Complex sentence: Meanwhile, at the opposite end of the scale, Step 5 for homes represents a home that is net-zero energy ready--the most energy-efficient home that can be built today-a level of performance similar to the rigorous Passive house standard.
Split into simpler sentences: Meanwhile, at the opposite end of the scale, Step 5 for homes represents a home that is net-zero energy ready. A Step 5 home is effectively the most energy-efficient home that can be built today, roughly equivalent to the rigorous Passive house standard.