Operational and embodied carbon: commercial
The use of concrete in buildings can lead to questions regarding its embodied CO2, which is often thought to be much higher than other construction materials. In reality, there is little or no difference, and is insignificant when compared to a building's operational CO2 emissions over its life.
In buildings where the inherent thermal mass of concrete forms part of the cooling strategy, any additional embodied CO2 burden can in fact be offset many times over. This can be shown quite simply by comparing the embodied and operational CO2 emissions per m2 for a typical air-conditioned office with those of a typical mixed-mode office i.e. one that is cooled using thermal mass in conjunction with natural and mechanical ventilation.
A source of data for the embodied CO2 of office buildings is life cycle assessment research on steel and concrete framed buildings. One of the conclusions of the study was that overall there is no significant difference between steel composite, reinforced concrete and precast concrete options with regard to embodied CO2. For a small to medium rise office, built to a developer's standard specification, the range of embodied CO2 for different options was equivalent to only 16 months CO2 emissions from an energy-efficient, air-conditioned office [1,2].