissions from space heating (and unless you change the heating system too you won’t get to zero emissions from space heating) There’s still water heating and electricity to address. So insulating the walls and roofs as you suggest is an important but limited part of the picture.
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