Electric-Ready Codes Raise a New HVAC Sizing Question

Some states and cities are now requiring new homes built with gas furnaces or water heaters to also include a properly sized electrical circuit for a future electric heat-pump replacement. Colorado, California, Rhode Island, Massachusetts, and New York have adopted versions of these "electric-ready" rules, which aim to make it easier for homeowners to switch to electric heating or hot water later, without a costly rewiring job, when the gas equipment eventually needs replacing.

The catch is a technical one: figuring out how big that circuit should be. Sizing an electrical circuit for equipment that hasn't been chosen yet, or doesn't exist on the market yet, is tricky, and code officials are still working out the right approach. Colorado's new energy code, for example, requires the backup circuit to be sized to handle a heat pump with capacity comparable to the home's heating needs, but the details of how to calculate that are still being sorted out.

This mostly matters to homeowners in states adopting these rules, and more broadly for anyone building new or doing a major renovation. It doesn't change what's required for existing homes that aren't undergoing new construction. But it signals a broader trend: building codes are starting to plan ahead for electrification, so that switching a furnace or water heater to an electric heat pump down the road is simpler and cheaper. If you're in one of these states and building new, it's worth asking whether your project falls under these requirements.