At public presentations and other talks, we're often asked: How much extra does it cost to build a Net-Zero house? The only correct answer is: it depends, because every construction project is unique and every builder works differently. BERG does not make guarantees about its home plans for this reason. That being said, here's an honest attempt to answer the question.
If the subject is total first cost, we think the premium for a Zero-Energy house is about 10-15% more than a standard home. You need a bit more insulation and better air sealing. You need better windows. You need a heat pump rather than a furnace, a heat exchanger, and an above-standard water heater. And you need PV panels. (Keep in mind that after this investment, the home will be worth more than a standard home. It's not like buying a new car, where your first costs are immediately translated into lost value.)
If the subject is monthly cost, we think there is no added premium for a Zero-Energy house if you consider mortgage + utility bills. Your mortgage will be higher, but your utility bills will be lower. It is likely you'll come out even, or marginally ahead. Our friend Gene Myers of New Town homes in Denver markets his "ZEN homes" on this basis: