In the coming years, the Netherlands is expected to face various climate change-related challenges. Until 2030, the Dutch government has set the goal for the development of nearly a million dwellings (De Jonge, 2022), whereby 600,000 dwellings are being carried out in areas prone to flooding (Deltares, Bosch Slabbers, & Sweco, 2021; Groenemeijer & van der Lelij, 2021). In literature, work has been done regarding the current use of adaptation pathways, policies and their impact on decision-makers and practitioners (Restemeyer, van den Brink, & Woltjer, 2017; van Alphen, Haasnoot, & Diermanse, 2022; Yousefpour & Hanewinkel, 2016). However, limited efforts have been made regarding their practicality in the real estate sector. This research seeks to address the fundamental question, “who pays what, when?”. At its core, this research revolves around the influence of climate risks on the investment decision-making process in polder-area developments in the Netherlands and examines the research question: “In which way do water risks impact the investment decision-making process in polder-area development projects in the Netherlands?”. In this qualitative study, the urban area development projects Westergouwe (Gouda) and Gnephoek (Alphen aan den Rijn) are compared and analyzed. With the use of explorative interviews, and semi-structured in-depth interviews, the research strived to answer the research question. Afterward, an expert panel is held to bridge the gap to standard practice. This research found that the integration of adaptive measures into the investment decision-making process is currently insufficient. There is a need for clear policy, clear distribution of responsibilities and prioritization of water safety over financial considerations in the investment decision-making process. By navigating this complexity, driven by collaborative efforts, a holistic approach becomes imperative to forge a path toward a more resilient built environment.

Land subsidence poses significant damage risks to residential real estate, including pile rot, differential settlements, pluvial flood risk, and dewatering risk amounting tens of thousands of euros. In the Netherlands, the number of affected houses has surpassed one million and is estimated to reach two million, accounting for a quarter of all houses in the country. Without an action perspective homeowners are left to their own devices which this research shows can lead to postponing action until risks materialize. To mitigate these risks, multiple adaptation strategies are available. This thesis focuses on determining the cost-effectiveness of two general pathways for residential real estate constructed with either a wooden pile foundation or a shallow foundation: renovating existing houses or replacing them entirely. The study also investigates whether incorporating additional measures aimed at improving overall benefits such as increasing the amount of living space or transitioning towards a more sustainable house with energy label A, is cost-effective by comparing the costs and benefits associated with the adaptation strategies. When the benefits outperform the costs the strategy is labelled favourable. Through a comprehensive analysis, this research provides valuable insights into economically viable approaches for addressing land subsidence-related risks in residential real estate in relation to the location specific characteristics. It proves additional measures are required to make either renovation or replacement a cost-effective adaption strategy. Two options are shown to be cost-effective. Firstly, renovation including additional investments to
increase square meters of living space and transitioning to an energy performance A-label. Secondly, replacement including densification by building back more square meters of living space, increasing the amount of houses or a combination of the two. Both require large investments resembling around 75% to 150% of the current housing price respectively. Increasing the amount of square meters even further improves the result however this increasingly affects the character of the neighbourhood and its social composition. With these results, this thesis hence provides an action perspective to homeowners and stakeholders including policy makers and financial institutions by means of a solution space to address
land subsidence in an economically favourable way, whilst simultaneously reflecting on the differences in implications for the parties involved.