Volts podcast: Saul Griffith and Arch Rao on electrifying your house

In this episode, Saul Griffith (co-founder of Rewiring America) and Arch Rao (founder and CEO of Span, which makes smart electrical panels) discuss the need to electrify US homes, the challenges standing in the way, the kinds of solutions that will ease the process, and much more.

Full transcript of Volts podcast featuring Saul Griffith and Arch Rao, June 28, 2021

(PDF version)

David Roberts:

Those of you who have been reading or listening to Volts for a while know that I am fairly obsessed with clean electrification, which involves shifting all the things we do now with fossil fuels over to electric equivalents (while cleaning up electricity supply).

One important nexus of electrification is the residential sector. US homeowners are in a position to electrify their power supply (with solar panels), their heating and cooling (with heat pumps), and their transportation (with electric vehicles). How can we induce millions of them to make the decision to electrify, starting today? How can we make it cheaper and easier for them?

To discuss that and related issues, I was excited to connect with two of the smartest people working in this space. The first is analyst, inventor, tinkerer, and entrepreneur Saul Griffith, who will be familiar to longtime readers — I've cited his work numerous times, especially his most recent work with Rewiring America, which advocates for rapid electrification. There is probably no one on earth with a better understanding of the US energy system. (He’s got a book on electrification coming out in October.)

Griffith is a backer of and investor in a startup called Span, which makes smart electrical panels that offer homeowners fine-grained control over all their individual appliances, lights, and devices (via an app on their phones, of course). The founder and CEO of Span, my other guest, is Arch Rao. Rao was the project lead for Tesla's Powerwall home battery before leaving to start Span, so it goes without saying that he is intimately familiar with the technical and economic challenges of home electrification.

Welcome to Volts, Saul and Arch! Saul, I want to start with you. We're going to talk about home electrification today, and just by way of setting context — it's pretty easy to make the case that home electrification is fun, it's cool. But what is the case that it is necessary, and not only necessary, but necessary quickly? Set the bigger picture for us.

Saul Griffith:

There's a few components to that. Let's start with the climate component: the urgency.

There's a concept called committed emissions — that is the emissions that a machine that exists today will emit while it lives out its lifetime. So if you bought a petrol or gasoline car last year, it'll keep burning gasoline for another 20 years; if you bought a natural gas furnace last year, it'll keep burning natural gas for 25 years; a hot water heater, 15 years; an oven burning natural gas, another 12 years. So those are committed emissions, the same as a new coal plant opening last year would go on operating for another 50 years. We now know that if all of the machines that exist on the planet today live out their natural life, the committed emissions of those machines take us to about 1.8 degrees Celsius, over three degrees Fahrenheit of warming. So the practical reality is every time any of our machines fails or needs to be replaced, we need to upgrade it with a zero-carbon option. And the only real zero-carbon option that has emerged is electrification, and that's electrification of our heat with heat pumps, of our vehicles with electric vehicles, and then tying that all together and balancing the grid.

David Roberts:

Right. And what chunk of emissions comes from residential?

Saul Griffith:

Historically, we put emissions into sectors: residential, commercial, industrial, and transportation. The residential sector is responsible for 10 or 15 percent of total emissions, by that measure, but it's actually much higher than that because in reality, you make the decision about your car and your home. And when we electrify our cars, they're going to be charged at home. And then today, as it stands, a huge amount of our economy in the U.S. — close to 10% — is used to find, mine and refine fossil fuels, so that's the pipelines and the trains moving coal. And that's all filed under industrial emissions. So if you wrap up your pro rata share of that in your household, you wrap up the electrification of your vehicles, the decisions you make around your kitchen table are actually about 40 or 42 percent of our total emissions. In our small businesses and offices, what's traditionally known as the commercial sector, it's about another 20 percent.

As I like to say now, there's two types of emissions. There's a small number of big machines, and there's a large number of small machines. The small number of big machines is a few hundred coal plants and a few hundred LNG terminals and a few hundred oil tankers, but the real game in town is the 200 million vehicles, the 128 million households, the 70 million natural gas furnaces, etc. That's the large number of small machines, which is what we need to electrify when we electrify the household.

David Roberts:

And it’s individuals in charge of those decisions.

One objection I hear to home electrification is that, from an household point of view, the boring stuff like insulation and weather-sealing is a better value. What's your general response to that?

Saul Griffith:

I don't think that's true. It’s empirically wrong. Retrofits like the envelope and ceiling can be very, very expensive, because you have to remove walls, you have to stuff new insulation in those walls.

I just got a quote on doing that for my house, which is in a mild climate but is nevertheless freezing. It was about $28,000. That would give me a small efficiency win in this house, of maybe 20 percent less energy use, whereas buying the heat pumps to heat the house is about a $2,500 project. They will lower my energy for heating the house by two-thirds compared to how it's currently heated.

So the big efficiency win in this house is the heat pump.

Arch Rao:

Just to expand on that, we have to be looking at technologies that change the outlook for us, not just looking back, but looking ahead. Things like fundamentally changing how we heat our homes or how we think about cooking and heating our water supply are the big game changer here.

David Roberts:

Following up on that: Span makes these smart electrical panels. What's the pitch that intelligence is important, or a necessary component of this, versus just dumb-appliance replacement?

Arch Rao:

That's a very good question. Often people have to be walked through the second-order effects that a solution like the Span panel can have for your home and your carbon footprint.

A very useful analog, perhaps,