Will Hawkins, Angus Peters and Tim Mander argue for designers to challenge overspecification and grasp the opportunity that reduced floor loads offer for low-carbon structural design.

To align with climate targets, we must reduce the embodied carbon of building structures by 10% each year. Using lower design loads might be considered low-hanging fruit for reducing material consumption; a simple change which affects all structural building components, requires no alterations to design methods, no new construction technology and minimal coordination with other members of the design team. This article explores the real imposed loads in buildings, how these compare with various design codes around the world, and examines the potential savings in embodied carbon.

Measured loading in buildings

We know that the imposed loadings used for design are vastly greater than those reached in real buildings. MEICON collated data from eight published studies where the real loading in offices was measured manually, covering a total floor area of 2,500,000/m2. Based on an area-weighted calculation, the mean load was found to be 0.60kN/m2, with a standard deviation of 0.34kN/m2, and 99.97% of the measured floor area had a load below 2.5kN/m2. These studies also highlight a tendency for higher variability over smaller sampling areas.