Programmable thermostats work well during the times of year when temperatures are consistently hot or cold. You can set your thermostat to the appropriate heat or cool mode and forget about it. But they aren't as effective nor convenient when fluctuating temperatures are the norm. Home owners and businesses are forced to repeatedly change the modes to adjust for each day's conditions. Recent weather across much of the country has provided an example of the unpredictable temperatures the fall and spring seasons bring. These conditions are when smart thermostats are true heroes of energy efficiency and your nerves.