Embodied carbon of structural frames

There are multiple ways in which the structure of a building can be delivered using a concrete frame, and optimising the amount of material used can make a significant difference to the embodied carbon. There are many parameters to be considered when improving the material efficiency of a building, and selecting appropriate design criteria including grid spacing and loading is vital. 

The structural floor system adopted for a given application can have a significant impact on the material efficiency of the structural frame. The best framing solution for each case depends on a number of factors, including building use, load and span. Typically deeper systems, such as ribbed slabs or slabs on beams are more materially efficient than shallow systems, such as flat slabs. 

There is a range of guidance available to assist with calculating the embodied carbon of structural frames, including Concept and Comparison of embodied carbon in concrete structural systems.

Lower embodied carbon figures may be achieved by changing the specification of the concrete and it is recommended that you involve the concrete supplier at an early stage. Their input can help to achieve the lowest embodied carbon concrete for the project, considering location, application and performance requirements. 

Unlike other materials, additional fire linings or finishes (and therefore carbon) are not usually required by concrete frames to meet full performance requirements. The embodied carbon associated with the remaining life cycle stages (construction, use and end of life) of each frame is likely to be fairly similar, and typically less significant. A whole life carbon assessment of the building is recommended to account for elements beyond, but impacted by, the structural frame, such as foundations, building height and service life, as well as the potential embodied in use and operational carbon savings from omitting finishes and utilising the thermal mass as part of a low energy servicing strategy.

Note: Extracts from Concrete Frames Explained (pages 32-35)