Connected thermostats are believed to achieve efficiency improvements over conventional programmable thermostats primarily because:

1. Connectivity supports streamlined program verification of efficient settings
2. Improved interface and support for multiple set-back schedules increases the likelihood of thoughtful programming
3. Limited-duration overrides maintain comfort during unusual events while preserving efficient settings for normal operation 
4. Many conventional programmable thermostats do not support fan mode scheduling  

The measure's largest savings components are expected to be heating and fan energy.  Cooling savings is expected to be relatively small because unoccupied periods are usually at night, when cooling load is low due to mild outdoor temperatures and low internal gains.  Economizer improvements are not a significant part of this measure because those often require hardware improvements beyond the thermostat (e.g., control module, sensors, or expanded wiring bundle connecting thermostat and RTU).  However, some eligible connected thermostats support remote viewing of granular time series for power draw and/or cooling mode, and this functionality may help programs identify systems that are promising candidates for custom economizer interventions.