Hi all,
I’m looking to reduce my electric bill.
Details
Electricity Usage
On average, I use about 1900kWh a month, with summer months being almost 3000kWh. Here’s my usage graph:
Most of this appears to be HVAC usage. I understand an HVAC should be running only about 15 minutes an hour on average, but I’m looking at closer to 30-45 minutes with my HVAC running for about 12-14 hours total a day.
House Info
(Some info from original buying inspection)
My house has 2 above ground floors and 1 below ground floor, with a total sqft between them of 2500 sqft. It is a cape cod wood-framed structure with a Bedford stone and brick veneer. The exterior walls do not seem to have insulation based on spot checks but I haven’t checked every room.
The roof is a gable design covered with asphalt/fiberglass shingles in the first half of their useful life. The attic above the living space is insulated with fiberglass batted insulation, approximately six to eight-inches in depth. Additionally, the knee walls of the attic are missing insulation.
The current HVAC system is a Trane 4TTR4036L1000AA AC Unit and TUH1B080A9421CB Furnace. There is 1 vent in the basement, 2 vents upstairs, and the rest of the vents on the main floor. The 3 return vents are on the main floor as well. Notable is that the upstairs vents are metal ducting until they hit the basement in which there’s a 8-10ft section on each that is insulated flex duct.
Previous attempts
First thing I bought was a Nest Learning Thermostat and an additional temp sensor for upstairs so I could have usage statistics.
In 2022, I started Supercooling the house. This might have reduced the electric bill more if I was on a time of day rate, but I’m on a flat rate.
This year, I patched a vent sized hole in the ductwork that was dumping all the cool air downstairs that I didn’t previously know existed and have stopped Supercooling.
Advice needed
I want to do more to reduce my HVAC and electricity usage. Currently, I’m considering the following 3 things:
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Vinyl Siding - I don’t think the exterior bricks were helpful when I was trying to supercool the house previously. I’ve been told they radiate captured heat after the sun goes down which likely wasn’t making it as easy on the HVAC.
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Insulation - An obvious choice. Although, I’d have to tear off all the existing drywall (and trim? I’ve never done this before). This will be a lot of work as I’ll have to move a ton of furniture and likely have whatever room being down unusable during that time. On the plus side, I could some of the ungrounded outlets grounded and ethernet run while in there.
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Mini-split upstairs - Between upstairs missing some insulation, not having a return vent, and well… being upstairs where heat rises to, the upstairs usually has a 10F or higher temperature difference. I’ve heard that doing this has halved some people’s electricity bills but I’m skeptical
Any tips are appreciated. Thank you!
General order of operations
-When is the last time your AC was serviced? Are the filters or condenser coil blocked with dirt and dust and killing it’s performance? Is the condenser installed under a deck or somewhere stupid with no airflow?
-Fix air leaks. These are the biggest loss of energy. You can diy or have someone preform a home energy audit where they hookup a fan to see how much air loss there is. Then seal gaps, replace worn weatherstripping, etc and retest. There are incentive programs here in many states to help pay for these audits
-Is you attic properly vented? Look for soffit vents and ridge vents. You may only have gable vents in an older home which is not going to cut it. Your attic becomes an oven if it’s improperly vented. There is a certain ratio of ventilation to square footage of attic that needs to be met, 150:1 if I recall.
-Insulate attic: You didn’t specify your region but 8 inches of old fiberglass isn’t going to cut it in the majority of regions. That could be as little as R20. Adding additional insulation to the attic is cost effective and there are incentives programs to do so. Check what the recommended r value is for your zone. R49 will cover most of the US if I recall.
-insulate walls: You don’t need to tear down the drywall to insulate. They drill holes into each joist bay and blow loose fill insulation in. Then patch all the holes. Same as attic but slightly more work.
-windows: are your windows/storm windows using double pane glass? If they are, how old are they? have their seal been broken? Also look into curtain treatments for windows that get heavy sun.
The very last thing you should do is be looking at replacing HVAC gear. If you do it out of order then you’ll buy oversized equipment that will short cycle when you add insulation.
Also more generally, trees. Plant them. Let them get big and grow around your house for shade. Not exactly an overnight fix but mature trees can reduce massive thermal loads. Especially if they shade your AC from direct sunlight.
And one last note, please don’t add vinyl ontop of your brick veneer. That’s a great way to devalue your home. Yes technically you can put vinyl up with a layer of foam insulation board underneath but that’s really a last resort.
Less than 6 months ago. Wife is still paying $17/mo for their “service plan” they convinced her to sign up for
Only Energy Audit company in my city hasn’t returned my calls
There’s 4 vents but I believe they only have access to 1/2 the attic at best
A quick google search gave me R-38 to R-60
Looking like insulating the walls and attic is the plan atm unless I can find someone from out of town to do the energy audit.