Most materials have a fixed ability to conduct heat, but a team of researchers from MIT has demonstrated that applying a voltage to the thin films of material drastically changes its thermal properties. They have designed a device called “electrical heat valve,” which can change the thermal conductivity on request. The researchers used the thin films of the material called strontium cobalt oxide (SCO). When oxygen was added to SCO in a crystalline form called brownmillerite, thermal conductivity dramatically increased. Whereas, it was decreased by adding hydrogen. They successfully showcased that material’s ability to conduct heat can be controlled by a factor of 10 at room temperature. The new technology paves the way for controllable insulation in smart windows, smart walls, smart clothing, or even new ways of harvesting the energy of waste heat.