Mysterious electrical energy savings
In beginning of the first year, I had already replaced most of the regularly-used lights with LEDS and CFLs (previous owners loved and used lots of incandescent lights - there were over 80 track light fixtures and two chandeliers that used 9 x 60W bulbs). I also reshimmed doors so they were sitting squarely in frame as you could see light through many of them (had to do that again later in the year as the cardboard I used compressed so I replaced these with plastic shims). Probably the biggest saver - done late in the calendar year, relatively early in the heating season and challenge year - was to replace the non and then a simple programmable thermostat with an advanced OEM one which allows auxiliary heating lockout (we only allow that when outside air temp drops below freezing). The two previous thermostats allowed the heat pump auxiliary heating to engage as soon as (or soon after) the heat pump came on. In the middle of the heating season, we got a chest freezer (house came with a refrigerator only which we still have). One other change was to deactivate and/or replace motion-sensor lights. Previous owners had too many hardwired (couldn't switch them off except at the circuit breaker panel). When some of these were staying on, I deactivated them by unscrewing the bulbs. These were replaced with new ones which were switched (found the unused wire for a swicth I couldn't figure out what it was for) so you could turn them off.
In the second year (~ 1 month into the savings challenge year), we had a somewhat-unexpected need to replace the electric hot water tank and went from a 60 IG (we think) tank to a 42 IG one. I did take out the HW recirculation pump (and will reinstall it sometime) but we never used it. The new HWT has 3" of foam insulation and is supposed to cool only 5F over 24 hrs. 2nd month into the challenge year, we topped the attic insulation to ~R-55 and tightened down the attic hatch (will double insulate it). There appears to be some result (did a regression of power consumption and average outside air temp before and after) though it didn't help so much with an unseasonably-cold February where power use was higher than the year before. Doors were squared better so they leaked less. I also had insulated the 3 light tunnels better to prevent warm air from getting into the tunnel. Still doesn't explain the reduced non-heating season/summer usage. AC was used perhaps 10-20 hours the previous year due to heat and excessive smoke from forest fires. I did tape up the ducting to minimize heated air leak but I understand this is a wash.
No real change in heating usage (we're home most of the time) or light usage. Not using the electrical cooking elements or oven any less. No real change in laundry (haven't increased hang drying anymore and we only use the dryer ~once in every 8-12 loads or more and only for the dish towels and rags). A few more track lights were converted to LEDs but these are not used very much (bulk of them are the transformer ones so change to LED probably won't save much so we don't use them). One big change was finding the cause of water in the glass-enclosed sun room (there was a leak in the roof). We don't heat the space in winter like the previous owners did (would explain their reported $600 p.m. electrical bills in winter when power here is $0.12/KWh max). We still use the dehumifidier and fan in there (condensation on the glass when the temperature drops substantially overnight to 0C or colder), but this has been reduced over the previous year with the leak fixed. I did put foam insulation between the glass wall and roof but this is very marginal and space is unheated. On the entertainment front, a bigger pair of speakers and a second subwoofer (latter on standby and I don't always turn off the power bar at night) have entered the house. The main stereo system has got the preamplifier back but these are not used much (I imagine they - tube CD player, tube pre amp and pair of tube power amp monoblocks - are power hogs).
Going into the next heating season, all we have for usage reduction is an ECM motor in the air handler which may save a couple of 100Wh.