HeatMat: Simulation of City Material Impact on Urban Heat Island Effect

TL;DR

HeatMat is a high-resolution city-scale simulation tool that analyzes the impact of urban materials on the Urban Heat Island effect using open data, computer vision, and a fast 2.5D heat transfer model.

Contribution

It introduces a novel approach combining open data, vision-language models, and a 2.5D simulator to analyze urban materials' impact on UHI at high resolution.

Findings

Enables detailed analysis of urban materials' impact on UHI.

Uses open data and vision models to estimate building materials.

Achieves 20x speedup over traditional 3D simulations.

Abstract

The Urban Heat Island (UHI) effect, defined as a significant increase in temperature in urban environments compared to surrounding areas, is difficult to study in real cities using sensor data (satellites or in-situ stations) due to their coarse spatial and temporal resolution. Among the factors contributing to this effect are the properties of urban materials, which differ from those in rural areas. To analyze their individual impact and to test new material configurations, a high-resolution simulation at the city scale is required. Estimating the current materials used in a city, including those on building facades, is also challenging. We propose HeatMat, an approach to analyze at high resolution the individual impact of urban materials on the UHI effect in a real city, relying only on open data. We estimate building materials using street-view images and a pre-trained vision-language model (VLM) to supplement existing OpenStreetMap data, which describes the 2D geometry and features of buildings. We further encode this information into a set of 2D maps that represent the city's vertical structure and material characteristics. These maps serve as inputs for our 2.5D simulator, which models coupled heat transfers and enables random-access surface temperature estimation at multiple resolutions, reaching an x20 speedup compared to an equivalent simulation in 3D.