Check this out. 
Power Meter Logging SmartApps (PlotWatt, ThingSpeak, SmartEnergyGroups)
@brianlees, the long term logging is definitely beneficial in many ways.
I love seeing data like this in an easy to use and understand format. It makes it easier for me to monitor various home functions.
Unfortunately, I don’t have a means of integrating the Nest Protects in a useful manner, every time I try, it causes my ST app to crash once I add the first Nest Protect. I don’t use the Nest thermostats, as we only have boiler baseboard heat and no AC in the home. So, like you, I get all of my Nest data direct from the Nest app.
The HEM unit does definitely have a use within the ST universe, just not as active a use as I’d eventually like to see.
With some plug in energy monitoring appliance modules you can trigger an alert when power usage rises on that module, or when it drops in the event of say, the washing machine finishing it’s cycle.
I haven’t found a good use case for the HEM units to provide that level of alerting, as it is monitoring the entire home instead of an individual appliance or circuit.
Down the road, I’d like to add one of the multi-circuit Z-Wave monitors that checks each individual circuit and calculates usage on a per circuit level.