Green / Eco-Friendly

Mysterious electrical energy savings

  • Last Updated:
  • Jan 6th, 2020 8:38 pm
[OP]
Deal Addict
Jul 7, 2017
4588 posts
1998 upvotes
SW corner of the cou…
This past September yielded an (again mysterious) electrical usage reduction of ~20% over the previous September (vs 10% for August to August which would be expected). Had the same number of house guest days. A/C was not used this past year, and unlikely to have been used the same month in the previous year.

Unless the smart meter is wrong.
Cream rises to the top. So does scum.
Deal Addict
User avatar
Oct 9, 2010
2724 posts
902 upvotes
Windsor
thriftshopper wrote: This past September yielded an (again mysterious) electrical usage reduction of ~20% over the previous September (vs 10% for August to August which would be expected). Had the same number of house guest days. A/C was not used this past year, and unlikely to have been used the same month in the previous year.

Unless the smart meter is wrong.
I believe this September was considerably cooler than last September, so maybe that's it? My electrical consumption for September is 20% lower YoY as well.
One who is offended by truth, has no place among those who seek wisdom.
[OP]
Deal Addict
Jul 7, 2017
4588 posts
1998 upvotes
SW corner of the cou…
Didn't run HP this past September and almost certainly not in September the year before for heating or cooling, other than perhaps 1/2 hr to make sure it was working. I did turn off the electric air filter over the summer (always do). Heat pump was fired up a couple of nights ago as the house is starting to get cold in the evenings.
Cream rises to the top. So does scum.
[OP]
Deal Addict
Jul 7, 2017
4588 posts
1998 upvotes
SW corner of the cou…
So ended up reducing electrical consumption to 11.68 MWh from 15.57 MWh the previous year. Will try to maintain this level as I think a further 10% reduction will be difficult to achieve (for only $25 more).

Consumption for the 1st 25 days of October (heating season started about the same time) averaged 26.91 KWh per day with an average heating degree day of 7.9. Same period last year (before attic insulation, new water heater and ECM motor) was 30.1 KWh for 7.7 degree days. The first year with the mal-configured heat pump (auxiliary electric heat strips were coming on as soon as the heat pump started a heat cycle) was 51.7 KWh and 7.4 heating degree days. Took 6-8 weeks before we realised and rectified this.

The real test (of the ECM motor) will be from the end of December as the attic was insulated, heating cycle/settings identical, and water tank replaced.
Cream rises to the top. So does scum.
Deal Addict
User avatar
May 8, 2007
1052 posts
305 upvotes
Fraser Valley, BC
OP your house is relatively big I am guessing. My house is about 2000sf 2 story in BC, upstairs bedrooms are all electric heat and main floor is gas forced air plus a smaller gas fireplace. Monthly consumption ranges between 200 kWh summer and 700 kWh winter and average for last year is about 400 kWh. This is a 25 year old basic builder spec (cheap) house. I keep it a lot cooler than most people would like in winter, to keep the energy costs down. My electric consumption is only about half of comparable nearby houses, which is surprising to me considering my electric heat upstairs and my energy leaking metal frame windows. 2x4 walls.
[OP]
Deal Addict
Jul 7, 2017
4588 posts
1998 upvotes
SW corner of the cou…
Yes, this house is very big, and is pretty much heated (and cooled) by electricity only. We used to heat to 21C in the evenings but have reduced this to 20C for now. Temperature setting is kept relatively even as heat pumps don't like big changes so we only have a 1C difference (19-20) now, and used to have 4C (17-21). I am surprised you can keep your non-heating electricity consumption that low (we cook at home a lot, which may contribute). We only had ~4 days under 10-12 KWh this summer and that was when we had a housesitter who did not use the kitchen at all. Otherwise summer (no heating, barely any cooling, ran fan for ~30-40 hrs?) usage averaged 17.1 KWh/day. The fridge (only) and chest freezer probably doesn't help.

