I have a kill-a-watt, although I don't know a great way to get a remote comparison.

The kill-a-watt does do accumulation (as you likely know), although it is not stored in non-volatile memory. I used it to figure out how much my garage heater ran (and subsequent natural gas bill increase) by measuring the idle power usage, and then the heat-on power usage. The kill-a-watt would give me a total kwh used, and a total time. I knew that completely idle, the heater (really, the 24v control transformer) used around 5w. When the heat was on, it used about 500w (combustion fan, blower fan, gas galve).

This is pretty much middle school math probably, but I haven't had to solve equation pairs like this in a loooong time.

A = time heater idle at 5w

B = time heater heating at 500w

T = total cumulative time = 60h

W = total cumulative Wh = 4000Wh

A+B=T

(A*5)+ (B*500) = W

A+B=60

5A+500B=4000

A=60-B

5(60-

+ 500B = 4000

300-5B + 500B = 4000

-5B+500B= 3700

495B=3700

B= 7.47

So the heater ran for 7.47 cumulative hours out of the 60 hours monitored. At 45kbtu input, and an average price of 75 cents a therm, that is about 45,000 (btu/hr heater) * 7.47 (hours) / 100,000 (btu/therm) * 0.75 = $2.50 in natural gas for those 60 hours. Extrapolate that usage to a full month an you are at $2.50/60 * 744 = $31/month.

Who ever thought you could estimate gas usage by using an electricity monitor! (tying back to main subject haha)