The development of efficient cooling technology based on environmentally friendly and biobased materials is crucial to many day-to-day activities. A novel, highly efficient cellulose nanocrystal aerogel radiative cooler acts as a dual-function thermal insulator and daytime passive radiant cooler. These aerogel coolers can save on average more than 35% in cooling energy consumption and they are capable of achieving a nearly 9 degree C drop under direct sunlight, they even work effectively ...