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Tracing the impact: Flemish non-residential buildings under the microscope

Maud Haverbeke

Abstract

The urgent need to reduce the carbon footprint of buildings stems from the building sector's substantial contribution to global CO2 emissions. Despite growing awareness, practitioners such as contractors and architects often lack actionable knowledge to effectively mitigate environmental impacts. A deeper understanding is required of the specific building components that drive these impacts, and of the influence material selection exerts throughout the life cycle. Although residential buildings have been the primary focus of environmental impact studies, non-residential typologies remain underexplored. This study addresses that gap by analysing nine recently built Belgian non-residential buildings or apartment blocks. The sample includes an office building, a primary school, three childcare centres, an apartment complex, two warehouses and an assisted living facility, representing a range of typologies and construction systems, including solid, massive timber, and timber construction. The environmental performance is assessed using Life Cycle Assessment (LCA), encompassing the embodied impact. The analysis provides initial insights into which building elements contribute most significantly to environmental impact, and the role of material choices. Future research will focus on identifying more cost-effective construction assemblies that can further reduce the environmental impact of the building sector, thereby supporting a transition toward more sustainable and economically viable practices.

Full text

TRACING THE ENVIRONMENTAL IMPACT: FLEMISH NON-RESIDENTIAL BUILDINGS UNDER THE MICROSCOPE INTRODUCTION LCA METHODOLOGY CONCLUSION RESULTS CASE STUDIES RESEARCH GROUP BUILDING PHYSICS Maud Haverbeke, Yanaika Decorte, and Marijke Steeman [email protected] •Urgent need for lowering greenhouse gas emissions, with the building sector responsible for 37%. •The building sector is not on track to reduce its emissions by 2050. •Lowering the operational energy use implies a significant increase in the share of the embodied impact. •High focus on residential dwellings, non-residential typologies remain underexplored. •Addressing this gap by providing initial insights into which building elements (e.g., walls, floors, and roofs) contribute most to environmental impact, and the role of material choices. •According to the Belgian LCA-tool, TOTEM •Reference Study Period = 60 years •Functional Unit = m² Gross Floor Area (GFA) •Life Cycle Inventory = Ecoivent 3.11 database •Life Cylce Stages = production stage (A1-A3), construction stage (A4-A5), replacement stage (B4), and end-of-life stage (C1-C4) •Including envelope elements (i.e., external walls, slab on grade, roof, external doors, and windows), and internal elements (i.e., internal walls, internal floors, and internal doors) •Results expressed in GWP Primary school - assisted living facility - childcare centres - apartment building –offices - warehouses 0 200 400 600 800 1000 1200 1400 1600 0 100 200 300 400 500 600 700 800 O-WH1 ALF OB PS APP CC1 CC2 CC3 O-WH2 Circular Stone Wood Steel Total embodied impact [tonnes CO2-eq] Embodied impact per GFA [kg CO2-eq/m²] Embodied carbon per building element Beams and columns External door Internal door Window Internal floor Slab on grade Pitched roof Flat roof Non-bearing internal wall Bearing internal wall Party wall External wall Total embodied impact 0 200 400 600 800 1000 1200 1400 1600 0 100 200 300 400 500 600 700 800 O-WH1 ALF OB PS APP CC1 CC2 CC3 O-WH2 Circular Stone Wood Steel Total embodied impact [tonnes CO2-eq] Embodied impact per GFA [kg CO2-eq/m²] Embodied carbon by bill of quantities item Openings External finishing Internal finishing Insulation Structure Total embodied impact •Large spread in GWP results due to differences in building size and material composition. •The circular building (O-WH1) shows the best performance per m² GFA, highlighting the positive impact of circular materials. •The childcare centre with CLT (CC3) has the lowest absolute impact, due to its small GFA and simple design →fewer materials and GFA = smaller environmental footprint. •Most important building elements: floors, with the slab on grade as main element (due to the concrete slab), walls, and roofs. •Structure and internal finishing have biggest potential for reduction.