Heat Waves and Innovation in Air Conditioning in the United States

Abstract This study investigates whether extreme heat episodes (heat waves) have contributed to the development of air conditioning (AC) technology in the United States. To this end, we use weather data to identify days at which heat and relative humidity were above levels comfortable to the human body, and match these with patent data at the county level for nearly a hundred years. We find that in the 2 years after a county has experienced extreme heat AC patents increase. Overall, average extreme heat exposure results in an increase of 7.5% greater innovation. We find no similar increase in the frequency of non-AC-related patent filings, and therefore conclude that heat waves result in innovation targeting their mitigation. Significance Statement The possibility of more extreme heat because of global warming has raised the question of whether society will be able to invent new technology to adapt to the likely greater frequency and severity of heat waves. The purpose of this paper is to consider the development of air conditioning in the United States and investigate whether extreme heat has indeed driven innovation in cooling technology. It is shown that, in counties with episodes of extreme heat, the number of air conditioning patents filed increased in the aftermath of these episodes, but that this increase was short-lived.