Last week I drove past a building site proudly displaying a sign stating “low carbon construction”, that got my interest, so I took a closer look.
Not much to see apart from a massive concrete slab on top of concrete foundations with multiple 10m high steel posts set in it. How depressing, presumably they’re referring to the low energy input that the finished house will achieve, because they have already pumped more carbon dioxide into the atmosphere than most families will in 100 years!
Concrete is the second largest global CO2 producer, 923kg of CO2 per m3, steel is the biggest polluter on the planet, 1900kg co2 per tonne of steel. This is a catastrophe before we consider all the other chemicals released into the environments such as carbon monoxide and sulphur dioxide.
An average house with 50 tonnes of concrete and 4 tonnes of steel has already pumped more co2 into the atmosphere than you and I will in our daily lives, if we live to 500 years old.
But it is even worse than this, your concrete and steel structure is unlikely to last more than 50 to 100 years, so you get a chance to rape the planet over and over again in the pursuit of a £50 saving on your heating bill.
If you specify concrete and steel you’re no better than the illegal loggers in the Amazon or the poachers killing rhinos in Africa, possibly worse, because the poachers don’t pretend to be angels by driving a hybrid car.
Oak structures on the other hand are carbon negative, sustainable and durable, built with stone and lime mortar we know they can last 800 years.