Urban trees can face heat stress from surrounding built materials. This paper proposes a raytracing framework that integrates LiDAR and tree species trait data with a biophysical model to simulate hourly leaf temperatures and species-specific physiological responses. Simulating 25 scenarios with 147 trees reveals that the landscape vegetation ratio is more effective at reducing heat stress than façade vegetation. High landscape coverage decreased risk by 5.2%, whereas high façade vegetation could increase risk by up to 12.8%. This open source workflow enables landscape architects to make data-driven material decisions to enhance urban forest health.