A Net Zero home is a home that produces as much energy as it uses for heating/cooling, hot water, lights, and major appliances.

A Net Zero ready home is a house that is built to be NetZero but has no on-site renewable power generation installed yet.

Example:

It will have conduit piping running from the roof to the utility room for PV solar panels, when the build is completed on the home. The panels will be purchased later by the homeowner. This way no additional holes need to be made in the roof, and the air barrier can remain sealed.