Does the T2000 have the ability to show energy use? My understanding is the Nest can do this, can the T2000?
How does Nest meter energy use (the thermostat itself)?
I’m struggling to think off the top of my head how that would even work. Even if an electric HVAC, power is not routed through your thermostat to the furnace, it is just low voltage switching current. Nest itself is not a metering device of any kind.
No thermostat I am aware of meters energy use and cost. I could be wrong.
To meter home energy use, you would use Energy Management and metering devices which attach either to your mains or individual circuits.
Nest’s Energy History shows how much energy the Nest Thermostat uses to heat or cool your home each day. You can find your Energy History by selecting ENERGY in the Nest Thermostat menu.
https://nest.com/support/article/How-to-read-my-Energy-History-on-the-Nest-Learning-Thermostat
Ah, so it is an approximation of time spent “On” vs “off”. I suppose that is novel to see, but I wonder if it actually does anything with relation to the weather events or does it just admit that it flushed a bunch of money because it was really hot outside? (I hope Nest does have a similar override, but ADC extreme temp overrides automatically adjust the thermostat so heavy usage spikes due to weather do not happen)
There is no time based history for the ADC Smart Thermostat that I am aware, though who knows, it may be added. They are developing peripherals for it. I’ll ask ADC.
Using an actual power meter is going to be a fair bit more exact.
That’s cute but ultimately not very useful. I get some nice granular info from my power company, even broken down to 15 minute increments throughout the day and that’s way more relevant to the issue of increased usage due to weather or time of day. The T2000 with the smart away or extreme temp settings seems to be a good way to manage things. I’m looking forward to when ADC (hopefully) brings back some smart monitoring with environmental sensors.
Well if I do recall, peripheral wireless temperature sensors for additional rooms are being developed. Whole home smart energy management using security sensors for data is being retooled to my knowledge.
I would also like to see future integration of Energy Management and Heating/Cooling in some capacity. I wouldn’t mind my thermostat to override the target temp based on energy usage in addition to weather forecast.
Yes, the more environmental, motion, geopresence and other activities can be leveraged, the better the energy management will work. If you’re working with a set energy budget then managing based on actual overall $$ usage is a biggie too.
Another thought…couldn’t Green Button work in this instance too provided your utility is supported?
Mine isn’t and they have their own competing program called mPower that allows them to remotely control thermostats in case of high demand. They’ll also track energy usage on a $$ basis and provide warnings if you’re exceeding a budget. I’m not about to give them control of anything inside my four walls though 
Green button data obviously provides very accurate information since it’s the power company’s actual measurement of your energy usage. It’s just overall home usage though, not specific to your HVAC system. It’s also not immediate.
You can measure your whole home energy usage in real time with a Z-Wave Home Energy Meter and Alarm.com gives pretty good reports based on that. You can also measure energy usage at finer granularity with individual energy meters. Alarm.com Energy Management can track individual devices and lets you organize them in a hierarchy so none of them get double counted.