I figured it was time to do an update on how these energy efficiency updates have been reflecting in my energy use and in turn my monthly bills. I’m going to share my numbers as I like statistics and I’m sure there’s other out there like me wondering if it’s worth it. First as a recap things I’ve done to increase the efficiency in the house and track my energy use:
- Installed a Nest thermostat
- Had a free home energy audit performed on the home (BGE)
- Movement to nearly all CFL light bulbs in the house
- Sealing of all vent edging with aluminium tape
- Sealing off of extraneous vents with magnetic covers
- Had a full home performance check (through Retrofit Baltimore)
- Increase my attic insulation
- Addition of gaskets behind outlet covers for exterior walls
While I was slow to implement these (thus I won’t see drastic energy use changes) I would expect to see slow decreases of energy (both gas and electric) over time. The Nest thermostat is pretty cool in that it notices when you are home and when you aren’t so it can move to your “away” settings and use less energy. For each day that you meet it’s efficient use criteria it gives you a leaf. These leaves are tracked and compared with other Nesters in your zipcode and emailed to you monthly to tell you how you stack up with the neighborhood. I’m pretty proud of my leafs: 31 leafs for December and 340 for 2015. I’m fairly certain those missing 25 leafs were from the summer when it was hot out and I just wanted to have air conditioning. But note you have no idea how many those are or what their leaf numbers are. I’d love to get ahold of the mean and median and total Nester numbers…
Top 15% for December!
BGE also enjoys making me feel good by emailing monthly a report from my smart meter to show how I’m doing compared with people 80 nearby homes. Note that this would be a different demographic from the Nest data. My December report is below, again in the top tier of minimal energy use, and 13% less than my efficient neighbors. Whatever “efficient” means. I’m also unclear as to if the vacant homes are included in this data and where they would fall if they were.
While this does make me feel good (just like badges for my Fitbit), I do want to know if there was a real energy use change. Which gets me into the nitty gritty. My new attic insulation was added in late October, and that was one of my largest changes, so I’ll compare October, November, and December of 2014 with 2015. I downloaded my data from the BGE website (look for the cool green button at the bottom of your My Energy Use tab) to look at this.
Electricity: Since my furnace is gas and my ac wasn’t running during these months my use should be about equal between 2014 and 2015. The only things that should affect this would be exchanged light bulbs and changes in my energy use patterns. My average electricity use those months were 317.3 kWh for 2014 compared with 251.7 kWh for 2015. That’s an average saving of 65.5 kWh per month. Which is kind of cool. I don’t think all this can be chalked up to light bulbs alone, but general awareness of my usage most likely also played a large role.
My months compared according to BGE
Gas: This year saw the install of the insulation and the dishwasher, shoring up the vents, addition of door sweeps, adding a few outlet gaskets and a generally warmer winter to lower this bill. It also has an increase in the average water heater temperature and a generally warmer winter which could counteract these changes. The savings were slow accumulations so I honestly don’t know that I will save anything yet based on this.
Looking at my BGE bills proves to be unhelpful for this comparison as my smart meter was not so smart and stopped sending them data, causing them to estimate my use based on my neighbors from September 2014 until March 2015. Bummer I’ll have to wait a few more months to do a nice comparison that way.
Faulty math at work, don’t believe what you see, 90 days vs 34
I do have my Nest data to fall back on for the furnace use at least. Nest estimates each month what to expect: more due to temperature, less due to being away more, more due to you overriding the schedule, etc. If you look at both years I tend to beat the estimated amount of change from month to month (if it estimates I should have 15 hrs more of use, I have 13 hrs more use that month). But I’m not sure I can say more until I can look at the full BGE data in March.
All in all it’s interesting from both the smart meter and the Nest I am more cognizant of how much energy I use, and have a benchmark to tell me when I’m doing “good”. Which helps on the bills front and gives me an idea of where I’ll be for the next month.