A study highlights how waste heat from air-conditioners in a very narrow street can raise the local pedestrian-level outdoor air temperature by up to 8°C (about 14 to 18 degrees Fahrenheit).

 

A study highlights how waste heat from air-conditioners in a very narrow street can raise the local pedestrian-level outdoor air temperature by up to 8°C (about 14 to 18 degrees Fahrenheit). This microclimate warming effect significantly worsens the urban heat island phenomenon compared to city-wide averages.

The Science and Impact

• Waste Heat (Anthropogenic Heat): Air-conditioners do not destroy heat; they move it from inside a building and exhaust it outside via compressor units.
• Street Geometry: Narrow streets trap this expelled heat. Poor ventilation prevents the hot air from dispersing quickly.
• Feedback Loop: Higher outdoor temperatures reduce the efficiency (coefficient of performance) of the air-conditioners, forcing them to work harder and consume more power, which expels even more heat.
• Orientation Factor: The temperature spike is most severe when exhaust units face directly into the pedestrian walkways of the canyon-like street