Karina Hershberg’s transition from focusing on energy to focusing on carbon began six years ago. An electrical engineer at PAE Consulting, Hershberg was working on a project with deep sustainability goals. Net-zero energy (NZE) was a given. The team was considering taking the project entirely off grid and was thinking about a 300-year time horizon.
That timeframe got them looking at replacement cycles for photovoltaics (PV) and batteries, and questioning the wisdom of organizing around net-zero energy as the primary goal. They switched to focusing on emissions instead, and they haven’t looked back. “Where my research has landed shows that we need to focus on carbon emissions,” Hershberg says. “Energy can sometimes be a proxy for it, but sometimes it isn’t.
“The blunt instrument of [NZE] is kind of an outdated concept,” says Commissioner Andrew McAllister of the California Energy Commission. If the “real goal is carbon-free energy and decarbonization,” he says, net energy use over the course of a year may not be that helpful as a metric.
What’s driving this re-think? The U.S. is now adding renewable energy generation faster than any other source, which is putting us on a path to rapidly decarbonize the electric grid. In some parts of the U.S., the grid is already relatively clean. And Biden’s Clean Electricity Standard proposed through his Infrastructure Plan would set us on a path toward 80% clean energy on the grid by 2030.
This increase in renewable energy sources both hastens the need for NZE buildings to become partners in that transition and exacerbates the ways that traditional NZE buildings will fall short on reducing carbon emissions. NZE projects are a big step in the right direction, but we must start designing and operating them differently to accelerate the transition away from carbon emissions in the building sector.
Below we list eight ways that NZE projects miss the mark on climate goals, including how they affect the electricity grid, transportation, embodied carbon, and resilience, and how we can course-correct to achieve our goals.