If one’s kitchen hints at what one values in life, it’s pretty clear what Keya Chatterjee’s priorities are. The refrigerator she picked out is not the kind that would appear in most catalogs—her deep, extremely energy-efficient fridge is optimized for use on a boat, and is often used by doctors to store vaccines. Some time ago, she deemed her oven overly wasteful and it has since been unplugged. It is now just another part of the counter, on which a plug-in burner sits.

The logistical reason Chatterjee’s kitchen uses so little electricity stands in her compact backyard in Southwest Washington, D.C. It’s a set of solar panels—the source of nearly all the power for the house that Chatterjee, the executive director of the U.S. Climate Action Network, a nonprofit, shares with her husband and her son. The panels generate less electricity than most American households use in a day, but Chatterjee and her family have adjusted their energy use so that it is often plenty for their extremely pared-down needs. On the occasions that it isn’t, they buy modest amounts of electricity from the grid.

The rest of their home is arranged according to this efficient logic. On top of one of the house’s toilets, there is a small, custom-built sink that runs, after each flush, with the clean water that is about to refill the toilet. The fans throughout her house are “tenfold” more efficient than the next most efficient model, she says—a characterization I have no trouble taking her word on, given that instead of selecting them based on their Energy Star rating, she went directly to the EPA’s website and pored over the spreadsheets that detailed the performance of each model.