Preparing an Old Home for Electrification, Part 2 – GWC Mag

The electrification movement is accelerating, so let’s go back to this topic again and look at how to electrify an older house. In part 1 of this series, I listed some important questions to ask. Today, I’ll cover some steps that can make the transition to an all-electric home easier. I’m not going to get into incentives, but the Inflation Reduction Act (IRA) is putting a lot of money out there to help with changing out fossil fuel appliances with electric versions. And that’s not all. The IRA also can help you get the electrical system upgraded if necessary.

But first, let me put a little disclaimer out here. Making changes to your house can be dangerous. It can go wrong in many ways. Working with electricity requires a level of skill and attention that doesn’t suit every do-it-yourselfer. The suggestions I give below are meant to be general advice to get you thinking in the right direction. Don’t take on projects that you aren’t competent to complete. Call an electrician or other qualified professional when necessary.

Plan your conversion

Start with an inventory of your current fossil fuel-burning combustion equipment. Go through the house and determine what fuel is used for your:

• Heating system
• Fireplace
• Water heater
• Clothes dryer
• Range

Once you know where you’re using gas, oil, or propane, you’ll need to decide how far down the electrification path you want to go. All the way? Heating only? All but one appliance?

Once you have that, assess the age and condition of each appliance you want to replace. If they’re old and less efficient than newer models, you have a good incentive to make the switch. You need to replace them anyway, and going to a high-efficiency electric model can help pay for the conversion.

If you’re afraid to switch from a furnace to a heat pump, one thing you can do is go to a dual-fuel system. It heats with a heat pump down to a certain temperature and then switches over to the furnace. See my recent article on dual fuel heat pumps.

Finally, come up with a timeline. Do you want to do it all at once? Or make the conversion over an extended period, say five years? The more you have to do—and spend—to convert, the longer it may take you to get it all done.

Do you need a wiring upgrade?

The big obstacle that can turn what seems like a simple conversion into an expensive upgrade is the current state of your electrical system. Wiring in older homes is often a mess. If your home still uses knob-and-tube wiring (photo below), that’s a mandatory conversion. It’s a fire risk and you should take care of that right away. Get an electrician to evaluate the wiring and see if you need to make any general changes.

Do you need a panel upgrade?

Then there’s the electrical panel. If yours looks like the one in the lead photo above, it’s definitely due for an upgrade. If it looks like a standard breaker box, you may be OK. The next step is to find out what the maximum capacity of the panel is and how close you come to it. New homes these days generally come with a 200 amp (A) service, but older homes may have a maximum of only 100 A or less.

The good news is that a great many homes with smaller electrical services are still OK to go all-electric. Home Energy Analytics got electric utility data for more than 22 thousand customers in California and analyzed their peak power usage. The graph above tells the tale. A measly 2% had peak electrical current greater than 88 A, and 86% had peaks below 50 A.

Find your peak electrical current

That’s great news for those older homes because it means the majority can go all-electric without needing a panel upgrade. Of course, to proceed without a panel upgrade, you’ll need to have an idea of what your peak current level is. Then you’ll have to find out how much electrical load it will add to switch fuels.

For example, let’s say you have a 100 A service, and your measured peak current is 45 A. If the heating and cooling loads are small, you may be able to install an efficient heat pump that adds no more than 20 A. That brings you to 65 A total. That still leaves 35 A, which should be enough to switch to an electric water heater, too. If you want to charge an electric vehicle, though, you may well need an upgrade. Maybe. But see the last section of this article for another option.

One way to get at this is to install a whole-house electricity monitor. I use the Emporia Vue system and have explained the concept of whole-house electricity monitoring as well as written about my first full year of electricity monitoring data. The smartphone app that goes with the monitor allows you to look at the data in units of power or current.

The screen shot above shows the instantaneous current draw in my house on an early September morning when the outdoor temperature is 81 °F (27 °C). We have a 200 A service, and we were drawing only 17 A at the time. (You have to add the A and B currents for the total because the electricity comes in through two mains.)

Map your circuits

One problem you may run into even if you have peak capacity to spare is room in the electrical panel. When you switch from a furnace to heat pump or gas to electric water heater, you’ll need to add circuits. But what if every slot in the panel already has a breaker in it?

I went through the exercise of mapping out all the circuits in my house last year, and it helped solve that problem for me. All the slots in my panel were being used, leaving no room to add more. But when I mapped out every room and electrical load in the house, I found a few circuits that were no longer in use or no longer needed. Also, there were a couple of places where circuits could be combined.

Electrification tidbits

Once you go through the steps above, you’ll have a good idea about how to approach the electrification of your house. Be sure to check out other resources, too. See the Home Energy Analytics page on electrification, where the graph above came from. And a great resource to help you reduce your load is the Watt Diet Calculator from Redwood Energy.

Also, there are a lot of new products that can help. Circuit splitters, for example, let you share one circuit between two loads. Let’s say you already have an electric dryer and want to add a charger for an electric vehicle. A circuit splitter can allow you to add the EV charger without adding another circuit. You plug both into the splitter, and it allows only one to run at a time.

These are exciting times in the world of electrification. I took my house all-electric in 2019 and am loving it for a bunch of reasons—single fuel, combustion safety, indoor air quality, gas. That’s the before and after above, showing the gas meter removed.

Have you already electrified? If not, are you thinking about it?

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Allison A. Bailes III, PhD is a speaker, writer, building science consultant, and the founder of Energy Vanguard in Decatur, Georgia. He has a doctorate in physics and is the author of a bestselling book on building science. He also writes the Energy Vanguard Blog. For more updates, you can subscribe to the Energy Vanguard newsletter and follow him on LinkedIn. Images courtesy of author, except where noted.