Presentation on Going All-Electric
Hi Folks,
After taking much advice from GBA, the website and its community of experts, I managed to reduce carbon emissions by 56% in my 1934 Boston-area cape.
My town of Arlington, MA is running an “Electrify” program where they are encouraging more folks to move off fossil fuels to cleaner energy.
I’ve been asked to present my experience at an Adult Education class next week. Here’s my presentation, still in progress: https://docs.google.com/document/d/1VDBdenGBZ-Y4bT8ip3t7Do8_gdhIj2Mc/edit?usp=sharing&ouid=105136535012413632640&rtpof=true&sd=true
It would be awesome if anyone here has the bandwidth to provide any feedback on the presentation. Thank you in advance!
Best wishes, Kris (Arlington Town Meeting Member, Pct 11)
Note: Arlington Town Meeting has also passed a bylaw which will eliminate new gas hookups in new construction, if passed by the State’s AG!
GBA Detail Library
A collection of one thousand construction details organized by climate and house part
Replies
I don't have much to critique on you presentation. I think it is well done and I especially appreciate your effort to keep it real. There's always a temptation to gloss over the practical limitations of what you're trying to do on a preexisting house. It's a balancing act and you explained that well.
There's only one nitpick. A geothermal heat pump isn't actually less efficient than a ASHP. But there are numerous reasons to not install a geothermal related to upfront costs, and maintainability. I don't think anyone should install a geothermal on an existing home. It just isn't practical. I would leave the concept of geothermal completely out of your presentation.
thanks for your input! I've received more info and have edited the statement about geothermal. Here's the edited sentence:
"ASHPs are slightly less efficient, but cost far less to install than geothermal, so I went with ASHPs."
Thanks for doing this, advocacy like this is really important.
I would say that the geothermal efficiency question is even more nuanced. Geothermal has higher theoretical efficiency. But air-source heat pumps are mass-market products, while geothermal is still a niche market. So innovation tends to move through the market more quickly with the air-source units, and their actual performance can be higher.
I looked at geothermal, until it was pointed out to me -- by a salesman for air-source heat pumps -- that some air-source heat pumps have SEER ratings that exceed the Energy Star standard for geothermal.
I am curious what were your blower door test numbers before and after air sealing? ACH50
What R value of insulation were you able to retrofit into your walls and attic?
Did you get heat pumps with vapor injection IE Hyper Heat?
How did you do the math to decide at what point to turn on the gas furnace?
Given the monthly fees for a gas meter does the math say it is less expensive to keep the gas than add resistance back up heat for the few coldest days?
Walta
Good morning Walta,
Before air sealing work 4108 CFM50. After air sealing work: 2900 CFM50.
Before: 11.69 ACH50. After: 8.25 ACH50.
I'm not sure the R value of the insulation in the attic or walls, but here is the work that was done:
ATTIC
c. Install additional inches of cellulose to get to 16"
d. Install cellulose on 3 rear dormer ceilings from attic
e. Install Plywood dam and 2" polyisocyanurate insulation at stairs
f. Weatherstrip plywood dam
WALLS (note that i still have the original steam radiators that are built into the walls of the house. they will be removed in the future and the wall pockets will then be insulated):
c. Dense-pack cellulose in exterior walls from exterior
d. Foam plugs and tape
e. Shingles to be carefully cut and reused for patching
f. There is a possibility some shingle will be needed to be replaced
g. Install cellulose to 3 rear dormer walls from interior and patch
Yes, I got Hyper Heat ASHPs:
Mitsubishi Single Zone MUZ-FH06NA System (upstairs bedroom)
Mitsubishi Single Zone MUZ-FH06NA System (upstairs bedroom)
Mitsubishi MFZ-KJ09NA Low Floor Unit System (kitchen)
Regarding the math on deciding when to turn on the gas furnace:
I have been told that it is less expensive (in USD) to run the gas steam heat system when the temperature drops to 20 degrees. However, it's also important to understand that I am only midway done with my decarbonization project. To get to 100% electric heat year-round, I need to install another heat pump, possibly ducted, to my first floor for the living room, the dining room, and the study.
I have installed a wood fireplace insert/stove. But just this week, I looked at the carbon emissions associated with burning a cord of wood. It looks like burning wood is a bad substitution for nat gas!
Regarding the monthly cost of the gas meter and resistance back up heat: I'm not worried about having backup heat for my ASHPs. I'll hold off on cursing the gas company for their stupid monthly meter fees for now. There's still a lot more work to do to wean the house off fossil fuel! and I'll get there... thanks so much for your advice over the months and years here.
“Regarding the math on deciding when to turn on the gas furnace:
I have been told that it is less expensive (in USD) to run the gas steam heat system when the temperature drops to 20 degrees. However, it's also important to understand that I am only midway done with my decarbonization project. To get to 100% electric heat year-round, I need to install another heat pump, possibly ducted, to my first floor for the living room, the dining room, and the study.”
The 20° may have been accurate at one time in the 1980s when it became conventional wisdom it is certainly not true given your high quality equipment. Take the time to do the math with your local fuel costs and the COP of your equipment at a few different temps. My guess is hyper heat equipment cost less to run at -10.
“Before air sealing work 11.69 ACH50. After 8.25 ACH50.”
30% is impressive but 8ACH is still abysmal. Seems like 2.5 ACH50 would be an achievable goal and would make a huge difference. Put a fan in a window use some incense sticks to find the leaks and plug them.
Walta
You mention in the presentation:
"I was over-optimistically expecting to offset my energy bills by 75%, which did not happen. But the recent rise in fossil fuel costs may cover financially my mistake in estimating energy conservation.
