A temperature control device comprising: a temperature sensing circuit configured to generate a temperature control signal indicating a temperature in a space around the temperature control device; at least one internal electrical load configured to generate heat when energized; and a control circuit configured to: receive the temperature control signal; control the internal electrical load; be in an idle state or an awake state; and receive a set point temperature; wherein, when the control circuit is in the idle state, the control circuit is configured to: cause the internal electrical load to consume less power as compared to when the control circuit is in the awake state; sample the temperature control signal; determine a sampled temperature based on the temperature control signal; and store the sampled temperature in memory; and wherein, when the control circuit is in the awake state, the control circuit is configured to: energize the internal electrical load; cease sampling the temperature control signal; use the sampled temperature stored in the memory in the idle state as a present temperature; compare the present temperature to the set point temperature; and based on comparing the present temperature to the set point temperature, control an HVAC system. a temperature sensing circuit configured to generate a temperature control signal indicating a temperature in a space around the temperature control device; at least one internal electrical load configured to generate heat when energized; and a control circuit configured to: receive the temperature control signal; control the internal electrical load; be in an idle state or an awake state; and receive a set point temperature; receive the temperature control signal; control the internal electrical load; be in an idle state or an awake state; and receive a set point temperature; wherein, when the control circuit is in the idle state, the control circuit is configured to: cause the internal electrical load to consume less power as compared to when the control circuit is in the awake state; sample the temperature control signal; determine a sampled temperature based on the temperature control signal; and store the sampled temperature in memory; and cause the internal electrical load to consume less power as compared to when the control circuit is in the awake state; sample the temperature control signal; determine a sampled temperature based on the temperature control signal; and store the sampled temperature in memory; and wherein, when the control circuit is in the awake state, the control circuit is configured to: energize the internal electrical load; cease sampling the temperature control signal; use the sampled temperature stored in the memory in the idle state as a present temperature; compare the present temperature to the set point temperature; and based on comparing the present temperature to the set point temperature, control an HVAC system. energize the internal electrical load; cease sampling the temperature control signal; use the sampled temperature stored in the memory in the idle state as a present temperature; compare the present temperature to the set point temperature; and based on comparing the present temperature to the set point temperature, control an HVAC system.