This is a high-frequency radio beam that can defrost things from a distance. For example it can defrost a frozen chicken from 3 miles away. The beams are not at all dangerous and can travel through soil, rock and concrete (except if the the concrete is reinforced with krypto-web fibres).
The Secure Command Center is equipped with a Defrost-Ping Emitter (developed and manufactured by Mgadigadi Technologies), and its beams can comfortably defrost anything on school premises.
Mr. Rosebank was once experimenting with transformers, but by mistake bumped his cup of tea onto the experiment control panel. This caused the transformer to mis-activate, and the resultant electro-magnetic feedback loop caused a Type-B data feedback vortex. As you well know, this is an extremely dangerous situation.
At the time, the transformer was pointing towards the Geography Building, which was transformed in an instant into a large block of ice, with 22 kids and teacher trapped inside.
Dash rushed to the SCC and sent out a Level-13 Emergency Defrost-ping. The block of ice instantly melted and Dash saved the day. Mr. Rosebank was very impressed.