6533b7d3fe1ef96bd12612f7

RESEARCH PRODUCT

Modeling impacts of super cool roofs on air temperature at pedestrian level in mesoscale and microscale climate models

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Abstract Passive daytime radiative cooling is gaining increasing relevance as recent studies report that newly developed materials with very high reflectivity and emissivity could be able to effectively reduce urban heat stress, when applied as roofing material (super cool roofs). A recent microscale sensitivity study with ENVI-met modeled the impact of super cool roofs with maximum air temperature reductions of around 0.85 K at pedestrian level for an idealized model area. To verify these findings in real urban structures featuring complex building morphologies and varying meteorological conditions, we conducted climate simulations for two contrasting cities: New York City, NY, and Phoenix, AZ. (Super) cool roof's cooling impacts are compared using mesoscale and nested microscale simulations in both cities with the Weather Research and Forecasting Model (WRF) and ENVI-met, respectively. While ENVI-met predicts daytime air temperature cooling at pedestrian level of up to 0.49 K (New York) and 0.94 (Phoenix), WRF estimates maximum cooling of 2.51 K (New York) and 3.31 K (Phoenix). Despite these differences both models showed high agreement in statistical analysis of modeled pedestrian-level air temperatures and roof surface temperatures. Climatological conditions could be identified as a major driver for cooling impact differences between New York City and Phoenix.