The European Green Deal presents architects and planners with the challenge of having to reduce the CO₂ built into buildings and caused by their operation to the greatest possible extent, while also retaining an architecturally appealing design with optimum functionality.
One effective way of saving CO₂ is to build smaller and more compact buildings, thereby achieving an excellent form factor. Form factors describes the ratio of the building envelope to the usable space and are decisive when it comes to the quantity of embodied carbon that can be used when manufacturing the building envelope.
A building with an unfavourable form factor and constant usable-space-related embodied carbon is permitted to have far less embodied carbon in the façade than a building with a more favourable form factor.
For a good form factor and material-sufficient solution, it is therefore vital that the building design focuses on a combination of the most compact building envelope possible with the greatest possible usable space.
A CO₂-favourable façade construction does not necessarily impair design freedom in the draft stage. CO₂-optimised constructions certainly offer plenty of scope for design freedom, but without having a negative impact on the overall balance of the building.
Operational carbon is particularly dependent on the form factor. The better the ratio of the building envelope to the usable space, the lower the energy requirements and CO₂ emissions when the building is in operation.
However, in future the proportional impact of the embodied carbon on the total emissions (whole life carbon) of a building will grow steadily. The energy required in the use phase – the operational carbon – is subject to continuous optimisation. At the same time, it is far harder to reduce embodied carbon, as resources are always consumed when manufacturing the materials required for construction.