Buildings, like transportation, are a major source of greenhouse gas emissions, so researchers at the Lawrence Berkeley National Laboratory in California have been looking for solutions in the unglamorous world of energy efficient roofing. The team used vanadium to make “cool roof” coatings which they found to be working in a wider range of temperatures.
TARC (temperature-adaptive radiative cooling) is a new energy efficient material based on vanadium developed by Berkeley Lab. TARC could save the average American household up to 10% on electricity.
Vanadium is a silvery transition metal that conducts electricity well without overheating. Vanadium dioxide is transparent to thermal-infrared light below 67°C (153°F). “At 67°C, vanadium dioxide transforms into a metal and absorbs thermal-infrared light,” Berkeley Lab adds.
This ability to switch from one phase to another — in this case, from an insulator to a metal — is characteristic of what’s known as a phase-change material.
In order to model the results for buildings in 15 climate zones across the continental US, the team created samples that resemble Scotch tape. The results were impressive.
Although TARC still reflects about 75% of sunlight for the year in total, it deflects more heat in warmer weather, and it retains more heat in colder weather. The team must now scale up the prototype to see if it is a viable solution.
Reference- Berkeley Lab Media Center, Science Alert, Futurism, New Atlas