Ranked in these QuestionsQuestion Ranking
Pro Can work completely offline
If using the DashBox, internet outages or router downtime will not necessarily mean gaps/holes in data.
Pro Monitors water, gas, temperature, and electricity usage simultaneously
There are four pulse counter inputs which can be used to measure gas, water, possibly other things.
1 temperature bus/ 8 temperature inputs for tracking heating patterns.
32 current transformers
Overall a comprehensive monitoring solution for utilities.
Pro Flexible and modular
It's nice that they let the user modify the package to suit their needs, particularly network method and whether to use a cloud service, keep it local, or a combination of both.
Even if no module is selected it still comes with a DB9 cable for RS232 access.
Pro Measures true power
Other options are inaccurate. This option is supposedly as dead on as the electric company metering is.
Con Slightly inaccurate
It measures apparent power (S).
Con Installation & setup is lengthy
It will take a long time to install all the monitors and setup the system to show you everything about your home's carbon footprint.
Con Not really "smart"
GEM can only report whole house energy measurements and measurements per circuit. It can't tell you anything "smart" about your appliances. This means more investigative effort involved to understand how much your appliances use. Especially if something is faulty or working inefficiently.
Once you add optional modules such as Wifi, Ethernet, Zigbee connectivity options; DashBox (data storage /local webapp server for presenting the data), and Current Transformers the cost approaches $700.