Unpacking households' environmental footprint: Comparing price and quantity effects in Flemish food consumption

Household food consumption is a major driver of environmental impacts, yet existing assessments often overlook how household characteristics shape these impacts. Most studies rely on expenditure-based approaches that assume constant elasticities between spending and environmental pressure. This study reassesses the role of income and other household characteristics by contrasting expenditure-based and functional-unit approaches to measuring food consumption. We combine data from the 2022 Belgian Household Budget Survey with a detailed life cycle assessment database to estimate environmental impacts for Flemish households. We use log–log OLS regressions to evaluate how household characteristics influence food demand measured in quantities and expenditures, as well as the associated environmental footprints. Dominance analysis is applied to assess relative contribution of each characteristic to explained variance. The results challenge the assumption that higher income proportionally increases food-related environmental impacts. Across product groups, income elasticities are higher for expenditures than for quantities. The global warming footprint ranges from 3.0 to 3.6 tons CO₂-equivalent across income groups, a narrower spread than in previous studies. Household size and composition are the main drivers of variation, with larger households exhibiting lower per-capita impacts, consistent with economies of scale. Age is also significant, as older households tend toward consumption patterns linked to higher-impact food categories. By contrast, households in smaller dwellings and more urbanized areas tend to have lower impacts. These findings highlight the importance of methodological choices in environmental impact assessment and suggest that reliance on expenditure data alone may lead to incomplete conclusions about drivers of environmental impacts.