It is often used as an argument to retain Victorian terraced housing, as this is more efficient in terms of carbon.Hmmm, perhaps.
Having spent many years refurbishing 19th century and earlier properties I am constantly struck by the poor underlying quality of construction, even in the most prestigious looking buildings.
A number of things need to be understood about older buildings. Air movement is crucial, open fires need air. Moving to modern heating and standards of ventilation means that moisture created by living in the building cannot escape. Rear additions create cold corners where condensation will occur.
That is before discussing the structural horrors that are encountered, from token foundations to single brick walls running the height of a five-storey structure. And as perhaps the final question to be thought about is the way the building has been treated over its life. Not all neglect is harmful, not all restoration work is beneficial.
Preserving an existing structure needs careful and sober thought; any architectural or historicmerit needs to be weighed against the costs of renovation, the operating costs of the building and the value created from the work.
If a major investment is needed now and there is a continuing liability created for maintenance then the value created needs to justify that cost. In part this may be aesthetic or cultural, there needs to be a commercial element to this, too.
Thinking about the embedded carbon, I can accept that upcycling an existing structure retains the carbon embedded in it but this needs to be offset against the carbon embedded in the works required to carry out the renovation work, the carbon impact of maintenance and of using it.
At some point the structure will need to be redeveloped or will require increasingly expensive, disruptive investment.
There is a standard methodology for assessing the commercial costs of renovations and this can be combined with running costs to produce a financial budget for the project.
To be truly green perhaps the approach needs to apply the same principles to carbon, what is the present value of the carbon it will take to restore, sustain and, when necessary, replace the structure?
Perhaps this needs to extend to applying a negative discount to future carbon, making it more costly to spend carbon in the future. Commercial calculations discount future costs and receipts, for carbon the reverse should apply placing a future obligation on a building owner should be made more expensive not less, in terms of carbon.
Restoration may still be a greener option, but there will be rigour underneath the emotional response.
Photo by Alex Pepperhill