energy monitor

EHH week 33: energy monitor

This house is aiming to be a net zero energy dwelling.  In order to reach that ambitious goal, the homeowners will need to carefully manage their energy usage throughout the course of the year.


Reading the main utility meter only tells the total electricity consumed.  But if it is running high, they need to know where exactly the power is going.  Is it the hair dryer?  Are the garage door openers on standby?


There are several inexpensive ($100) energy monitors on the market, which in my view are worth little more than saving a trip outside to read the meter on the wall.  There are also a number of fancy and expensive ($10,000) energy monitoring systems with flat screen displays and all sorts of information intended for the lobbies of office buildings or high schools. 


So I was delighted to turn up a small local company called Converged Green that provides an affordable device that can monitor every single circuit in the house and lets us customize how we log and display it.  Best of all, it only draws 5 watts of power so it does not waste energy saving energy!


The electricity is measured using current transducers (CTs), which are little metal donuts that encircle the hot wire of each circuit in the electrical panel.  Each piece of equipment (range hood, water heater, etc) has its own dedicated circuit anyway.  But we had to instruct the electrician to group lighting on lighting-only circuits so that we get pure readings for each category.