Simulating Building Heat Emissions in Los Angeles County
Detailed hourly profiles reveal significant seasonal and diurnal variations in anthropogenic heat, with surface convection as the largest component in Los Angeles County buildings.
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The main challenge in this field is understanding how waste heat from buildings affects urban temperatures, especially during heatwaves. Our key finding is that buildings in Los Angeles County significantly contribute to higher urban temperatures, particularly at night. This waste heat, known as anthropogenic heat, comes mainly from building surfaces, HVAC systems, and air exchange. Dense urban areas with many industrial and older buildings produce the most heat. During a heatwave in July 2018, this waste heat increased nighttime temperatures by up to 2.9°C, highlighting the need for policies to reduce heat emissions from buildings.
This research tackles the issue of urban heat in Los Angeles caused by waste heat from buildings, known as anthropogenic heat (AH). This heat raises city temperatures, especially during heatwaves, leading to increased air conditioning use and more heat release, creating a vicious cycle. Our study uses detailed simulations with local climate data to map AH from 1.7 million buildings in LA County. We found that older, densely packed buildings, particularly industrial ones, contribute the most to AH. This research aids in understanding building heat's impact on urban climates and can inform policies to reduce city heat, influencing urban planning, public health, and environmental science.
We present a comprehensive study on the impact of anthropogenic heat (AH) from buildings in Los Angeles (LA) County, using a bottom-up simulation approach to generate detailed annual hourly AH profiles for 1.7 million buildings. Our findings reveal significant seasonal and diurnal variations in AH, with peaks in May and maximum values reaching 878 W/m² in certain hotspots. The study identifies surface convection as the largest AH component, contributing to 78% of the total AH, followed by HVAC systems and zonal air exchange. Notably, older buildings and areas with high building density and industrial activities exhibit higher AH levels.
During the July 2018 heatwave, building AH (excluding surface components) led to a daily maximum ambient temperature increase of up to 0.6°C and a daily minimum increase of up to 2.9°C. These findings underscore the importance of considering AH reduction in urban planning and policy-making to mitigate the urban heat island effect and enhance heat resilience. The study also highlights the need for targeted interventions in dense urban regions with significant industrial and commercial activities to reduce AH and its adverse impacts on urban climate and public health.