Light absorbing substances sprayed on houses, trees and roads could enable cities to use phosphorescent light instead of electricity-powered lamps to reduce energy consumption.
In a recently published report, Arup describes how making electrical street lighting less necessary, cities around the world could considerably reduce their carbon footprint – an important development in the age of advancing climate change and intensifying global warming.
Technology enabling such carbon-free lighting is currently being tested as part of a public footpath constructed in Christ's Pieces park in Cambridge, UK.
A product called Starpath, developed by a UK company Pro-Teq has been sprayed on solid surfaces to make it glow in the dark.
The coating contains particles that harvest the sun's rays during the day and emit a soft blue light at night.
"Starpath has the potential to reduce the need for complex lighting installations in parks and alleyways while allowing for the introduction of lighting and the safety and security that brings," Arup said in a recently published report on future environmentally friendly cities. "Another benefit is that since it's non-reflective and relatively low intensity, it doesn't add to light pollution."
The report highlights various natural solutions such as preventing flooding by replacing hard concrete and tarmac with permeable surfaces, and increasing tree cover.
To meet the increasing demand for food, vertical "urban farms" are also forecast with crops being grown in and on city buildings.
Parks could also contribute to food supplies by providing places where people can forage for fruits, edible greenery and even insects.
Tom Armour, landscape architecture group leader at Arup, said: "By 2050, it is predicted that the human population will have reached nine billion with 75 per cent of people living in cities.
"Adaptations to existing city spaces, enabled by rapid technological innovation, will serve as major catalysts in the shift toward increasing sustainability, resilience and adaptability in dense urban environments."