Chameleon city:thermochromic urban floor

Abstract

The rapid rise in global temperatures due to climate change has led to increasingly sweltering summers in many cities worldwide. As a result, the urban population is facing unbearable heat waves, exacerbated by the urban heat island effect and lack of green spaces. Prolonged exposure to high temperatures can lead to heat-related illnesses, dehydration, and even mortality, particularly among vulnerable groups such as the elderly, young children, and those with pre-existing medical conditions. In order to improve the temperature peak during summer time in the urban environment we need to take measures at a greater scale than before, making changes at city level. The biggest surface of the city is the ground surface itself, covered in great proportion with asphalt and concrete that are absorbing the heat from solar radiation, increasing the ground level temperature above the comfort levels, often higher than 60°C. As we know, white-colored surfaces can reflect a significant amount of light and heat back into the environment, keeping the surrounding environment cooler. In contrast, darker colors tend to absorb more light and heat, causing them to warm up more quickly and emit less reflected radiation. Taking all this into consideration, I am proposing a solution that can reduce the ground level temperature during summertime and increase the temperature during the cooler season: the use of a new upper layer material for the surfaces of streets, walkways and squares in all urban exterior environment as a technique of passive energy retrofit. Such a material is an asphalt mixed with a dark thermochromic pigment that changes colour depending on temperature. Few °C degrees under activation temperature pigment colour starts to fade and when temperature reaches 30°C the pigment becomes fully white.This bold, ambitious and forward-looking concept could reimagine the way future generations live in the city environment in the context of climate change and severe weather conditions.