BURLINGAME, Calif. — You might think that a home using zero net energy would be chilly inside. I visited one last night, and it wasn’t. It was a pleasant 72 degrees.

The Palo Alto, Calif., home owned by Marc Porat, an IT-turned-clean-tech entrepreneur, is a showcase of the latest technologies that can be used to ratchet down the amount of energy that homes consume. Porat, who has founded three companies that are developing better, greener building materials–including window and drywall maker Serious Materials–wanted to walk the talk with his own home, a historic 1936 home designed by architect Pedro de Lemos.

A net zero energy house produces as much energy as it consumes over the course of a year. Porat turned to San Francisco home energy retrofitter Sustainable Spaces (which will rename itself Recurve next week) to do the job, which took about two years. Sustainable Spaces’ Adam Winter says that by putting in dense-pack cellulose wall insulation (made from ground up newspapers), changing the heating and air conditioning system to an air-to-water heat pump, improving the ventilation and lighting systems and adding windows that insulate better, his team was able to reduce the amount of energy the home uses by 62%.