Material quantities and embodied carbon dioxide in structures

Abstract

This paper analyses data from 200 buildings to identify the embodied environmental impact of building structures. In recent years, the percentage of embodied carbon dioxide in the whole life cycle impact of buildings has been increasing while innovations have lowered operational carbon dioxide. Operational carbon dioxide emissions are due to heating, cooling, ventilation and lighting, whereas embodied carbon dioxide is associated with materials extraction, manufacturing, transportation, construction, maintenance and demolition. Limited research on the latter prevents an accurate evaluation of the whole life cycle impact of buildings. Therefore, leading engineers have emphasised the urgent need for a global, standard assessment method for embodied carbon dioxide. To this end, this paper offers a uniform method by describing current work, quantifying material weights and finally calculating embodied carbon dioxide ranges. The approach is cradle-to-gate but can be expanded to cradle-to-grave. The survey contains data on 200 recently completed buildings obtained from industry. The results show that structural material quantities vary between 200 kg/m2 and 1800 kg/m2 and embodied carbon dioxide caries on the range 150–600 kgCO2e/m2. These numbers are analysed by programme type, structural system, size, number of floors and Leadership in Energy and Environmental Design (Leed) certification. In doing so, the paper emphasises the important role that structural engineers play in sustainability.