Dr. Miguel Martin Postdoctoral Research Fellow
M.Martin@tudelft.nl

To date, my research has primarily focused on building energy performance and urban overheating, utilizing physics-based models of thermal interactions between buildings and their outdoor environment. In light of findings reported in various studies¹², I have come to realize that urban decarbonization must extend beyond building energy performance to tackle climate change. Through my participation in the PLEA 2024 conference and review of recent scientific contributions in urban sustainability ³⁴, I have come to understand that new building materials and urban designs possess the potential to transform cities into carbon sinks. Although carbon sink strategies offer new perspectives to accelerate urban decarbonization, I observed that limited data and simulation tools are available for assessing their efficacy in capturing carbon dioxide in the outdoor air. This observation enabled me to sharpen my research vision on urban sustainability around three pillars:

1. Developing novel monitoring approaches, drawing on my expertise in large sensor networks and thermal cameras, to detect sources and sinks of heat and carbon dioxide at multiple scales within a city;
2. Leveraging physics-based modeling and machine learning to accurately and effectively simulate thermal and carbon interactions between buildings and their outdoor environments at multiple scales, in different climates, and for various applications; and
3. Utilizing data and models to assess the capabilities of new building materials and urban designs in reducing energy consumption in cities and transforming them into carbon sinks.

The figure below depicts my research vision, which builds upon my past research and charts a path toward becoming a leading expert in climate-neutral and smart cities.

For the past five years, I have studied monitoring approaches to observe factors contributing to and mitigating urban overheating. During my tenure at a collaborative research alliance between the University of California Berkeley (UCB) and the National University of Singapore (NUS), I reviewed approaches relying on infrared thermography¹ and established Singapore’s first rooftop observatory for neighborhood-scale studies². The rooftop observatory served as the foundation for a project administered by NUS, in which I participate as a research collaborator (see the link here). It was also used as a reference to collect thermal images of the outdoor built environment at the Carnegie Mellon University (CMU) campus (see the link here). My expertise in monitoring urban overheating is currently being sought by Rowan Williams Davis and Irvin Inc..

Building on this expertise, my objective is to observe urban carbon sources and sinks. I plan to deploy large sensor networks to analyze carbon concentration in several built environments. While valuable, sensor networks are one of many monitoring approaches. To enhance multiscale observations, I intend to explore approaches using satellites and mobile systems as well. Multiscale observations of urban carbon sources and sinks could be used for a better assessment of urban carbon footprint in future investigations³.

In addition to observing urban carbon sources and sinks, I suggest to develop novel models of carbon exchanges between buildings and their outdoor environments, which will extend my previous work on physics-based thermal interaction modeling conducted at the Masdar Institute of Science and Technology (MIST) and NUS ^{1 2 3 4}. To address the computational cost and parameter complexity of physics-based models ⁵, I collaborated with CMU on machine learning. While faster and simpler, machine learning requires extensive training data and lack interpretability ^{6 7}. My current research aims to determine the scales, climates, and applications for which physics-based models and/or machine learning are suitable for simulations of thermal interactions. Among applications, city digital twins are certainly of the most significant interest to industry leaders and policy makers.

Existing models, whether based on physics or machine learning, have focused on thermal interactions ⁵, sufficient for building energy and urban overheating studies, but inadequate for complete decarbonization analysis. To address this gap, models should incorporate carbon exchanges between buildings and their outdoor environment. As a first step, I am developing an urban building energy model that serves as input for computational fluid dynamics to simulate carbon dispersion within the urban canopy. The next step is to determine whether carbon exchange can be accurately simulated using simplified physics and machine learning. Similar to thermal interactions, the accuracy and performance of carbon exchange models should be assessed across various scales and within different climates.

Models of thermal and carbon interactions between buildings and their outdoor environment offer a promising perspective for evaluating strategies that reduce building energy consumption and increase urban carbon sequestration. They can thus form the basis of support tools for scientists, industry leaders, and policymakers to create a comprehensive city decarbonization roadmap aligned with Paris Agreement targets. To develop such tools and become a world leader in climate-neutral and smart cities, I am seeking research collaborations. My initial objective is to collaborate with Building Material Science researchers to quantify the potential for carbon sequestration by timber and innovative building materials. Subsequently, I intend to collaborate with Urban Planning experts to investigate urban design strategies that incorporate vegetation for maximized outdoor thermal comfort and carbon sequestration.

Beyond urban sustainability, I aim to achieve scientific recognition in the field of building heat resilience. According to Hong et al. ¹, achieving building heat resilience demands knowledge across Energy Systems and Human Behavior, in addition to understanding thermal interactions between buildings and their outdoor environment. For this reason, I would welcome the opportunity to collaborate with specialists in these two fields.