UCLA Luskin Center for Innovation

THIS STUDY EXAMINES how urban designinfluences the human experience of heat inPacoima, a neighborhood in the San FernandoValley region of Los Angeles. The primary metricfor heat exposure is Mean Radiant Temperature(MRT), which measures a variety of factors (e.g.,sun, surfaces, air, humidity, wind speed) thatcontribute to that experience, though we alsoexamine Land Surface Temperature (LST; anindicator for the “skin” temperature of the Earth)using estimates from satellite imagery.We find that the dominance of impervioussurfaces like buildings, parking lots and roads,as well as the scarcity of vegetative coverlike trees, shrubs and grass, contributes tohigh LST. In examining MRT using observedand simulated data to evaluate the humanexperience of heat, however, we find that theprimary factor in reducing heat burden is shade.Thus, areas of Pacoima that lack shade leavepeople vulnerable to extreme heat. This effect isespecially noticeable at Fernangeles ElementarySchool, which has less than 20% shade coveragethroughout the day and less than 10% shadecoverage during the midday recess period.Fernangeles Elementary is much hotter than itssurrounding residential neighborhood acrossall surfaces (grass, asphalt, concrete, rubber,soil) because it has so little shade. Both theschool and residential areas of Pacoima couldbenefit from increased shade but would also becandidates for a suite of interventions includinggreening, cool pavements and site-specificbuilding design.