The first Pick and Shovel for Electrification: Digital Twins

Sucking boba through a cocktail straw...

With about four hours of work, a roll of duct tape, and a can of spray foam, Dave Barnes, an HVAC and home comfort expert (my description of his job), managed to reduce the leakage rate of our 1400 sf Markleeville cabin from 2065 ft.³ per minute at 50 Pa to 1555 CFM. So a 25% reduction with duct tape and spray foam. This translates to a 25% reduction in heating requirements. That’s not adding insulation or windows - just duct tape and spray foam.  He thinks that, with a little more work, we could easily get down to 1000 ft.³ per minute, which means a 36,000 BTU heating unit and a 24,000 BTU cooling unit. To put this into perspective, our current furnace generates 88,000 BTUs. That HUGE difference translates into purchase price savings and energy savings for me on my electrification journey.  Imagine being able to see that impact virtually.  

As Saul Griffith points out in his excellent book “Electrify”, the way to get to zero carbon is to electrify everything.  Especially our buildings, which generate 27% of our national emissions come from just operating (not including building them in the first place).  Zeroing these emissions requires electrifying 100 million single-family homes (SFH), 5.2 million multifamily residential buildings (everything from duplexes to large high rises) that contain 40 million housing units, 5.5 million commercial buildings, and 350,000 industrial buildings.  It’s a huge problem - and opportunity.  The next few months of this newsletter will be my learnings as I dive deep into the industry.

The first big problem (and opportunity):

Electrifying every home is 100 million unique problems to solve.  Every home’s journey will be some combination of insulation projects, plumbing projects (to replace gas hot water heaters), electrical projects (upgrading the panel to support additional loads), HVAC projects (likely replacing gas or oil furnaces with modern heat pumps) and possibly solar to power the new electrical load.  

As a homeowner, or even as a company trying to combine these various contractors into a single customer-facing journey (such as Helio, Sealed, QuitCarbon and Elephant Energy), it’s really hard to evaluate the pros and cons of each option AND the tradeoffs between them. Here are just a few of the concepts that I’d like to model:

• How do the heating requirements change if I seal the house?  For example, on our 1300 square-foot cabin in Markleeville, three hours of sealing the envelope resulted in a 40% reduction in the leakiness of the house - and thus the required heating and cooling load.  (see below for my own journey)

• What’s the impact on humidity and other aspects of comfort if I use mini-split ductless heat pump?  

• What would it cost if all the power was drawn from the grid?  What if power was drawn from the solar array, counting financing requirements for solar?

• Can I do everything I want to do (heat pump, hot tub, EV charger, stove) on a 100 amp panel? What is the smallest number of changes that I can make to accommodate what I want to do?  This is a really basic spreadsheet that is hard to find.

• What’s the sequence of changes that makes the most sense given the dependencies in the projects?

• Given the total changes that I want to make, what are the financing options available? How do state, federal and utility rebates apply? PACE? 

• What would the carbon credits be worth if I remove fossil-fueled machines from service?

The fact that it’s hard to answer these questions as a single homeowner might give a sense of how hard it will be to electrify 100 million homes.  

So how could we make it easier?  Create the digital twin.  Just as Google’s Waymo creates digital worlds to train their autonomous vehicles, I wonder if it’s possible to create a digital twin of every house in the country to be able to explore the possible paths to electrify your house.  Imagine having sliders to be able to see how changing the leakiness of your house changes the cost of heating.  

Yes, modeling airflow in entire buildings is not trivial. But what would be 80% of it?  Microsoft’s Bing has a footprint of 129 million buildings in the US.  We could probably take a guess at the likely floor plan of the house and its mechanical systems based on building standards when and where it was built.  This can be augmented by publicly available permit information to model renovations and other improvements.  It could also be augmented by just asking homeowners (like claiming your home on Zillow - who wants to be shortchanged?).  Finally, those who want to improve upon the guess either move a floor plan around or use a Matterport camera to create a CAD-quality interior layout.  

How to make money?

A few revenue streams seem possible for the digital twin:

• I’m certainly an early adopter, but, as a homeowner, I would pay to be able to model all of these proposed changes and understand the repercussions. 

• Cities that might pay to access the model to understand how to reduce emissions of their entire building stock.  

• Utilities that want to understand how to reduce emissions of their customers (gas usage goes down but electrical usage goes way up) if they made electrification or insulation easier.

• Third-party companies that might want to approach homeowners with a proposal. Right now, every aspect of electrification relies on the initiative of the homeowner. Imagine if we could create a proposal for every house in the country, just how Blocpower created proposals for every building owner in Ithaca.  

In a larger sense, this seems one of the many “picks and shovels” we are going to have to create to electrify everything. 

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Resources for this newsletter

Rewiring America - some of the best educational materials currently available.  Joel Rosenberg’s book is super informative.

Nate “The House Whisperer” Adam’s YouTube course on HVAC and his Home Comfort Book - this is the single best resource for HVAC.  

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Thank You’s

Thank you to Latham Turner, Elliot Gluck and Karena de Souza for helping think through all of these ideas. We’ve been meeting weekly to learn together and find opportunities in the industry.

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My Own Electrification Journey 

Dave’s visit was more than just spray foam. He also shed some light on the mystery of the concave filter. We’ve had three HVAC visits at $220 per visit to try to solve the furnace inexplicably shutting off. Dave’s theory is that it’s shutting off because the air return register (which sucks air from one part of the house so the furnace can blow out the vents on the other side) and filter are grossly undersized for the 1144 ft.³ of air the furnace needs when it’s running.  To use an analogy my daughter would understand, the furnace is trying to suck air through a cocktail straw when it should have a boba straw. No matter how hard it pulls, it can’t get enough air, so it ends up overheating and shutting off.  This might explain the fact that the filter is concave from all the air being sucked through - it just doesn’t have enough surface area. 

It also means that the HVAC company that installed it, as well as the HVAC company that has visited three times while charging me $700, is just negligent.  They just wanted to install and service a machine - and not look at the larger comfort, economic and climate issues. 

We have to make this easier…..