A Carbon footprint of an office building

Current office buildings are becoming more and more energy efficient. In particular the importance of heating is decreasing, but the share of electricity use is increasing. When the CO2 equivalent emissions are considered, the CO2 emissions from embodied energy make up an important share of the total, indicating that the building materials have a high importance which is often ignored when only the energy efficiency of running the building is considered. This paper studies a new office building in design phase and offers different alternatives to influence building energy consumption, CO2 equivalent emissions from embodied energy from building materials and CO2 equivalent emissions from energy use and how their relationships should be treated. In addition this paper studies how we should weight the primary energy use and the CO2 equivalent emissions of different design options. The results showed that the reduction of energy use reduces both the primary energy use and CO2 equivalent emissions. Especially the reduction of electricity use has a high importance for both primary energy use and CO2 emissions when fossil fuels are used. The lowest CO2 equivalent emissions were achieved when bio-based, renewable energies or nuclear power was used to supply energy for the office building. Evidently then the share of CO2 equivalent emissions from the embodied energy of building materials and products became the dominant source of CO2 equivalent emissions. The lowest primary energy was achieved when bio-based local heating or renewable energies, in addition to district cooling, were used. The highest primary energy was for the nuclear power option