How the Lights Stay On
Chapter 13: The Order of Operations
The single most common question a homeowner asks when they start thinking about clean energy is: “Should I get solar?”
This is the wrong question.
Not because solar is bad. Solar is genuinely good. Millions of American homes have solar panels and have reduced their electric bills and their carbon footprint as a result. But solar is, almost always, the last major step a household should consider in clean-energy upgrades, not the first.
The reason this matters is that most homeowners only have the time, money, and attention to make a few big changes. If they spend their budget on the visible thing — the panels on the roof — they often run out of energy and money before they get to the less visible things that would have done more for them, and for the planet.
This chapter is about the right order of operations. It is about what an honest, thoughtful homeowner — or someone advising one — should think about first, second, third, and last.
It is also, indirectly, about a deeper lesson that comes up over and over in this book: the most important things are often invisible.
Here is the honest order, cheapest carbon reduction per dollar first.
Seal the leaks. Insulate.
Replace the furnace and air conditioner with a heat pump.
Replace the water heater with a heat pump water heater.
Replace the gas stove with induction (when it dies, not before).
Install solar.
Buy an electric car (if you were buying a car anyway).
Add a battery (last, and only sometimes).
Each step on this list does more for less money than the steps below it, and most of them do more than the steps below them by a lot.
The list is also almost the exact reverse of how most American households actually do it.
The reason for the reversal is not stupidity. It is a combination of three things.
First, visibility. Solar panels are visible. A new heat pump is invisible. So is insulation. If your goal is partly to signal your values to your neighbors — which is fine, by the way — solar wins automatically.
Second, marketing. There are tens of thousands of solar salespeople in America. There are maybe a few hundred dedicated air-sealing contractors. The industry that wants to sell you something is heavily tilted toward the things that are higher-margin and more visible.
Third, incentives. Federal and state programs have, historically, been heavier on solar tax credits than on insulation rebates. The Inflation Reduction Act of 2022 changed this somewhat, but solar still dominates the marketing.
The result is that a typical American clean-energy journey starts with a solar quote, includes some panels going up, and then the homeowner declares victory and goes back to having the same drafty walls and the same gas furnace they had before.
Let’s walk through the right order, step by step.
The single best clean-energy investment most Americans can make in their homes has nothing to do with electricity. It has to do with the fact that their houses leak air like a screen door.
A typical older American house — say, anything built before 2000 — has gaps around windows, doors, plumbing penetrations, attic hatches, electrical outlets, and the rim joist where the foundation meets the framing. Through these gaps, in winter, warm indoor air leaks out and cold outdoor air leaks in. In summer, the opposite. The heating and cooling system runs harder to compensate. Every year, a significant fraction of the energy you pay for is being used to heat or cool the outdoors.
The fix is not exciting. A contractor with a blower door — a fan that pressurizes the house — finds the leaks. They get caulked or foamed shut. Attic insulation gets added. Maybe basement walls get sealed and insulated. The work takes a few days. It costs, depending on the house, anywhere from $2,000 to $10,000.
The payback is real and large. A weatherized house can use 20 to 30 percent less energy for heating and cooling than the same house unweatherized. Over the lifetime of the house, this is more than enough to pay back the cost — usually within five to ten years on energy bills alone.
And here is the deeper point. Every step after this one becomes cheaper and more effective when the house is properly sealed and insulated.
A heat pump for a leaky house has to be bigger and more expensive than a heat pump for a tight house. Solar panels for a leaky house have to be more numerous, because the house is using more electricity. A battery for a leaky house has to be larger. Everything downstream is sized for the demand of the house, and the demand is set largely by how tight the house is.
This is why “seal and insulate first” is not just the cheapest step. It is the step that makes every other step less expensive.
It is also the step that is almost never on a homeowner’s mind, because it does not show up on the roof.
If you have heard about one piece of clean-energy technology in the last few years that you should care about, this is the one.
A heat pump is a single device that replaces both a furnace and an air conditioner. In summer, it works like an air conditioner — moving heat from inside the house to outside. In winter, it works the same way in reverse — moving heat from outside the house to inside. Yes, even when it is cold outside, there is heat in the air. Cold air has less heat than warm air, but it has more than zero. The heat pump extracts that heat and moves it indoors.
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