Quantifying the impact of air conditioner waste heat on neighbourhood scale microclimate and building energy demand in hypothetical urban blocks
4 affiliations
- 1Marwadi University Research Centre, Department of Mechanical Engineering, Faculty of Engineering & Technology, Marwadi University
- 2School of Engineering and Technology, K. R. Mangalam University
- 3Department of Mechanical Engineering, Teerthanker Mahaveer University
- 4Manipal School of Architecture & Planning, Manipal Academy of Higher Education
Abstract
With the advent of ongoing population growth and rapid urbanization, building density has increased significantly. This trend has been responsible for increased urban temperatures and thus resulting in higher reliance on air-conditioning (AC) systems. Although these systems improve indoor comfort, they also release waste heat into the outdoor environment. This waste heat can worsen the urban microclimate and thus represents a hidden thermal cost of AC. This study investigates the influence of AC waste heat on neighbourhood-scale microclimate using an uncoupled computational fluid dynamics (CFD) and building energy modelling framework. The study utilises a hypothetical urban area consisting of 16 buildings under the hot semi-arid climate of Rajkot, Gujarat, India. A total of six air conditioner deployment scenarios with different condenser locations were analysed to evaluate heat build-up and its impact on cooling energy demand. The results indicate that façade-mounted AC systems can increase pedestrian-level temperatures, with interior street canyons warming by more than 1 ℃ due to limited airflow and heat trapping. In contrast, rooftop-mounted systems allowed heat to disperse more effectively and resulted in lower heat accumulation within the canyons. These changes in the urban microclimate also affected building cooling demand, with façade-mounted configurations increasing annual cooling energy consumption by up to 2113.6 kWh, whereas rooftop installations limited the increase to about 513.6 kWh. To assess the combined thermal and energy impacts of AC waste heat, an Urban Cooling Energy Penalty (UCEP) metric was developed. The UCEP values ranged from 0.65 for rooftop-mounted configurations to 11.94 for façade-mounted configurations. These findings suggest that AC condenser placement can influence thermal conditions and cooling energy demand and may therefore be considered in urban planning and building design.
Related
- Spatializing Air Conditioner and Evaporative Cooler Ownership, Use, and Inequality across 400+ Districts Pan-India: Unpacking Social, Environmental, and Urbanization Correlates
- Microclimate persistence in island montane cloud forests
- Trapped in a hot microcosm: how flower microclimate contributes to pollination syndrome in a thermogenic system
- Conditional Flow Matching for Generation of 3D Multi-variable Instantaneous Urban Microclimate Fields
- Terrestrial lidar versus field surveys to assess microclimate temperature buffering in forests
BibTeX
@article{verma2026quantifying,
title = {{Quantifying the impact of air conditioner waste heat on neighbourhood scale microclimate and building energy demand in hypothetical urban blocks}},
author = {Shubham Kumar Verma and Chandrmani Yadav and Ankush Mehta and Rohit Kumar Singh Gautam and Shantharam Patil},
journal = {Scientific Reports},
year = {2026},
month = jul,
doi = {10.1038/s41598-026-62477-4},
url = {https://doi.org/10.1038/s41598-026-62477-4},
note = {CC BY},
}
RIS
TY - JOUR
TI - Quantifying the impact of air conditioner waste heat on neighbourhood scale microclimate and building energy demand in hypothetical urban blocks
AU - Shubham Kumar Verma
AU - Chandrmani Yadav
AU - Ankush Mehta
AU - Rohit Kumar Singh Gautam
AU - Shantharam Patil
PY - 2026
DA - 2026/07/01
JO - Scientific Reports
DO - 10.1038/s41598-026-62477-4
UR - https://doi.org/10.1038/s41598-026-62477-4
AB - With the advent of ongoing population growth and rapid urbanization, building density has increased significantly. This trend has been responsible for increased urban temperatures and thus resulting in higher reliance on air-conditioning (AC) systems. Although these systems improve indoor comfort, they also release waste heat into the outdoor environment. This waste heat can worsen the urban microclimate and thus represents a hidden thermal cost of AC. This study investigates the influence of AC waste heat on neighbourhood-scale microclimate using an uncoupled computational fluid dynamics (CFD) and building energy modelling framework. The study utilises a hypothetical urban area consisting of 16 buildings under the hot semi-arid climate of Rajkot, Gujarat, India. A total of six air conditioner deployment scenarios with different condenser locations were analysed to evaluate heat build-up and its impact on cooling energy demand. The results indicate that façade-mounted AC systems can increase pedestrian-level temperatures, with interior street canyons warming by more than 1 ℃ due to limited airflow and heat trapping. In contrast, rooftop-mounted systems allowed heat to disperse more effectively and resulted in lower heat accumulation within the canyons. These changes in the urban microclimate also affected building cooling demand, with façade-mounted configurations increasing annual cooling energy consumption by up to 2113.6 kWh, whereas rooftop installations limited the increase to about 513.6 kWh. To assess the combined thermal and energy impacts of AC waste heat, an Urban Cooling Energy Penalty (UCEP) metric was developed. The UCEP values ranged from 0.65 for rooftop-mounted configurations to 11.94 for façade-mounted configurations. These findings suggest that AC condenser placement can influence thermal conditions and cooling energy demand and may therefore be considered in urban planning and building design.
SN - 2045-2322
ER -