I don't know what BC Hydro uses for comparable/similar houses as it appears almost every house in the neighbourhood has wood heat and it is used. During the summer, we used about 9 KWh less per day than the stated similars (~26 KWh). For the current heating season so far, we're at 26.7 vs 40+. It looks like these neighbours really like to burn power!
Cream rises to the top. So does scum.
[OP]
Deal Addict
Jul 7, 2017
4588 posts
1998 upvotes
SW corner of the cou…
Just over a year since I increased attic insulation from R-10/20 (depending on the spot) to ~R-55. I did a rolling 30 day average of electrical consumption and it was about 2 KWh a day lower for almost a heating degree-day cooler (about 4% less on heating based on summer consumption). That would include the benefit of the ECM blower motor instead of the PSC one. From now on, savings will be mostly from the ECM motor. The next upgrade will be replacing three patio doors (metal-clad wood frame) that leak and are not thermally broken with triple-glazed, coated uPVC-fiberglass doors with a triple gasket and 7 locking cams per door. Air leaks be gone, hopefully.

The Hydro consumption comparison missed the last day of the year but consumption is only down 8% over the year before for 2 months and nearly a week into the reduction challenge (we chose to maintain).
Last edited by thriftshopper on Jan 6th, 2020 2:57 pm, edited 1 time in total.
Cream rises to the top. So does scum.
Deal Guru
Feb 9, 2006
11557 posts
6082 upvotes
Brampton
thriftshopper wrote: Just over a year since I increased attic insulation from R-10/20 (depending on the spot) to R-20. I did a rolling 30 day average of electrical consumption and it was about 2 KWh a day lower for almost a heating degree-day cooler (about 4% less on heating based on summer consumption). That would include the benefit of the ECM blower motor instead of the PSC one. From now on, savings will be mostly from the ECM motor. The next upgrade will be replacing three patio doors (metal-clad wood frame) that leak and are not thermally broken with triple-glazed, coated uPVC-fiberglass doors with a triple gasket and 7 locking cams per door. Air leaks be gone, hopefully.

The Hydro consumption comparison missed the last day of the year but consumption is only down 8% over the year before for 2 months and nearly a week into the reduction challenge (we chose to maintain).
Is that right?
[OP]
Deal Addict
Jul 7, 2017
4588 posts
1998 upvotes
SW corner of the cou…
tebore wrote: Is that right?
Thanks, corrected.

Since near year end to now (sample of just 8 days), average daily consumption is 49.15 KWh with an average HDD of 10.6. Same pariod previous year was 46.64 KWh and 12.1 HDD so it would seem from this very small sample that consumption is up (major difference is the ECM blower motor). Will have to see what the numbers look like with more data.
Cream rises to the top. So does scum.
Deal Guru
Feb 9, 2006
11557 posts
6082 upvotes
Brampton
thriftshopper wrote: Thanks, corrected.

Since near year end to now (sample of just 8 days), average daily consumption is 49.15 KWh with an average HDD of 10.6. Same pariod previous year was 46.64 KWh and 12.1 HDD so it would seem from this very small sample that consumption is up (major difference is the ECM blower motor). Will have to see what the numbers look like with more data.
I'm following you to see what the ECM difference is.

I took immediate readings when I did mine but I never trended my PSC power usage so I didn't find the value in treading it after I got the ECM.

At a high level it's about what I'm seeing it. It's a considerable amount of savings.
It's even bigger during summer heat waves where the AC almost never cycles off.

Are you running your ECM on continuous on low?
[OP]
Deal Addict
Jul 7, 2017
4588 posts
1998 upvotes
SW corner of the cou…
tebore wrote: I'm following you to see what the ECM difference is.
I am curious myself but too many changes. The attic insulation was probably the big one.
At a high level it's about what I'm seeing it. It's a considerable amount of savings.
It's even bigger during summer heat waves where the AC almost never cycles off.
Fortunately cool here in summer so the A/C is ever hardly on (just to make sure the HP and reversing valve are working).
Are you running your ECM on continuous on low?
Not normally. My goal is to connect the low speed tap into the normal fan tap (only one speed) with a relay that will set the speed to another speed (low-med) but I haven't been able to find a 24VAC switch wire near the air handler.
Cream rises to the top. So does scum.

Top