In 2007, Zainab Mugavi and her husband bought a fix-rupper in Cambridge, Massachusetts.

It was clearly a home that was loved, but it had a very ancient furnace that even had a little door to put your garbage in and burn it.

Our producer, Felix Poon, talked to her about it.

Did you use it?

No. No. No. Zainab had two kids, and she knew there was a link between natural gas and kids getting asthma.

I didn't want to burn anything inside the house.

So no combustion.

It creates particulate matters, and it's bad for your health.

So she looked into her best options to replace the old gas furnace.

And she wanted it to be really climate friendly.

What she landed on was geothermal.

It seemed really obvious.

Geothermal heating and cooling was basically blowing everything else out of the water.

When you hear geothermal, you might be thinking about places like Iceland.

They have the kind of industrial plants that tap into super hot water and steam underground that's

been heated up by hot rocks and magma. Those plants need to be in volcanic regions.

And they also need to have these massive boreholes that go a mile or two below the surface.

But there's another kind of geothermal that doesn't need volcanoes or very, very deep boreholes.

This type of geothermal relies on the fact that just about 10 to 20 feet underground, the temperature stays at a constant 50 to 60 degrees.

That is year-round and in most places around the world.

You tap into that, and you've got geothermal power heating and cooling for your home.

For Zainab, it was a no-brainer.

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