The scope of work was walked back because it was too expensive and too invasive to do everything at once. I didn’t want to have to move out of the house while the work was being done and I wanted to stay true to the goal of focusing on work that would pay for itself in energy savings."
I realize that you will not be reading this word for word but I would simply avoid talking about "mistakes" because it could have a negative impact on a very positive presentation. When radio disk jockeys or new readers make a mistake they are told to not apologize just correct themselves and move on. This is something I also learned in one of the public speaking trainings that I took a while back. Besides, you did not make a mistake.
You made a projection, you measured the final outcome and you had a variance. Explaining the variance is what will be important. People need to understand that they will plan their project and they need to be ready to adjust as the project unfolds. Adjusting as you go is something that people need to expect. I think you do a good job of explaining how you adjusted.
thanks for these thoughts! I've made some edits to be a little less negative. My goal is to inspire folks to conserve energy. I was also being a little hard on my solar installer, so i've edited that a bit. The actual energy production on my solar array is only 15% less than what was quoted in the contract. And, a year ago, the solar installer reached out and offered to pay the difference, as their production projections were guaranteed.
I wouldn't take out the "mistakes" completely, just focus more on what you did to fix things and overcome challenges. Basically focus more on the solutions themselves and not so much on the "mistakes" that led to the need for those solutions.
I would also talk about phasing the project. There is no need to do things all at once, and trying to do it all at once often makes the cost look insurmountable. You can, for example, do an air sealing project as one step (which often makes sense to do along with insulation upgrades), then appliance upgrads, lastly a solar installation. There are lots of ways to split up a large project. The most important part is to make each stage of the project a logical step so that you don't have to double back and do any "double work". An example is to upgrade the insulation at the same time you're replacing siding, so that you don't have to rip off the siding again to do the insulation in the future. The exact mix of what to do when depends on each particular project, but I like to give some ideas to people so that they know it's not an "all or nothing" proposal. For many people, air sealing and insulation upgrades will get them most of the comfort benefits, so that's a big first step. Solar is another thing that is easy to make it's own seperate piece of the project too.
Bill
Two things I noticed: 1. Heat pumps aren’t in their infancy, they’re a top heating method in the US. They’re just not as widely used in the North yet. Cold climate heat pumps are newer for sure. 2. As much as financial calculations appeal to me, I’d be tempted to leave them out of the presentation. Of the financial metrics, payback is the least helpful and despite being simple, relies on many assumptions. Even if it was perfect, does your audience care? It seems like most homeowners spend money on home improvement projects because they want to, not because of financial calculations.
thanks for this, Paul. I am one of three speakers presenting at this event. The other two residents will be talking about net zero gut-renovations. Most folks won't be able to afford that approach and I'm not sure the carbon cost of a gut renovation. So the two main points that i want to get across in my presentation are:
1. Conserving energy through air sealing and insulating, adding solar generation to the roof, and moving to highly efficient electric ASHPs, can be cheaper than doing nothing - even in the most challenging older homes.
2. The state of Massachusetts and the town of Arlington have set some aggressive goals to reduce carbon emissions. We are not on track to meeting those goals. IMO, it won't be possible to meet those goals unless there are (more) subsidies aimed at residential energy conservation, electrification, and making renewable energy more affordable.
I'll add a slide to the end of the presentation that makes this very clear. Thank you!!
Very good presentation. An important item to add to the section on phasing the Deep Energy Retrofit is to start with an Energy Audit and a formal plan to get you as close as possible to your Net Zero on site energy or other goals. The work can be spread out over multiple years, but the plan needs to be done at the start, so you don't do things that make the end goal more difficult or have to redo work at a later stage.
Hi Kris: Gary Reysa of BuildItSolar.com has compiled a very good summary entitled "The Half Program" which comprises a list of separate projects having the lowest cost and/or best cost benefit ratio at his cold climate house in Montana. Gary estimates The Half Project saves 50% of the energy at his residence location. The Transportation projects provided a 62% return on investment, while the home energy conservation projects provided a 47% ROI. (These are after tax returns, because home energy is purchased using after tax dollars in typical cases).
https://builditsolar.com/References/Half/Projects.htm
https://builditsolar.com/References/Half/ProjectsConservation.htm
https://builditsolar.com/References/Half/ProjectCharts.htm
Perhaps some of Gary Reysa's projects (he provides detailed implementation instructions and photos) might be relevant to your thinking as well?
Jan Juran
We have to be careful with ROIs. LEDs, heat pumps replacing AC, and solar are usually awesome financial investments but many improvement projects are awful if you just look at $ savings (and you have to stay in the house, there’s no widespread resale value for these improvements yet) . Preferably these improvements can justify themselves other ways, financially will likely not be enough unless energy rates are very high AND interest rates are rock bottom.
The notion that heat pumps are new was addressed in one of the replies. I was surprised to learn how old the technology really is and felt compelled to share.
Milestones:
1748: William Cullen demonstrates artificial refrigeration.
1834: Jacob Perkins builds a practical refrigerator with diethyl ether.
1852: Lord Kelvin describes the theory underlying heat pump.
1855–1857: Peter von Rittinger develops and builds the first heat pump.****
1945: John Summer builds a full scale water source heat pump in Norwich
1983: Lämpöässä build their first heat pump in Lapua, Finland
***The first heat pump as we know it today was built by Peter von Rittinger in 1856.
Source: https://finn-geotherm.co.uk/the-history-of-heat-pumps/
Not something to present but there is almost certainly going to be a question about the reliability of this « new » technology. Having this up your sleeve could prove helpful.