Where and how do people live? : Modelling the occupation of the German building stock by households

Abstract

Living space needs to be heated in winter and partially cooled in summer and the construction of new buildings requires high amounts of energy and materials. Total living space is increasing, driven by continuously rising average per-capita spaces. The reasons for this are numerous and include the trend to smaller households who live in larger flats, increasing numbers of single-family houses, elderly people remaining in oversized dwellings, e.g. after their children moved out, the unavailability of adequately sized and priced dwellings on the market, and ongoing construction of new buildings even in regions with shrinking or stagnating populations. Prospective scenarios for a sustainable transition of the building stock thus need to account for these factors, in order to be able to endogenously model impacts of different policy measures and other influencing parameters on the distribution and amount of living space. This paper presents the approach of the INHABIT model for the German building sector which is currently under development. Based on Socio-Economic Panel (SOEP) data, we model dwelling occupancy, by matching the German population to the dwelling stock. Historical data shows that dwelling space is increasing for older and wealthier households, even more so in single family homes, and that under-occupation of dwellings concerns exactly these groups: over 50 % of households aged >60 live in under-occupied dwellings. Finally, we find that also moving rates follow similar patterns and are on average lower for these groups, perpetuating the situation. The proposed model will aim at a simulation of the future of possible occupancy pathways, also as a function of policies that may address prevailing inequalities and inefficiencies in German dwelling occupation