The turnover dynamics of residential buildings

The construction and operation of buildings is one of the most resource-intensive elements of the economy, therefore buildings are a central focus of efforts to reduce energy use and hence greenhouse gas emissions. Because of their long- lasting nature, buildings are also important factors in deciding the inertia of economies, and determining the turning point of economies in net-zero transitions. Traditionally buildings are assigned single representative timescales of the order of 80 years. However, building investments may be seen as investments in components, each having its own service life ranging from seconds to centuries, with returns expected over this interval. The aim of this thesis is to explore the relationship between investments in buildings and their turnover timescales, which I refer to as the investment-timescale distribution, and to identify its role in the capital inertia of the building sector in the climate transition. In chapter 2, this investment-timescale distribution is first developed for a single building using the financial costs of components and their expected service life. >This is then extended to a representative building (RB) by applying a well- established mortality function for the service life of each component. The resulting investment-timescale distribution of an RB is a near continuous yet multi-modal distribution with a first moment of 38 years, remarkably close to the expected working lifetime of its inhabitants. I explore the implication of this investment-timescale distribution in chapter 3, in particular for the dynamic maintenance schedule and economic performance of an RB in the UK. This is done by simulating maintenance costs to counter the depreciation of components as they approach their performance thresholds. I evaluate the performance of this simulation using return on investment (ROI). The result is a near stochastic maintenance schedule despite the deterministic nature of the simulation. This provides a strong indication as to why the interaction of timescale spectra with maintenance thresholds yields the complex and hard to predict maintenance dynamics we see in real property portfolios. Finally, in chapter 4, I apply the investment-timescale dynamics to simulate the dynamics of energy demands and carbon liabilities of an RB. This simulation contrasts these dynamics under a net-zero carbon policy and a business-as-usual (BAU) scenario. The results show that, for new build, the longer-lived (>70 years) carbon-intensive components avoid much of their maintenance carbon liability if the economy decarbonizes in the interim. This also suggests that delaying currently carbon intensive construction until less carbon intensive options are developed should be considered during the transition to net-zero.