The term programmable communicating thermostat (PCT) is used by the California Energy Commission to describe programmable thermostats that can receive information wirelessly.
The first version of the PCT introduced in the 2008 building standards proceeding also required that PCTs allow temperature control during emergency events to avoid blackouts.
A talk at the S4 SCADA security conference in January 2008 indicated adding a public key encryption scheme to the specification, giving each thermostat a random 160-bit number.
Using this method, the PCT would receive messages only from the operator(s) explicitly agreed to by the homeowner.
Thermostats can also communicate wirelessly through the Internet or via a home automation technology, such as Insteon.