In cities which have concentrated populations and are strongly affected by climate change, it is important to implement effective climate change countermeasures in the future. In this context, in 2020, the spread of the COVID-19 infection led to urban lockdowns in many countries around the world, and "stay home" has been promoted in Japan. Although such drastic changes in human activities will affect the climate and energy consumption of cities, it has been difficult to quantitatively understand the impacts. Understanding these impacts will give us an important suggestion of "How effective will staying home during the daytime to avoid the summer heat stress in the future as an urban climate change adaptation strategy?"

The researchers, in collaboration with Meisei University and DOCOMO Insight Marketing, Inc., estimated that staying home due to the COVID-19 outbreak had led to 40% reduction in electricity consumption (12 W floor-m^-2) and a 0.13 °C temperature decrease (Fig, within the restricted area) in urban office areas with decreased population. On the other hand, in residential areas where the population increased slightly (right figure, pink area), the electricity consumption increased by 18% (1.4 W floor-m⁼²), and the temperature remained the almost same as before staying home.

These impacts due to the COVID-19 are three- to ten-fold the impacts of the restrictions with G20 Osaka Summit in June 2019. These results suggest that promoting staying home (teleworking style) could mitigate urban heat island and reduce energy consumption in office areas. The method that the researchers have newly developed, "Urban climate modelling + Realtime population data," will be useful for predicting urban temperature and electricity consumption in the "new normal" world, and is also effective to suggest effective climate change adaptation strategy in urban areas.