A comparative study of the whole life carbon of a radiant system and an all-air system in a non-residential building

Kan Shindo*, Jun Shinoda, Ongun B. Kazanci, Dragos-Ioan Bogatu, Shin-ichi Tanabe, Bjarne W. Olesen

*Corresponding author for this work

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There is an urgent need to reduce carbon emissions from the building sector. This study focused on the whole life carbon of a building’s heating, ventilation, and air conditioning system. A methodology to compare the whole life carbon of different HVAC systems was proposed and used in a case study with boundary conditions in Denmark. All-air system and radiant systems were compared, as they have different working principles and the potential for differences in both their embodied and operational carbon. The radiant system was a Thermally Active Building System (TABS), and the all-air system was a packaged variable-air-volume system with reheat. The building model was based on the medium-sized office of prototype buildings developed by the U.S. Department of Energy. Life cycle stages of the building were classified based on EN15978:2011. Two models, one for dynamic building simulation and the other for measuring the mass of materials (e.g., concrete), were adopted in a novel approach. The operational carbon of the HVAC systems was calculated under very similar indoor thermal comfort conditions. The whole life carbon was 10.1 kgCO2-eq/m2/year and 9.0 kgCO2-eq/m2/year for the all-air system and TABS, respectively. Compared to the all-air system, TABS reduced annual total primary energy use by 34% and whole life carbon by 11%. If dynamic carbon intensity of the grid were to be implemented, further reduction of carbon emission is expected with TABS, owing to its flexibility in operation with the activated thermal mass.
Original languageEnglish
Article number113668
JournalEnergy and Buildings
Number of pages16
Publication statusPublished - 2023


  • Building energy
  • Embodied carbon
  • Whole life carbon
  • Thermally active building system (TABS)
  • All-air system
  • Circular economy


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