From 2023, there are limits on how much CO2 a building may emit during the entire life of the building. That is why there is great interest in sustainable building materials. You can see this for yourself during a visit to the Building Green 2022 fair in Forum yesterday and today.
Recycled steel
The fair has its primary focus on housing construction and architecture, but on the few stands from the heavy material suppliers from the steel and concrete industry, there was great interest in the green transition. Give Steel, a major supplier of steel trusses for the Fehmarn Tunnel, presented green steel at the fair – metaphorically. The steel was still grey-black but contained up to 98 per cent recycled steel. The recycled steel comes from other buildings in connection with demolitions or conversions.
A few euros more expensive
Steel with a high content – up to 98 per cent – of recycled steel is a few euros more expensive per kilo than “fresh” steel. But judging by the interest at Give Steel’s stand, it was not a problem for contractors and builders.
New cement for bridges and tunnels
However, the biggest CO2 culprit in modern construction is concrete. Cement production emits so much CO2 that Aalborg Portland is Denmark’s uncrowned CO2 king. But it is becoming affordable. Aalborg Portland has just launched Aalborg Solid cement, which emits up to 17 per cent less CO2 than traditional cement for civil engineering, such as bridges and tunnels. But it can be even better.
Concrete with 25 per cent less CO2
At the fair, the concrete supplier Unicon’s stand was also a bit of a draw. Here, the fair visitors could get to know the new Uni-green concrete, which, according to Unicon itself, emits 25 per cent less CO2 than standard concrete. The trick is a new type of cement, Futurecem, in which approximately one-third of the CO2-heavy cement clinker has been replaced with calcined (burnt) clay and lime filler. The clay is also dug up from the ground in northern Jutland, so there is not a large CO2 footprint in relation to the transport either.
Not even green green concrete
Unicon had brought two more or less perfectly shaped concrete blocks to the occasion. One was made of traditional concrete, the other of Uni-green concrete. The two blocks were apparently identical – although one may be slightly more reddish-brown in tone than the other. And thus, the audience could make sure that there was no difference in the final product. It might well be the same. Unicon is – just like the cement producer in Aalborg – phasing out the standard concrete in favour of the new, greener one. As mentioned, there is no trace of green, but rather concrete coloured with a touch of reddish brown.
