Effect of service life in the emission assessment of ventilation systems. A case study in an office building

Abstract

In the construction sector, the total carbon footprint of a building measures the greenhouse gas (GHG) emissions associated with all the stages in the building’s life cycle, including the replacement of elements over the years. The calculations are very relevant for installation systems, which generally have a shorter lifetime than the building itself and need to be replaced for proper operation of the building. Ventilation systems, particularly, are complex and include diverse components of various materials, functions and service lifetime. The literature data about the service life in years for the components is fragmented, different in diverse guidelines, or not specified for each composing component. The impact of replacing ventilation system components was studied in a case study in an office building in Bergen, Norway. The emissions from the replacement were assessed for three replacement scenarios during the service life of 60 years. The first scenario was based on the experience of specialists dealing with ventilation systems and data from the literature. Two other border scenarios were considered: one frequent and one rare replacement of components through the years. From the expert-assumed values, the emissions from the replacement are approximately 1.5 times higher than the emissions from the production of the components. When a frequent substitution occurs over the years, the emissions from the replacement cover approximately 2.5 times the emissions from the production, while when the replacement occurs rarely, the emissions are less than half of the embodied emissions. The assessment showed high fluctuations in the results when different scenarios were applied, highlighting the need for further work in the field to determine and unify the service life of components. A comprehensive database with service lives for installation components, and an increase of EPDs for such products from the producers would facilitate the assessment and integration of the carbon emissions of such systems in the overall carbon footprint of the building.