David Brancaccio

Not just as something that consumes energy, Jen, but something designed to produce it.

It's called net zero.

Less a technical target than a way of designing homes to meet their own energy needs.

Building for tomorrow doesn't always require new construction.

Sometimes it means rethinking what already exists.

In Cambridge, Massachusetts, Zainab Maghavi has spent nearly two decades retrofitting her 100-year-old house, turning it into a net-zero experiment and extending its life well into the next century.

When Mugabe bought this house in 2007, it was constructed for another era.

This kind of retrofit isn't about tearing everything out at once.

It's about sequencing, making the changes that are hardest to undo first and leaving room for what comes later.

As we walk through the house, it's not just the big systems that stand out, but how much thought went into the parts that you don't actually see but feel every day.

As we step outside the home's envelope, the shell that separates living space from everything else, we come face to face with the mechanical systems that quietly keep this house running.

Geothermal is the final step in Mugabe's 18-year experiment in future-proofing an old house.

Crews drill deep into the ground to reach the Earth's constant temperature, then pipe that steady heat to the basement, where a heat pump replaces the gas boiler, heating and cooling the home while the pipes and radiators inside remain the same.

It's worth noting that Mugabe also leads a nonprofit advocating for geothermal heating and cooling.

But more than a demonstration home, this house is about thinking in generations.

Zainab Maghavi shows what's possible when we rethink the buildings we already have, how much longer they can last and how much less energy they can use.

Yeah, what's striking, Jen, is that none of those questions stand on their own.

They're all connected.

I keep coming back to this burnt, empty property here and thinking about the house that used to be

Not as something to dwell on about, but really as a reminder that a house shapes the way we live, often in ways that we don't even realize.